Community acquired pneumonia resident survival guide
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Chetan Lokhande, M.B.B.S [2]
Overview
A lower respiratory tract infection in a previously normal individual acquired through normal social contact rather than contracting it in a hospital. Community-acquired pneumonia (CAP) is a disease in which individuals who have not recently been hospitalized develop an infection of the lungs. CAP is a common illness and can affect people of all ages. It often causes problems like dyspnea, fever, chest pain, and cough. CAP causes fluid accumulation in the alveoli leading to poor gas exchange. CAP is common worldwide and is a leading cause of illness and death. Causes of CAP include bacteria, viruses, fungi, and parasites. CAP can be diagnosed by history and a physical examination alone, though x-rays, sputum examinations, and other diagnostic tests are often used. As CAP is often bacterial, the primary empiric treatment consists of wide-spectrum antibiotics. Some forms of CAP, such as pneumococcal pneumonia may be prevented by vaccination.
Causes
Life Threatening Causes
Life-threatening causes include conditions which may result in death or permanent disability within 24 hours if left untreated. Complications of community acquired pneumonia, such as pleural effusion, lung abscess, bacteremia and septicemia are life-threatening conditions and must be treated as such irrespective of the causes.
Common Causes
Following are the causes listed according to the microbiological etiology
- Typical Bacteria
- Streptococcus pneumoniae
- Haemophilus influenzae
- Escherichia coli
- Klebsiella pneumoniae
- Pseudomonas aeruginosa
- Atypical Bacteria
- Viruses
Following are the causes listed according to the the location of the patient[1][2][3]
- Outpatient
- Streptococcus pneumoniae
- Mycoplasma pneumoniae
- Haemophilus influenzae
- Chlamydophila pneumoniae
- Influenza A and B, adenovirus, respiratory syncytial virus, parainfluenza
- Inpatient (non-ICU)
- Streptococcus pneumoniae
- Mycoplasma pneumoniae
- Chlamydophila pneumoniae
- Haemophilus influenzae
- Legionella
- Aspiration
- Influenza A and B, adenovirus, respiratory syncytial virus, parainfluenza
- Yersinia enterocolitica
- Inpatient (ICU)
- Streptococcus pneumoniae
- Staphylococcus aureus
- Legionella
- Gram-negative bacilli
- Haemophilus influenzae
- Acinetobacter baumannii
Management
Shown below is an algorithm depicting the management of community acquired pneumonia according to the Infectious Diseases Society of America (IDSA) and Thoracic Society Consensus Guidelines on the Management of Community Acquired Pneumonia in Adults.[4][5]
Examine the patient: Vital signs
❑ Respiratory rate (tachypnea may be present) Respiratory examination: Signs of increased severity: Look for signs suggestive of the infectious agent: Inquire about history clues suggestive of the infectious agent: Consider alternate diagnosis: | |||||||||||||||||||||||||||
Order laboratory tests: ❑ Complete blood count (CBC)
❑ Blood urea nitrogen (BUN)
Order imaging studies:
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Does the patient have any of the following conditions that warranty additional testing? ❑ Admission to ICU due to severe pneumonia | |||||||||||||||||||||||||||
Yes Additional lab tests are recommended | Additional lab tests are optional | ||||||||||||||||||||||||||
Order additional testing: ❑ Blood gram stain and culture
❑ Expectorated sputum gram stain and culture
❑ Endotracheal aspirate gram stain and culture (if patient is intubated)
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Does the patient meet any of the following criteria for hospital admission? ❑ CURB-65 score ≥ 2, OR | |||||||||||||||||||||||||||
Yes Treat as inpatient | No Treat as outpatient | ||||||||||||||||||||||||||
Does the patient have any of the following criteria for ICU admission? ❑ Invasive mechanical ventilation (major criteria), OR
| |||||||||||||||||||||||||||
Yes Admit to ICU | No Admit to general medical floor | ||||||||||||||||||||||||||
❑ Begin empiric antibiotic treatment | |||||||||||||||||||||||||||
❑ Follow up with cultures (if ordered) and change antibiotics according to the resistance profile | |||||||||||||||||||||||||||
Does the patient have the following criteria of clinical stability? ❑ Temperature ≤ 37.8 c | |||||||||||||||||||||||||||
Yes | No | ||||||||||||||||||||||||||
Continue antibiotics | Consider alternative diagnoses | ||||||||||||||||||||||||||
❑ Duration of treatment is not sufficient (< 72 hours)
❑ The causative agent is not covered by antibiotics
❑ The drug concentration is not sufficient (Vancomycin trough < 15 to 20 μg)
❑ Resistant organism (MRSA or pseudomonas)
❑ Nosocomial superinfection
❑ Parapneumonic effusion
❑ Parapneumonic empyema
❑ Abscess
❑ Metastatic infection (endocarditis, arthritis, meningitis)
❑ Drug fever
❑ Exacerbation of an existing comorbidity
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Empiric Antibiotics
Scenario | Empiric Antibiotics | |
Outpatient | ||
Previously healthy and no use of antimicrobials within the previous 3 months | A macrolide Doxycyline | |
Presence of comorbidities such as chronic heart, lung, liver or renal disease; diabetes mellitus; alcoholism; malignancies; asplenia; immunosuppressing conditions or use of immunosuppressing drugs | A fluoroquinolone (moxifloxacin, gemifloxacin, or levofloxacin [750 mg]) A b-lactam plus a macrolide | |
