SUSCEPTIBILITIES OF CLINICAL ISOLATES TO ANTIBACTERIAL AGENTS

A STUDY MAINLY FOCUSED ON OFLOXACIN (THE SECOND REPORT)

Abstract

Susceptibilities of various clinical isolates to ofloxacin (OFLX) and other antibacterial drugs were examined at 128 hospital laboratories in 36 prefectures throughout Japan between April, 1986 and March, 1987. The results were totalized with an emphasis mainly on OFLX and were compared with data obtained in the previous year. In this study, identification and susceptibility tests of the isolates were carried out at each hospital laboratory and the tests were performed according to the 1-dilution or 3-dilution disc method in which susceptibilities are classified into 4 grades: +++, ++, +, and-.
Similarly to the study performed in the previous year, species showing susceptibilities to OFLX included Staphylococcus aureus (4,205 strains), Staphylococcus epidermidis (2,009 strains), Entercoccus faecalis (1,697 strains), Streptococcus pneumoniae (702 strains), Escherichia coli (4,097 strains), Klebsiella pneumoniae (1,375 strains), Enterobacter cloacae (762 strains), Enterobacter aerogenes (296 strains), Citrobacter freundii (406 strains), Proteus mirabilis (613 strains), Morganella morganii (320 strains), Serratia marcescens (869 strains), Haemophilus influenzae (1,282 strains), Pseudomonas aeruginosa (4,206 strains), Acinetobacter calcoaceticus (351 strains), Acinetobacter sp.(415 strains), and Campylobacter jejuni (151 strains). Neisseria gonorrhoeae (26 strains) were exceptional due to their smaller number this time than that of the previous year and only the susceptibility to OFLX was investigated with this species. As results, OFLX showed strong antibacterial activities (similar to the previous year) against S. aureus, S. epidermidis, N. gonorrhoeae, E. coli, K. pneumoniae, E. cloacae, E. aerogenes, C. freundii, P. mirabilis, M. morganii, H. influenzae, A. calcoaceticus, Acinetobacter sp., and C. jejuni. However, when these susceptibilities shown in the present study were compared to those obtained in the previous year, many species showed decreases in the occurrence of +++ or increases in-, though they were rathersmall changes.
The following species were not totalized in the previous year due to their low numbers but were summarized in combination with those examined in this study: Streptococcus pyogenes (944 strains), Streptococcus agalactiae (815 strains), Enterococcus faecium (146 strains), Branhamella catarrhalis (135 strains), Citrobacter diversus (128 strains), Klebsiella oxytoca (873 strains), Proteus vulgaris (438 strains), Serratia liquefaciens (266 strains), Pseudomonas cepacia (433 strains), Pseudomonas putida (154 strains), Xanthomonas maltophilia (272 strains), Vibrio parahaemolyticus (120 strains), Bacteroides fragilis (98 strains), and Bacteroides sp.(279 strains). As results, OFLX showed strong antibacterial activities against B. catarrhalis, K. oxytoca, P. vulgaris, C. diversus, S. liquefaciens, and V. parahaemolyticus.
Susceptibilities of the main species to OFLX were compared with the proportion (in %) of+++ as the index for different sampled materials such as sputum, urine, pus and otorrhea to understand susceptibility changes occured for different species from the previous year to this year. It was recognized that many species showed decreases in the proportion of +++.
Consequently, the results show that bacteria resistant to OFLX have appeared following its widespread use and they tended to increase in number.