Abstract: This report is based on a 1-year recruitment of all of the culture-positive Mycobacterium tuberculosis cases in Trinidad and Tobago (n = 132). The study population was characterized by a high male-to-female sex ratio of 4 and a human immunodeficiency virus-tuberculosis (TB) coinfection rate of 30%. It mainly occurred among African descendants, who represent 37.5% of the total population but 69.7% of all TB cases (P < 0.001). Spoligotyping resulted in 25 different patterns and 12 clusters (2 to 74 strains per cluster), with the predominance of a highly conserved spoligotype international type clone, SIT566.
Abstract: In 2006, the first isolate of KPC-2-producing Pseudomonas aeruginosa in the world was identified in Colombia. Recently, similar strains have been reported in Puerto Rico. We now report KPC-2-producing P. aeruginosa in Trinidad and Tobago. Surveillance for similar strains is warranted, considering their wide geographic spread and known association with mobile genetic elements.
Abstract: We report on a fine molecular and phylogenetical characterization of circulating Mycobacterium tuberculosis strains isolated from patients during a 1-year period in Trinidad and Tobago (T&T). The spoligotyping data coupled to minisatellite typing and available epidemiological data showed that a single major clone of "evolutionary modern" tubercle bacilli (SIT566) was responsible for more than half of the tuberculosis (TB) cases. It preferentially infected younger age groups (mean 39.1 years versus 47.7 years for other genotypes, p<0.0005), and was overrepresented in Port-of-Spain (1 out of 3 patients). A comparison of genotyping results to data gathered for 6 Caribbean countries (n=2653 clinical isolates) showed that the overall lineage distribution in T&T was completely different from its neighbors, e.g., T&T was the only country harboring a unique sublineage of the Latin American & Mediterranean (LAM) family, designated LAM-10CAM with phylogeographical specificity for Cameroon and neighboring countries in West Africa; interestingly 3/4 of the patients within this group in T&T were African descendants. Similarly, strains belonging to East African Indian (EAI) lineage with phylogeographical specificity for the Indian subcontinent, were found in T&T (13% of all strains), but were absent among the neighboring countries. Although the predominant SIT566 was not yet detected elsewhere in the Caribbean, available information underlined that this genotype was already present in the United States as imported cases of disease among T&T-born patients. Characterization of SIT566 strains using 12-, 15- and 24-loci MIRU typing, and comparison of results to international databases showed that these isolates were characterized by a common 12-loci MIRU pattern 224315153324 corresponding to MIRU International Type-MIT633 in 21/25 strains tested, as well as its 4 variants; an orphan pattern , MIT27-, MIT117-, and MIT1158-. Extended 24-loci MIRU typing led to a predominant pattern 224315153324323483334323 in a total of 16/21 MIT633 isolates, as well as identification of 3 supplemental patterns. Comparison of 24-loci MIRU data with the international database MIRU-VNTRplus showed the unique nature of the patterns obtained in T&T. Further analysis using the Levenshtein algorithm showed that the first 2 closest matches with the SIT566/MIT633 clone belonged to the X lineage strains in MIRU-VNTRplus. This observation corroborates our preliminary spoligotyping-based analysis using minimum spanning and neighbor-joining trees, which suggested a phylogenetical relatedness of the SIT566 clone with SIT119, which represents X1 lineage prototype in SpolDB4 database. We hypothesize that the predominant SIT566 clone might have evolved from a pool of X lineage M. tuberculosis strains with phylogeographical affinity for Anglo-Saxon descendants.
Abstract: Background: There are variations in the epidemiology, prevalent pathogens and antimicrobial susceptibility patterns of infections in the intensive care unit (ICU) from one health care facility to another, hospital to hospital, and country to country. This study was undertaken to determine and document the frequency of occurrence of microbial isolates and their antibiotic susceptibility pattern from clinical specimens received from the ICU of a tertiary regional hospital in Trinidad and Tobago.
