Organisms That Can Cause Pneumonia (Bacteria)

Type of Organism	Disease	Most Common Mode of Transmission	Classic Features
Bacteria  Gram positive cocci
Streptococcus pneumoniae *most common cause of community acquired pneumonia in adults	*Typical pneumonia	inhalation of droplets	rusty sputum
Streptococcus pyogenes	Typical pneumonia	inhalation of droplets	Group A Streptococcus, pneumonia that killed Jim Hensen (The Muppets creator)
Streptococcus agalactiae common cause of pneumonia in 0-2 month old patients	Typical pneumonia	inhalation of organisms as neonate passes down birth canal	Group B Streptococcus, usually causes pneumonia in neonates.
Staphylococcus aureus	Typical pneumonia	IV drug use, inhalation of droplets, post-influenza	Multiple bilateral nodular infiltrates with central cavitation. In children one can see ill-defined, thin walled cavities (“pneumatoceles”), bronchopleural fistulas, and empyema. Common cause of pneumonia in cystic fibrosis patients
Peptostreptococcus sp.  anaerobe	**Aspiration pneumonia	Aspiration	fluid-air levels, and abscess formation oftentimes seen on radiographs, foul breath, infiltrates in dependant lung segments
Bacteria Gram positive rods
Bacillus anthracis	Typical pneumonia, Anthrax, Wool-Sorters disease	inhalation	Associated with wool sorting,  with animal handlers, and veterinarians.
Nocardia sp.	***Chronic pneumonia	inhalation; immunocompromised hosts	beaded  filamentous appearance of the  rod shaped bacteria, Pleura and chest wall involvment
Actinomyces sp.  anaerobe	Chronic pneumonia	Aspiration	sulfur granules and a beaded appearance of the branched filamentous rod shaped bacteria, Rib destruction, Cutaneous sinuses, cavitation, spreads to pleura and chest wall
Bacteria Gram negative cocci
Neisseria meningitidis	Typical pneumonia	inhalation	epidemics in military recruits
Moraxella catarrhalis	Typical pneumonia	inhalation
Bacteria Gram negative Rods
Klebsiella pneumoniae	Typical pneumonia	aspiration	Current Jelly sputum, more commonly seen in patients with COPD, alcoholics, and the elderly, Bulging fissure sign of chest radiograph, lung necrosis
Escherichia coli common cause of pneumonia in 0-2 month old patients	Typical pneumonia	aspiration	usually seen in neonates, lung necrosis
Pseudomonas aeruginosa	Typical pneumonia	aspiration or inhalation	green sputum, abscess formation, Common cause of pneumonia in cystic fibrosis patients and those with  severely compromised respiratory defenses.
Acinetobacter sp.	Typical pneumonia	aspiration or inhalation , often found on  respiratory therapy equipment and on human skin	very difficult to treat due to multiple drug resistance.
Burkholderia pseudomallei	Typical pneumonia	inhalation	exposure with contaminated soil
Burkholderia mallei	Typical pneumonia	inhalation	exposure with contaminated soil
Yersinia pestis	Typical pneumonia, Pneumonic plague	Inhalation, or by hematogenous spread to lungs	Initial plague patients acquire this disease via flea bites
Francisella tularensis	Typical pneumonia, Tularemia	Infection is via tick bite or contact with contaminated rabbits.
Hemophilus influenzae	Typical pneumonia	inhalation	more commonly seen in patients with COPD, alcoholics, and the  elderly.
Bordetella pertussis	Whooping cough	inhalation	bronchopneumonia
Bacteroides melaninogenicus anaerobe	Aspiration pneumonia	Aspiration	fluid-air levels, and abscess formation oftentimes seen on radiographs, foul breath, infiltrates in dependant lung segments
Fusobacterium sp.  anaerobe	Aspiration pneumonia	Aspiration	fluid-air levels, and abscess formation oftentimes seen on radiographs, foul breath, infiltrates in dependant lung segments
Porphyromonas sp.   anaerobe	Aspiration pneumonia	Aspiration	fluid-air levels, and abscess formation oftentimes seen on radiographs, foul breath, infiltrates in dependant lung segments
Prevotella sp.  anaerobe	Aspiration pneumonia	Aspiration	fluid-air levels, and abscess formation oftentimes seen on radiographs, foul breath, infiltrates in dependant lung segments
Proteus sp.	Typical pneumonia	inhalation, aspiration	lung necrosis
Serratia sp.	Typical pneumonia	inhalation, aspiration	usually seen in immunocompromised hosts
Bacteria that do not gram stain or gram stain poorly
Mycobacterium tuberculosis	Chronic pneumonia	inhalation	ghon complexes, coin lesions, cavitation.
Other Mycobacterium sp.	Chronic pneumonia	inhalation, usually seen in immunocompromised host
Legionella pneumophila	****Atypical pneumonia	inhalation, usually the elderly or immunocompromised host	Relative bradycardia, abdominal pain, Vomiting and diarrhea, hematuria, mental confusion, abnormal liver and renal function tests, increased CPK
Mycoplasma pneumoniae – colonies Most common cause of Atypical pneumonia in adults.	Atypical pneumonia	inhalation	bullous myringitis, cold agglutinin positive, cobweb like infiltrates of lungs
Chlamydia trachomatis	Atypical pneumonia	inhalation	an afebrile pneumonia, usually seen in 2 wk to 6 months of age
Chlamydia psittaci	Atypical pneumonia	inhalation	acquired from certain birds (ex. parrots), normal or low leukocyte count
Chlamydia pneumoniae TWAR agent	Atypical pneumonia	inhalation
Coxiella burnetii (Q-fever)	Atypical pneumonia	ingestion of comtaminated milk, or inhalation of contaminated aerosols from barnyard animals	abnormal liver function tests

