Diagnosis:
The diagnosis of pneumonia in infants and children can be readily established by the patient’s history, physical examination and chest roentgenogram, but the microbial etiology of pneumonia is difficult to determine. Chest roentgenogram does not always distinguish viral from bacterial pneumonia. Blood cultures may be positive only in 5-10% of the cases. Rapid bacterial antigen detection is test in serum, urine and pleural fluid may be positive in as many as 25% but is not specific for the bacterial etiology of pneumonia.

Guidelines for hospitalization in a patient presenting with pneumonia
a. Associated conditions (diabetes mellitus, neoplasm, immunosuppression, heart or kidney involvement)
b. If the suspected cause is staph aureus, gram negative or anaerobes
c. Severe leukopenia (< 500 wbc/ml)
d. Inability to take oral medications or failure of outpatient management
e. Tachypnea
Tachycardia
Hypotension (<90 mm of Hg systolic)
Hypoxemia (PaO2 < 60 mm of Hg)
f. Altered mental status
g. Associated suppurative conditions like septic arthritis, meningitis, empyema.

Treatment: The decision to give antimicrobial therapy is most often based on the physicians assessment of the probability of bacterial infection. This decision and the choice of antibiotic therapy is based on the clinical findings (severity of illness), the most likely organism for the patient’s age, immunological competence of the host, and epidemiological factors. (Refer Table - 2)

Duration of therapy: A total duration of 7-10 days therapy is recommended for treating uncomplicated pneumonia. Those with complications like pleural effusion, or empyema require 2 to 4 weeks of therapy.

Nosocomial or hospital acquired pneumonia: Nosocomial viral respiratory infections are common in winter and are caused by RSV or influenza viruses. Hospital acquired bacterial pneumonias commonly occur in children who are intubated and are receiving mechanical ventilation. Fever, change in the character of the sputum and newer pulmonary infiltrates on the chest roentgenogram suggest possible pneumonia in such patients. The bacterial etiologic agents are those that colonise the orotracheal airway. Initially antibiotic therapy is directed against the organisms colonising the host and the known nosocomial pathogens within the ICU. In general an aminoglycoside is included in the initial antibiotic regimen, since gram negative organisms commonly colonise in this setting. If MRSA is endemic within the unit, vancomycin is used.

Pneumonia in the immuno compromised host: Patients who are immunocompromised as in those with HIV infection or on chemotherapy for leukemia or those who develop neutropenia, are susceptible to gram negative bacterial infections.A combination of an aminoglycoside (gentamicin, amikacin) and an extended spectrum of ß- lactiam, such as mezlocillin, piperacillin or ceftazidime is appropriate. Addition of antistaphylococcal agent is to be considered if the child has an indwelling central line and thus is prone to G+ bacteremia.

Infection with pneumocystis carinii is suspected in these individuals who present with cough, fever, exertions/dyspnea hypoxia and diffuse alveolar infiltrates. Parenteral co-trimoxazole (20 mg/kg of TMP) is the drug of choice. Amphotericin B is indicated for children with suspected or proven fungal pneumonia.

S.pneumoniae and H.influenza are predominant pathogens in children with AIDS. Cefuroxime is an appropriate choice for initial therapy.