FUNDAMENTAL AND CLINICAL STUDIES ON SERRATIA MARCESCENS. II

Sensitivity to Aminoglycoside Antibiotics

Abstract

A total of 341 strains of Serratia marcescens isolated from clinical specimens in 1977 was examined for their sensitivities to various antibiotics. The results in comparison with those of older isolates were described in the preceding report. It was found that more of the new isolates than of the old ones were resistant to gentamicin, nalidixic acid and miloxacin. As the increase in number of GM-resistant strains was prominent, these isolates were re-examined for their sensitivities to aminoglycoside antibiotics. Strong antibacterial activities were shown with gentamicin, KW-1062 and sisomicin. There were, however, many strains that were resistant to these antibiotics; 41% of the strains tested was resistant to gentamicin, 47.7% to KW-1060, and 50.9% to sisomicin.
Many of the isolates from urine were resistant strains, most of which were nonchromogenic.
As to the resistant pattern, hexa-resistant strains (gentamicin, amikacin, tobramycin, dibekacin, KW-1062, and sisomicin) were most abundant, occupying 25.8%, followed by triple-resistant (amikacin, tobramycin, and dibekacin), occupying 16.8%, and penta-resistant (gentamicin, tobramycin, dibekacin, KW-1062, and sisomicin), occupying 11.8%.
A larger portion of gentamicin-resistant strains was sensitive to amikacin, but was cross-resistant to the other four antibiotics.