Virulence Profiles among Gastrointestinal and Extraintestinal Clinical Isolates of Plesiomonas shigelloides.

The genus Plesiomonas, represented by a single species, Plesiomonas shigelloides, is a gram-negative bacillus associated with gastrointestinal and extraintestinal diseases in humans. In this study, 44 clinical isolates (gastrointestinal, n = 41; extraintestinal, n = 3) were genetically confirmed to be P. shigelloides using the hug gene. All 20 virulence genes were detected in the gastrointestinal isolates, ranging from 7.7% to 100%; however, only 12 genes were detected in the extra-gastrointestinal isolates, ranging from 33.3% to 100%. The phlA gene was significantly associated with the gastrointestinal isolates (P = 0.0216). The results of this study suggest that phlA may play a role in gastrointestinal infections. However, pilF, tolC, and fur were detected in both gastrointestinal and extraintestinal clinical isolates, and further investigations are warranted to elucidate their role in the pathogenesis of P. shigelloides.

Ceftriaxone resistance and genes encoding extended-spectrum ß-lactamase among non-typhoidal Salmonella species from a tertiary care hospital in Kuala Lumpur, Malaysia.

The prevalence of ceftriaxone resistance and the associated genes encoding extended-spectrum ß-lactamase (ESBL) was determined in 149 non-duplicate non-typhoidal Salmonella isolated in 2008-2009 from patients in a tertiary care hospital in Kuala Lumpur, Malaysia. The resistance rate to ceftriaxone was 2.7% (2/74) in 2008, 4.0% (3/75) in 2009, and 3.4% (5/149) overall. CTX-M ESBL genes were detected in 2 of the 5 ceftriaxone-resistant isolates. The prevalence of ceftriaxone resistance, although low, is a concern because it limits therapeutic options. Continued surveillance of ceftriaxone resistance is important to monitor its trends.

Characterization of drug resistant Salmonella enterica serotype Typhimurium by antibiograms, plasmids, integrons, resistance genes and PFGE.

Forty-seven Salmonella Typhimurium (33 zoonotic, 14 clinical) strains were tested for antimicrobial resistance using the standard disk diffusion method. Presence of relevant resistance genes and class 1 integrons were investigated by using PCR. Pulsed-field gel electrophoresis (PFGE) and plasmid profiling were carried out to determine the genomic diversity of Salmonella Typhimurium. Approximately 57.4% of S. Typhimurium were multidrug resistant (MDR) and showed high resistance rates to tetracycline (70.2%), sulphonamides (57.4%), streptomycin (53.1%), ampicillin (29.7%), nalidixic acid (27.6%), kanamycin (23.4%), chloramphenicol (21.2%) and trimethoprim (19.1%). Resistance towards cephalosporins was noted for cephalothin (27.6%), cephradine (21.2%), amoxicillin clavulanic acid (17.0%) and cephalexin (17.0%). Resistance genes, blaTEM, strA, aadA, sul1, sul2, tet(A), tet(B) and tet(C) were detected among the drug resistant strains. Thirty-three strains (70.2%) carried class 1 integrons, which were grouped in 9 different profiles. DNA sequencing identified sat, aadA, pse-1 and dfrA genes in variable regions on class 1 integrons. Thirty-five strains (74.4%) were subtyped to 22 different plasmid profiles, each with 1 - 6 plasmids (2.0 to 95 kb). PFGE subtyped the 47 strains into 39 profiles. In conclusion, high rates of multidrug-resistance were found among the Malaysian Salmonella Typhimurium strains. The emergence of multidrug-resistant Salmonella Typhimurium to cephalosporin antibiotics was also observed. The strains were very diverse and no persistent clone was observed. The emergence of MDR Salmonella Typhimurium is a worldwide problem and this report provides information for the better understanding of the prevalence and epidemiology of MDR S. Typhimurium in Malaysia.

Genetic fingerprinting and antimicrobial susceptibility profiles of Pseudomonas aeruginosa hospital isolates in Malaysia.

