Salmonella enterica is one of the major causes of bacterial foodborne infection. The aims of this study were to determine the antibiotic resistance and the genetic diversity of Salmonella enterica isolated from street foods and clinical samples and to understand the correlation between the prevalence of serovars and genotypes with their source (street food and clinical samples) and geographic origin (Negeri Sembilan, Malacca and Selangor in Peninsular Malaysia). The enterobacterial repetitive intergenic consensus (ERIC) PCR analysis distinguished the Salmonella isolates into 19 ERIC types, with one untypable isolate. Dendrograms were specifically constructed for the S. Biafra and S. Typhi isolates. Identical or very similar ERIC types among the S. Biafra isolates from street food samples indicate transmission of the S. Biafra among the street foods, as well as possible cross-contamination of the street foods. In addition, the identical or very similar ERIC types among the S. Typhi isolates from human samples examined suggest possible similarity in their source of infection. All the twenty four isolates were resistant to rifampin and none were resistant to cefuroxime. Most isolates displayed multiple resistances. Dendrogram of antibiotic resistances produced six clusters, with similarity levels between 18.8% and 100%. Generally, street food and clinical isolates tend to cluster apart. Dendrogram to cluster the antibiotic groups showed that they could be grouped according to classes based on mode of inhibition. The findings suggest that street food contaminated with drug-resistant Salmonella enterica can be an important factor in the continuous emergence of antibiotic resistant Salmonella enterica.
Broiler part samples (80 fresh and 80 chilled) were examined for the prevalence and numbers of C. jejuni and C. coli by employing most-probable-number (MPN) and polymerase chain reaction (PCR) techniques. The prevalence of the bacteria was high where C. jejuni was detected in 92.5% fresh and 53.8% chilled samples while C. coli in 80.0% fresh and 56.3% chilled. The number of these bacteria in the positive fresh and chilled samples was from 3 to more than 2400 MPN/g and from 3 to 290 MPN/g, respectively. Antibiotic resistance test (using Kirby-Bauer disc diffusion method) on 10 C. jejuni and 13 C. coli isolates toward ampicillin, tobramycin, enrofloxacin, ciprofloxacin, tetracycline, cephalothin, gentamicin and norfloxacin revealed high resistance toward all antibiotics (20.0% - 100.0%). All isolates were resistant to at least two antibiotics. This study highlights the potential of multidrug-resistant C. jejuni and C. coli transmission to humans through fresh and chilled broiler parts. Consecutive studies with bigger sample sizes and covering all over Malaysia are warranted in future.
Listeria monocytogenes is a gram positive, facultative intracellular pathogen with the capacity to cause
food poisoning outbreaks as well as severe illness in vulnerable human population groups. It can cause a rare but serious disease called listeriosis with high fatality rates (20–30%) compared with other foodborne microbial pathogens. Although Listeria monocytogenes is infective to all human population groups, it is more likely to cause severe problems among pregnant women, immunocompromised individuals, the elderly and neonates. There are a variety of phenotyphic and genotyphic methods for the detection of Listeria monocytogenes in foods. Recent technological advances have increased the ability of scientists to detect Listeria monocytogenes. The purpose of this review is to discuss molecular characteristics of the Listeria monocytogenes pathogen, standard detection methods of this pathogen in foods based on culture methods, confirmation of species and subtyping based on phenotypic and genotyphic methods.