Clinical sources and prevalence of resistance to antimicrobials of Klebsiella pneumoniae strains in Trinidad

To assess the frequency of Klebsiella pneumoniae [K. pneumoniae] recovery from clinical specimens from hospital and community patients, their antibiotic profile, the extent of extended-spectrum beta lactamase [ESBL] production among such isolates, and the impact on patient management. The study recovered 1,118 K. pneumoniae strains from various clinical specimens from hospital and community patients, from 1995 to 2004, at the Eric Williams Medical Sciences Complex. All 1,118 isolates underwent testing for multi-antibiotic resistance, of which 480 that fulfilled the criteria for possible ESBL production underwent further examination, according to guideline recommendations of the National Committee for Clinical Laboratory Standards. From 68,537 specimens processed, 62.9% were from hospital patients and 37.1% from community patients. Approximately 21% of the specimens yielded positive bacterial cultures from which, 1118 were K. pneumoniae strains. Ciprofloxacin, imipenem, aztreonam, nalidixic acid and gentamicin showed the greatest efficacy [>95% sensitivity] against isolates from both hospital and community sources. Tetracycline and ampicillin showed almost 100% resistances. The other antibiotics displayed varying degrees of resistance. The prevalence of ESBL production was approximately 8.5% and most ESBL producers [51.2%] were from urine, followed by wounds [22.0%], blood [19.5%], and lower respiratory tract specimens [4.9%]. Five K. pneumoniae isolates were resistant to the carbapenem, and imipenem. The study isolated K. pneumoniae from 8% of patients. All K. pneumoniae isolates were resistant to more than 2 antibiotics. The prevalence of ESBL production was 8.5%. Five [12.2%] strains of ESBL producers were resistant to imipenem. Continued infection control measures and prudent use of antibiotic agents are essential in reducing the spread of multi-resistant ESBL producing K. pneumoniae

Resistance patterns among selective Gram-negative bacilli from an intensive care unit in Trinidad, West Indies

To determine the prevalence of antimicrobial resistance among gram-negative aerobic bacteria isolated from infected patients on the intensive care unit [ICU] and the outcome of infected patients. Over a 5-year period [January 1998 to December 2002], all gram-negative aerobic bacteria [GNB] consecutively isolated from infected ICU patients at General Hospital, San Fernando, Trinidad and Tobago, West Indies. were tested for susceptibility to 10 commonly prescribed antimicrobial agents. Bacterial strains were identified according to standard microbiological procedures. The antimicrobial agents used and the amounts consumed by patients on the ICU were obtained from the hospital pharmacy records. Hospital discharges and deaths due to infectious complications were obtained from the medical records office and the ICU. During the study period, there were 1160 admissions to the ICU. From this, 530 [45.7%] were suspected episodes of nosocomial infection and 445 [84%] were culture positive for GNB. Sputum, urine and blood accounted for approximately 85% of isolates. Pseudomonas aeruginosa [P. aeruginosa], Klebsiella pneumoniae [K. pneumoniae], Citrobacter spp and Enterobacter spp were the predominant isolates from sputum, while from urine; it was P. aeruginosa and K. pneumoniae. The major isolate from bloodstream infection on the ICU was Citrobacter spp. Of the 10 antimicrobial agents, the least effective was ampicillin that showed 87.8% resistance, while the most effective against GNB were imipenem [94.2%], ciprofloxacin [93.9%] and piperacillin-tazobactam [88.5%]. The most common isolate was P. aeruginosa which is sensitive to >82% of the antimicrobials. Antimicrobial consumption was 2282 grams and the most frequently prescribed drugs were ampicillin, cefuroxime and amoxicillin-clavulanic acid, with consumption of the beta-lactam antimicrobials being 87.3% of the total. There were 280 [24.1%] deaths on the ICU during the study period and 42.9% [120 of 280] were said to be due to, or associated with overall hospital-acquired infectious complications. Mortality associated with GNB infection was approximately 33%. All fatal cases were associated with pneumonia and bloodstream infections. The predominant organisms were Citrobacter spp, Enterobacter spp, Acinetobacter spp and P. aeruginosa, with Citrobacter spp associated with both pulmonary and bloodstream fatalities. In general, the isolates were relatively antimicrobial susceptible. Imipenem, ciprofloxacin and piperacillin-tazobactam were found good empiric choices for treatment of most GNB infection in the ICU. The study showed that resistance among ICU pathogens depended on the site of infection and that increased drug consumption of any antimicrobial agent may lead to increase resistance to those drugs. The need for policies governing the prudent use of antimicrobial agents cannot be overemphasized. Many endeavors aimed at introducing an antibiotic policy have encountered repeated failure and attempts at rational prescribing through educational programs have met with limited success. Hope is seen however, in proper implementation of infection control procedures aimed specifically to curtail lateral transmission of resistant organisms

