Prevalence, Risk Factors, and Result Features in the Detection of Latent Tuberculosis Infection in Thai Healthcare Workers Using QuantiFERON-TB Gold Plus.

Introduction Latent tuberculosis infection (LTBI) is an enormous reservoir for tuberculosis (TB), and healthcare workers (HCWs) are at high risk for TB infection. QuantiFERON-TB Gold Plus (QFT-Plus) is an alternative to the tuberculin skin test for LTBI detection, but data on its application and LTBI detected by QFT-Plus in high TB burden countries are limited. This study aimed to determine the prevalence of LTBI and its risk factors, and to investigate the QFT-Plus results in Thai HCWs. Methods A cross-sectional analytical study was conducted among HCWs at a secondary care hospital in Health Region 5, Thailand. Eligible HCWs were enrolled and underwent QFT-Plus testing. Interferon-gamma (IFN-γ) values in tubes were analysed. The prevalence and associated risk factors for LTBI were assessed based on laboratory and sociodemographic data. Logistic regression analyses were applied to calculate odds ratios (OR, aOR) reported with 95% confidence intervals (CI). Results Of the 269 participants enrolled, their median age was 42 years and 93.31% (n = 251/269) were female. The majority (n = 178/269, 66.17%) were nurses or nurse assistants and 42.75% (n = 115/269) worked in the inpatient medical wards. Overall, the QFT-Plus results showed 110 (40.89%) positive with good agreement (93.68%; κ 0.87) and high correlation (Spearman's ρ 0.91) of IFN-γ concentrations in the two antigen tubes. A true difference in IFN-γ values for predicting a recent infection was found about 7.81% (n = 21/269). By univariate and multivariate analyses, the participants' age > 40 years (OR = 3.21, 95% CI: 1.84-5.64%; aOR = 2.05, 95% CI: 1.07-3.96%), and employment duration > 10 years (OR = 3.19, 95% CI: 1.66-6.37%; aOR = 2.34, 95% CI: 1.05-5.21%) were significantly associated with the increased risk of LTBI (p-value < 0.05). Conclusions The prevalence of LTBI among these HCWs was high, and the increased risk factors for LTBI according to QFT-Plus positivity were age over 40 years and working time in the hospital for more than 10 years. It is important to screen HCWs in this setting for LTBI, particularly those with long employment durations and older ages. The high prevalence of LTBI suggests that LTBI management, such as regular screening and treatment, should be considered together with strengthening preventive measures, especially in high-risk groups.

Antimicrobial Activity Profiles and Potential Antimicrobial Regimens against Carbapenem-Resistant Enterobacterales Isolated from Multi-Centers in Western Thailand.

The spread of carbapenem-resistant Enterobacterales (CRE) constitutes a global health burden. Antimicrobial susceptibility and types of carbapenemase differ by geographic region. This study aimed to (1) examine the minimum inhibitory concentrations (MICs) and antibiotic resistance genes and (2) investigate antibiotic dosing regimens against CRE using Monte Carlo simulation. Clinical carbapenem-resistant Klebsiella pneumoniae (CRKP), Escherichia coli (CREC), and Enterobacter cloacae (CREclo) isolates were collected from various hospitals in western Thailand. Broth microdilution was performed, and the types of carbapenemase and mcr-1 genes were detected using polymerase chain reaction (PCR). Monte Carlo simulation was used to establish optimal antimicrobial dosing regimens meeting the criterion of a cumulative fraction of response (CFR) >90%. A total of 150 CRE isolates from 12 hospitals were included. The proportion of CRKP (76%) was greater than that of CREC (22%) and CREclo (2%). Regional hospitals reported higher rates of resistance than general hospitals. Most isolates were resistant to aztreonam and ceftazidime/avibactam, whereas they were highly susceptible to aminoglycosides. Most carbapenemases were NDM (47.33%), OXA-48 (43.33%) and NDM plus OXA-48 (6.67%); five OXA-48 positive isolates carried mcr-1 genes. Currently, high-dose tigecycline is the only optimal regimen against CRE isolates. Further extensive research on antibiotic synergism or new antibiotics should be conducted.

Molecular epidemiology and genotype distribution of noroviruses in children in Thailand from 2004 to 2010: a multi-site study.

This study identified norovirus in children presenting with acute gastroenteritis and determined the capsid genotypes of the circulating norovirus strains in multiple regions in Thailand during October 2004 to December 2006 and March 2008 to August 2010. A total of 7,420 stool samples were collected from both cases (3621) and controls (3799). The stool samples were screened by two real-time RT-PCR assays to detect genogroup I and genogroup II noroviruses. Norovirus-positive samples were identified in 516 cases (14.3%) and 181 controls (4.8%) with more than half of norovirus positive samples from 7-24 months old children. Positive samples were sequenced and genotyped for the capsid gene. GII.4 was the genotype observed most frequently (56.4%) followed by GII.3 (28.2%). Five peaks of infection were observed, with predominant capsid genotypes that alternated during the surveillance periods between GII.4 and GII.3. Analyses of positive samples showed variation in genotype from each region as well as from different study periods. This emphasizes the importance of multi-site studies to investigate norovirus epidemiology. Additionally, the observed regional and temporal variations suggest that a systematic nation-wide surveillance effort in Thailand is needed to track the continually changing norovirus epidemiology.

