BackgroundIdentification of the prevalence and spread of ESBL-mediated antibiotic resistance is essential especially in the hospital setting. It is for this reason, more and more studies are highlighting the importance of complementing phenotypic ESBL-detection techniques with molecular techniques in order to understand the basis and extent of this form of resistance among clinically evolved bacterial populations, especially those belonging to the Enterobacteriaceae family. However, in Trinidad and Tobago and other Caribbean countries, very little is known regarding ESBL detection rates and/or the prevalence of genes conferring ESBL resistance.MethodologySixty-six Klebsiella pneumoniae isolates from clinical specimens phenotypically identified by the Microscan Walkaway-96 System as potential ESBL-producers were analysed in this study. Screening and confirmation of these isolates as ESBL producers was done by the Clinical and Laboratory Standards Institute (CLSI) approved methods. Polymerase chain reaction amplification of beta-lactamase genes bla TEM, bla SHV, bla CTX-M1, bla CTX-M2 and bla AmpC was performed to identify mechanisms of β-lactam resistance.ResultsESBL-producing K. pneumoniae was confirmed in 78.8% (41/52) from isolates collected from a variety of sources during the period, April–July 2015. bla SHV (84.8%) and bla CTX-M (46.9%) were the predominant β-lactamase genes identified. A single K. pneumoniae isolate possessed a bla CTX-M group 2 beta-lactamase gene. RAPD analysis identified a number of epidemiologically related isolates. However, current isolates were unrelated to isolates from previous years.ConclusionThis study revealed that among K. pneumoniae isolates exhibiting extended spectrum β-lactam resistance, there was a high prevalence of bla SHV and bla CTX-M genes. This result highlights the need for a reliable epidemiological apparatus that involves the molecular characterisation of ESBL resistance.Electronic supplementary materialThe online version of this article (doi:10.1186/s12941-017-0209-x) contains supplementary material, which is available to authorized users.
Shigella sonnei is an emergent cause of diarrheal disease in middle-income countries. The organism causes endemic disease and is also associated with sporadic outbreaks in susceptible populations. In 2010 and 2011 there were two suspected outbreaks of diarrheal disease caused by S. sonnei in La Pampa province in central Argentina. Aiming to confirm these as outbreaks and provide insight into the relationship of the strains causing these infections we combined antimicrobial susceptibility testing and pulsed field gel electrophoresis (PFGE) with whole genome sequencing (WGS). Antimicrobial susceptibility testing suggested the two events were unrelated; organisms isolated in 2010 exhibited resistance to trimethoprim sulphate whereas the 2011 S. sonnei were non-susceptible against ampicillin, trimethoprim sulphate and cefpodoxime. PFGE profiling confirmed the likelihood of two independent outbreaks, separating the isolates into two main XbaI restriction profiles. We additionally performed WGS on 17 isolates associated with these outbreaks. The resulting phylogeny confirmed the PFGE structure and separated the organisms into two comparatively distantly related clones. Antimicrobial resistant genes were common, and the presence of an OXA-1 was likely associated with resistance to cefpodoxime in the second outbreak. We additionally identified novel horizontally transferred genetic material that may impinge on the pathogenic phenotype of the infecting strains. Our study shows that even with a lack of supporting routine data WGS is an indispensible method for the tracking and surveillance of bacterial pathogens during outbreaks and is becoming a vital tool for the monitoring of antimicrobial resistant strains of S. sonnei.
Objective: Previous studies done in the hospital setting in Guyana have shown that the frequency of isolation of methicillin-resistant Staphylococcus aureus isolates far exceeds the worldwide estimate of 50%. These past studies have been based on the use of the Kirby-Bauer disk diffusion methodology. The present study was conducted to determine the minimum inhibitory concentration of clinical isolates of methicillin-susceptible and methicillin-resistant S. aureus using the broth microdilution method. Design and Methods: A total of 101 consecutive, non-repetitive S. aureus isolates obtained from the GPHC medical lab during a six-week period were included in the study. These isolates were identified as MRSA and MSSA by laboratory personnel using the cefoxitin disk diffusion method. The oxacillin MICs for all isolates obtained were determined using prepared oxacillin broth microdilution trays with concentrations ranging from 4 μg/ml to 256 μg/ml. All results were interpreted according to CLSI guidelines. Results: The prevalence of MRSA at GPHC was found to be 65.35% with a majority of the isolates being high level oxacillin resistant strains with MICs > 256 μg/ml (84.85%). In our study, most resistant isolates were collected from patients admitted to the FSW (16.67%), Paediatric Wards (13.65%), MSW (13.64%), and FMW (12.12%). Additionally, 35 (79.55%) MSSA were suspected oxacillin susceptible with MIC < 4 μg/ml. The relationship between the cefoxitin disc diffusion and oxacillin broth microdilution results was found to be statistically significant with a p < 0.001. Conclusion: Methicillin-resistance continues to be a major problem in the hospital setting, and this study has should that commonly used conventional techniques are unlikely to identify all of the potentially resistant isolates. Recommendation: The high prevalence and high oxacillin MIC of MRSA at GPHC suggests that more emphasis should be placed on infection control and surveillance programs within the hospital setting.
Background and Aim: Methicillin-resistant Staphylocccus aureus (MRSA) continues to be a major problem globally. Previous data had suggested that the prevalence of MRSA infections in the tertiary hospital setting was 51%. The aim of this study was to conduct a point prevalence survey of MRSA infections occurring at a tertiary-care hospital in Georgetown, Guyana, and to determine to what extent methicillin-resistance was occurring among Staphylococcus aureus isolates utilising the minimum inhibitory concentration (MIC) data. Study Design: This study was based on a prospective, analytical design. Place and Duration of Study: Microbiology department, Georgetown Public Hospital Corporation (GPHC), and Department of Medical Technology, University of Guyana, between May 2019 and July 2019. Methodology: A total of 101 consecutive, non-repetitive, laboratory-identified MRSA and methicillin-susceptible Staphylococcus aureus (MSSA) isolates were tested using an oxacillin broth microdilution method. Results: We found that 65.4% of Staphylococcus aureus were oxacillin (methicillin) resistant with a majority of the isolates being high level oxacillin resistant strains (i.e., MICs > 256 μg/ml) (84.85%). Most of the resistant isolates were collected from patients admitted to medical and surgical wards. Conclusion: Methicillin-resistance continues to be a major problem in the hospital setting and conventional techniques are unlikely to identify all of the potentially resistant isolates.
The Book of Abstracts Student Research 2020 is a collection of student undergraduate research emerging from the Department of Environmental Studies at the Faculty of Earth and Environmental Studies, University of Guyana. This first volume comprises topics covering climate change, air and water quality, ethno-meteorology, and wildlife ecology; and demonstrates the quality and diversity of research pursued by our students. It is our hope that this book will enhance interest in the respective subject areas, and that the findings are applied to inform development in Guyana.
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