Nosocomial spread of class 1 integron-carrying extensively drug-resistant Pseudomonas aeruginosa isolates in a Thai hospital.

Fifty non-duplicate multiresistant isolates of Pseudomonas aeruginosa from a regional hospital in Northern Thailand were investigated for their antimicrobial susceptibility, presence of class 1 integrons and arrangement of gene cassettes as well as their genetic relationships. All but one isolate were classified as extensively drug-resistant P. aeruginosa (XDR-PA). Forty-one isolates (82%) were found to carry class 1 integrons. Amplification of the variable regions of class 1 integrons revealed seven diverse bands ranging in size from 0.7 kb to 7.0 kb. Sequence analysis of class 1 integron variable regions revealed the presence of several gene cassettes associated with resistance to aminoglycosides (aac, aad and aph), including the aac(3)-Ic cassette reported for the first time in Thailand. Gene cassettes encoding resistance to chloramphenicol (cmlA), ß-lactams (bla(PSE), bla(OXA) and bla(VEB)) and rifampicin (arr) were found. The putative small multidrug resistance protein (smr) and an open-reading frame with unknown function (orfD) were also detected. The aadA6-orfD cassette array was the most common integron found in this study. Integron-positive isolates had higher frequencies of antimicrobial resistance than isolates lacking integrons. Pulsed-field gel electrophoresis (PFGE) demonstrated the occurrence of horizontal gene transfer. Interestingly, a large number of XDR-PA isolates carrying identical integrons clearly exhibited the same PFGE pattern, indicating nosocomial spread of these isolates. The presence of XDR-PA carrying class 1 integrons is implicated in the possible spread of drug-resistant organisms, therefore screening for integron-positive P. aeruginosa might be necessary for protection against nosocomial infection.

Class 1 integron containing metallo beta-lactamase gene blaIMP-1 in carbapenem-resistant Pseudomonas aeruginosa in Thailand.

We investigated the genetic properties of two carbapenem-resistant Pseudomonas aeruginosa isolates collected from a regional hospital in the north of Thailand. Both isolates demonstrated high-level resistance to extended-spectrum cephalosporins and carbapenems. Detection of the MBL genes was positive for bla (IMP) in both isolates. Pulsed field gel electrophoresis (PFGE) analysis showed that the two P. aeruginosa isolates were nonclonal. Molecular analysis of the bla (IMP) in isolate 837 showed the presence of a bla (IMP-1) gene inserted in a class 1 integron. The bla (IMP-1) was plasmid-mediated according to the transformation assay. This is the first case of the bla (IMP-1) gene in carbapenem-resistant P. aeruginosa in Thailand, suggesting the further dissemination of this gene in Southeast Asia.

Carbapenem-resistant Acinetobacter baumannii producing OXA-23 in Thailand.

We investigated the resistance determinant of 13 clinical isolates of carbapenem-resistant Acinetobacter baumannii collected from a regional hospital in the north of Thailand. All isolates were multidrug resistant and produced the OXA-23 carbapenemase. The bla(OXA-23) gene was found adjacent to ISAba1. Furthermore, two isolates carried the metallo beta-lactamase gene, bla(IMP). The bla(OXA-23) and bla(IMP) genes were plasmid-mediated according to the transformation assays. This is the first description of OXA-23-producing A. baumannii from Thailand.

Hepatitis C virus infection among Thai blood donors: antibody prevalence, risk factors and development of risk screening form.

Hepatitis C virus (HCV) infection is an important blood-borne infection in many countries, including Thailand. For epidemiological surveillance and controlling the infection, 2167 blood donors were screened for antibody to HCV by an enzyme immunoassay method and interviewed by using a structured questionnaire which consisted of personal health history and some risk behaviors. The prevalence and risk factors were assessed and the risk screening form was developed. The results revealed that the prevalence of anti-HCV was 2.90%. Male blood donors had relatively higher anti-HCV positive rate than females (3.21% vs 1.77%). The significant risk factors from univariate analysis were: (a) gender as male, OR = 1.94 (p = 0.042), (b) education to the primary level, OR = 4.15 (p < 0.001), (c) occupation as laborer or agriculture workers, OR = 2.87 (p < 0.001), police and military, OR = 1.82 (p = 0.046), (d) residence in a rural area, OR = 3.09 (p < 0.001), (e) a history of receiving blood or blood products, OR = 5.21 (p < 0.001), (f) a history of tattooing, OR = 1.70 (p = 0.043), (g) a history of IDU (Infecting Drug Use), OR = 41.43 (p < 0.001), (h) a history of STDs (sexually transmitted diseases) in the last year, OR = 3.87 (p = 0.021), and (i) a history of sexual service, OR = 4.24 (p = 0.017). After multivariate analysis, four variables related to HCV infection among the studied samples included education to the primary level, OR = 3.34 (p = 0.0036), occupation as a laborer or agriculture worker, OR = 2.14 (p = 0.0092), a history of receiving blood or blood products, OR = 4.13 (p = 0.0029), and a history of IDU, OR = 3.82 (p < 0.0001). The risk screening form was developed using risk scores. The validity was calculated by the Receiving Operating Curve. The sensitivity of this form was approximately 55.3% and the specificity was 85.7% when a cut-off score at risk > or =7 was used. If the cut-off score was > or =6, the screening form showed 77.1% of specificity and 61.3% sensitivity. This risk screening form should be applied not only for blood donation but also for pre-marital health screening.

Seroprevalence of hepatitis B, hepatitis C and human immunodeficiency virus among blood donors, Phitsanulok Regional Blood Center, Thailand.

Human immunodeficiency virus (HIV), hepatitis C virus (HCV) and hepatitis B virus (HBV) infections are important blood-borne infections in many countries including Thailand. For epidemiological surveillance and controlling these infections, a cross-sectional group of 2,167 blood donors were screened for HBsAg, antibodies to HCV and HIV by enzyme immunoassay methods. The results revealed that the prevalence of HBsAg positive among studied blood donors was 4.61%, anti-HCV was 2.90% and anti-HIV was 0.69%. When the prevalence was classified by selected socio-demographic variables, it was found that variables including age, gender, marital status and occupation were significant for HBsAg positive rate (p=0.0068, p=0.0019, p=0.0048 and p=0.0017, respectively). For anti-HCV prevalence, studied variables including educational level, occupation and domicile were significant (p<0.0001, p=0.0027, and p<0.0001, respectively), while only educational level was a significant variable for anti-HIV prevalence (p=0.0021). These findings suggest that we should present integrated information and educational programs for preventing and controlling HBV, HCV and HIV transmission among this target group.