What are the common causes of bacterial pneumonia. How can you recognize the symptoms of bacterial pneumonia. What are the most effective treatment options for bacterial pneumonia. Who is at higher risk for developing bacterial pneumonia. How can you prevent bacterial pneumonia.

Understanding Bacterial Pneumonia: An Overview

Bacterial pneumonia is a serious lung infection caused by various bacteria, with Streptococcus pneumoniae (pneumococcus) being the most common culprit. This condition occurs when bacteria invade the air sacs in your lungs, causing inflammation and fluid buildup. While these bacteria can exist harmlessly in a healthy person’s throat, they can become problematic if the immune system is compromised.

What makes bacterial pneumonia different from other types of pneumonia? Unlike viral or fungal pneumonia, bacterial pneumonia is specifically caused by bacterial pathogens and often responds well to antibiotic treatment. However, it can be more severe and progress more rapidly than other forms of pneumonia, making prompt diagnosis and treatment crucial.

Common Bacterial Culprits Behind Pneumonia

While Streptococcus pneumoniae is the most frequent cause of bacterial pneumonia, several other bacteria can also lead to this condition. These include:

• Haemophilus influenzae
• Staphylococcus aureus
• Mycoplasma pneumoniae
• Legionella pneumophila
• Chlamydophila pneumoniae

Each of these bacteria can cause pneumonia with varying degrees of severity and potentially different symptoms. For instance, Legionella pneumophila is known to cause Legionnaires’ disease, a severe form of pneumonia often associated with contaminated water sources.

The Role of Opportunistic Bacteria

In some cases, bacteria that are normally harmless can become opportunistic pathogens, causing pneumonia in individuals with weakened immune systems. These may include:

• Pseudomonas aeruginosa
• Klebsiella pneumoniae
• Moraxella catarrhalis

Understanding the specific bacterial cause of pneumonia is crucial for effective treatment, as different bacteria may respond to different antibiotics.

Recognizing the Symptoms of Bacterial Pneumonia

Bacterial pneumonia can manifest with a range of symptoms, which may develop rapidly or gradually over several days. What are the key signs to watch for?

• High fever (up to 105°F or 40.6°C)
• Productive cough with greenish, yellow, or bloody mucus
• Severe chills and shaking
• Shortness of breath, especially during physical activity
• Extreme fatigue
• Loss of appetite
• Sharp or stabbing chest pain, particularly when coughing or breathing deeply
• Profuse sweating
• Rapid breathing and increased heart rate
• Bluish tint to lips and fingernails (cyanosis)
• Confusion or disorientation, especially in older adults

It’s important to note that symptoms can vary in severity and presentation, particularly in older adults, young children, or individuals with compromised immune systems. In these groups, the symptoms may be less pronounced or atypical, making diagnosis more challenging.

Differentiating Bacterial from Viral Pneumonia

How can you tell if pneumonia is bacterial or viral? While it can be difficult to distinguish based on symptoms alone, there are some general differences:

• Bacterial pneumonia often has a more sudden onset with higher fever and more severe symptoms
• Viral pneumonia may develop more gradually and is often preceded by symptoms of an upper respiratory infection
• The appearance of the sputum can sometimes provide clues – bacterial pneumonia often produces thicker, colored mucus

However, a definitive diagnosis typically requires medical evaluation and potentially laboratory tests or imaging studies.

Risk Factors for Developing Bacterial Pneumonia

While anyone can develop bacterial pneumonia, certain factors can increase your risk. What puts you at higher risk for this infection?

• Age: Being 65 or older, or very young (under 2 years old)
• Chronic health conditions: Asthma, diabetes, heart disease, or COPD
• Recent surgery or hospitalization
• Malnutrition or vitamin deficiencies
• Weakened immune system: Due to conditions like HIV/AIDS, cancer, or organ transplantation
• Lifestyle factors: Smoking, excessive alcohol consumption
• Recent viral infections, especially influenza
• Living in crowded conditions or long-term care facilities

Understanding these risk factors is crucial for prevention and early intervention. If you fall into any of these high-risk categories, it’s important to be vigilant about respiratory symptoms and seek medical attention promptly if you suspect pneumonia.

The Impact of Chronic Diseases on Pneumonia Risk

Chronic diseases can significantly increase the risk of bacterial pneumonia. How do specific conditions affect this risk?

• COPD: Impairs the lungs’ natural defense mechanisms
• Diabetes: Can weaken the immune system and impair circulation
• Heart disease: May lead to fluid buildup in the lungs, creating an environment conducive to bacterial growth
• Kidney disease: Can affect overall immune function and fluid balance

Managing these underlying conditions effectively is an important part of reducing pneumonia risk.

Diagnosis and Testing for Bacterial Pneumonia

Accurate diagnosis of bacterial pneumonia is crucial for appropriate treatment. What methods do healthcare providers use to diagnose this condition?

• Physical examination: Listening to lung sounds with a stethoscope
• Chest X-ray: To visualize inflammation or fluid in the lungs
• Blood tests: To check for signs of infection and identify the causative organism
• Sputum culture: Analyzing coughed-up mucus to identify the specific bacteria
• Pulse oximetry: Measuring oxygen levels in the blood
• CT scan: For a more detailed view of the lungs, if necessary
• Bronchoscopy: In severe or complicated cases, to directly visualize the airways

The choice of diagnostic tests depends on the severity of symptoms, the patient’s overall health, and the suspected cause of pneumonia.

Advanced Diagnostic Techniques

In some cases, more advanced diagnostic techniques may be employed. These can include:

• Polymerase Chain Reaction (PCR) tests: To rapidly identify bacterial DNA
• Pleural fluid analysis: If there’s fluid buildup around the lungs
• Procalcitonin test: To help distinguish between bacterial and viral infections

These advanced tests can provide more precise information about the causative organism, helping to guide treatment decisions.

