Antimicrobial resistance: patterns and trends in the National University Hospital, Singapore (1989-1991).

The commonly isolated organisms, Staphylococcus aureus, Escherichia coli, Klebsiella species, Pseudomonas aeruginosa, Acinetobacter species, Proteus species and Enterobacter species from clinical material other than blood, cerebrospinal fluid and stool, were analysed for their incidence and increasing trends of resistance to the commonly used antimicrobials. Staphylococcus aureus was tested against penicillin, methicillin, erythromycin, gentamicin and co-trimoxazole; Pseudomonas aeruginosa against amikacin, ceftazidime, gentamicin, piperacillin and cefsulodin; and gram negative bacilli against ampicillin, co-trimoxazole, cephalexin, cefuroxime, ceftriaxone, nalidixic acid and nitrofurantoin. Methicillin sensitive Staphylococcus aureus exhibited a high degree of resistance to penicillin only (83%), but methicillin resistant Staphylococcus aureus (34-46%) showed nearly 100% resistance to all drugs tested except for co-trimoxazole over the period of study. A high incidence of resistance was found among Klebsiella species, Enterobacter species, Acinetobacter species and Pseudomonas species. Increasing trends of resistance against cephalosporins were noticed with respect to Acinetobacter species, Klebsiella species and Enterobacter species for cefuroxime and ceftriaxone; Pseudomonas aeruginosa for ceftazidime and cefsulodin. The overall resistance of organisms is notably high. Methicillin-resistant S. aureus is endemic and accounts for about 39% of all S. aureus isolates. The typical nosocomial organisms like Acinetobacter species and Klebsiella species are increasingly developing resistance to useful drugs such as gentamicin, cephalexin and ceftriaxone.