Determination of virulence and antibiotic resistance pattern of biofilm producing Listeria species isolated from retail raw milk

Abstract

BackgroundOne of the foodborne pathogens is Listeria monocytogenes, which causes serious invasive illness in elderly and immunocompromised patients, pregnant women, newborns and infants ranking second after salmonellosis because of its high case fatality rate. Listerial cow mastitis marked by abnormal milk, increased cell counts and reduced production has not been reported. Therefore, apparently healthy cows can be reservoirs of L. monocytogenes. A number of 203 udder milk samples from apparently healthy animals (buffalo, n = 100; cow, n = 103) were collected and tested for Listeria. Isolated colonies on the PALCAM agar were Listeria species confirmed according to their biochemical and the Christie–Atkins–Munch-Petersen (CAMP) reactions. The Listeria species pathogenicity of was tested by phosphatidylinositol-specific phospholipase C, DL-alanine-β-naphthylamide HCl, Dalanine-p-nitroanilide tests, chick embryo, mice inoculation tests, Vero cell cytotoxicity and biofilm formation. The virulence-associated genes, hlyA, plcB, actA and iap associated with Listeria were molecularly assayed.ResultsThe 17 isolated Listeria spp. represented a prevalence rate of 8.4 %. Of these 3 (1.4 %), 2 (1 %), 5 (2.5 %), 4 (2 %) and 3 (1.5 %) were confirmed as L. monocytogenes, L. innocua, L. welshimeri, L. seelegeri, respectively. While the L. monocytogenes isolate displayed all the four virulence-associated genes, L. seelegeri carried the hlyA gene only. The L. monocytogenes had a strong in vitro affinity to form a biofilm, in particular serotype 4 which is associated with human infections. L. monocytogenes showed resistance for 9/27 antibiotics.ConclusionsThe biofilm forming capability of the Listeria spps. makes them particularly successful in colonizing surfaces within the host thus being responsible for persistence infections and due to their antimicrobial resistant phenotype that this structure confers. In addition, strains belonging to serotypes associated with human infections and characterized by pathogenic potential (serotype 4) are capable to persist within the processing plants forming biofilm and thus being a medical hazard.

Çiğ Süt ve Süt Ürünlerinde Listeria monocytogenes Varlığı ve Antibiyotik Direnci

“…The highest resistance has been found against trimethoprim-sulfamethoxazole. In parallel to our findings, Jamali et al [1] , Usman et al [29] , Osman et al [34] and Harakeh et al [39] reported resistance to trimethoprim-sulfamethoxazole. On the other hand, Karadal and Yıldırım [37] and Mackiw et al [40] indicated no resistance to trimethoprim-sulfamethoxazole.…”

“…On the other hand, Karadal and Yıldırım [37] and Mackiw et al [40] indicated no resistance to trimethoprim-sulfamethoxazole. Many researchers [1,9,13,16,29,34,38,39] reported resistance to penicillin G. In parallel to these results, our study also determined resistance to penicillin G. On the other hand, Karadal and Yıldırım [37] and Conter et al [41] reported no resistance to penicillin G. Aydın et al [42] reported that L. monocytogenes strains of food origin are resistant to meropenem, penicillin G and trimethoprim-sulfamethoxazole. In parallel to these findings, this study also determined resistance to the three antibiotics indicated.…”

“…at 13% and 8.3% respectively. On the other hand, Sağun et al [10] , Soyutemiz et al [11] , Rahimi et al [16] Aygün and Pehlivanlar [30] , Mahmodii [31] , Shamloo et al [32] , Ünlü et al [33] and Osman et al [34] reported isolation of L. monocytogenes at the rates of 1.2%, 3%, Aygün and Pehlivanlar [30] and Mahmodii [31] reported isolation of L. monocytogenes from white cheese at the rates of 2.35% and 3.3-6.7% respectively (at two different production sites). Our study also determined that 3% of the white cheese samples were L. monocytogenes positive which is a finding close to those of the above-mentioned researchers.…”

“…Our findings are consistent with the findings of certain researchers [9,39,41] . However, some researchers [1,16,34,38] reported that there was no vancomycine resistance. L. monocytogenes isolates can develop resistance by acquiring mobile genetic components such as mobilizable plasmids and conjugative transposons.…”

Prevalence, Pathogenicity, Virulence, Antibiotic Resistance, and Phylogenetic Analysis of Biofilm-Producing Listeria monocytogenes Isolated from Different Ecological Niches in Egypt: Food, Humans, Animals, and Environment

“…The current study examined the frequency of L. monocytogenes in different retail food and in animals or human clinical cases of abortion and septicemia in the Greater Cairo Area, based on the prevalence as determined in previous national studies on milk samples [32][33][34]. L. monocytogenes were found in 20/1607 (1.3%) samples analyzed (including 1406 retail food samples, 136 veterinaries, and 65 clinical samples).…”