Treatment Strategies for Bacterial Pneumonia

The primary treatment for bacterial pneumonia is antibiotics. However, the specific treatment plan can vary based on the severity of the infection, the patient’s overall health, and the suspected or confirmed bacterial cause. What are the key components of bacterial pneumonia treatment?

• Antibiotic therapy: The cornerstone of treatment, typically started empirically and adjusted based on culture results
• Rest and hydration: To support the body’s natural healing processes
• Pain and fever management: Over-the-counter medications like acetaminophen or ibuprofen
• Cough suppressants: Used judiciously to allow for sleep while still permitting productive coughs
• Oxygen therapy: For patients with low blood oxygen levels
• Hospitalization: For severe cases or high-risk patients

It’s crucial to complete the full course of antibiotics as prescribed, even if symptoms improve, to prevent antibiotic resistance and ensure complete eradication of the bacteria.

Supportive Care and Complementary Treatments

In addition to antibiotics, several supportive care measures can help manage symptoms and promote recovery:

• Chest physiotherapy: To help clear mucus from the lungs
• Humidified air: To ease breathing and loosen secretions
• Nutritional support: To maintain strength and support immune function
• Smoking cessation support: For patients who smoke

These complementary treatments can significantly improve comfort and speed recovery when used alongside appropriate antibiotic therapy.

Prevention Strategies: Protecting Yourself from Bacterial Pneumonia

Preventing bacterial pneumonia involves a combination of lifestyle choices, vaccinations, and general health practices. What are the most effective ways to reduce your risk of developing this infection?

• Vaccination: Get recommended pneumococcal vaccines (PCV13 and PPSV23) as per your age and risk factors
• Hand hygiene: Regular handwashing, especially before eating and after using the bathroom
• Healthy lifestyle: Maintain a balanced diet, regular exercise, and adequate sleep
• Avoid smoking: Quit smoking or avoid secondhand smoke exposure
• Limit alcohol consumption: Excessive alcohol use can impair immune function
• Manage chronic conditions: Keep conditions like diabetes or heart disease under control
• Practice respiratory hygiene: Cover your mouth when coughing or sneezing
• Avoid close contact with sick individuals when possible

These preventive measures can significantly reduce your risk of developing bacterial pneumonia and other respiratory infections.

The Role of Vaccination in Pneumonia Prevention

Vaccination plays a crucial role in preventing bacterial pneumonia, particularly pneumococcal pneumonia. What should you know about pneumonia vaccines?

• PCV13 (Prevnar 13): Recommended for all children under 5, adults 65 and older, and individuals with certain risk factors
• PPSV23 (Pneumovax): Recommended for adults 65 and older, smokers, and those with certain chronic conditions
• Influenza vaccine: While not directly preventing bacterial pneumonia, it can reduce the risk of secondary bacterial infections following influenza

Consult with your healthcare provider to determine which vaccines are appropriate for you based on your age, health status, and risk factors.

Recovery and Long-Term Outlook for Bacterial Pneumonia Patients

Recovery from bacterial pneumonia can vary depending on the severity of the infection, the patient’s overall health, and how quickly treatment was initiated. What can patients expect during the recovery process?

• Symptom improvement: Most people start feeling better within a few days of starting antibiotics
• Gradual energy return: Fatigue may persist for several weeks
• Cough resolution: A lingering cough can last for weeks to months
• Follow-up care: Regular check-ups to monitor lung function and overall recovery
• Potential complications: In some cases, complications like lung abscesses or pleural effusions may require additional treatment

Full recovery can take anywhere from a few weeks to several months, depending on the individual case. It’s important to follow your healthcare provider’s instructions and attend all follow-up appointments to ensure proper healing.

Long-Term Effects and Complications

While most people recover fully from bacterial pneumonia, some may experience long-term effects or complications. These can include:

• Reduced lung function: Particularly in severe cases or in patients with pre-existing lung conditions
• Increased susceptibility to future infections: Some patients may be more prone to respiratory infections following pneumonia
• Cardiovascular complications: Pneumonia has been associated with an increased risk of heart problems in some patients
• Cognitive impairment: Particularly in older adults, severe pneumonia can sometimes lead to long-term cognitive changes

Regular follow-up care and a focus on overall lung health can help mitigate these potential long-term effects.

Emerging Research and Future Directions in Bacterial Pneumonia Management

The field of bacterial pneumonia research is constantly evolving, with new insights into prevention, diagnosis, and treatment emerging regularly. What are some of the exciting developments on the horizon?

• Novel antibiotics: Research into new classes of antibiotics to combat resistant strains of bacteria
• Improved diagnostic tools: Development of rapid, point-of-care tests for faster and more accurate diagnosis
• Immunomodulatory therapies: Exploring ways to boost the body’s natural immune response to bacterial infections
• Personalized medicine approaches: Tailoring treatment based on individual patient characteristics and bacterial strain
• Microbiome research: Investigating the role of the lung microbiome in pneumonia susceptibility and recovery
• Advanced vaccine technologies: Development of more effective and broadly protective pneumococcal vaccines

These research directions hold promise for improving outcomes and reducing the global burden of bacterial pneumonia in the future.

The Role of Antibiotic Stewardship

As antibiotic resistance continues to be a growing concern, antibiotic stewardship programs are becoming increasingly important in the management of bacterial pneumonia. These programs aim to:

• Optimize antibiotic selection and dosing
• Minimize unnecessary antibiotic use
• Reduce the development of antibiotic-resistant bacteria
• Improve patient outcomes while reducing healthcare costs

The implementation of effective antibiotic stewardship programs is crucial for preserving the efficacy of current antibiotics and ensuring effective treatment options for future patients with bacterial pneumonia.

