Antibiotic Resistance Profile and association with Integron Type I among Salmonella Enterica Isolates in Thailand

Salmonella infection is the second most common cause of diarrhea in Thailand; however, the data on antimicrobial resistance is limited. There were137 Salmonella strains, isolated from patients and 126 strains isolated from chicken meat, collected from Nonthaburi, Thailand during 2002. The top five serotypes of patients isolates were Enteritidis (22%), Typhimurium (11%), Weltevreden (8.8%), Rissen (8%), and Choleraesuis (6.6%) while the top five serotypes of chicken meat isolates were found as follows: Schwarzengrund (11.91%), Hadar (11.11%), Rissen (8.73%), Amsterdam (7.94%), and Anatum (7.94%). Salmonella strains were most resistance to the class of antibiotics that act as inhibitor to nucleic acid synthesis such as antifolates group (Trimethoprim;SXT) and fluoroquinolones (Nalidixic acid; NA, Ciprofloxacin; CIP),while the β lactam antibiotic was more effective, i.e. the 3rd gen cephalosporin (Ceftazidime; CAZ, Cefotaxime ; CTX), Monobactam (Aztreonam; ATM) and carbapenams group (Imipenem; IMP, Meropenem; MEM). The role of class I integron element in transmission of the resistance gene was revealed by detection the gene cassette associated with a class 1 integron in plasmid preparation among 80% of the isolated strains. The gene cassettes containing resistant genes of dhfrA12 (resistant to trimethoprim) and aadA2 (resistant to streptomycin and spectinomycin), were detected more frequently in the resistant strains. These gene cassettes were likely to be transmitted via plasmid, as it could not be detected in genomic DNA

A Use of 56-kDa Recombinant Protein of <i>Orientia tsutsugamushi</i> Karp Serotype in Serodiagnosis of Scrub Typhus by Enzyme-Linked Immunosorbent Assay in Thais

Scrub typhus is a mite-borne disease caused by a Gram-negative obligately intracellular bacillus, Orientia tsutsugamushi. The disease is endemic in the Asia–Australia–Pacific region, including Thailand. Scrub typhus generally manifests as acute undifferentiated febrile fever along with myalgia, rash, and lymphadenopathy. An eschar can be a valuable diagnostic clue, but this skin lesion may be missed in some patients. The disease symptoms resemble those of other febrile illnesses such as leptospirosis, typhoid, murine typhus, malaria, and dengue fever, making a laboratory diagnosis necessary for the definitive diagnosis. In this study, we expressed a recombinant protein derived from 56-kDa type-specific antigen of O. tsutsugamushi Karp serotype and tested its ability to detect and differentiate scrub typhus infection. IgM and IgG antibodies were determined in sera from scrub typhus (n = 92) and other febrile illness patients (murine typhus (n = 25), melioidosis (n = 36), leptospirosis (n = 42), and dengue (n = 35)) from Thailand. Sensitivities of 87.0% and 59.8% with a specified assay cut-off were obtained for IgM and IgG indirect ELISAs, respectively, with a specificity of 100% in both tests. The sensitivity was increased to 95.7% when a combination of IgM and IgG ELISAs results was considered. Our study suggested a potential of the 56-kDa recombinant protein for further development and evaluation for use in scrub typhus serodiagnosis