Materials & methods: Microbial isolates from patients admitted to the ICU of the EricWilliams Medical Sciences Complex over a 4-year period were investigated. Automated systems and Standard microbiological methods including BACTEC 9240 (Becton-Dickinson Microbiology Systems), MicroScan Walk Away 96 SI (Dade Behring, USA), modified Kirby Bauer disc diffusion and Etest were used. Clinical specimens from 1,128 patients admitted to the ICU during the study period were processed, and 869 pathogens were recovered from 638 positive cultures.
Results: The most frequent pathogens were recovered from respiratory tract specimens, while the Enterobacteriaceae groups of organisms were the most prevalent isolates. Except for Acinetobacter species that exhibit a consistent
multiple drug resistant patterns, all the pathogens showed variable susceptibility to the readily available antimicrobials in the country. A 4.2% incidence rate of ESBL producers was encountered among the K. pneumoniae and E. coli isolates from the unit. Methicillin-resistant S. aureus was noted to be on the decline in this unit, but we
observed the emergence of genuine vancomycin resistant methicillin-resistant S. aureus.
Conclusions: Although Enterobacteriaceae and Pseudomonas aeruginosa were the most frequent isolates, there are still sufficient treatment options for patients infected with these organisms in the unit. Continuous surveillance and monitoring for multiple drug resistant pathogens in the unit should still be paramount especially with the ongoing establishment of the National Oncology Center and National Organ Transplant Units at the complex. There is an equal need for further studies on the determinants of drug resistance in this unit.
Abstract: OBJECTIVES: To evaluate and determine the most cost effective, rapid and specific method for detection of methicillin resistance in clinical isolates of S. aureus in a setting with limited personnel and resources. METHODS: Standard laboratory methods were used to identify S. aureus isolates. The conventional Methicillin Resistance Staphylococcus aureus (MRSA) detection methods used included, 1 microg oxacillin disk diffusion, oxacillin salt agar screen (CLSI), penicillin binding protein (PBP 2') latex agglutination test and E-tests oxacillin. Results of conventional tests were compared with a polymerase chain reaction (PCR) method for detecting MRSA isolates. Polymerase chain reaction detection of the mecA gene in S. aureus was used as the "gold standard" for MRSA identification. RESULTS: All methods had 100% sensitivity except for oxacillin disk diffusion and oxacillin-salt agar screening with 98% and 99%, respectively. Specificity was also 100% for all methods except for oxacillin-disk diffusion (99%). Turn around time (TAT) for detection of MRSA was calculated to be within six hours for PCR. The fastest TAT of 1.25 hours was obtained for PBP 2' latex agglutination. Total cost for labour and materials to perform each method was highest for E-test, US$13.76/isolate. The cost for PCR when compared to that of latex agglutination was not statistically significant (US$3.74 vs US5.91, p = 0.4). CONCLUSIONS: All methods presented high sensitivity and specificity, but the latex agglutination test had the advantage of giving a reliable, rapid and most cost effective result that compares well to PCR in this environment.
Abstract: The incidence and distribution of ESBL producing microorganisms such as E. coli and K. pneumoniae have been demonstrated and varies in different health care facilities and as well as other countries This study was carried out to determine the frequency of occurrence and the antimicrobial susceptibility pattern of ESBL producing E. coli and K. pneumoniae species from clinical isolates at a tertiary hospital in Trinidad & Tobago. Standard microbiological procedures and automated MicroScan System was used to identify, screen for putative ESBL production and determine antimicrobial susceptibility of 1,118 clinical isolates of Enterobacteriaceae species at the microbiology laboratory of the Eric Williams Medical Science Complex, Trinidad & Tobago over a 36 months period. All ESBL producing isolates flagged by the automated system were further confirmed by E-test method. The E-test confirmed a 15.2% ESBL rate among the K. pneumoniae isolates and 9.3% among the E. coli isolates. There was also a 1.8% rate of ESBL production in K. pneumoniae and 0.2% in E. coli isolates from specimens received from community health facilities into the laboratory. Isolates recovered from the intensive care unit of the hospital had 2.1% E. coli and 8.2% K. pneumoniae ESBL producers. Although all ESBL positive isolates were completely susceptible to imipenem and meropenem; and all positive K. pneumoniae isolates were susceptible to amikacin, there was a low susceptibility of ESBL positive E. coli to the aminoglycosides. However, susceptibility of these ESBL producing isolates to the fluoroquinolones varied. There is a high rate of ESBL production among isolates of E. coli and K. pneumoniae at this hospital that is linked to the extensive inappropriate use of third generation cephalosporins in the country. Further molecular studies are needed to characterize the types of these ESBL prevailing in the country.