Bacterial Pneumonia: Symptoms, Causes, Treatment, Prevention

Written by WebMD Editorial Contributors

• Symptoms
• Prevention
• Diagnosis
• Treatment

Bacterial pneumonia is an infection of your lungs caused by certain bacteria. The most common one is Streptococcus (pneumococcus), but other bacteria can cause it too. If you’re young and basically healthy, these bacteria can live in your throat without causing any trouble. But if your body’s defenses (immune system) become weak for some reason, the bacteria can go down into your lungs. When this happens, the air sacs in your lungs get infected and inflamed. They fill up with fluid, and that causes pneumonia.

You have a higher risk of getting bacteria pneumonia if you:

• Are 65 or older
• Have other conditions like asthma, diabetes, or heart disease
• Are recovering from surgery
• Don’t eat right or get enough vitamins and minerals
• Have another condition that weakens your body’s defenses
• Smoke
• Drink too much alcohol
• Have viral pneumonia

People who have a weakened immune system also have an increased risk for bacterial pneumonia. These include those who recently had an organ transplant. People who are HIV positive, or who have leukemia, lymphoma, or severe kidney disease also stand a greater chance of developing the infection.

The symptoms can come on fast and furious, or they can creep up on you over a few days. Common symptoms are:

• High fever up to 105 F
• Coughing out greenish, yellow, or bloody mucus
• Chills that make you shake
• Feeling like you can’t catch your breath, especially when you move around a lot
• Feeling very tired
• Low appetite
• Sharp or stabby chest pain, especially when you cough or take a deep breath
• Sweating a lot
• Fast breathing and heartbeat
• Lips and fingernails turning blue
• Confusion, especially if you’re older

There are two kinds of shots for bacterial pneumonia:

PCV13 (Prevnar 13) is for:

• People 65 or older
• Kids under 5 years
• People who have a high risk of bacterial pneumonia

PPSV23 (Pneumovax) is for:

• People 65 or older
• Children older than 2 who have a high risk of bacterial pneumonia
• People between 19 and 64 who smoke or have asthma

Talk to your doctor to find out if you or your child should get a shot.

Besides getting shots, you can lower your risk of getting bacterial pneumonia by doing these things:

• Wash your hands regularly, especially after you go to the bathroom and before you eat.
• Eat right, with plenty of fruits and vegetables.
• Exercise.
• Get enough sleep.
• Quit smoking.
• Stay away from sick people, if possible.

Your doctor might be able to tell if you have bacterial pneumonia just by examining you and asking questions about your symptoms and general health. They’ll probably listen to your lungs with a stethoscope. That will allow them to hear sounds that show there’s fluid in your lungs. But if they are not sure, you might have to get a chest X-ray.

Some people may need extra tests. These might include:

• Pulse oximetry (a small gizmo clipped to your finger that checks for enough oxygen in your blood)
• Blood tests
• Tests of the gunk you cough up (“sputum”)
• CT scan to look more closely at your lungs

Your doctor probably will prescribe antibiotics. It’s very important that you finish all of these. Otherwise the bacteria may not all be killed and you could get sick all over again. Your doctor might also suggest medication for pain and fever.

Other things you can do to help yourself get better:

• Get lots of rest.
• Drink plenty of fluids (they’ll loosen up the gunk in your lungs so you can cough it out).
• Use a humidifier or take a warm bath (more gunk-loosening).
• Don’t smoke.
• Stay home until your fever goes down and you aren’t coughing anything out.

Most people who are treated for bacterial pneumonia start feeling better in a few days, but it can take a few weeks before you feel 100% better. Make sure you keep your follow-up appointments so your doctor can check your lungs.

If the pneumonia is stubborn or severe, you might have to go to the hospital. If you go to the hospital you might get:

• Oxygen treatment
• IV fluids and medications
• Treatments to help loosen up the gunk

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Bacterial lung infections. Animal models

Keywords:

bacterial pneumonia

laboratory animals

rats

mice

rabbits

primates

Streptococcus pneumoniae

Klebsiella pneumoniae

Pseudomonas aeruginosa

Pneumonia is a leading cause of morbidity and mortality worldwide, especially among children and the elderly. Nosocomial pneumonia in a hospital setting is one of the most serious infectious complications often caused by opportunistic pathogens. There is an urgent need for better methods of treating and preventing pneumonia. Therefore, animal models have been developed to better understand the pathogenesis of the disease and to test new drugs and vaccines. This review summarizes data from scientific studies of animal modeled bacterial pneumonia, as well as the main causative agents of the disease, the route of administration of infectious agents, and the assessed indicators. The causative agents of bacterial pneumonia are various microorganisms, this review considers Streptococcus pneumoniae, Legionella pneumophila, Haemophilus influenzae, Neisseria meningitidis, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Acinetobacter baumannii, Klebsiella pneumoniae.

The most popular microorganism used to model pneumonia is Streptococcus pneumoniae . According to the data given in scientific articles, mice, rats, rabbits, pigs and primates are used as a test system for modeling bacterial pneumonia. The most suitable animals for the study of bacterial pneumonia are mice. This type of animal is easy to handle, and a sufficient number of individuals can be used to evaluate the results. The main evaluated parameters of the pneumonia study are the results of clinical manifestations, survival rates, bacteremia, the number of bacteria in the lungs, pathological and histological characteristics, quantitative assessment of antibody titers, inflammation markers, etc. Depending on the purpose of the study, different methods of introducing the inoculum are used. To determine virulence, intravenous and intraperitoneal routes of administration are used, to study the effectiveness of new antibiotics – intratracheal, in the development of new vaccines against bacterial pneumonia, animals are injected with inoculum intramuscularly. The choice of animals depends on the purpose of the study, the tasks and the type of microorganism, the method of infection and the estimated parameters.

Introduction

Pneumonia is not a separate disease, but a group of specific infections, each of which has a different epidemiology, pathogenesis and clinical course [1].

