Study on antimicrobial susceptibility of bacteria causing neonatal infections: a 12 year study (1987-1998)

The method of Manual of Clinical Microbiology was used to identify bacteria. We investigated the epidemiological characteristics of bacterial agents and their antimicrobial susceptibility as empirical treatment for neonatal infections. Disk diffusion tests were also done for antimicrobial susceptibility.

From January 1987 to December 1998, 2,244 bacterial strains were isolated in our neonatal ward. The first three predominant species were Staphylococcus epidermidis (23.9%), Staphylococcus saprophyticus (19.9%) and Escherichia coli (12.6%) in group I (infections acquired outside of hospital). Escherichia coli, Klebsiella and Pseudomonas aeruginosa accounted for 18%, 15.2% and 12.6% respectively in group II (nosocomial infections). The sensitivity rates of those antimicrobials that are seldom used for newborns were found to be higher, while the resistant rates of the commonly used antimicrobial drugs have increased significantly. The resistant rates of bacterial isolate from group II to antimicrobial agents including penicillin and ampicillin were significantly higher than those isolated from group I (p<0.05)The sensitivity rate was 82.2% (717/833) by using amikacin only, when combined with penicillin, rose to 89%(741/833).

Gram-negative bacteria were mainly responsible for nosocomial infections of neonates in our hospital. Infections acquired outside the hospital were mainly caused by Gram-positive bacteria. Nosocomial pathogens produced drug resistance easily. Combination of amikacin and penicillin can be recommended as the initial antibiotics for treatment of neonatal infections.