ABSTRACT
Discriminatory powers of various molecular techniques were evaluated for typing of methicillin-resistant Staphylococcus aureus (MRSA) isolated in Siriraj Hospital, Bangkok, Thailand. Thirty MRSA isolates were randomly selected in this study. They were characterized by pulsed-field gel electrophoresis, Clal-mecA and Clal-Tn554 polymorphisms, ribotyping, and PCR-based methods including SCCmec typing, spa and coa gene polymorphism, and repeat units in hypervariable region downstream of mecA. Individual molecular typing technique distinguished those MRSA isolates into 2 to 5 types. Eleven genetic backgrounds of MRSA isolates were elucidated by combination of typing methods with trimethoprim/sulfamethoxazole (TMP/SXT) susceptibility. Combination of all typing methods including TMP/SXT susceptibility yielded a discriminatory index of 0.94. Combination of PCR-based methods and TMP/SXT susceptibility, with the discriminatory index of 0.89, is a practical typing approach suitable for rapid epidemiological investigation of MRSA isolates in a hospital setting.
Subject(s)
Anti-Bacterial Agents/pharmacology , Bacterial Typing Techniques , Base Sequence , DNA, Bacterial/chemistry , Electrophoresis, Gel, Pulsed-Field/methods , Molecular Epidemiology , Humans , Methicillin Resistance , Microbial Sensitivity Tests , Polymerase Chain Reaction/methods , Polymorphism, Genetic , Polymorphism, Restriction Fragment Length , Reproducibility of Results , Ribotyping , Sensitivity and Specificity , Staphylococcal Infections/diagnosis , Staphylococcus aureus/classification , ThailandABSTRACT
OBJECTIVES: To study bacterial contamination of fresh vegetables before cleaning and before serving to patients in 14 hospitals. MATERIAL AND METHOD: Aerobic plate count was performed and emphasized on total viable aerobic bacteria, fecal coliform, fecal Escherichia coli and enteric pathogens in fresh vegetables including romaine lettuce, onion, parsley, celery and tomato before cleaning and before serving. Hospital nutrition officers who were involved in food purchasing and processing were interviewed. RESULTS: One hundred and six of 403 of fresh vegetable samples (26.3%) before cleaning were contaminated with > 10(7) colony forming unit per gram (CFU/gram) of viable aerobic bacteria, 106 of 178 samples (59.6%) contained MPN/fecal coliform >1,100 /gram, 78 samples (43.8%) contained MPN fecal E. coli >10/gram. Enteric bacteria were isolated from 7.2% of the total 304 samples including non typhoid Salmonella (1 sample), Vibrio cholerae non O1/O139 (7 samples) and Aeromonas species (14 samples). Forty of 396 ready to serve vegetable samples (10.1%) contained > 10(7) CFU/gram of viable aerobic bacteria. Seventy five of 183 (40.9%) samples contained >1,100 MPN fecal coliform/gram and 43 (23.5%) contained >10 MPN fecal E. coli/gram. Enteric bacteria were also detected in 7.6% of the samples including V. cholerae non O1/O139 (6 samples) and Aeromonas species (17 samples). There were three different ways in obtaining fresh vegetables to the hospitals: by auction (50%), wholesalers (21.4%) and retailers (14.2%). There were also different standards of transportation, packaging, delivery and food processing, particularly cleaning methods. CONCLUSION: Ready-to-eat fresh vegetables were contaminated in high percentages with microorganisms in the number that exceeded the standard. Better management is required to safeguard patients.
Subject(s)
Food Handling , Food Microbiology , Food Service, Hospital/standards , Gastrointestinal Diseases/etiology , Humans , Infection Control , Purchasing, Hospital , Risk Assessment , Risk Factors , Thailand , Vegetables/microbiologyABSTRACT
Staphylococcus aureus with reduced susceptibility to vancomycin has been reports worldwide. Here we report the first pediatric case of heterogeneous vancomycin intermediate resistance Staphylacoccus aureus (hVISA) causing endocarditis in Thailand. A 4 months old girl with truncus arteriosus type IV and ventricular septal defect developed methicillin-resistant S. aureus (MRSA) bacteremia and endocarditis after total repair operation. The patient did not respond to combination antimicrobial treatment including vancomycin. The strain was susceptible to trimethoprim-sulfamethoxazole and vancomycin by conventional antimicrobial susceptibily test. The vancomycin minimal inhibitory concentration by E-test was 2 microg/ml. The strain was judged to be possible heteroresistant when screening was done by one-point population analysis. The subsequent population analysis and testing for the emergence of mutants with reduced susceptible to vancomycin confirmed that this strain was hVISA. Despite the treatment with vancomycin, amikacin, rifampicin and cotrimoxazole, the patient died. hVISA should be suspected in MRSA infections that were refractory to vancomycin therapy could be due to. The emergence hVISA underscored the importance of the prudent use of antibiotics, the laboratory capacity to identify MRSA and hVISA and proper communication with treating clinicians, and the meticulous infection-control measures to prevent transmission.
Subject(s)
Anti-Bacterial Agents/pharmacology , Endocarditis, Bacterial/drug therapy , Female , Humans , Infant , Staphylococcal Infections/drug therapy , Staphylococcus aureus/drug effects , Thailand , Vancomycin/pharmacology , Vancomycin ResistanceABSTRACT
Pseudomonas aeruginosa is a leading cause of nosocomial infections. One thousand two hundred and twenty strains of mucoid and non-mucoid types of P. aeruginosa isolated from different patients were examined at Siriraj Hospital from January 2001-October 2003. The prevalences of P. aeruginosa mucoid type and non-mucoid type were 3.6% and 96.4%, respectively. Susceptibility testing was performed by Kirby-Bauer disk diffusion method as recommended by NCCLS. The isolates with mucoid phenotypes were more susceptible than the non-mucoid isolates. The antimicrobial susceptibility pattern of both types should provide guidelines for the selection of appropriate drugs for treatment.