Prevalence and molecular epidemiology of Clostridium difficile infection in Thailand.

Little is known about Clostridium difficile infection (CDI) in Asia generally, and specifically in Thailand. Given the high prevalence of inappropriate antibiotic usage in this region, CDI is likely to be common. This study investigated the prevalence and molecular epidemiology of CDI in Thailand. Stool specimens collected from inpatients with diarrhoea at Siriraj hospital in Bangkok (n = 422) were cultured on ChromID Cdiff agar and any presumptive C. difficile colonies were identified, PCR ribotyped and toxin profiled. As part of the routine C. difficile testing at Siriraj Hospital, 370 specimens also underwent testing with the BD MAX Cdiff assay to detect the presence of tcdB. With direct culture, 105 different isolates of C. difficile were recovered from 23.7% (100/422) of the stool specimens. The prevalence of toxigenic and nontoxigenic isolates was 9.2% (39/422) and 15.6% (66/422), respectively. Of the toxigenic isolates, 69.2% (27/39) and 30.8% (12/39) were tcdA and tcdB positive (A+B+), and A-B+, respectively; none contained binary toxin genes. The five most prevalent ribotypes (RTs) were 014/020 group (17/105), 010 (12/105), 017 (12/105), 039 (9/105) and 009 (6/105). Using toxigenic culture as the reference standard, the sensitivity, specificity, positive predictive value and negative predictive value of the BD MAX Cdiff assay were 68.6, 95.1, 63.2 and 96.1%, respectively. The high proportion of A-B+, RT 017 strains emphasises the need for diagnostic tests that detect either both toxins or just tcdB. Continued surveillance that involves stool culturing will allow molecular tracking and assist in elucidating the epidemiology of CDI in Thailand.

Optimizing intravenous fosfomycin dosing in combination with carbapenems for treatment of Pseudomonas aeruginosa infections in critically ill patients based on pharmacokinetic/pharmacodynamic (PK/PD) simulation.

OBJECTIVE: The purpose of the study was to determine the optimal dosing regimen of intravenous fosfomycin for the treatment of Pseudomonas aeruginosa (PA) based on PK/PD targets. METHOD: A total of 120 PA isolates were recovered from various clinical specimens at university hospital in Thailand. Minimum Inhibitory Concentrations (MICs) of all the isolates were determined by the E-test method. PK parameters were obtained from a published study. Monte Carlo simulation was performed to calculate the percentage of target attainment (PTA) and cumulative fraction of response (CFR). RESULTS: MIC90 of fosfomycin alone, fosfomycin in combination with carbapenem, carbapenems alone and carbapenems in combination with fosfomycin were >1,024, 1,024, >32 and 32µg/ml, for multidrug resistant (MDR)-PA and 512, 128, 8 and 3µg/ml respectively, for non-MDR PA. Approximately 40% of the non-MDR PA were carbapenem-resistant strains. For non-MDR PA with CRPA, fosfomycin 16g continuous infusion in combination with carbapenems provided %PTA of approximately 80 and %CFR of > 88. While, %PTA and %CFR > 90 were achieved with fosfomycin 24g/day prolonged infusion in combination with carbapenem. CONCLUSIONS: Prolonged infusion of fosfomycin 16 - 24g combined with extended carbapenem infusion could be used in non-MDR PA treatment with CRPA.

In vitro activity of doripenem and other carbapenems against contemporary Gram-negative pathogens isolated from hospitalised patients in the Asia-Pacific region: results of the COMPACT Asia-Pacific Study.

The Comparative Activity of Carbapenems Testing (COMPACT) Study was designed to determine the in vitro potency of doripenem compared with imipenem and meropenem against a large number of contemporary Gram-negative pathogens from more than 100 centres across Europe and the Asia-Pacific region and to assess the reliability of Etest methodology for doripenem minimum inhibitory concentration (MIC) determination against these pathogens. Data from eight countries within the Asia-Pacific region, which collected 1612 bacterial isolates, are presented here. Etest methodology was found to be a reliable method for MIC determination. Doripenem showed in vitro activity similar to or better than meropenem and at least four-fold better than imipenem against Enterobacteriaceae. Against Pseudomonas aeruginosa, doripenem was also the most active of the three carbapenems in vitro. However, in vitro results do not necessarily correlate with clinical outcome.

Identification of bacteria recovered from clinical specimens by 16S rRNA gene sequencing.

The sequence of the 16S rRNA gene has been used extensively for phylogenetic classification, identification, and genotypic typing of bacteria. Identification of bacterial isolates by 16S rRNA gene sequencing, though generally performed in reference laboratories, has been recently introduced for routine use in clinical laboratories to identify isolates that cannot be identified by conventional methods. Described in this report is the use of 16S rRNA gene sequencing to identify uncommon bacteria, or bacteria with unusual phenotypic properties, with four brief case presentations to illustrate its clinical application. The feasibility, usefulness and limitations of performing this approach in the clinical laboratory are also discussed.