Clinical relevance of virulence genes in Campylobacter jejuni isolates in Bahrain

Abstract

There are no data describing the genetic make-up of Campylobacter strains (an important aetiological agent of diarrhoea) circulating in the Arabian Gulf region. Here, the molecular characterization of two virulence genes in Campylobacter jejuni from Bahrain and the relationship with clinical infection are reported. Molecular screening for cytolethal distending toxin (cdtB) and invasion-associated marker (iam) genes was carried out on C. jejuni stool isolates collected from January 2002 to January 2004 in Bahrain. The molecular characterization was correlated with the patients' socio-demographic and clinical parameters. Of the 96 C. jejuni strains tested, 50 (52 %) were cdtB + /iam + , 30 (31 %) were cdtB + /iam " and 16 (17 %) were cdtB. Sixty-nine per cent (66/96) of patients were less than 3 years old, with significantly higher detection of cdtB + /iam + and cdtB + /iam " strains (P <0?001 and P <0?01, respectively) in this age group.Seventy patients (73 %) were symptomatic. In the group that were less than 3 years old, 62 and 85 % of those with cdtB + /iam + and cdtB + /iam " strains, respectively, were symptomatic compared with 100 % for those over 3 years of age. However, the presence of cdtBstrains still resulted in clinical infection in the children under 3 years but not in the older patients. This is the first report describing the molecular characterization of virulence genes in Campylobacter isolates from this region. The findings indicate that strains of different virulence genetic make-up are circulating in the population, with children under the age of 3 years being most vulnerable. Further work on the molecular characterization, gene expression and determination of the invasive phenotypes of C. jejuni strains circulating in different regions is needed.

Occurrence of virulence genes among Campylobacter jejuni and Campylobacter coli isolates from domestic animals and children

“…strains from children. Similar results were obtained by Al-Mahmeed et al (2006). However, Rizal et al (2010) estimated iam gene occurrence in human C. jejuni samples to be 77.7%.…”

“…It has been linked with subsequent development of Guillain-Barré syndrome (GBS), which usually develops 2 up to 3 weeks after the initial illness (van Doorn 2009). This wide range of clinical symptoms cannot be explained as pertaining only to the host's response; characteristics of the bacterial pathogen may contribute (Rożynek et al 2005, Al-Mahmeed et al 2006. Adherence, invasion and cytotoxin production appear to be essential virulence factors (Wardak et al 2006).…”

Campylobacter jejuni infection and virulence-associated genes in children with moderate to severe diarrhoea admitted to emergency rooms in northeastern Brazil

“…In accordance with our findings, other studies regarding the prevalence of VAGs worldwide also found a very high proportion of these genes in different types of clinical and animal samples (Datta et al, 2003;Al-Mahmeed et al, 2006;Talukder et al, 2008;Ripabelli et al, 2010;Andrzejewska et al, 2011;Hamidian et al, 2011), especially ciaB (95-98 %) and the cdtABC operon (85-100 %).…”

“…This differed from a previous report that found a higher rate of detection of two VAGs in one particular symptomatic group (Al-Mahmeed et al, 2006). Once again, this lack of association may be caused by geographical factors or individual circumstances relating to the Campylobacter infections.…”

IgM seroconversion to Campylobacter jejuni in the first two years of life of children with gastrointestinal symptoms

“…Utvrđeno je, da je nivo antitela na Campylobacter jejuni mnogo viši kod dece koja žive u zemljama u razvoju, a utvrđeni su i blaži klinički oblici bolesti u odnosu na decu iz razvijenih zemalja (12). O patogenezi kampilobakterioze i razvoju posledičnog protektivnog imuniteta u toku infekcije, danas se vrlo malo zna (13).…”