Detection of Virulence Genes in Vibrio cholerae Isolated from Aquatic Environment in Kerala, Southern India

Kumar, Praveen; Peter, Wilson A.; Thomas, Sabu

doi:10.1007/s12010-008-8184-5

Cited by 11 publications

(8 citation statements)

References 17 publications

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“…These results support previous findings that the non-O1 serogroup is distributed ubiquitously in the aquatic environment (Chakraborty et al, 2000;Rivera et al, 2001;Kumar et al, 2008). There are several reports of outbreaks or sporadic cases of gastroenteritis and extraintestinal infections in humans caused by non-O1 serogroup V. cholerae (Bagchi et al, 1993;Ou et al, 2003).…”

Section: Prevalence Of V Cholerae Non-o1 Serogroups In Edible Icesupporting

confidence: 90%

“…Virulence genes found in V. cholerae non-O1 serogroups Generally, non-O1 serogroup isolates do not harbour virulence genes (Sack et al, 2004), although this scenario continues to evolve, with these non-O1 environmental isolates acquiring virulence genes (Kumar et al, 2008;Jagadeeshan et al, 2009;Kumar et al, 2010). In our study, 75 % of the isolates harboured the toxR gene, and it was distributed in both O1 and non-O1 serogroups of V. cholerae (Table 2).…”

Section: Prevalence Of V Cholerae Non-o1 Serogroups In Edible Icementioning

confidence: 47%

“…The presence of virulence genes is usually associated with the O1 group (Sack et al, 2004). However, this scenario has been evolving slowly in recent years, and several studies have reported the presence of virulence genes in non-O1 environmental isolates (Kumar et al, 2008;Jagadeeshan et al, 2009;Kumar et al, 2010). The O1 serogroup is subdivided into the classical and El Tor biotypes.…”

Section: Introductionmentioning

confidence: 99%

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Edible ice in Jakarta, Indonesia, is contaminated with multidrug-resistant Vibrio cholerae with virulence potential

Waturangi

Wennars

Suhartono

et al. 2013

Journal of Medical Microbiology

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Consumption of street food is considered a major health risk in the absence of public-health inspection programmes in Indonesia. It is hypothesized that ice used in street food could be one of the major sources of Vibrio cholerae contamination. This study documented V. cholerae contamination in edible ice from different areas of Jakarta, the capital city of Indonesia, and attempted to characterize the virulence potential of the strains. A selective medium was used to isolate 98 V. cholerae strains and their identity was confirmed using biochemical assays. Serological tests classified the majority (78 %) in the non-O1 serogroup. Multiplex PCR was used to detect the presence of V. cholerae virulence genes, namely ctxA, ompU, tcpA, ace, zot and toxR. The toxR, ctxA, ompU and zot genes were detected in 75, 26, 15 and 1 % of isolates, respectively. The ace and tcpA genes were not detected in any of the isolates. The ctxA gene encoding the cholera toxin subunit A, which has been associated only with clinical strains of O1, here was present in both serogroups. The antibiotic-resistance profile showed that 65, 60, 52, 39, 37, 19 and 3 % of the isolates were resistant to ampicillin, streptomycin, kanamycin, sulfamethoxazole-trimethoprim, erythromycin, tetracycline and ciprofloxacin, respectively. A large proportion of V. cholerae isolates came from west and south Jakarta, and these strains exhibited multidrug resistance to ampicillin, streptomycin, tetracycline, erythromycin, kanamycin and sulfamethoxazole-trimethoprim. Many of these isolates from west and south Jakarta also harboured toxR, encoding a regulator, and ctxA. The presence of multidrug-resistant V. cholerae with virulence genes in edible ice, which could cause a severe outbreak, reflects the poor water quality in Jakarta, and indicates an urgent need for better surveillance and management. INTRODUCTIONIce products are often used in street foods and are consumed by most people, especially in tropical countries such as Indonesia. Microbial infections acquired from contaminated ice are not uncommon and have been reported for Escherichia coli O157 : H7, Legionella pneumophila, Salmonella enteritidis and Norwalk-like virus (Kim & Harrison, 2008;Seo et al., 2006;Boccia et al., 2002;Graman et al., 1997). A significant number of cholera cases are due to consumption of contaminated water rather than personto-person transmission (Schild et al., 2008).The causative agent of cholera is Vibrio cholerae. Although it is a marine organism, it can also be found in fresh-water rivers. There are two V. cholerae serogroups, O1 and non-O1. Members of the O1 group are associated with epidemic cholera, whereas non-O1 members isolated from estuaries are associated with sporadic illness. The presence of virulence genes is usually associated with the O1 group (Sack et al., 2004). However, this scenario has been evolving slowly in recent years, and several studies have reported the presence of virulence genes in non-O1 environmental isolates (Kumar et al., 2008;Jagadeeshan et al., 2009...