Community-acquired pneumonia in adults: MedlinePlus Medical Encyclopedia

Pneumonia is a breathing (respiratory) condition in which there is an infection of the lung.

This article covers community-acquired pneumonia (CAP). This type of pneumonia is found in people who have not recently been in the hospital or another health care facility such as a nursing home or rehab facility. Pneumonia that affects people in or recently released from a health care facility, such as hospitals, is called hospital-acquired pneumonia (or health care-associated pneumonia).

Pneumonia is a common illness that affects millions of people each year in the United States. Germs called bacteria, viruses, and fungi may cause pneumonia. In adults, bacteria are the most common cause of pneumonia.

Ways you can get pneumonia include:

• Bacteria and viruses living in your nose, sinuses, or mouth may spread to your lungs.
• You may breathe some of these germs directly into your lungs.
• You breathe in (inhale) food, liquids, vomit, or fluids from the mouth into your lungs (aspiration pneumonia).

Pneumonia can be caused by many types of germs.

• The most common type of bacteria is Streptococcus pneumoniae (pneumococcus).
• Atypical pneumonia, often called walking pneumonia, is caused by other bacteria.
• A fungus called Pneumocystis jirovecii can cause pneumonia in people whose immune system is not working well, especially people with advanced HIV infection.
• Viruses, such as the flu virus, and most recently SARS-CoV-2 (which causes COVID-19), are also common causes of pneumonia.

Risk factors that increase your chance of getting pneumonia include:

• Chronic lung disease (COPD, bronchiectasis, cystic fibrosis)
• Cigarette smoking
• Dementia, stroke, brain injury, cerebral palsy, or other brain disorders
• Immune system problem (during cancer treatment, or due to HIV/AIDS, organ transplant, or other diseases)
• Other serious illnesses, such as heart disease, liver cirrhosis, or diabetes
• Recent surgery or trauma
• Surgery to treat cancer of the mouth, throat, or neck

The most common symptoms of pneumonia are:

• Cough (with some pneumonias you may cough up greenish or yellow mucus, or even bloody mucus)
• Fever, which may be mild or high
• Shaking chills
• Shortness of breath (may only occur when you climb stairs or exert yourself)

Other symptoms include:

• Confusion, especially in older people
• Excess sweating and clammy skin
• Headache
• Loss of appetite, low energy, and fatigue
• Malaise (not feeling well)
• Sharp or stabbing chest pain that gets worse when you breathe deeply or cough
• White nail syndrome, or leukonychia

The health care provider will listen for crackles or abnormal breath sounds when listening to your chest with a stethoscope. Tapping on your chest wall (percussion) helps the provider listen and feel for abnormal sounds in your chest.

If pneumonia is suspected, the provider will likely order a chest x-ray.

Other tests that may be ordered include:

• Arterial blood gases to see if enough oxygen is getting into your blood from the lungs.
• Blood and sputum cultures to look for the germ that may be causing the pneumonia.
• CBC to check white blood cell count.
• CT scan of the chest.
• Bronchoscopy. A flexible tube with a lighted camera on the end passed down to your lungs in selected cases.
• Thoracentesis. Removing fluid from the space between the outside lining of the lungs and the chest wall.
• Nasopharyngeal swab to assess for viruses like influenza and SARS-CoV-2.

Your provider must first decide whether you need to be in the hospital. If you are treated in the hospital, you will receive:

• Fluids and antibiotics (or antivirals) through your veins
• Oxygen therapy
• Breathing treatments (possibly)

If you are diagnosed with a bacterial form of pneumonia, it is important that you are started on antibiotics very soon after you are admitted. If you have viral pneumonia, you will not receive antibiotics. This is because antibiotics do not kill viruses. You may receive other medicines, such as antivirals, if you have the flu.

You are more likely to be admitted to the hospital if you:

• Have another serious medical problem
• Have severe symptoms
• Are unable to care for yourself at home, or are unable to eat or drink
• Age 65 years old or older
• Have been taking antibiotics at home and are not getting better

Many people can be treated at home. If so, your provider may tell you to take medicines such as antibiotics.

When taking antibiotics:

• Do not miss any doses. Take the medicine until it is gone, even when you start to feel better.
• Do not take cough medicine or cold medicine unless your provider says it is OK. Coughing helps your body get rid of mucus from your lungs.

Breathing warm, moist (wet) air helps loosen the sticky mucus that may make you feel like you are choking. These things may help:

• Place a warm, wet washcloth loosely over your nose and mouth.
• Fill a humidifier with warm water and breathe in the warm mist.
• Take a couple of deep breaths 2 or 3 times every hour. Deep breaths will help open up your lungs.
• Tap your chest gently a few times a day while lying with your head lower than your chest. This helps bring up mucus from the lungs so that you can cough it out.

Drink plenty of liquids, as long as your provider says it is OK.

• Drink water, juice, or weak tea
• Drink at least 6 to 10 cups (1.5 to 2.5 liters) a day
• Do not drink alcohol

Get plenty of rest when you go home. If you have trouble sleeping at night, take naps during the day.

With treatment, most people improve within 2 weeks. Older adults or very sick people may need longer treatment.

Those who may be more likely to have complicated pneumonia include:

• Older adults
• People whose immune system does not work well
• People with other serious medical problems, such as diabetes or cirrhosis of the liver

In all of the above conditions, pneumonia can lead to serious illness or even death, if it is severe.

In rare cases, more serious problems may develop, including:

• Life-threatening changes in the lungs that require a breathing machine
• Fluid around the lung (pleural effusion)
• Infected fluid around the lung (empyema)
• Lung abscesses

Your provider may order another x-ray. This is to make sure your lungs are clear. But it may take many weeks for your x-ray to clear up. You will likely feel better before the x-ray clears up.