Children and the elderly are at risk. Most people who have had pulmonary pneumonia are prone to complications associated with cognitive decline, depression, cardiovascular disease, and reduced life expectancy [2]. Despite the use of effective antibiotics and intensive care, pneumonia-related mortality has not significantly decreased from 1960s [3].

Worldwide, pneumonia is the leading cause of child mortality, especially among children under 5 years of age [4]. In children, bacterial pneumonia is most often caused by microorganisms such as Streptococcus pneumoniae and Haemophilus influenzae type b (Hib). In the first place among the causative agents of pneumonia is Streptococcus pneumoniae, , while the second most important pathogen is Haemophilus influenzae type b (Hib) [5].

The increased risk in the elderly is likely due to impaired body defenses and existing comorbidities (heart failure, liver disease, and underlying lung disease) that increase the risk of aspiration pneumonia, which can occur due to dysphagia and gastroesophageal reflux disease [6].

Among nosocomial diseases, pneumonia ranks first in terms of the number of deaths. Patients in the intensive care unit are at greater risk [7]. The main causative agents of nosocomial pneumonia during mechanical ventilation (ALV) were most often Pseudomonas aeruginosa, Staphylococcus aureus and Acinetobacter baumannii . However, recent data show that bacteria of the Enterobacteriaceae family, in particular Escherichia coli , are currently common causative agents of nosocomial pneumonia during mechanical ventilation [8].

At the moment, there is an urgent need in the world for more advanced methods of treatment and prevention of the disease, new knowledge about the pathogenesis of pneumonia is required. Pharmacological models using laboratory animals are needed to better understand the mechanisms underlying the emergence of resistant strains and decipher host-pathogen interactions, especially when it comes to polymicrobial invasion, while exploring new treatments and the complications that pneumonia causes.

This review describes the most commonly used animal models in the study of bacterial pneumonia, summarizing the data from scientific studies of bacterial pneumonia modeled on rodents, rabbits, pigs and primates.

Bacterial strains

Streptococcus pneumoniae is a gram-positive bacterium, an extracellular, opportunistic microorganism that colonizes the surface of the human mucosa. About 27-65% of children and 10% of adults are carriers of S. pneumoniae [9]. The bacterium leads to the development of diseases such as pneumonia, local infections of the middle ear, purulent meningitis, and is able to actively penetrate into the bloodstream, causing bacteremia and sepsis [10].

Legionella pneumophila is a Gram-negative intracellular bacterium that is a common pathogen that causes hospital-acquired and community-acquired pneumonia. It is one of the most common causative agents of severe pneumonia, with a mortality rate of 10% in Europe and North America [11]. Only one case of 9 transmission has been reported so far0005 L. pneumophila from person to person [12], the vast majority of cases are associated with infection by airborne droplets due to contaminated water. Contaminated water is distributed as a water-air aerosol by air conditioning systems [13].

Haemophilus influenza is a gram-negative coccobacillus, encapsulated and non-encapsulated strains occur (untypable H. influenzae , NTHi). NTHi is a dangerous pathogen that causes otitis media, sinusitis, conjunctivitis, and pneumonia in children and respiratory infections in adults, mainly in patients with chronic obstructive pulmonary disease [14]. Encapsulated strains are divided into 6 serotypes (Hia-f). The Hib serotype is the main causative agent of bacterial meningitis in children worldwide [15].

Neisseria meningitidis is a Gram-negative bacterium that asymptomatically colonizes the nasopharynx in 4–20% of people [16]. The main route of transmission of the pathogen is airborne from person to person. Meningococci can cause diseases dangerous to humans, such as meningococcal septicemia, meningitis, or pneumonia [17].

Escherichia coli — Gram-negative, non-sporing, facultative anaerobic bacterium of the family Enterobacteriaceae [18]. Despite the fact that a huge amount of data has been accumulated on the pathogenicity of E. Coli , which causes intestinal, urological, central nervous system and blood flow diseases, there is little evidence of infections in the lungs [19].

Pseudomonas aeruginosa – Gram-negative obligate aerobe. It is an opportunistic pathogen that causes disease in immunocompromised people. Most often becomes the causative agent of nosocomial infections. P. aeruginosa provokes diseases of various etiologies, often affecting the respiratory system and urinary tract [20].

Staphylococcus aureus is a Gram-positive opportunistic pathogen that causes a wide range of diseases. Approximately 30% of people worldwide carry S. aureus. It is a frequent causative agent of nosocomial infections [21].

Acinetobacter baumannii – Gram-negative coccobacillus. Causes mostly nosocomial infections. A. baumannii is the main causative agent of ventilator-associated nosocomial pneumonia [22].

Klebsiella pneumonia is a gram-negative, encapsulated, immobile bacterium that lives in the environment, including soil and surface water [23]. K. pneumoniae can cause serious infections in immunocompromised people such as pneumonia, bacteremia, or meningitis [24].

Animal models of pneumonia

The pneumonia model can be replicated in a variety of animal species. The choice of animal species depends on the objectives of the study. Non-mammals (insects and fish) are the most inexpensive and ethically most attractive. The use of such models gives limited results, but can be useful for obtaining information about the innate immune responses of the body and the virulent properties of pathogenic microorganisms that cause bacterial infections of the lungs [25].

You can also find studies on pigs and dogs. The most preferred model in translational studies of the lungs are small animals (eg, rodents). Such models ideally comply with the 3R principles; their small size and high reproduction rate make them the most practical and accessible for laboratory research [26].

Mouse models

Mouse models are often used in the study of pneumococcal pneumonia. Since the main research is carried out on mice, there is a huge amount of scientific work related to the study of the mouse body and immunity in general. Mice are most commonly used to evaluate antibiotic efficacy, pharmacokinetics, disease pathogenesis, virulence factors, and vaccine testing [27].

