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Aeromonas dhakensisis an emergent human pathogen with medical importance. This study was aimed to determine the sequence types (STs), genetic diversity, and phylogenetic relationships of different clinical sources of 47 A. dhakensisfrom Malaysia using multilocus sequence typing (MLST), goeBURST, and phylogenetic analyses. The analysis of a concatenated six-gene tree with a nucleotide length of 2994 bp based on six housekeeping genes (gyrB, groL, gltA, metG, ppsA, and recA)and independent analyses of single gene fragments was performed. MLST was able to group 47 A. dhakensisfrom our collection into 36 STs in which 34 STs are novel STs. The most abundant ST521 consisted of five strains from peritoneal fluid and two strains from stools. Comparison of 62 global A. dhakensiswas carried out via goeBURST; 94.4% (34/36) of the identified STs are novel and unique in Malaysia. Two STs (111 and 541) were grouped into clonal complexes among our strains and 32 STs occurred as singletons. Single-gene phylogenetic trees showed varying topologies; groLand rpoDgrouped all A. dhakensisinto a tight-cluster with bootstrap values of 100% and 99%, respectively. A poor phylogenetic resolution encountered in single-gene analyses was buffered by the multilocus phylogenetic tree that offered high discriminatory power (bootstrap value = 100%) in resolving all A. dhakensisfrom A. hydrophilaand delineating the relationship among other taxa. Genetic diversity analysis showed groLas the most conserved gene and ppsAas the most variable gene. This study revealed novel STs and high genetic diversity among clinical A. dhakensisfrom Malaysia.

There is widespread resistance of Salmonella species to commonly prescribed antimicrobials the world over. We aimed to determine the antimicrobial susceptibility and serovar distribution of non-typhoidal Salmonella (NTS) isolated from blood cultures of Malaysian children. Positive isolates of NTS from blood cultures obtained from children admitted to the pediatric wards of University of Malaya Medical Center (UMMC), a large urban hospital from Kuala Lumpur (1991-2001), and Hospital Kota Bharu (HKB), from the predominantly rural state of Kelantan (1991-1999), Malaysia, were reviewed retrospectively. Serovar distribution and antimicrobial susceptibility were ascertained. A total of 64 and 55 isolates of NTS were obtained from blood cultures of children admitted to UMMC and HKB, respectively. The commonest serovar isolated was Salmonella enteritidis in both centers. The NTS isolated were highly sensitive to the antimicrobials tested: ampicillin 98 per cent, chloramphenicol 98 per cent, gentamicin 97 per cent, trimethoprim-sulfamethoxazole (TMP-SMX) 98 per cent, and ceftriaxone 100 per cent in UMMC; ampicillin 100 per cent, chloramphenicol 87 per cent, kanamycin 100 per cent, streptomycin 96 per cent, TMP-SMX 93 per cent, and tetracycline 89 per cent in HKB. There were only one and five multi-resistant isolates in UMMC and HKB, respectively. In conclusion, NTS isolated from blood cultures of Malaysian children from Kuala Lumpur and Kota Bharu were highly sensitive to commonly prescribed antibiotics. We speculate that this is due to the restriction of sales of antimicrobials in Malaysia except by prescription. Continuing vigilance and frequent antmicrobial surveillance is necessary.

ABSTRACTThe incidence of food-borne salmonellosis due to Salmonella entericaserotype Weltevreden is reported to be on the increase in Malaysia. The pulsed-field gel electrophoresis (PFGE) subtyping method was used to assess the extent of genetic diversity and clonality of Salmonellaserotype Weltevreden strains from humans and the environment. PFGE of XbaI-digested chromosomal DNA from 95 strains of Salmonellaserotype Weltevreden gave 39 distinct profiles with a wide range of Dice coefficients (0.27 to 1.00), indicating that PFGE is very discriminative and that multiple clones of Salmonellaserotype Weltevreden exist among clinical and environmental isolates. Strains of one dominant pulsotype (pulsotype X1/X2) appeared to be endemic in this region, as they were consistently recovered from humans with salmonellosis between 1996 and 2001 and from raw vegetables. In addition, the sharing of similar PFGE profiles among isolates from humans, vegetables, and beef provides indirect evidence of the possible transmission of salmonellosis from contaminated raw vegetables and meat to humans. Furthermore, the recurrence of PFGE profile X21 among isolates found in samples of vegetables from one wet market indicated the persistence of this clone. The environment in the wet markets may represent a major source of cross-contamination of vegetables with Salmonellaserotype Weltevreden. Antibiotic sensitivity tests showed that the clinical isolates of Salmonellaserotype Weltevreden remained drug sensitive but that the vegetable isolates were resistant to at least two antibiotics. To the best of our knowledge, this is the first study to compare clinical and environmental isolates of Salmonellaserotype Weltevreden in Malaysia.