Contact your provider if you have:

• Cough that brings up bloody or rust-colored mucus
• Breathing (respiratory) symptoms that get worse
• Chest pain that gets worse when you cough or breathe in
• Fast or painful breathing
• Night sweats or unexplained weight loss
• Shortness of breath, shaking chills, or persistent fevers
• Signs of pneumonia along with a weak immune system (such as with HIV or chemotherapy)
• Worsening of symptoms after initial improvement
• Conditions (such as COPD or diabetes) that increase your chance of having severe pneumonia

You can help prevent pneumonia by following the measures below.

Wash your hands often, especially:

• Before preparing and eating food
• After blowing your nose
• After using the toilet
• After changing a baby’s diaper
• After coming in contact with people who are sick

Avoid coming into contact with people who are sick.

Do not smoke. Tobacco damages your lung’s ability to fight infection.

Vaccines may help prevent some types of pneumonia. Be sure to get the following vaccines:

• Flu vaccine can help prevent pneumonia caused by the flu virus.
• Pneumococcal vaccine lowers your chances of getting pneumonia from Streptococcus pneumoniae.
• COVID-19 vaccine can help prevent severe pneumonia from SARS-CoV-2 virus.

Vaccines are even more important for older adults and people with diabetes, asthma, emphysema, HIV, cancer, people with organ transplants, or other long-term conditions.

Bronchopneumonia; Community-acquired pneumonia; CAP

• Bronchiolitis – discharge
• Colds and the flu – what to ask your doctor – adult
• Colds and the flu – what to ask your doctor – child
• How to breathe when you are short of breath
• Oxygen safety
• Pneumonia in adults – discharge
• Pneumonia in children – discharge
• Using oxygen at home
• Using oxygen at home – what to ask your doctor
• When your baby or infant has a fever

• Respiratory system
• Pneumonia
• White nail syndrome

Daly JS, Ellison RT. Acute pneumonia. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 67.

Metlay JP, Waterer GW, Long AC, et al. Diagnosis and treatment of adults with community-acquired pneumonia. An Official Clinical Practice Guideline of the American Thoracic Society and Infectious Diseases Society of America. Am J Respir Crit Care Med. 2019;200(7):e45-e67. PMID: 31573350 pubmed.ncbi.nlm.nih.gov/31573350/.

Musher DM. Overview of pneumonia. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 91.

Updated by: Denis Hadjiliadis, MD, MHS, Paul F. Harron, Jr. Professor of Medicine, Pulmonary, Allergy, and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A. M. Editorial team.

Pneumocystis jirovecii pneumonia – Symptoms, diagnosis and treatment

Last viewed: 29 May 2023

Last updated: 26 January 2021

The microorganism Pneumocystis jirovecii was previously known as Pneumocystis carinii.

Pneumocystis pneumonia (PCP) is suspected based on clinical signs and symptoms of pneumonia in immunocompromised individuals, especially those with HIV infection.

Diagnosis is by detection of the microorganism in sputum or bronchoalveolar lavage (BAL).

Trimethoprim/sulfamethoxazole (TMP/SMX) is the drug of choice.

The incidence of PCP is decreasing with combination antiretroviral therapy (ART) and PCP prophylaxis.

Definition

Plasma cell pneumonia (PCP) is an infection in the lungs caused by the fungal organism Pneumocystis jirovecii (formerly known as Pneumocystis carinii). Typically, the pathogen causes disease in patients with severe immunodeficiency, in particular in HIV-positive patients with a CD4 cell count <200/μL, patients after hematopoietic cell and solid organ transplants, or patients on ongoing immunosuppressive therapy.