Mouse models of pneumonia allow the analysis of various parameters, including animal survival after infection, the presence of bacteria in the lungs and blood, levels of inflammation, and lung tissue histology. In addition, they are used in the quantitative assessment of antibody and antimicrobial titers, in pharmacokinetic studies of vaccines and drugs [28]. In the study of pneumonia, mice are kept in an individually ventilated system to protect personnel and the environment from infectious agents [29].

In both humans and mice, pneumococcal infection is the result of a complex interaction between bacterial and host factors that strongly influences the severity and location of the disease. Different strains of mice respond differently to pneumococcal stress in terms of timing, severity, and disease outcome, and this may not always translate to humans.

Rat models

Rat models are rarely used compared to mice for modeling bacterial infections of the lungs. Larger organ sizes compared to mice allow more biological material to be collected, but experimental groups are usually smaller, which can lead to significant statistical error. Induction of pulmonary pneumonia is carried out with the introduction of an infectious agent by intravenous, intrabronchial or intrapulmonary route. Research design is usually based on the study of survival of animals, observation of the overall clinical picture, histological examination of the lungs, determination of the number of bacteria in the lungs and blood. Rats are mainly used in studies to study the features of the course of pneumonia that occurs in patients with concomitant diseases [30]. You can also find scientific works where models of experimental pneumonia in rats are used to study the virulence of various pneumococcal serotypes [31] and evaluate the efficacy and safety of anti-pneumococcal vaccination [32].

Rabbit models

Rabbit models of pneumococcal pneumonia are suitable for studying the pathogenesis, survival, disease progression, and pharmacokinetic and pharmacodynamic characteristics of novel therapeutics and immunizations [33]. Rabbits are also generally useful in assessing different pneumococcal serotypes and resistance phenotypes in strains [34]. Rabbit models are also suitable for studying sepsis. Injected intraperitoneally pneumococci allow researchers to assess clinical parameters during disease progression [35].

Pig models

Pigs are similar to humans in terms of anatomy, genetics and physiology. Animals are omnivorous and have an adaptive and innate immune system that is 80% similar to the human one [36]. Compared to rodents and smaller animals, porcine models, due to their size and similar anatomy to humans, are used for a variety of surgical and non-surgical procedures [37]. Experiments on pigs have greater prognostic and therapeutic value than studies conducted on rodents [38]. Pig models are most suitable for assessing ventilator-associated pneumonia, as animals must be in the supine position (to prevent atelectasis) [39].

Primate models

The most attractive models are primates, whose immunity and physiology are similar to those of humans and are generally susceptible to human pathogens. However, the use of primates in research raises serious ethical issues [40]. Primates are not natural carriers of pneumococci, and there are no data on isolation of pneumococci from the nasopharynx in primates. However, there is evidence of experimental infection of primates with the human strain S. pneumoniae , as a result, about 100% of the animals had signs of colonization after 2 weeks and about 60% of the animals after 7 weeks after infection, these data indicate that primates are an excellent human-like model for studying carriage [41]. Primates infected with S. pneumoniae, develop similar symptoms to those seen in humans with a lower respiratory tract infection characterized by fever, bacteremia, cough, and labored breathing [42]. Primates are suitable for research related to the study of pathogenesis. Studies of lung infections in baboons have confirmed that increasing doses of pneumococcal inoculation (serotype 19A-7) elicit a host response ranging from mild illness (106 cfu) to severe pneumonia (109 cfu). Cytokine levels in bronchoalveolar lavage confirmed severe pneumonia [43]. Another group of researchers showed that a baboon infected with S. pneumoniae (serotype 4) 109 CFU developed symptoms of bacterial pneumonia 4 days after infection. Clinical findings were similar to those that developed in humans and included cough, tachypnea, dyspnea, tachycardia, and fever. All animals developed leukocytosis and bacteremia 24 hours after infection. A severe inflammatory response after infection was reflected in an increase in serum cytokines, including interleukins (IL) 1Ra, IL-6 and IL-8. Ultrasound of the lungs revealed lobes of the lungs affected by pneumonia, which was confirmed by pathomorphological examination. The severity of lung pathology had a high degree of correlation with the severity of the disease [44].

Pneumonia Model Types

One Punch Acute Pneumonia Model

This pneumonia model is considered simple because of the method of introducing bacterial inoculum into the lungs. Intratracheal instillation is the most commonly used method for investigating pneumonia and involves injecting a bacterial suspension directly into the trachea or lungs [45]. This method provides the most precise control over the set dose. However, in this method, one has to resort to surgical opening of the trachea, which entails subsequent suturing of the incision, which provokes an inflammatory reaction in the organ, which can have a significant impact on the final result. On the other hand, endotracheal administration of bacteria requires intubation of the animal to facilitate instillation of the bacterial solution into the lungs and is as accurate as the intratracheal instillation method [46]. Less invasive methods are intranasal administration, in which a fixed bacterial dose is injected into the nostrils of animals [47], or aerosol administration, which is used for aggressive animals [48]. However, the exact dose reaching the lower respiratory tract in both methods cannot be calculated, and animals often develop upper respiratory tract infections [47] or infections other than pneumonia [48]. In the aerosol method, to control the established dose, it is required immediately after aerosolization to subject several animals to euthanasia for quantitative counting of bacteria [48].

Mechanical ventilation as a model of pneumonia

Mechanical ventilation is an important component in the pathogenesis of pneumonia. Ventilation has been shown to develop a sterile inflammatory reaction in the lungs, in which various tissue injuries occur, such as overstretching of the lungs, barotrauma and overvolume trauma, air leakage due to breach of the airspace wall, pulmonary edema, and atelectasis (re-opening and closing of the alveoli) [49].

