Detection of Resistant and Enterotoxigenic Strains of Staphylococcus warneri Isolated from Food of Animal Origin.

The topic of this work is the detection of antimicrobial resistance to Staphylococcus warneri strains and the genes encoding staphylococcal enterotoxins. It is considered a potential pathogen that can cause various-mostly inflammatory-diseases in immunosuppressed patients. The experimental part of the paper deals with the isolation of individual isolates from meat samples of Oryctolagus cuniculus, Oncorhynchus mykiss, Scomber scombrus, chicken thigh, beef thigh muscle, pork thigh muscle, and bryndza cheese. In total, 45 isolates were obtained and subjected to phenotypic (plasma coagulase activity, nuclease, pigment, hemolysis, lecithinase, and lipase production) and genotypic analyses to confirm the presence of the S. warneri species. The presence of genes encoding staphylococcal enterotoxins A (three isolates) and D (six isolates) was determined by PCR. Using the Miditech system, the minimum inhibitory concentration for various antibiotics or antibiotics combinations was determined, namely for ampicillin; ampicillin + sulbactam; oxacillin; cefoxitin; piperacillin + tazobactam; erythromycin; clindamycin; linezolid; rifampicin; gentamicin; teicoplanin; vancomycin; trimethoprim; chloramphenicol; tigecycline; moxifloxacin; ciprofloxacin; tetracycline; trimethoprim + sulfonamide; and nitrofurantoin. Resistance to ciprofloxacin and tetracycline was most common (73%). At the same time, out of a total of 45 isolates, 22% of the isolates were confirmed as multi-resistant. Isolates that showed phenotypic resistance to ß-lactam antibiotics were subjected to mecA gene detection by PCR.

Effects of vacuum packaging conditions on the quality, biochemical changes and the durability of ostrich meat.

In this study, the effects of vacuum packaging conditions on the concentrations of lactic acid, malondialdehyde, pH, microbial and sensory analysis were determined during chilled storage of ostrich meat. Meat was packed as follows: vacuum packed from 1st day (VP-1), vacuum packed from 3rd day (VP-3) and non-vacuum packed (NVP). Analysis were performed at 1st, 7th, 14th, 21st day after slaughter. Meat consisted of 74.69% water, 2.29% fats, 20.95% proteins. Package conditions had significant effect on the pH (NVP: 6.54 on the 14th day, VP-1: 6.05 and VP-3: 6.07 on the 21th day p<0.001), amount of malondialdehyde (NVP: 8.62mg/kg on the 14th day; VP-1: 1.95 and VP-3: 2.55 on the 21th day; p<0.001) and total microbial count (NVP: 7.4 log CFU/g on the 14th day; VP-1: 6.7 and VP-3: 6.8 on the 21th day p<0.01). Based on these results we can assess that vacuum packed from 1st day is necessary for the 21 days storage of ostrich meat.

Species identification and antimicrobial resistance of coagulase-negative staphylococci isolated from the meat of sea fish.

UNLABELLED: Seventy-eight isolates of staphylococci obtained from the meat of Theragra chalcogramma, Scomber scombrus, and Clupea harengus were identified and tested in this study. 16S rDNA sequence specific for the genus Staphylococcus was detected in all isolates with the help of PCR method. All of 78 isolates were coagulase-negative, and DNAse activity was only confirmed in 4 of them. The following species of staphylococci were identified using MALDI-TOF mass spectrometry: S. warneri (52%), S. epidermidis (33%), S. haemolyticus (6.4%), S. pasteuri (3.8%), S. sciuri (1.2%), S. capitis (1.2%), and S. hominis (1.2%). Antimicrobial resistance to 7 antibiotics was determined in each isolate with the help of agar dilution method. In general, resistance against ampicillin was observed in majority of isolates (87%). On the contrary, the best sensitivity of CoNS was determined to gentamicin (96%). Only 1 S. warneri strain showed resistance to cefoxitin. Furthermore, 83% of staphylococcal isolates were simultaneously resistant to 2 or more antibiotics. PRACTICAL APPLICATION: This study confirmed the need of monitoring antimicrobial resistance in coagulase-negative staphylococci not only in the meat of slaughter animals but also in retail marine fish. The results showed that MALDI-TOF mass spectrometry is useful, accurate, and rapid method for species identification of food pathogens including Staphylococcus spp.