Abstract: The rapid identification of drug-resistant strains of Mycobacterium tuberculosis is crucial for the timely initiation of appropriate antituberculosis therapy. The performance of the Genotype MTBDRplus assay was compared with that of the Bactec 460 TB system, a "gold standard" culture-based method. The Genotype MTBDRplus assay was quicker and more cost-effective for the detection of rifampin resistance, but it was not as good for the detection of isoniazid-resistant strains in our setting.
Abstract: OBJECTIVES: Methicillin-resistant Staphylococcus aureus (MRSA), first reported in a British hospital in the early 1960s, has now reached global proportions. Geographic spread of one or several MRSA clones in a city, country, and even among countries and continents has been identified by molecular techniques. We sought to determine whether clonal spread of MRSA has occurred in Trinidad and Tobago from all MRSA isolates collected between 2000 and 2001. METHODS: Clinical isolates of MRSA from three major hospitals in Trinidad and Tobago were identified by standard laboratory methods and analyzed using multiplex polymerase chain reaction (PCR) and pulsed-field gel electrophoresis (PFGE) after SmaI digestion. RESULTS: There was a 12.8% prevalence of MRSA in three major regional hospitals in Trinidad and Tobago. All 60 randomly selected MRSA strains from these hospitals produced similar PFGE banding patterns, suggesting a genetic relatedness among strains and that they belonged to a single clonal family. All isolates were negative for the Panton-Valentine leukocidin gene (pvl). These strains shared a PFGE banding pattern approximately (96%) the same as a Canadian strain called CMRSA-6 in the Canadian National Microbiology Laboratory database. CONCLUSIONS: We conclude that only one major PFGE genotype of MRSA clone is circulating among the three major regional hospitals in Trinidad and Tobago suggesting one of three possible scenarios of microevolution: (1) all were from the dissemination of a single epidemic MRSA clone prevailing in these hospitals in Trinidad and Tobago; or (2) MRSA in Trinidad and Tobago is evolving more slowly than in other countries; or (3) that if other MRSA clones have been present in Trinidad and Tobago, they have not persisted.
Abstract: OBJECTIVE: This study was undertaken to determine the prevalence of human immunodeficiency virus-type 1 (HIV-1) infection in patients with pulmonary tuberculosis at the National Chest Hospital in Jamaica. METHODS: This retrospective study reviewed the hospital records of 537 patients admitted over a seven-year period from 1995 to 2001. We used a standardized data collection form to obtain data for sociodemographic characteristics, clinical features, signs and symptoms, laboratory diagnosis, treatment and outcome. RESULTS: We found that 11.6% (47/406) of the patients who met the inclusion criteria and were diagnosed as having pulmonary tuberculosis were HIV-1 seropositive. Most HIV-positive patients with tuberculosis were males, and prevalence of HIV coinfection among patients with tuberculosis was highest in patients aged 30-39 years. The mortality rate in patients with tuberculosis and HIV infection was 23.4% (11/47) compared to 3.9% (14/359; P = 0.001) in HIV-negative patients. Patients were treated with standard quadruple drug therapy. No multiple drug resistance was noted in the Mycobacterium tuberculosis isolates. CONCLUSIONS: The prevalence of HIV in patients with tuberculosis in Jamaica is similar to that in other developing countries, but the mortality rate is higher and this warrants prompt diagnosis of HIV infection and early institution of highly active antiretroviral therapy.
