Extended-spectrum beta-lactamase producing enterobacteriaceae in a tertiary care hospital in Trinidad and Tobago

Extended-spectrum beta-lactamase (ESBL) mediated resistance to third generation cephalosporins, amongst the family Enterobacteriaceae, is emerging worldwide. This is the Caribbean's first survey on ESBL production, and was conducted during two six-month periods in 1998 and 2001, in a tertiary health institution in Trinidad and Tobago. Consecutive ampicillin resistant isolates of the family Enterobacteriaceae from in-patients were screened for resistance to third generation cephalosporins, and for ESBL production. The proportion of isolates found to be ESBL producers was similar in both samples (40 of 560 and 23 of 361). Overall, ESBL production was more frequent in enterobacter, citrobacter and proteus (and related organisms) than in Klebsiella and Escherichia (11.2 and 4.6, respectively, p < 0.001). In the 1998 sample, this proportion (9.8 versus 5.8) was significant (p < 0.05), but the difference was more marked in the 2001 sample (13.6 versus 2.9, p < 0.001). Continued distribution of these resistant bacterial strains is of concern. In the Caribbean region, more laboratory surveillance and increased infection control vigilance are recommended, with focus on specific genera in the family

Determination of high level resistance to aminoglycosides among enterococci.

Two hundred and ten strains of enterococci showing resistance to gentamicin (10 micrograms/disc) were tested for high level resistance by detecting the minimum inhibitory concentration and by using high content disc diffusion test. Only 67 per cent of these had high level resistance to gentamicin. High level kanamycin resistance in the group was 84 per cent, while high level streptomycin resistance was 61 per cent. Only 85 of the 140 strains with high level gentamicin resistance had similar streptomycin resistance. Results using locally made high content discs, correlated 100 per cent with MIC results. High level resistance to enterococci should be reported on a routine basis, especially when isolated from patients with serious infections.