P40 The phenotypic and molecular analysis of β-lactam resistance in Pseudomonas aeruginosa and Escherichia coli samples in Trinidad

TL;DR

This study analyzed β-lactam resistance in Pseudomonas aeruginosa and Escherichia coli from Trinidad and Tobago, finding high resistance rates and new gene variants.

Contribution

The first comprehensive phenotypic and molecular analysis of β-lactam resistance in Trinidad and Tobago, including the first report of OXA, SHV, and CTX genes in local isolates.

Findings

33.8% of E. coli and 23.5% of P. aeruginosa were cephalosporin resistant.

9.2% of E. coli and 23.4% of P. aeruginosa were carbapenem resistant.

OXA, SHV, and CTX genes were first reported in Trinidad and Tobago isolates.

Abstract

Beta Lactam Resistance is an ever increasing global phenomenon. Tracking both the phenotypic and molecular incidence of β-lactam resistance is of paramount importance.

To (i) use AST methods to gain an understanding of the extent of antimicrobial resistance of Pseudomonas aeruginosa and Escherichia coli in Trinidad and Tobago; and (ii) use PCR to understand the molecular basis of antimicrobial resistance in P. aeruginosa and E. coli in Trinidad and Tobago.

The study collected 132 Pseudomonas aeruginosa and 154 E. coli and used phenotypic methods to detect antimicrobial susceptibility. The Polymerase Chain reaction (PCR) was used to identify six ESBL genes (TEM SHV, CTX, AmpC, KPC and OXA in the samples.

Of the E.coli samples collected, 52 (33.8%) of them were cephalosporin resistant, while among the P. aeruginosa samples, 31 (23.5%) of the samples were cephalosporin resistant. 9.2 % of the E. coli samples and 23.4 % of the P. aeruginosa samples were found to be carbapenem resistant. Of the Pseudomonas isolates tested, SHV, CTX, AmpC, OXA and KPC genes were found and within the E. coli samples TEM, SHV CTX and OXA genes were found. More than one gene was detected in some isolates.

The results described in this study represent the first and most comprehensive published phenotypic analysis of cephalosporin and carbapenem resistance of both E. coli and P. aeruginosa in Trinidad and Tobago. The rates of resistance are in line with other studies that have been published internationally. This represents the first time the OXA gene has been described in Trinidad and Tobago and the first time that SHV and CTX type β-lactamase genes have been described in Pseudomonas isolates in Trinidad. This study provides opportunity for more research to be conducted on Gram-negative isolates in Trinidad and Tobago and the Caribbean region as many of the tested resistant isolates did not possess any of the genes interrogated, implying that other yet undescribed molecular causes may be responsible. New ESBL and carbapenemase variants have been described in samples showing antimicrobial resistance in Trinidad and Tobago. These findings contribute to the wealth of knowledge of the molecular mechanisms of antibiotic resistance globally but also provide opportunities for further study.