Susceptibility patterns and serotypes of non-typhoidal salmonella in Trinidad

To study the serotype distribution of non-typhoidal salmonella isolated from clinical specimens and to evaluate their susceptibility patterns to the most commonly prescribed antimicrobial agents used in this region. A retrospective study during the period 1993- 1999 was carried out at the Eric Williams Medical Sciences Complex Microbiology Laboratory, a teaching hospital in the northwestern part of Trinidad. Strains of non-typhoidal salmonella were serogrouped with polyvalent Salmonella O antiserum and sent to the local Public Health Laboratory for confirmation and further serotyping. A total of 412 strains of non-typhoidal salmonella were serotyped. Of the 13 serotypes, Salmonella enteritidis was the most prevalent 57%, followed by Salmonella typhimurium, 25%, Salmonella virchow 5% and Salmonella heidelberg, 4%. Three hundred and sixty-two [87.5%] non-typhoidal salmonella were isolated from stool, 38 [9%] from blood, 8 [2%] from urine and 4 about 1% from infected wounds. Of the 13 serotypes only Salmonella enteritidis, Salmonella typhimurium, Salmonella virchow and Salmonella heidelberg were simultaneously isolated from blood and stool. One serotype, Salmonella aberdeen, was encountered for the first time in 1993. All isolates were fully sensitive to chloramphenicol, gentamicin, cefuroxime and ceftrioxone. Resistance to ampicillin, augmentin and co-trimoxazole was less than 4%. One third of all non-typhoidal salmonella isolates were resistant to tetracyclines. The most prevalent serotypes were Salmonella enteritidis and Salmonella typhimurium which accounted for 82% of all isolates. The prevalence of resistance of non-typhoidal salmonella to antibiotics was very low [5%]. Therefore, due to this low prevalence of resistance, we did not provide details of resistance in relation to serotype. However, it was observed that of the 137 non-typhoidal salmonella resistant to tetracycline, more than 80% were Salmonella enteritidis and Salmonella typhimurium strains. Of the 9 antibiotics, tetracycline was the only drug to which one-third of the non-typhoidal salmonella were resistant. Due to the risk of resistance continued surveillance of susceptibility patterns of non-typhoidal salmonella to antibiotics must be maintained and encouraged

Urinary tract infections in general practice in a rural community in South Trinidad

A prospective study was carried out at a General Practice in South Trinidad, to assess the sensitivity profiles of urinary isolates in this remote rural community. Quantitative bacteriologic cultures were performed according to standard procedures. Identification of isolates was based on gram reaction, morphology and biochemical reactions. Susceptibility testing was carried out using commonly prescribed antimicrobials for the treatment of urinary tract infections. From 779 urine specimens, 49% were culture positive for counts >105 organisms per ml. Three hundred and eighteen were aged 21 years and above and 85.5% of these were females. The lowest incidence of urinary tract infections, 8%, was seen among the 13-20 year old age group. Most males above 50 years had indwelling urethral catheters due to prostatic disease. Escherichia coli was the predominant isolate, 71%, followed by Proteus mirabilis, 9%, and Klebsiella pneumoniae, 7%. All urinary tract infections isolates were fully sensitive to ofloxacin and >96% [except for Citrobacter species, 63%] were sensitive to cefuroxime. Apart from Enterococcus faecalis and Staphylococcus saprophyticus, the overall sensitivity to ampicillin by all isolates was <33%. The prevalence of multi-resistant Pseudomonas aeruginosa in community-acquired urinary tract infections is increasing. All Pseudomonas aeruginosa were fully sensitive to gentamicin and ofloxacin. The high frequency of single and multiple antibiotic resistances in this rural community should cause alarm. The ease of procuring antibiotics in these areas without a prescription can result in uncontrolled self-medication. Also, the absence of antibiotic prescribing policies and inadequate information on patterns of bacterial resistance, may all contribute to the emergence of resistant strains