COMMUNITY ACQUIRED PNEUMONIA
community-acquired pneumonia: Pneumonia occurring in outpatients, often caused by infection with streptococcus, Haemophilus influenzae, Staphylococcus aureus, and atypical organisms. Mortality is approximately 15% but depends on many host and pathogen features
History COMMUNITY ACQUIRED PNEUMONIA
- Cough, fever, dyspnea, chills
- Chest pain (pleuritic or nonpleuritic)
- Thick, yellow-green, bloody or rusty sputum
- Mental status changes: Anxiety, confusion, restlessness, obtundation, coma
- Abdominal pain, anorexia, diarrhea
- Insidious onset of dry cough
- Extrapulmonary symptoms: Diarrhea, headache, myalgias, sore throat
- Asthma patients
- Immunosuppressed patients
- Age more than 70 years
- Congestive heart failure
- Cerebrovascular disease
- Tobacco smoking
- Male patients
- Black race
- HIV infected patients
- End stage renal disease Leukopenia.
Etiology of Community Acquired Pneumonia (CAP)
- The organism causing pneumonia may be isolated from:
- Blood culture Sputum
- Pleural fluid
- Pulmonary tissue Bronchial secretion
- Pleural fluid
- Nasopharyngeal swab.
- Community acquired pneumonia or CAP may be caused by bacteria, fungi, viruses and parasites.
- The infecting agent is usually
- Streptococcus neumoniae Hemo hilus influenzae Staphylococcus aureus B’ycoplasma pneumon@e C. pneumoniae
- Moraxella catarrhalis k-egionel@
- Aerobic gram negative bacteria Influenza virus
- respiratory syncytial virus.
- Out of all these S. pneumoniae is the commonest.
Clinical manifestations of CAP
- Onset may be sudden, or slow / insidious.
- Pleuritic chest pain
- Chills and rigors
- . Shortness of breath
Other Additional symptoms:
- Nausea, vomiting, diarrhoea Myalgia, arthralgia
- Fatigue, weakness Confusion
- Cough, with no sputum or rust-coloured or purulent sputum.
Physical Exam COMMUNITY ACQUIRED PNEUMONIA
- Pulse oximetry to evaluate oxygenation
- Tachypnea, tachy/bradycardia, cyanosis
- Decreased breath sounds, rales, friction rub
- Consolidation: Egophony, increased fremitus, pectoriloquy, dullness to percussion
- Abdominal tenderness or pain
- VAP is suspected when a patient receiving mechanical ventilation develops a new or progressive infiltrate with fever, leukocytosis, or purulent tracheobronchial secretions; increased respiratory rate, increased minute ventilation, decreased tidal volume, decreased oxygenation, or a need for more ventilator support or inspired oxygen
Physical signs COMMUNITY ACQUIRED PNEUMONIA
- Tachynea – Respiratory rate more than 25/ min.
- Iness on percussion of lungs
- Increased vocal fremitus
- Whispering pectoriloquy Crackles
- Pleural friction rub.
Pneumonia is considered severe and has a bad prognosis if :
- Patient has confusion Blood urea is increased
- Respiratory rate is more than 30/min
- Systolic blood pressure is less than 90 mmHg Patient needs ventilator
- Patient requir~s vasopressors
- There is multi lobar involvement
- Mortality rate is high with infection with Pseudomonas aeruginosa, Klebsiell, E. coli, Staph aureus, Acinetobacter
- In healthy patients it takes 5 – 14 days to recover from community acquired pneumonia.
Fatal complications are:
- Respiratory failure Congestive heart failure Shock
- Atrial arrhythmias Myocardial infarction GI bleeding
- Renal failure.
Community acquired pneumonia in immunocompromised persons
- Pneumonia is common in HIV patients, transplant recipients, patients of malignancy.
Investigations and Chest x-ray
Initial Lab Tests COMMUNITY ACQUIRED PNEUMONIA
- Routine diagnostic tests to identify an etiologic diagnosis are optional for outpatients with CAP.
- Complete blood count (CBC) with differential (leukocytosis with left shift), Chem 7
- If age >60 years or with coexisting illness, arterial blood gases (ABGs) for low PO2or for suspected acidosis
- Sputum Gram stain and culture: Good sample >25 polymorphonuclear neutrophils (PMNs) and <10 epithelial cells/low-power field (LPF)
- Blood culture before antibiotics: 5–14% positive
- These show conasolidation, pulmonary opacities, cavity, lung abscess, air-fluid levels, crescent or meniscus sign in aspergillosis, miliary shadows, pleural effusion.
- Should be taken if patient has temperature more than 38.50C i.e. hyperthermia,
- temperature <36°C i.e. hypothermia, patient is alcoholic, and hospitalized patients.
- Two blood cultures should be sent.
- Most commonly S. pneumoniae, S. aureus and E. coli
- are isolated
Sputum slide and culture:
- Gram’s stain of sputum should be done to see Gram positive diplococi,
- M. tuberculosis,
- AFB stainin for tuberculosis.
- Monoclonal antibody staining for pneumocystis pneumonia.
- Special stain for fungi.
Detection of Antigens in urine:
- Legionnaires disease can be diagnosed by antigen in urine of patients by ELISA (enzyme linked immunosorbent assay).
- S. pneumoniae can also be diagnosed by ELISA for urinary antigen.
- IgM antibody. levels for specific pathogens are increased in
- M. pneumoniae,
- C. pneumoniae,
- C. burnettii,
- Other tests are complement fixation, ELISA, IgG antibodies.
Polymerase chain reaction (PCR) :
- A multiplex PCR detects DNA of the pathogen.
- Outpatient treatment and no risk factors for drug-resistant S. pneumoniae(DRSP) infection:
- Macrolide e.g., azithromycin, clarithromycin, or erythromycin, doxycycline
- Doxycycline is alternative in face of comorbidities or other risk for DRSP infection: Chronic heart failure; lung, liver, or renal disease; diabetes mellitus; alcoholism; malignancies; asplenia; immunosuppressing conditions or use of immunosuppressive drugs; use of antimicrobials within the previous 3 months (in which case an alternative from a different class should be selected)
- Respiratory fluoroquinolone (e.g., moxifloxacin, gemifloxacin, or levofloxacin 750 mg) Lactam plus a macrolide High-dose amoxicillin (1 g t.i.d.) or amoxicillin-clavulanate (2 g b.i.d.); alternatives include ceftriaxone, cefpodoxime, and cefuroxime (500 mg b.i.d.) and doxycycline