Assessment of the Antibiotic Resistance Profile, Genetic Heterogeneity and Biofilm Production of Methicillin-Resistant Staphylococcus aureus (MRSA) Isolated from The Italian Swine Production Chain

Abstract

The main aim of the present study was to evaluate the level of antibiotic resistance, prevalence and virulence features of methicillin-resistant Staphylococcus aureus (MRSA) isolated from heavy swine at abattoir level and farming environments in Lombardy (Northern Italy). With this scope, 88 different heavy swine farms were surveyed, obtaining a total of n = 440 animal swabs and n = 150 environmental swabs. A total of n = 87 MRSA isolates were obtained, with an overall MRSA incidence of 17.50% (n = 77) among animal samples and a 6.67% (n = 10) among environmental. Molecular characterisation using multilocus sequence typing (MLST) plus spa-typing showed that sequence type ST398/t899 and ST398/t011 were the most commonly isolated genotypes, although other relevant sequence types such as ST1 or ST97 were also found. A lack of susceptibility to penicillins, tetracycline and ceftiofur was detected in >91.95, 85.05 and 48.28% of the isolates, respectively. Resistance to doxycycline (32.18%), enrofloxacin (27.59%) and gentamicin (25.29%) was also observed. Additionally, a remarkable level of antibiotic multiresistance (AMR) was observed representing a 77.01% (n = 67) of the obtained isolates. Genetic analysis revealed that 97.70% and 77.01% of the isolates harboured at least one antibiotic resistance or enterotoxin gene, respectively, pointing out a high isolate virulence potential. Lastly, 55.17% (n = 48) were able to produce measurable amounts of biofilm after 24 h. In spite of the current programmes for antibiotic reduction in intensively farming, a still on-going high level of AMR and virulence potential in MRSA was demonstrated, making this pathogen a serious risk in swine production chain, highlighting once more the need to develop efficient, pathogen-specific control strategies.

Correlation Between Biofilm-Formation and the Antibiotic Resistant Phenotype in Staphylococcus aureus Isolates: A Laboratory-Based Study in Hungary and a Review of the Literature

“…In this report, the same methodology was utilized (plate-based quantitative measurements), and spa-typing was also performed: overall, isolates belonging to the ST398/t899 and ST398/t011 were the most common among biofilm-producers. 63 El-Nagdy et al detected biofilm-forming S. aureus (using the CRA plate method, complemented with scanning and transmission electron microscopy) from febrile neutropenic patients in Egypt; interestingly, they have found that 72.7% of isolates were biofilm-positive. Among the tested strains, 37.5% were positive for icaA , and 22.9% were positive for icaD ; however, only 50% of biofilm-producers carried either the icaA or icaD genes.…”

Occurrence of Methicillin-Resistant Coagulase-Negative Staphylococci (MRCoNS) and Methicillin-Resistant Staphylococcus aureus (MRSA) from Pigs and Farm Environment in Northwestern Italy

“…The detection of only one MRSA positive sample out of almost 200 tested animals was unexpected. Indeed, the prevalence of MRSA in finishing pigs in another region of northern Italy, Lombardy, was recently estimated at 17.5% [25]. Furthermore, in the south of Italy, prevalences higher than 45% were reported, with the majority of positive samples from intensively reared animals [26,27].…”

First Case of Staphylococci Carrying Linezolid Resistance Genes from Laryngological Infections in Poland

“…Data from one S. aureus strain belonging to t4474 isolated in Switzerland were submitted to a Ridom Spa Server database. Ho et al published a study concerning MRSA from slaughtered pigs sampled from local markets in Hong Kong in 2012 [ 53 ], and Rodríguez-López et al characterized MRSA from the Italian heavy swine production chain in 2020 [ 54 ]. Therefore, the worldwide distribution of this particular spa type is not exactly known.…”