Prevalence of extended-spectrum beta-lactamase and class 1 integron integrase gene intl1 in Escherichia coli from Thai patients and healthy adults.

Among 120 Escherichia coli isolates from Thai patients, 37 and 9 isolates were extended-spectrum beta-lactamase (ESBL) and suspected ESBL producers respectively while 5 E. coli isolates from 120 Thai healthy adults were suspected ESBL producers. Integrase (intl1) gene was detected in 99% of the clinical and 87% of the non-clinical isolates. Among 37 ESBL producers, percent recovery of bla(TEM), bla(CTX-M), bla(SHV) and bla(VEB) was 78%, 78%, 8% and 8%, respectively. Twenty-five isolates of ESBL producers carried both bla(TEM) and bla(CTX-M), 2 isolates carried 3 genes (bla(TEM), blac(CTX-M), and bla(SHV)) and 3 showed no detectable bla gene. Among the 14 suspected ESBL producers, intl1 and bla(TEM) were detected in 13 isolates. ESBL producers from clinical samples were resistant to most of the tested antimicrobial agents compared to non-ESBL producers and isolates from healthy adults with about half of the latter susceptible to all tested antimicrobial agents. Only one clinical isolate was resistant to imipenem. Susceptibility to trimethoprim/sulfamethoxazole among the clinical isolates in ESBL producer group (27%) and non-producer group (33%) were comparable, whereas the percent susceptibility of the non-clinical isolates was about twice that of the clinical isolates.

Discriminatory powers of molecular typing techniques for methicillin-resistant Staphylococcus aureus in a university hospital, Thailand.

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.

Antifungal susceptibility and molecular typing of candida albicans isolated from AIDS and non-AIDS Thai patients.

The antifungal susceptibility of Candida albicans isolated from 2 groups of Thai patiens; AIDS patients and non-AIDS patients was investigated. Two hundread and seventeen C. albicans were isolated from the specimens from 54 AIDS patients and 163 non AIDS patients. All isolate were included in the antifungal susceptibility test against amphotericin B, fluconazole, ketoconazole and nystatin. A hundred isolates were randomly selected from both groups for the electrophoretic karyotypes determination. There was not much difference in the value of Mic, MIC50 and MIC90 of all antifungal agent for C. albicans isolates between AIDS and non-AIDS patients. The amphoter B MIC for 61.0% if AIDS isolates and 71.0% of non-AIDS isolates were >0.5 mg/l, while ketoconazole MIC for 94.4% of AIDS and 74.9% of non-AIDS isolates were >0.125 mg/l and fluconazole MIC of 100% of AIDS and non-AIDS isolates were 2.0 mg/l. For nystatin, the MIC for more than 90% of both isolates was <8 mg/l. The MIC50 and MIC90 of all antifungal agents for the two groups of isolates were almost at the same concentration except for fluconazole which showed a two-fold difference of MIC50. The chromosomal DNA karyotypic of C. albicans indicated genetic diversity among all isolates. Twenty-three distinct pulsed-field gel electrophoresis karyotypes and molecular sizes ranging from 3.5 to 0.5 megabases were identified. Most isolates (61%) from both AIDS and non-AIDS isolates belong to type 1 and type 3. Among the AIDS isolates, 38.3% and 29.8% were type 1 and 3, respectivety, and non-AIDS isolates, 20.8% and 33.9% were type 1 and 3, respectively. C. albicans isolates were show to have 8 to 10 chromosomal DNA brands. Most of the isolates (78%) along with C. albicans FC18 control strain had 8 band patterns. The recovery of the common karyotypes in AIDS patients, as well as in non-AIDS patients, suggests that C. albicans infection may develop from a common source by the cross contamination between both groups of patients.