Abstract
OBJECTIVES: To review the epidemiology of community acquired, nursing home acquired and nosocomial pneumonia in terms of clinical. bacteriological and radiological features and to examine the spectrum of and response to antimicrobial agents used in its management.DESIGN: A retrospective review of all hospital records with pneumonia coded in the discharge diagnoses over a five-year period from April 1987 to March 1993.SETTING: University-affiliated, community-based hospital with a mixed primary to tertiary referral base.PATIENT SELECTION: Patients included in the study were all patients with a diagnosis of pneumonia as identified by computer records of diagnostic codes of all discharges: patients with a specific diagnosis of Pneumocystis carinii pneumonia were excluded. One thousand seven hundred and eighty-two patients out of 74.435 discharges over the five-year period met the inclusion criteria.RESULTS: The initial 1300 of the 1782 cases of pneumonia are included in this interim report. Mean age was 65 years (range 16 to 103) wilh 60% men and 40% women. Sixty-two percent of all cases were community acquired, 29% were hospital acquired and 9% were nursing home acquired. One thousand two hundred and sixty (97%) patients had al least one concomitant medical condition. mainly cardiac disease. alcoholism and chronic obstructive lung disease. Chest roentgenogram was abnormal in 98%. Cultures of sputum, bronchoalveolar lavage fluid, blood and/or serology revealed positive results in 785. The most common pathogens were Streptococcus pneumoniae (154). Haemophilus influenzae (147). Staphylococcus aureus (111) and Pseudomonas aeruginosa (100). In the group with community acquired pneumonia, S pneumoniae and H influenzae predominated. In the hospital acquired pneumonia group S aureus and P aeruginosa were more common. although S pneumoniae remains a significant pathogen. In the nursing home acquired pneumonia group. Gram-negative agents were the most common. The pattern of antimicrobial agents used, usually begun empirically when culture results are pending. showed that the majority of patients was treated with combination antibiotics for both Gram-positive and Gram-negative coverage. Ceftriaxone was usually prescribed with either erythromycin or clindamycin. In about half the patients. the ceftriaxone dose was 1 g per clay. Ninety-six (7%) patients developed complications of pneumonia and 207 (16%) patients required intensive care unit admission. Nine hundred and fifty-nine (73%) patients were cured or improved at time of discharge, 21 ( 1.5%) patients discharged themselves against medical advice and 320 (25%) patients died during admission to hospital, of whom 165 cases had pneumonia listed as a cause on the death certificate.CONCLUSIONS: Pneumonia remains a significant illness with high morbidity and mortality. Those affected and requiring hospitalization are elderly and ill. The most common pathogens overall continue to be S pneumoniae and H influenzae, although Gram-negative organisms and S aureus were also significant agents in nosocomial and nursing home acquired pneumonia. The high percentage of Gram-negative infections in the community acquired group has not been previously described and may represent a change in the pattern of pathogens affecting this group. Three of the 53 community acquired cases in whom P aeruginosa was implicated were detected on blood cultures and were definitely pathogens. Ten of the 53 patients had underlying bronchiectasis or cystic fibrosis and one patient had a history of hematogenous malignancy. Whether the finding of P aeruginosa represents true pathogenicity or colonization in the 53 cases is difficult to differentiate in a retrospective fashion. However. all but two received antibiotic therapy. and 10 of the 40 survivors in this subgroup received adequate coverage for pseudomonas. Although yield from routine investigations is only 60% (785 of 1300 patients in this study), cultures of blood and sputum should be sent in all patients as it may help to narrow choice of antimicrobial agents and aid in oral step-down selection . Only in select patients should serum serology and more costly and invasive procedures such as bronchoscopy and thoracocentesis be done. It appears that the current pattern of antimicrobial use is appropriate for management of pneumonia given the pattern of offending organisms seen. In the present study, pragmatic use of ceftriaxone at 1 g/24h in these sick patients appeared to result in a therapeutic outcome similar to other antibiotic combination therapy.