Eighty-four strains of Vibrio cholerae O1, O139 and non-O1/non-O139 from clinical and environmental sources were investigated for the presence of the toxin co-regulated pilus gene, tcpA, the virulence cassette genes ctxA, zot, ace and cep and also for their ability to elaborate haemolysin and protease. The ctxA and zot genes were detected using DNA–DNA hybridization while the ace, cep and tcpA genes were detected using PCR. Production of haemolysin and protease was detected using mammalian erythrocytes and an agar diffusion assay respectively. Analysis of their virulence profiles showed six different groups designated Type I to Type VI and the major distinguishing factor among these profiles was in the in vitro production of haemolysin and/or protease. Clinical O1, O139 and environmental O1 strains were similar with regard to presence of the virulence cassette genes. All environmental O1 strains with the exception of one were found to possess ctxA, zot and ace giving rise to the probability that these strains may actually be of clinical origin. One strain which had only cep but none of the toxin genes may be a true environmental isolate. The virulence cassette and colonization factor genes were absent in all non-O1/non-O139 environmental strains but production of both the haemolysin and protease was present, indicating that these may be putative virulence factors. These findings suggest that with regard to its pathogenic potential, only strains of the O1 and O139 serogroup that possess the tcpA gene which encodes the phage receptor, have the potential to acquire the CTX genetic element and become choleragenic.

Forty-three clinical strains of V. cholerae O1 biotype El Tor were isolated between 3 May and 10 June 1998 during an outbreak in the metropolitan area of Kuala Lumpur and its suburbs. With the exception of three Inaba strains that were restricted to three members of a family, all the others belonged to the Ogawa serotype. The strains were analysed for clonality using ribotyping and pulsed-field gel electrophoresis (PFGE). Two ribotypes, V/B21a and B27, were identified among 40 Ogawa isolates using BglI restriction endonuclease. Ribotype V/B21a has been described previously from Taiwan and Colombia and several Asian countries while B27 has been reported among isolates from Senegal. The three Inaba strains belonged to one ribotype, designated type A, not previously reported. PFGE analysis using NotI revealed that all isolates within a ribotype had identical profiles demonstrating clonality amongst the strains. Dice coefficient analysis of the two Ogawa genotypes revealed 89% similarity on ribotype patterns and 91.3% on PFGE profiles. Ribotype V/B21a isolates were associated with cases from dispersed areas of Kuala Lumpur and its suburbs while ribotype B27 was restricted to cases from one particular area suggesting a common-source outbreak.

A study was undertaken to determine the role of Helicobacter pylori in non-ulcer dyspepsia (NUD) and to determine the efficacy of colloidal bismuth subcitrate (CBS) in the treatment of NUD. Seventy-one patients were randomly allocated (double blind) to CBS or placebo, two tablets twice daily for 4 weeks. The severity of dyspepsia was scored and endoscopies performed before and after treatment, and antral biopsy specimens were taken for bacteriologic and histologic examination. Forty patients had H. pylori infection, and all had changes of chronic active gastritis. H. pylori was cleared from 17 of 21 patients (81%) treated with CBS, whereas none of the 19 patients treated with placebo cleared the bacteria. Improvement in histology was noted in 15 of 21 patients (71.4%) treated with CBS, whereas no improvement was noted in any of the placebo controls. Thirty-one patients were negative for H. pylori. All had either normal gastric histology or minor degrees of inflammation. Seventeen of these patients received CBS, and 14 received placebo. All groups reported improvement in the symptom score; however, the H. pylori-positive, CBS-treated group recorded a significantly higher improvement than the other groups (p < 0.001). Relapse of H. pylori infection after initial clearance of the bacteria was high. Twelve of 16 patients evaluated relapsed 1 month after withdrawal of CBS.