Abstract: The prevalence and significance of coagulase negative staphylococci (CoNS) isolated from blood cultures at the University Hospital of the West Indies (UHWI) during a six-month period were investigated. Standard and automated microbiological procedures were used to process 3001 blood culture specimens received from 2363 patients and 658 (21.9%) of the blood cultures yielded 854 bacterial isolates. The highest prevalence of positive blood cultures (60%) and the lowest prevalence of blood isolates of CoNS (12%) were found in the intensive care unit (ICU). The blood isolates of CoNS were most frequent in the surgical wards (13%) and lowest in obstetrics and gynaecology (2%). High rates of resistance to methicillin, other anti-staphylococcal penicillins, and cephalosporins used in the treatment of CoNS were observed All blood isolates of CoNS (100%) were susceptible to vancomycin. In conclusion, the results show that coagulase-negative staphylococci are the most prevalent bacterial isolates in blood cultures at the UHWI occurring mostly as contaminants. The practice of proper venepuncture and hand-washing techniques by medical staff are recommended to facilitate appropriate antibiotic usage.
Abstract: BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) has become increasingly prevalent worldwide since it was first reported in a British hospital. The prevalence however, varies markedly in hospitals in the same country, and from one country to another. We therefore sought to document comprehensively the prevalence and antimicrobial susceptibility pattern of MRSA isolates in Trinidad and Tobago. METHODS: All Staphylococcus aureus isolates encountered in routine clinical specimens received at major hospitals in the country between 2000 and 2001 were identified morphologically and biochemically by standard laboratory procedures including latex agglutination test (Staphaurex Plus; Murex Diagnostics Ltd; Dartford, England); tube coagulase test with rabbit plasma (Becton, Dickinson & Co; Sparks, MD, USA), and DNase test using DNase agar (Oxoid Ltd; Basingstoke, Hampshire, England). MRSA screening was performed using Mueller-Hinton agar containing 6 mug oxacillin and 4% NaCl, latex agglutination test (Denka Seiken Co. Ltd, Tokyo, Japan) and E-test system (AB Biodisk, Solna, Sweden). Susceptibility to antimicrobial agents was determined by the modified Kirby Bauer disc diffusion method while methicillin MICs were determined with E-test system. RESULTS: Of 1,912 S. aureus isolates received, 12.8% were methicillin (oxacillin) resistant. Majority of the isolates were recovered from wound swabs (86.9%) and the least in urine (0.4%) specimens. Highest number of isolates was encountered in the surgical (62.3%) and the least from obstetrics and gynaecology (1.6%) facilities respectively. Large proportions of methicillin sensitive isolates are >85% sensitive to commonly used and available antimicrobials in the country. All MRSA isolates were resistant to ceftriaxone, erythromycin, gentamicin and penicillin but were 100% sensitive to vancomycin, rifampin and chloramphenicol. CONCLUSION: There is a progressive increase in MRSA prevalence in the country but the present rate is still low in comparison to values in some other countries. Vancomycin is still the drug of choice for treating multidrug resistant MRSA infections. Further use of molecular studies to monitor the epidemiology of MRSA in these hospitals in the country is highly recommended too.
Abstract: Stenotrophomonas maltophilia is emerging worldwide as a nosocomial pathogen. It is associated with certain risk factors and a wide range of infections. This study was done to document its emergence at the University Hospital of the West Indies and to determine the incidence, distribution and risk factors associated with it. A retrospective study was conducted over the period April 1997 to December 2000. Clinical records were available for 46 of the 66 patients identified over the study period. Fifty-five per cent of the cases came from the Intensive Care Unit (ICU) and the rest from other wards. There was a slight increase in the prevalence of infection with increasing age. The surgical service accounted for the largest number of isolates. Of the cases presented, 95.7% were exposed to a wide range of antibiotics and had some form of instrumentation. Underlying disease was found in 71.7% of the patients. S maltophilia was found most often in the sputum of ICU patients whereas it was most often isolated from wound swabs in the ward patients. The organism was isolated from blood more often in ICU patients (23.3%) than in ward patients (9.5%) and there was a 44% mortality rate among the cases in ICU compared with those on the wards (4.8%). Stenotrophomonas maltophilia is an important nosocomial pathogen and occurs in a wide cross-section of patients. The risk factors must be addressed and infection control measures implemented to restrict the spread of this organism.