Two main methods have been used to create animal models of ventilation. In the first method, the bacterial suspension is injected into the lungs before mechanical ventilation [50], in the second, the bacterial suspension is injected after ventilation, which mimics a more natural evolution of the disease [51]. However, when using the second method, the results show an increased bacterial load on the lungs, a more severe course of the disease and a high mortality compared with the first method [51].

Experimentally induced tracheal stenosis along with prolonged mechanical ventilation (up to 4 days) has been shown to cause spontaneous development of pneumonia with endogenous microbiota in piglets, and opportunistic pathogens of human pneumonia, species such as Pseudomonas and Klebsiella [39].

Agar (chronic) pneumonia model

This model was originally developed in rats and is used in the field of cystic fibrosis [52]. To form a biofilm, agar or algae alginate granules are used as extracellular polymeric substances, into which bacteria are loaded, mixed with mineral oil and sorbitan monooleate emulsifier to increase the uniformity of the granules. For control groups of animals, sterile pellets are prepared using phosphate buffered saline or saline, however, sterile pellets can themselves induce an inflammatory response leading to increased cellular infiltrates in the lungs and increased release of cytokines, which can significantly affect the results of the study [53].

Interestingly, although bacteria can migrate from agarose beads in vivo, bacterial growth is slow and limited to beads, similar to the process observed in bacteria living in biofilms [54]. In addition, bacterial clearance is impaired and animals are less likely to develop acute sepsis. The agar model is able to better model the chronic lung infection seen in humans in terms of histopathological features, elevated lung neutrophil levels, and fluid accumulation of cytokines [55].

Conclusions and conclusions

Most often, researchers model pneumonia in mice. The main parameters of the studies to be assessed are: collection of data on pathogenesis, survival, determination of the number of bacteria in the lungs and blood, pathological and histological characteristics, quantitative assessment of antibody titers. Also on mice, the virulence of bacterial strains is being studied, the effectiveness of new antibiotics and the mechanisms of body defense are being studied. Methods of introducing the inoculum depend on the objectives of the study, for example, to assess virulence, an intravenous route of administration is used. When studying the effectiveness of new antibiotics, the bacterial inoculum is administered intratracheally. Rats are mainly used in research to study the course of pneumonia, the virulence of various pneumococcal serotypes, and to evaluate the efficacy and safety of pneumococcal vaccination. The bacterial pneumonia model in rabbits is suitable for determining clinical parameters during disease progression and drug efficacy using the intrabronchial and intraperitoneal routes of inoculum administration. Experiments in pigs are of great prognostic and therapeutic value, so pig models are used in the development of therapies aimed at the treatment of pneumococcal pneumonia and vaccines. Primate models are suitable for studies related to the assessment of the severity of the disease. We tried to systematize all of the above in a table, which can allow the researcher to navigate through a variety of models and choose the design of the study that meets the objectives.

Pneumococcal disease in humans is diverse and multifaceted, and no animal model can fully mimic human disease. Nevertheless, despite the limitations, animal experiments remain undoubtedly a valuable tool for elucidating the pathogenetic mechanisms of the disease. This review provides insight into the development and application of various animal models used to mimic and study pneumonia. All animal models are useful tools for elucidating aspects of disease pathogenesis and testing the efficacy of antibiotics and other treatments. The main methods of infection are described in this review. The use of mice as models is convenient from an economic point of view, they are easy to handle, which allows screening drugs and vaccines with high statistical power. Larger animals have the advantage of increased ease of performing surgical procedures, but they are more expensive and the results may not be statistically significant due to the use of smaller groups.

The development of pneumococcal disease depends on both bacterial factors (eg, capsular serotype and other determinants of virulence) and host factors (eg, genetic background, immune response, age, sex). Before embarking on the study of pneumococcal infection in vivo, one should carefully consider the choice of not only animals, but also bacterial strains.

Acknowledgments

The work was done without sponsorship.

Author contributions

L.R. Khaibunasova – collection of data from literary sources, collection and analysis of data, writing and editing the text of the article

M. N. Makarova – concept and design of the study, editing the text of the article, scientific advice and approval of the final version of the article for publication

К.Е. Borovkova – editing the text of the article, scientific consulting

Yu.V. Salmova – drafting the text of the article

What diseases are caused by bacteria and what do you need to know about them?

In this article you will find a list of diseases that can be caused by bacteria, such as pneumonia, tuberculosis, cholera and others. Learn more about the symptoms, treatment, and prevention of these conditions.

Bacteria are the cause of many infectious diseases that occur in the human body. They come in a variety of shapes and sizes, as well as properties that can lead to a variety of health conditions.

One of the best known examples of bacterial infections is salmonellosis caused by the bacterium Salmonella. This disease can be caused by eating contaminated food such as raw eggs, chicken, fish, and other foods. Symptoms may include diarrhea, nausea, vomiting, and fever.

Another common bacterial infection is pneumonia. It is caused by various bacteria such as Streptococcus pneumoniae, Mycoplasma pneumoniae, Haemophilus influenzae, Legionella pneumophila and others. Symptoms may include cough, difficulty breathing, fever, and chest pain.

Bacterial infections can be very serious and in some cases even fatal. Therefore, it is important to monitor your health and take precautions to avoid infection.

Examples of diseases caused by bacteria

Tetanus is an acute infectious disease that is transmitted through wounds in the skin. It is caused by the bacterium Clostridium tetani, which produces a toxin that increases muscle tone and leads to seizures. Tetanus can seriously damage the body, causing paralysis and even death.

Diphtheria is an infectious disease that affects the throat, nose, or skin. It is caused by a toxin produced by the bacterium Corynebacterium diptheriae. Diphtheria can lead to respiratory failure, pneumonia, paralysis, and even death if left untreated.