The effect of soy protein on the small bowel mucosa of 18 infants with acute gastroenteritis was studied. The infants were maintained on a protein hydro-lysate formula for 6–8 weeks, following which they were readmitted for soy protein challenge studies. Jejunal biopsy was performed before and 24 h after challenge. On the basis of the clinical and histological reaction to soy protein challenge, three groups were identified. Group 1 consisted of three infants who had clinical and histological reaction. There was associated depletion of mucosal enzymes, lactase, sucrase, malatase, alkaline phosphatase, and blood xylose levels. Group 2 consisted of seven infants who had histological reaction but no clinical symptoms. Two of these seven infants, however, developed clinical reaction when rechallenged with soy protein 2 and 90 days later. Following challenge, mucosal enzymes and blood xylose levels were depressed in five of the seven infants tested. Group 3 consisted of eight infants who did not have either a clinical or a histological reaction. The mucosal enzymes and blood xylose levels were not depressed in four infants tested. The present study shows that the small bowel mucosa of some young infants recovering from acute gastroenteritis remains sensitive to soy protein for a variable period of time. The feeding of soy protein to these infants may result in the persistence of mucosal damage and perpetuation of diarrhea. These findings have an important bearing in the nutritional management of infants recovering from AGE; the exclusion of soy protein from the diet of these infants, particularly during the period when the mucosa is damaged, may reduce the risk of the development of soy protein sensitive enteropathy and the attendant complication of protracted diarrhea.

Two methods of bacteriocin susceptibility typing for Serratia marcescens were compared. A total of 80 epidemiologically unrelated isolates from patients in a single hospital were typed by the cross-streaking method and the mitomycin C-induced (spotting) method. The cross-streaking method was found to be more discriminatory than the spotting method. Using the cross-streaking method, it was possible to differentiate 50 bacteriocin groups out of the 80 isolates, whereas only 31 groups could be obtained with the spotting method. The reproducibility and percentage typability of the cross-streaking method (82.5 and 93.75%, respectively) were found to be as good as, if not better than, those of the spotting method (78.75 and 90.0%, respectively). Other factors, such as lower economic cost, technical simplicity, and the relative ease in the scoring of results, indicate a preference for the cross-streaking method. The findings of this study support the choice of the cross-streaking method for the bacteriocin typing of S. marcescens in epidemiological studies.

The effect of soy protein on the small bowel mucosa of 18 infants with acute gastroenteritis was studied. The infants were maintained on a protein hydro-lysate formula for 6–8 weeks, following which they were readmitted for soy protein challenge studies. Jejunal biopsy was performed before and 24 h after challenge. On the basis of the clinical and histological reaction to soy protein challenge, three groups were identified. Group 1 consisted of three infants who had clinical and histological reaction. There was associated depletion of mucosal enzymes, lactase, sucrase, malatase, alkaline phosphatase, and blood xylose levels. Group 2 consisted of seven infants who had histological reaction but no clinical symptoms. Two of these seven infants, however, developed clinical reaction when rechallenged with soy protein 2 and 90 days later. Following challenge, mucosal enzymes and blood xylose levels were depressed in five of the seven infants tested. Group 3 consisted of eight infants who did not have either a clinical or a histological reaction. The mucosal enzymes and blood xylose levels were not depressed in four infants tested. The present study shows that the small bowel mucosa of some young infants recovering from acute gastroenteritis remains sensitive to soy protein for a variable period of time. The feeding of soy protein to these infants may result in the persistence of mucosal damage and perpetuation of diarrhea. These findings have an important bearing in the nutritional management of infants recovering from AGE; the exclusion of soy protein from the diet of these infants, particularly during the period when the mucosa is damaged, may reduce the risk of the development of soy protein sensitive enteropathy and the attendant complication of protracted diarrhea.