title: Prevalence, Virulence Potential, and Antibiotic Susceptibility Profile of Listeria monocytogenes Isolated From Bovine Raw Milk Samples Obtained From Rajasthan, India.
abstract: Listeriosis is a serious foodborne disease of a global concern, and can effectively be controlled by a continuous surveillance of the virulent and multidrug-resistant strains of Listeria monocytogenes. This study was planned to investigate prevalence of L. monocytogenes in bovine raw milk samples. A total of 457 raw milk samples collected from 15 major cities in Rajasthan, India, were analyzed for the presence of L. monocytogenes by using standard microbiological and molecular methods. Five of the 457 samples screen tested positive for L. monocytogenes. Multiplex serotyping showed that 3/5 strains belonged to serotype 4b followed by one strain each to 1/2a and to 1/2c. Further virulence potential assessment indicated that all strains possessed inlA and inlC internalins, and, in addition, two strains also possessed the gene for inlB. All strains were positive for Listeriolysin O (LLO) and showed phosphatidylinositol-specific phospholipase C (PI-PLC) activity on an in vitro agar medium with variations in production levels among the strains. A good correlation between the in vitro pathogenicity test and the chick embryo test was observed, as the strains showing higher LLO and PI-PLC activity were found to be lethal to fertilized chick embryos. All strains were resistant to the majority of antibiotics and were designated as multidrug-resistant strains. However, these strains were susceptible to 9 of the 22 tested antibiotics. The maximum zone of inhibition (mm) and acceptable minimum inhibitory concentration were observed with azithromycin, and thus it could be the first choice of a treatment. Overall, the presence of multidrug-resistant L. monocytogenes strains in the raw milk of Rajasthan region is an indicator of public health hazard and highlighting the need of consumer awareness in place and implementation of stricter food safety regulations at all levels of milk production.
authors.affiliation: Advanced Milk Testing Research Laboratory, Post Graduate Institute of Veterinary Education and Research , Mansarovar, Jaipur, Rajasthan, India .
authors.forename: Sanjita
authors.initials: S
authors.lastname: Sharma
authors.affiliation: Advanced Milk Testing Research Laboratory, Post Graduate Institute of Veterinary Education and Research , Mansarovar, Jaipur, Rajasthan, India .
authors.forename: Vishnu
authors.initials: V
authors.lastname: Sharma
authors.affiliation: Advanced Milk Testing Research Laboratory, Post Graduate Institute of Veterinary Education and Research , Mansarovar, Jaipur, Rajasthan, India .
authors.forename: Dinesh Kumar
authors.initials: DK
authors.lastname: Dahiya
authors.affiliation: Advanced Milk Testing Research Laboratory, Post Graduate Institute of Veterinary Education and Research , Mansarovar, Jaipur, Rajasthan, India .
authors.forename: Aarif
authors.initials: A
authors.lastname: Khan
authors.affiliation: Advanced Milk Testing Research Laboratory, Post Graduate Institute of Veterinary Education and Research , Mansarovar, Jaipur, Rajasthan, India .
authors.forename: Manisha
authors.initials: M
authors.lastname: Mathur
authors.affiliation: Advanced Milk Testing Research Laboratory, Post Graduate Institute of Veterinary Education and Research , Mansarovar, Jaipur, Rajasthan, India .
authors.forename: Amit
authors.initials: A
authors.lastname: Sharma
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001427:Bacterial Toxins / Q000235:genetics; D002642:Chick Embryo / Q000382:microbiology; D024901:Drug Resistance, Multiple, Bacterial; D005506:Food Contamination / Q000032:analysis; D005516:Food Microbiology; D059022:Food Safety; D005517:Foodborne Diseases / Q000382:microbiology*; D006360:Heat-Shock Proteins / Q000235:genetics; D006460:Hemolysin Proteins / Q000235:genetics; D007194:India; D008089:Listeria monocytogenes / Q000187:drug effects* / Q000302:isolation & purification* / Q000472:pathogenicity; D008088:Listeriosis / Q000188:drug therapy / Q000453:epidemiology*; D008826:Microbial Sensitivity Tests; D008892:Milk / Q000382:microbiology*; D015995:Prevalence; D012336:RNA, Ribosomal, 16S / Q000302:isolation & purification; D017423:Sequence Analysis, RNA; D012703:Serotyping
chemical_list: D000900:Anti-Bacterial Agents; D001427:Bacterial Toxins; D006360:Heat-Shock Proteins; D006460:Hemolysin Proteins; D012336:RNA, Ribosomal, 16S; C038705:hlyA protein, Listeria monocytogenes
keywords: Listeria monocytogenes; Listeriolysin O; antimicrobial resistance; chick embryo test; pathogenicity; serotyping