Tuberculosis is one of the most common diseases caused by the bacterium Mycobacterium tuberculosis. This disease mainly affects the lungs. It can cause coughing, weakness, weight loss, loss of appetite, and chest pain. Tuberculosis is dangerous because it can lead to death if not treated early.

Plague is an infectious disease caused by the bacterium Yersinia pestis. It is transmitted through the bites of fleas infected by rats. Plague can lead to an acute generalized infection accompanied by fever, excessive sweating, headache, vomiting, and diarrhea. If left untreated, you can die shortly after the onset of the disease.

Whooping cough is an infectious disease caused by the bacterium Bordetella pertussis. It is characterized by prolonged and severe coughing, attacks that can lead to vomiting and loss of consciousness. Whooping cough can lead to serious complications such as pneumonia and encephalopathy, especially in children who have not had whooping cough in the past.

Intestinal infections: a bacteria portal

Cholera

Cholera is an infection caused by the bacterium Vibrio cholerae. This bacterium lives in water and soil, and a person can become infected by drinking water or food contaminated with the bacterium. Symptoms of cholera include rapid fluid and electrolyte loss, which can lead to life-threatening dehydration. Cholera is especially dangerous in countries that lack clean water and sanitation.

Prevention:

• Purify and boil water before drinking
• Eat only fresh fruits and vegetables washed under running water
• Avoid raw or unboiled shellfish

Salmonellosis 9001 3

Salmonellosis is an infection caused by bacteria of the genus Salmonella. These bacteria can be found in the intestines of some animals, such as chickens, and can be transferred to animal-derived foods such as eggs and meat. Symptoms of salmonellosis include vomiting, diarrhea, and fever. Most people recover without treatment, but hospitalization may be required in some cases.

Prevention:

1. Keep animal products at low temperature
2. Avoid eating undercooked meat
3. Avoid drinking unpurified water

Sample list of ki Cholera Vibrio cholerae Contaminated water and food Salmonellosis Salmonella Products derived from animals Shigellosis Shigella Contact with infected or contaminated objects

9 0220 Examples of bacterial diseases in humans

Salmonellosis

Salmonellosis is an infectious disease caused by bacteria of the Enterobacteriaceae family, Salmonella. They can cause an acute intestinal infection that presents with fever, headache, nausea, vomiting, diarrhea, and painful abdominal cramps. In severe cases, salmonellosis can cause sepsis, osteomyelitis, meningitis, visceral abscesses, and cardiovascular and neurological damage.

Salmonella is found in the intestines of farm animals, birds and reptiles and can infect humans through handling or ingestion of contaminated foods such as meat, eggs, milk, cheese and vegetables. Children, the elderly and those with weakened immune systems are especially susceptible to infection.

• Symptoms of salmonellosis: fever, headache, nausea, vomiting, diarrhea, abdominal pain.
• Methods of infection: ingestion of contaminated food and contact with animals.
• Prevention: cook food thoroughly, avoid raw or undercooked foods, and maintain hygiene when handling animals.
• Treatment: Salmonellosis usually resolves on its own without sequelae after a few days. In severe cases, antibiotic therapy may be required.

Bacterial infections in humans: Shigellosis

What is shigellosis?

Shigellosis is an infectious disease caused by bacteria of the genus Shigella. The disease is transmitted through food and water, sometimes through contact with infected people or animals.

Shigellosis appears a few days after infection and presents with severe diarrhea, abdominal pain, chills and fever.

What are the types of shigellosis?

There are four types of shigellosis (S. flexneri, S. sonnei, S. boydii, S. dysenteriae) that differ in symptoms and aggressiveness. The most dangerous is S. dysenteriae, which can cause dysentery and even death.

How is shigellosis treated?

Shigellosis is treated with antibiotics, which must be prescribed by a doctor. It is also important to observe food and water hygiene in order to avoid re-infection. Symptoms usually resolve within a week.

How to prevent shigellosis?

• wash hands regularly and thoroughly before eating;
• use only clean water, use only bottled water;
• prepare and consume food only after it has been thoroughly washed and processed;
• avoid contact with infected people or animals.

Conclusion

Shigellosis is a serious disease that requires timely treatment and preventive measures. It is important to maintain hygiene related to food and water in order not to contract this infection.

Lymphogranulomatosis

Lymphogranulomatosis or Hodgkin’s disease is a malignant disease that can manifest itself in the form of enlarged lymph nodes, or damage to internal organs – the liver and spleen. This disease is a type of lymphoma.

Lymphogranulomatosis is caused by the bacterium Reed Sternberg, which grows in the lymphatic system and causes abnormal growth of lymphatic cells in the body. This disease can lead to disruption of the organs and lack of immunity.

Hodgkin’s disease can be treated with drugs, radiation therapy and surgery. The prognosis for recovery depends on the degree of damage to the body and contains some risks, including complications from treatment.

• Symptoms of lymphogranulomatosis:
  • Enlarged lymph nodes in the neck, armpits or groin
  • Night sweats
  • Fatigue and weakness
  • Weight loss

Bacterial diseases in humans: an example is tuberculosis

Tuberculosis is a disease caused by the bacterium Mycobacterium tuberculosis. It most often affects the lungs, but it can affect other organs as well. The disease is transmitted by airborne droplets through contact with an infected person.

Symptoms of tuberculosis may include cough, weight loss, fatigue and fever. The diagnosis is made on the basis of clinical manifestations, radiological and bacteriological studies.

Tuberculosis is treated with antibiotics for several months. Late or incorrect treatment can lead to the development of multiple antibiotic resistance and complicate the course of the disease.

Basic TB prevention measures include vaccination, regular testing for infection, and timely treatment of infected people.

Smallpox: a disease caused by a bacterium

What is smallpox?

Smallpox is an infectious disease caused by a bacterium called Bacillus anthracis. It can infect people, animals and even birds. A person can become infected with smallpox through contact with sick animals or soil that harbored the bacteria.