BACKGROUND AND PURPOSE: Pseudomonas aeruginosa is the third most common pathogen causing nosocomial infections. The objective of this study was to investigate the antimicrobial resistance profiles and genetic diversity of hospital isolates of P. aeruginosa and to investigate the presence of several resistance genes and integrons. METHODS: In this retrospective study, 48 clinical isolates of P. aeruginosa from 6 public hospitals in Malaysia were analyzed by antimicrobial susceptibility test and DNA fingerprinting techniques. RESULTS: Most of the P. aeruginosa isolates were resistant to tetracycline (73%) and chloramphenicol (60%) and, to a lesser extent, cefotaxime (40%), ceftriaxone (31%), cefoperazone (29%), ticarcillin (25%), piperacillin (23%), and imipenem (21%). Less than 20% of the isolates were resistant to ceftazidime, gentamicin, cefepime, ciprofloxacin, amikacin, piperacillin-tazobactam, and aztreonam (10%). Of the 48 isolates, 33 were multidrug resistant. Two isolates were extended-spectrum beta-lactamase (ESBL) producers using the double-disk synergy test. However, polymerase chain reaction (PCR) failed to detect any common ESBL-encoding genes in all isolates, except for bla(OXA-10) in PA7 that was found to be part of a class 1 integron-encoded aacA4-bla(IMP-9)-catB8-bla(OXA-10) gene cassette. Using PCR, class 1 integron-encoded integrases were detected in 19% of the P. aeruginosa isolates. Repetitive extragenic palindrome-PCR generated 40 different profiles (F = 0.50-1.0) and enterobacterial repetitive intergenic consensus-PCR produced 46 profiles (F = 0.51-1.0). Pulsed-field gel electrophoresis with SpeI-digested genomic DNA resulted in 45 different profiles (F = 0.50-1.00). CONCLUSIONS: Aztreonam appeared to be the most effective agent against multidrug-resistant P. aeruginosa isolates. Sixty nine percent of the P. aeruginosa isolates analyzed were multidrug resistant and the isolates were genetically diverse.

Comparative analysis of extracellular enzymes and virulence exhibited by Burkholderia pseudomallei from different sources.

To evaluate the potential role of extracellular proteins in the pathogenicity and virulence of Burkholderia pseudomallei, the activities of several enzymes in the culture filtrates of nine clinical and six environmental isolates were investigated in vitro and in vivo in ICR strain of mice. The production of protease, phosphatase, phospholipase C, superoxide dismutase, catalase and peroxidase were detected in the culture filtrates of all the 15 isolates at different time points of growth 4-24h. Over time, activity of each enzyme at each time point varied. Profile of secretion was similar among the 15 isolates irrespective of source, that is clinical or environmental. Catalase, phosphatase and phospholipase C were found to be increased in 60-100% of the isolates post-passage in mice. In vivo inoculation studies in ICR mice demonstrated a wide difference in their ability to cause bacteraemia, splenic or external abscesses and mortality rate ranged from few days to several weeks.

Further evaluation of a multiplex PCR for differentiation of Salmonella paratyphi A from other salmonellae.

Salmonella enterica serovar Paratyphi A is a causative agent of paratyphoid fever. The clinical syndrome caused by paratyphoid fever overlaps with other febrile illnesses and cannot be distinguished from typhoid fever. Conventional methods used for diagnosis are time consuming, costly, and labor-intensive. We evaluated the specificity, sensitivity, and application of a multiplex polymerase chain reaction (PCR) previously developed by the method (Ou, H.Y., Teh, C.S.J., Thong, K.L., et al., J. Mol. Diagn., 9, 624-630, 2007) using 6 S. Paratyphi A, 22 S. Typhi, and 85 other Salmonella serovars as well as 36 non-Salmonella strains. The detection limit of the multiplex PCR was 4 x 10(4) cfu ml(-1). In a blind test of the other 50 strains, this multiplex PCR correctly identified the only S. Paratyphi A in the panel of strains. The sensitivity of this PCR using spiked blood and stool samples was 1 x 10(5) cfu ml(-1) and 2 x 10(5) cfu ml(-1), respectively, but increased to 1 x 10(4) cfu ml(-1) and 2 x 10(3) cfu ml(-1) after 5-h enrichment. We believe that this multiplex PCR is a promising technique for the specific and sensitive detection of S. Paratyphi A in clinical, environmental, and food samples.