The changing trend in the pattern of infective etiologies in childhood acute lower respiratory tract infection

The etiologic agents causing acute lower respiratory tract infection (LRTI) in hospitalized children were compared for 1995 and 1988. Between May 1994 to April 1995, 397 children were admitted to Tan Tock Seng Hospital for acute LRTI compared to 240 children in 1988. The following criteria for LRTI were used: (i) age less than 12 years with a community-acquired LRTI; (ii) presence of cough or fever of less than 2 weeks' duration; and (iii) presence of tachypnea, chest retractions or pulmonary infiltrates on chest X-ray. Sputum cultures were considered suitable for culture if there were less than 25 epithelial cells per low power field. Moraxella catarrhalis was considered only if heavy growth of more than 3+ was seen. Etiological agents were found in about 70% of patients in both studies. Viruses constituted 41.3% of the etiologic agents in 1995 but constituted only 28% in 1988; 36% had a bacterial etiology in 1995 compared to 15% in 1988. The most common bacteria in 1995 was M. catarrhalis (34.7%) followed by non-type B Haemophilus influenzae (33%). In contrast, in 1988, Mycoplasma (33%) was the predominant organism followed by H. influenzae (17%) and M. catarrhalis (11.4%). The increased incidence of M. catarrhalis could be due to antibiotic selection. A mixed viral-bacterial etiology was found in 12.3% of the 1995 cohort. The majority of the bacteria were positive by sputum cultures; only 4 (3.3%) had positive blood cultures. No penicillin resistance was detected in 1988; however, in 1995, penicillin resistance was found in 17% of the Streptococcus pneumoniae, 38.5% of H. influenzae and 83% of M. catarrhalis. It was also found that 30% of the S. pneumoniae were also resistant to erythromycin, and 23% were resistant to sulfamethoxaxole-trimethoprim; 5% of the H. influenzae had multiple resistance to erythromycin, sulfamethoxazole-trimethoprim and chloramphenicol. Among those patients with antibiotic resistance, 30% had received prior antibiotics of which 18% had had two or more antibiotics, frequently erythromycin or amoxycillin/ampicillin. Judicious use of antibiotics is required to check the rising trend of antibiotic resistance.