History and examination

Key diagnostic factors

• HIV-positive

More key diagnostic factors

Other diagnostic factors

• oral candidiasis cavity
• recurrent bacterial pneumonia
• weight loss
• long duration of symptoms ( HIV-positive patients)
• rapid onset of symptoms (HIV-negative patients)
• fever
• dry cough
• shortness of breath
• fatigue
• normal chest examination
• tachycardia
• tachypnea or respiratory distress
• cyanosis
• extrapulmonary manifestations
• pleural chest pain
• unilateral attenuated breath sounds

Other diagnostic factors

Risk factors

• CD4 count less than 200/µl
• immunocompromised state
• chronic corticosteroid therapy
• previous pneumocystis pneumonia

More risk factors

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Diagnostic tests

Primary screening studies

• chest x-ray
• arterial blood gases
• serum LDH
• induced sputum

More tests that are indicated first

tests to consider

• high resolution computed tomography (HRCT) of the chest
• lung function tests
• bronchoscopy and bronchoalveolar lavage (BAL)
• biopsy

More tests to consider

Urgent tests

9B M. J. Best Practice

Treatment algorithm

Initial

high risk of developing pneumocystis pneumonia (PCP)

Acute

adults or adolescents: HIV positive

9000 3

children: HIV-positive or at risk of HIV infection

Immunocompromised adults or adolescents: HIV-negative patients and non-recipients of solid organs

Immunocompromised adults or adolescents: HIV-negative new patients and recipients parenchymal organs

CONTINUED

successfully completed treatment for PCP infection

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Compilers

Authors

Reviewers

Community-acquired pneumonia prevention

90 002 Community-acquired pneumonia is one of the most common infectious diseases in the world and the Russian Federation and is a leading cause of death from infectious diseases. Usually, community-acquired pneumonia develops during the rise in the incidence of SARS and influenza, but the incidence can also be recorded at any time of the year, even in summer.

Community-acquired pneumonia is an acute disease that occurs outside the hospital or is diagnosed within the first 2 days of hospitalization. Acute pneumonia (pneumonia) is an infectious disease in which the lungs are involved in the inflammatory process. In severe cases, pneumonia can be fatal.

The main group of microorganisms that can cause community-acquired pneumonia: pneumococcus, Haemophilus influenzae, Klebsiella, chlamydia, mycoplasma, legionella, respiratory viruses.

The source of infection is a sick person with signs of a respiratory tract infection, as well as people with asymptomatic infection, without clinical symptoms of the disease.

The main route of transmission is airborne (when sneezing, coughing, talking, breathing). The source of infection for chlamydial pneumonia can be a bird (parrots, chickens, ducks). Legionella can “live” in air conditioners if they are not properly cared for. Mycoplasmosis of the respiratory tract is an infectious disease caused by a microbe that spreads in groups through close contact with a sick person. Often, mycoplasma causes pneumonia, similar in course to the flu. Disturbed by dry cough, fever, shortness of breath.

In typical cases, acute pneumonia is manifested by the following symptoms: fever, chills, cough, which may be dry at first, and then become wet with sputum, shortness of breath – a feeling of difficulty in breathing, pain in the chest. Also, the patient may be disturbed by general symptoms, especially in severe cases: severe weakness, lack of appetite.

Unfortunately, due to the peculiarities of the microorganisms themselves, as well as due to the illiterate and incorrect uncontrolled use of antibiotics, for example, in acute viral respiratory diseases (ARVI or ARI), many bacteria acquire resistance to a number of antibiotics. Treatment is prescribed only by a doctor.

Key recommendations for the prevention of pneumonia:

Despite advances in treatment, pneumonia is considered a serious illness. Preventive measures will help reduce the likelihood of developing pneumonia and staying healthy in any weather.

1. Avoid hypothermia and stress.
2. Wash hands frequently with soap and water for 15-30 seconds to remove germs that can cause pneumonia;
3. Do not smoke. The decay products of nicotine damage the bronchi and lungs, reduce their resistance to respiratory infections.
4. Protect your respiratory system. Inhalation of dust, strong chemical compounds is harmful to lung tissue.
5. Try to give preference to food enriched with vitamins and microelements, watch your weight.
6. Do gymnastics. Breathing exercises (regular deep movements such as inhalation-exhalation, inflating balloons) are aimed at improving lung ventilation.
7. Avoid contact with patients with influenza, other respiratory infections, measles, chickenpox (if not sick with these infections).