Use of antimicrobials within the last 3 months | An alternative from a different class should be selected: A fluoroquinolone (moxifloxacin, gemifloxacin, or levofloxacin [750 mg]) (strong recommendation; level I evidence) | |
In regions with a high rate (125%) of infection with high-level (MIC 16 mg/mL) macrolide-resistant Streptococcus pneumoniae | A fluoroquinolone (moxifloxacin, gemifloxacin, or levofloxacin [750 mg]) A b-lactam plus a macrolide | |
Inpatient | ||
General medical ward admission | A respiratory fluoroquinolone A b-lactam plus a macrolide |
|
ICU admission | A b-lactam (cefotaxime, ceftriaxone, or ampicillin-sulbactam) plus azithromycin A b-lactam (cefotaxime, ceftriaxone, or ampicillin-sulbactam) plus a fluoroquinolone
| |
Concern about pseudomonas | An antipneumococcal, antipseudomonal b-lactam (piperacillintazobactam, cefepime, imipenem, or meropenem) plus either ciprofloxacin or levofloxacin (750 mg)
| |
Concern about community acquired MRSA | Add vancomycin or linezolid |
Empiric Antiviral
Scenario | Empiric Antiviral |
Symptoms suggestive of influenza and exposure to poultry in areas with previous H5N1 infection | Test for H5N1 Initiate droplet precautions Initiate routine infection control measures Treat influenza with oseltamivir Antibiotic coverage for S. pneumonia and S. aureus |
Considerations in Severe Cases
Scenario | Management |
CAP + persistent septic shock | Administer drotrecogin alpha |
CAP + hypotension requiring resuscitation | Screen for occult adrenal insufficiency |
Hypoxemia | Trial of noninvasive ventilation |
Severe hypoxemia (PaO2/FiO2 < 150) + bilateral alveolar infiltrates | Immediate intubation |
ARDS or diffuse bilateral pneumonia on ventilation | Low tidal volume ventilation (6 cm3/kg of ideal body weight) |
Pneumonia Severity Index
Step 1 Does the patient have any of the following conditions?
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
No
Risk Class I | Yes | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Step 2
Assess the following conditions and assign the corresponding scores:
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
∑ <70 = Risk Class II | ∑ 71-90 = Risk Class III | ∑ 91-130 = Risk Class IV | ∑ >130 = Risk Class V | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
CURB-65
Criteria | Score |
Confusion (defined as an AMT of 8 or less) | 1 |
Urea greater than 7 mmol/l (Blood Urea Nitrogen > 20) | 1 |
Respiratory rate of 30 breaths per minute or greater | 1 |
Blood pressure less than 90 systolic or diastolic blood pressure 60 or less | 1 |
Age 65 or older | 1 |
Do's
- If the patient presented to the emergency department, administer the fist dose of antibitoic therapy as soon as possible, preferably within 6 hours of presentation.[6]
- Among patients admitted to the hospital, switch from IV to PO antibiotics as soon as the patient is hemodynamically stable with clinical improvement and ability to tolerate oral intake. When the patient is switched to PO antibiotics, the patient can be discharged on PO home medications.
- The duration of antibiotics is at least 5 days; antibiotic treatment are not discontinued until the patient is afebrile for 48-72 hours and with not more than one sign of instability.
- Use fibre-optic bronchoscopy in immunocompromised individuals to detect less common organisms, obtain a tissue biopsy, and identify anatomic lesions if any.
- Treat influenza A with oseltamivir or zonamivir only if time from onset of symptoms < 48 hours.
- Consider a F/U chest X-ray at 6 weeks to rule out an underlying lung malignancy.
Dont's
- Inadvertently use of antibiotic for patients without community-acquired pneumonia who require treatment within 4 hours may increase the risk of Clostridium difficile colitis.[7] Hence, use antibiotics judiciously.
References
- ↑ Mandell LA, Wunderink RG, Anzueto A, Bartlett JG, Campbell GD, Dean NC, Dowell SF, File TM, Musher DM, Niederman MS, Torres A, Whitney CG (2007). "Infectious Diseases Society of America/American Thoracic Society consensus guidelines on the management of community-acquired pneumonia in adults". Clinical Infectious Diseases : an Official Publication of the Infectious Diseases Society of America. 44 Suppl 2: S27–72. doi:10.1086/511159. PMID 17278083. Unknown parameter
|month=
ignored (help) - ↑ Wong, KK.; Fistek, M.; Watkins, RR. (2013). "Community-acquired pneumonia caused by Yersinia enterocolitica in an immunocompetent patient". J Med Microbiol. 62 (Pt 4): 650–1. doi:10.1099/jmm.0.053488-0. PMID 23242642. Unknown parameter
|month=
ignored (help) - ↑ Oh, YJ.; Song, SH.; Baik, SH.; Lee, HH.; Han, IM.; Oh, DH. (2013). "A case of fulminant community-acquired Acinetobacter baumannii pneumonia in Korea". Korean J Intern Med. 28 (4): 486–90. doi:10.3904/kjim.2013.28.4.486. PMID 23864808. Unknown parameter
|month=
ignored (help) - ↑ "http://cid.oxfordjournals.org/content/44/Supplement_2/S27.full.pdf+html". Retrieved 13 March 2014. External link in
|title=
(help) - ↑ "MMS: Error".
- ↑ Wilson, KC.; Schünemann, HJ. (2011). "An appraisal of the evidence underlying performance measures for community-acquired pneumonia". Am J Respir Crit Care Med. 183 (11): 1454–62. doi:10.1164/rccm.201009-1451PP. PMID 21239689. Unknown parameter
|month=
ignored (help) - ↑ Meehan, TP.; Fine, MJ.; Krumholz, HM.; Scinto, JD.; Galusha, DH.; Mockalis, JT.; Weber, GF.; Petrillo, MK.; Houck, PM. (1997). "Quality of care, process, and outcomes in elderly patients with pneumonia". JAMA. 278 (23): 2080–4. PMID 9403422. Unknown parameter
|month=
ignored (help)