Fish-borne methicillin resistant Staphylococcus haemolyticus carrying atypical staphylococcal cassette chromosome mec (SCCmec) elements

G.K. Sivaraman, K.H. Muneeb, S. Sudha, Bibek Shome, Mark Holmes, Jennifer Cole

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Prevalence of staphylococci in fish and fish products pose high risk of foodborne diseases. As far as Staphylococcus haemolyticus as a reservoir of methicillin resistance is considered, main objective of the present study was to surveil the incidence of methicillin-resistant Staphylococcus haemolyticus (MRSH) in fishes and its genotypic characterization. 79 fish samples were collected from retail markets in three pre-decided sites in Assam. The collected fish samples were subjected to microbial analysis and as result 13 MRSH could be isolated.

Susceptibility of the isolates towards various classes of antibiotics was assessed by employing BD Phoenix M50 system. Polymerase chain reaction (PCR) was performed for the molecular detection of methicillin-resistance determinant. Molecular typing of the isolates was attempted by recruiting staphylococcal cassette chromosome mec (SCCmec) and pulsed-field gel electrophoresis (PFGE). Out of 79 fish samples collected from retail markets in Assam, 13 tested positive for MRSH. These isolates showed varying levels of resistance to different classes of antibiotics such as cephalosporin (100%), lincosamide (30.76%), macrolides (30.76%), aminoglycoside (53.85%), quinolones (38.46%) and sulfonamides (61.54%). BD Phoenix M50 instrument recognized a few isolates as inducible macrolide-lincosamide-streptogramin B (iMLSb) phenotype (30.76%).

Remarkably, all the isolates were reported as multi-drug resistant (MDR) as they showed resistant to ≥3 classes of antibiotics. All the studied isolates were positive for mecA gene and carrying multiple SCCmec elements. PFGE cluster analysis grouped the isolates into two major clusters and seven individual lineages. In short, the current study documented the incidence of multi-drug resistant, multiple SCCmec elements carrying S. haemolyticus in fishes. Considering the fact that S. haemolyticus contributes greatly in the dissemination of methicillin resistance owing to their extreme genome plasticity, the present study admonition the necessity of continuous monitoring the S. haemolyticus contamination in food.

The study also discussed role of prudent hygienic practices in flattening the AMR curves.
Original languageEnglish
Article number100982
Number of pages9
JournalGene Reports
Publication statusPublished - 27 Nov 2020


  • Antibiotic resistance
  • methicillin resistant Staphylococcus haemolyticus
  • mec (SCCmec) elements
  • Fish
  • India
  • Aquaculture

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