Symptoms of smallpox

Symptoms of smallpox may appear several days after infection and may range from mild to severe. The main symptoms are:

• Fever
• Chest pain
• Nausea and vomiting
• Sore throat and difficulty breathing

Smallpox can be fatal if left untreated, especially if it affects the lungs.

Treatment of smallpox

Smallpox is treated with antibiotics and anti-antitoxins. But the best way to fight smallpox is prevention. For example, people working with animals in hazardous areas should wear protective gear and monitor their hygiene.

Conclusion

Smallpox is a serious disease caused by the bacterium Bacillus anthracis. The symptoms of smallpox can be very dangerous, and without treatment, it can be fatal. Therefore, it is very important to monitor your health and take precautions if you have been in contact with potentially dangerous sources of infection.

Scarlet fever disease

Scarlet fever is one of the most common diseases caused by the group A bacterium streptococci. It is transmitted by airborne droplets and affects children between the ages of 5 and 15 years.

Symptoms of scarlet fever are skin rash, red tongue, fever, headache and abdominal pain. The disease can lead to the development of complications such as arthritis, glomerulonephritis, and communication between the cavities of the heart.

Treatment of scarlet fever includes antibiotic therapy and symptomatic therapy. Lack of treatment can lead to serious complications.

• Risk factors: low level of hygiene, violation of the integrity of the skin, being surrounded by patients.
• Prevention: observance of hygiene rules, preventive vaccination.

Diphtheria disease: causes, symptoms and treatment

What is this disease?

Diphtheria is an infectious disease caused by the bacterium Corynebacterium diphtheriae. It attacks the respiratory tract, lymph nodes, and scalp, causing bad breath and a gray coating in the throat.

How does infection occur?

Diphtheria bacteria can be spread by droplets when an infected person coughs and sneezes. Also, the infection can be transmitted by contact with objects that have bacteria.

What are the symptoms?

• high body temperature;
• Sore throat and difficulty swallowing;
• Weakness and fatigue;
• Large gray spots on back of throat and tongue;
• Enlarged lymph nodes in the neck;
• Painful itchy skin ulcers

How to treat?

Antibiotics must be used to treat diphtheria. In order to prevent the spread of infection, infected people should be isolated and treated in a medical facility. The use of prophylactic vaccines can prevent infection.

Bacterial infection – whooping cough

Whooping cough is a dangerous bacterial infection caused by the bacterium Bordetella pertussis. It is characterized by a persistent paroxysmal cough that can last up to 10 weeks and lead to rapid breathing and, in some cases, death.

Whooping cough is a highly contagious disease that is transmitted by airborne droplets from a sick person to a healthy person. The risk of the disease increases in the first few months of life, when the child does not have sufficient immunity from the mother, and in children from 5 to 10 years of age, in which the level of immunity may vary.

Whooping cough can be prevented by vaccination. Standard vaccination should be administered in three stages: the first at 2 months of age, the second at 4 months of age, and the third at 6 months to 4 years of age.

• Symptoms of whooping cough
  • Prolonged cough that lasts more than 2 weeks
  • Cough that ends in a whistling sound
  • No breathing during cough
  • chest from frequent coughing
  • Airway obstructions

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Q&A:

What diseases can bacteria cause?

Bacteria can cause a variety of illnesses, including urinary tract infections, pneumonia, gastroenteritis, dysentery, tuberculosis, and others.

How do bacteria cause urinary tract infections?

Bacteria can enter the bladder through the urethra and cause a urinary tract infection. This can happen as a result of poor hygiene, taking certain medications, sexual contact, or other factors.

What bacteria causes pneumonia?

Pneumonia can be caused by a variety of bacteria, including Streptococcus pneumoniae, Haemophilus influenzae, and Legionella pneumophila.

What causes gastroenteritis?

Gastroenteritis can be caused by various bacteria such as Salmonella, Escherichia coli, Staphylococcus aureus, Shigella and Campylobacter.

What are the symptoms of dysentery?

Dysentery causes gastrointestinal disturbances such as diarrhoea, abdominal pain, vomiting, loose stools with mucus and blood, fever and dehydration.

What precautions can you take to avoid contracting tuberculosis?

To prevent TB infection, practice good hand hygiene, avoid close contact with TB patients, avoid sharing dishes and linens, and seek medical attention immediately if you experience symptoms such as cough, weight loss, weakness, and fatigue.

Syphilis: one of the most common bacterial infections in humans

What is the danger of the disease?

Syphilis is a chronic bacterial infection that is transmitted through contact, mainly through sexual contact. The disease is caused by bacteria that can affect the human body at all stages of development, from the primary stage, which manifests itself as inflammation at the site of infection, to the advanced stages, which can damage internal organs, including the brain.

Syphilis can lead to serious complications such as heart and vascular disease, damage to the nervous system, and changes in bone structure. The disease also increases the risk of contracting HIV and other infections. If syphilis is not treated, it can lead to death.

How to recognize the disease?

The symptoms of syphilis depend on the stage of the disease. In the early stages, sores or warts may appear on the skin, causing itching and soreness. In later stages of the disease, rashes, skin eruptions, hair loss, headaches, and general malaise may occur.

Syphilis can be diagnosed using blood tests and conventional examination methods, such as testing for ulcers or syphilitic rashes, bacterial species testing in a laboratory, etc.

How to treat syphilis?

Treatment for syphilis can be effective at all stages of the disease, but the earlier the infection is found, the easier it is to treat. Usually, antibiotics prescribed by a doctor are used for treatment. In most cases, complex treatment includes several courses of antibiotics and other drugs that help prevent possible complications.

For pregnant women, the treatment of syphilis is very important, as there is a risk of transmission to the child during pregnancy or childbirth.