SCCmec Type IX Element in Methicillin Resistant Staphylococcusaureusspa Type t337 (CC9) Isolated from Pigs and Pork in Thailand.

Methicillin resistant Staphylococcusaureus (MRSA) have emerged among livestock in several countries. In this study, we describe the results of a screening performed in pigs and raw pork samples in Thailand. Ten pork samples and 15 nasal swabs from pigs were collected from 2 markets and 1 pig farm in the Samuth Songkhram province in Thailand. MRSA were isolated using selective isolation procedures and confirmed by mecA PCR. The MRSA were characterized by antimicrobial susceptibility testing, pulsed field gel electrophoresis (PFGE), spa typing, SCCmec typing, and MLST. Resistance and virulence markers were screened using a microarray. Five of the pork samples and six pig nasal swabs were positive for MRSA. All 11 isolates belonged to spa type t337 but showed diversity in antimicrobial resistance patterns and PFGE profiles. Additionally, the isolates were sequence-typed; ST9, ST2136, ST2278 belonging to the clonal complex; CC9. All isolates harbored SCCmec IX and were resistant to 7 out of 14 tested antimicrobials; additional resistances to all antimicrobials tested were found in some of the pork and pig isolates and 1 pork isolate was resistant to 13 antimicrobials tested. Microarray analysis identified blaZ, aac-aphD, vga(A), tetM, and a tet efflux marker, in all strains and additionally ermB and aadD, cat and fex(A) in the pork isolates. None of the isolates were found PVL-positive, but enterotoxins were identified in all isolates. To our knowledge, only a few descriptions of MRSA in livestock and food products in Thailand have been observed but this is the first observation of MRSA CC9 associated with SCCmec IX in pork. This study indicates a likely widespread distribution of MRSA in pig and pork in Thailand and further investigation on the prevalence and importance of livestock associated MRSA in Thailand is needed.

Serotypes and antimicrobial resistance of Salmonella enterica ssp in central Thailand, 2001-2006.

This study was carried out to elucidate the epidemiological trends and antimicrobial susceptibilities against Salmonella serovars among Thai patients and asymptomatic carriers during 2001-2006 in central Thailand. A total of 1,401 human and 260 non-human isolates from various sources were included. The isolates were characterized using serotyping and antimicrobial susceptibility testing. The most common serovars in patients submitting stool samples were S. Weltevreden, S. Stanley, S. Anatum, and S. Rissen. Significantly higher odds ratios were observed in blood samples versus stool sample for S. Choleraesuis, S. Enteritidis, S. Typhimurium, and S. Typhi. Children under five years old suffered the most frequently from gastroenteritis. The patients most commonly infected with an invasive serovar were children and people from 26 to 55 years of age. Antimicrobial susceptibility data revealed that S. Schwarzengrund, S. Choleraesuis, S. Anatum, S. Stanley, S. Rissen, and S. Typhimurium were the most resistant serovars observed. The invasive serovar, S. Choleraesuis was resistant to cefotaxime and norfloxacin. Antimicrobial resistance to cefotaxime, was observed in S. Agona, S. Rissen, S. Typhimurium, S. Anatum, and S. Weltevreden. An alarmingly high frequency of resistance to third generation cephalosporins was observed. We recommend Thai authorities take action in order to prevent spread of resistant S. Choleraesuis and other serovars among animals and humans by enforcing a more strict policy on the use of antimicrobials in food animals.

Molecular characterization of extended-spectrum cephalosporinase-producing Salmonella enterica serovar Choleraesuis isolates from patients in Thailand and Denmark.

The objective of this study was to characterize extended-spectrum cephalosporinase (ESC)-producing isolates of Salmonella enterica serovar Choleraesuis recovered from patients in Thailand and Denmark. Twenty-four blood culture isolates from 22 patients were included in the study, of which 23 isolates were recovered from 21 Thai patients during 2003, 2007, or 2008 and one isolate was recovered from a Danish traveler to Thailand. ESC production was confirmed in 13 out of the 24 isolates by MIC testing. Microarray and plasmid profiling (replicon typing and restriction fragment length polymorphism [RFLP]) were used to characterize the genetic mechanisms of antimicrobial resistance in the 13 ESC-producing isolates. Pulsed-field gel electrophoresis (PFGE) and MIC testing were used to compare the clonality between the 13 ESC-producing isolates and the 11 non-ESC-producing isolates. Based on susceptibility patterns, the ESC-producing isolates were more closely related than non-ESC-producing isolates. Microarray, PCR, plasmid profiling, and replicon typing revealed that the 13 ESC-producing isolates harbored either bla(CMY-2) containing incA/C or bla(CTX-M-14) containing incFIIA, incFrepB, and an unknown replicon located on plasmids ranging in size from 75 to 200 kb. The RFLP and replicon typing clustered the isolates into four distinct groups. PFGE revealed 16 unique patterns and five clusters; each cluster contained two or three of the 24 isolates. The isolate from the Danish patient was indistinguishable from two Thai clinical isolates by PFGE. This study revealed the emergence of the bla(CTX-M-14) gene among several clones of Salmonella serovar Choleraesuis. Numerous plasmids were identified containing up to two different ESC genes and four distinct replicons. A "travel-associated" spread was confirmed. Overall, a high degree of clonal diversity between isolates resistant and susceptible to cephalosporins was observed. The findings represent a serious threat to public health for the Thai people and tourists.