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Section: Prevalence Of V Cholerae Non-o1 Serogroups In Edible Icesupporting

confidence: 90%

Section: Prevalence Of V Cholerae Non-o1 Serogroups In Edible Icementioning

confidence: 47%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Edible ice in Jakarta, Indonesia, is contaminated with multidrug-resistant Vibrio cholerae with virulence potential

Waturangi

Wennars

Suhartono

et al. 2013

Journal of Medical Microbiology

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show abstract

“…There have been attempts to unravel the mechanisms of pathogenicity in environmental isolates from various regions of India where cholera is truly endemic and epidemic [1,16,34,45,46]. This study presents various extracellular and intracellular putative mechanisms of toxicity associated with environmental isolates from Gujarat and suggests that these mechanisms could lead to inflammatory and hemorrhagic responses in synergy with each other.…”

Section: Discussionmentioning

confidence: 98%

Synergistic Effect of Various Virulence Factors Leading to High Toxicity of Environmental V. cholerae Non-O1/ Non-O139 Isolates Lacking ctx Gene : Comparative Study with Clinical Strains

et al. 2013

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Background Vibrio cholerae non-O1/ non-O139 serogroups have been reported to cause sporadic diarrhoea in humans. Cholera toxins have been mostly implicated for hypersecretion of ions and water into the small intestine. Though most of the V. cholerae non-O1/ non-O139 strains lack these cholera toxins, several other innate virulence factors contribute towards their pathogenicity. The environmental isolates may thus act as reservoirs for potential spreading of these virulence genes in the natural environment which may cause the emergence of epidemic-causing organisms.ResultsThe environmental isolates of vibrios were obtained from water samples, zooplanktons and phytoplanktons, from a village pond in Gandhinagar, Gujarat, India. They were confirmed as Vibrio cholerae non-O1/ non-O139 using standard biochemical and serotyping tests. PCR experiments revealed that the isolates lacked ctxA, ctxB, tcpA, zot and ace genes whereas other pathogenicity genes like toxR, rtxC, hlyA, hapA and prtV were detected in these isolates. Compared with epidemic strain V. cholerae O1 El Tor N16961, culture supernatants from most of these isolates caused higher cytotoxicity to HT29 cells and higher hemolytic, hemagglutinin and protease activities. In rabbit ileal loop assays, the environmental isolates showed only 2-4 folds lesser fluid accumulation in comparison to N16961 and a V. cholerae clinical isolate IDH02365 of 2009. Pulsed Field Gel electrophoresis and Random amplification of Polymorphic DNA indicated that these isolates showed considerable diversity and did not share the same clonal lineage even though they were derived from the same water source. All the isolates showed resistance to one or more antibiotics.ConclusionThough these environmental isolates lacked the cholera toxins, they seem to have adopted other survival strategies by optimally utilising a diverse array of several other toxins. The current findings indicate the possibility that these isolates could cause some gastroenteric inflammation when ingested and may serve as progenitors for overt disease-causing organisms.

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“…They were all similarly negative for zot , the product of which can potentially increase the permeability of rabbit ileal mucosa by affecting the structure of the intracellular tight junction. However, they all did possess hlyA, a gene whose product is an exotoxin related to CT, and rtxA , a heat-stable enterotoxin, both of which can be found in non-O1 strains isolated from patients with cholera [41], or from environmental strains from endemic areas [5,24,42]. All strains possessed toxR, a 32-kDa transmembrane protein that acts as a master regulator of ctxAB gene [43].…”

Section: Resultsmentioning

confidence: 99%

Indigenous Vibrio cholerae strains from a non-endemic region are pathogenic

Islam¹,

Labbate²,

Djordjevic³

et al. 2013

Open Biol.

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Of the 200+ serogroups of Vibrio cholerae, only O1 or O139 strains are reported to cause cholera, and mostly in endemic regions. Cholera outbreaks elsewhere are considered to be via importation of pathogenic strains. Using established animal models, we show that diverse V. cholerae strains indigenous to a non-endemic environment (Sydney, Australia), including non-O1/O139 serogroup strains, are able to both colonize the intestine and result in fluid accumulation despite lacking virulence factors believed to be important. Most strains lacked the type three secretion system considered a mediator of diarrhoea in non-O1/O13 V. cholerae. Multi-locus sequence typing (MLST) showed that the Sydney isolates did not form a single clade and were distinct from O1/O139 toxigenic strains. There was no correlation between genetic relatedness and the profile of virulence-associated factors. Current analyses of diseases mediated by V. cholerae focus on endemic regions, with only those strains that possess particular virulence factors considered pathogenic. Our data suggest that factors other than those previously well described are of potential importance in influencing disease outbreaks.

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Detection of Virulence Genes in Vibrio cholerae Isolated from Aquatic Environment in Kerala, Southern India

Cited by 11 publications

References 17 publications

Edible ice in Jakarta, Indonesia, is contaminated with multidrug-resistant Vibrio cholerae with virulence potential

Edible ice in Jakarta, Indonesia, is contaminated with multidrug-resistant Vibrio cholerae with virulence potential

Synergistic Effect of Various Virulence Factors Leading to High Toxicity of Environmental V. cholerae Non-O1/ Non-O139 Isolates Lacking ctx Gene : Comparative Study with Clinical Strains

Indigenous Vibrio cholerae strains from a non-endemic region are pathogenic

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