One hundred and ninety seven samples of molluscs representing different species were tested for the presence of antibacterial substances using a microbiological diffusion test - “4-plate” method. It was found that 58 samples (29.4%) were positive. The percentage of positive samples depended on species and varied from 0 (Ostrea edulis, Perna canaliculis, Cardiumedule, Myretrix lyrata, Mercenaria mercenaria) to 41.2 (Mytilus edulis) and 50.0 (Tapes semidecussatus and Ruditapesphillipinarium). The randomly performed confirmatory analyses using HPLC -MS/MS method did not show the presence of any known antibiotics.
One hundred and nine samples of honey representing different botanical types were microbiologically retested for the total number of aerobic bacteria per 1 g, the presence of anaerobic bacteria in 0.1 g, and number of yeasts and moulds per 1 g after one year of storage. The samples displayed different levels of microbiological contamination. The mean of total number of aerobic bacteria varied from 1.9 x 101 CFU/g to 4.6 x 103 CFU/g depending on the type of honey. This value, in comparison with year 2010 was lower in the case of 75 samples (68.8%), higher in 14 samples (12.8%), and stable in the remaining 20 samples (18.4%). The mean number of moulds and yeasts was 9.8 x 101 CFU/g and it was lower in 46 samples (42.2%). In 46 samples no changes were noted. The presence of anaerobic spore forming bacteria was noted in 18 samples. The presence of these microorganisms in 73 honey samples (67.0%) did not change since 2010.
Raw, inhibitors free milk was spiked with penicillin G, ampicillin, cloxacillin, and ceftiofur at the levels 1 × MRL, 1.5 × MRL, and 2 × MRL, and oxytetracycline at the levels 100 ppb (MRL), 500 ppb and 700 ppb. The samples were stored at 4 ± 2 C and -18 ± 2 C and were tested every day and week, respectively. The analyses were performed using microbiological diffusion test Delvotest SP-NT and receptor assay CHARM ROSA MRL BL/TET for the detection of β-lactams and tetracyclines. In cooled samples antibiotics were detected up to 72 h. After this time, the samples were acidulated and not suitable for investigations. In frozen samples, depending on type and concentration of antibiotics, these substances were detected from one week (penicillin G - 4 ppb) to 35 weeks (ampicillin and ceftiofur).
The aim of the study was a preliminary determination of occurrence of extended spectrum β-lactamases (ESBL)- and AmpC-producing Escherichia coli (E.coli) in raw meat samples collected from slaughter-houses located in different regions of Poland. A total of 141 samples were tested, comprising 78 pork samples, 44 beef samples, and 19 chicken meat samples. Isolated and identified E. coli strains were examined for the ESBL and/or AmpC β-lactamases production by the use of four disc diffusion and minimum inhibitory concentration tests. All strains positive in one or both tests were examined by PCR for the presence of the blaCTX, blaTEM, blaSHV, and blaCMY-2 group genes. During the study, 154 E. coli strains were isolated from 95 samples. Among these, 18 (11.7%) strains were identified in phenotypic tests as ESBL-producing and seven (4.5%) strains as AmpC-positive. The presence of the genes encoding selected ESBL-s (TEM, CTX, SHV) was identified in 14 of the strains recognised as ESBLpositive in phenotypic tests. All AmpC-positive isolates showed the presence of the CMY-2 group encoding genes. One of these strains had also the CTX-M and TEM genes, and four of them expressed the TEM marker.
In the present study, 25 Escherichia coli strains isolated from beef, pork, and poultry meat, and producing extendedspectrum β-lactamases (ESBL) (18 strains) or AmpC- cephalosporinases (7 strains) were tested for antimicrobial resistance using the minimum inhibitory concentration method with 16 antimicrobial agents. All examined strains were resistant to ampicillin and the first-generation cephalosporins. Variable resistance to the third-generation cephalosporins (40%-100% among ESBLproducing strains and 0-72% among AmpC-producing strains) was noted. Less than 30% of examined strains were resistant to ciprofloxacin. All isolates were susceptible to the fourth-generation cephalosporins, cephalosporins connected with inhibitors of β-lactamases, carbapenems, and gentamycin
Introduction: The aim of the study was to evaluate the occurrence of enterococci in inflammatory secretions from mastitic bovine udders and to assess their antimicrobial resistance.
Material and Methods: A total of 2,000 mastitic milk samples from cows were tested in 2014–2017. The isolation of enterococci was performed by precultivation in buffered peptone water, selective multiplication in a broth with sodium azide and cristal violet, and cultivation on Slanetz and Bartley agar. The identification of enterococci was carried out using Api rapid ID 32 strep kits. The antimicrobial susceptibility was evaluated using the MIC technique.
Results: Enterococci were isolated from 426 samples (21.3%). Enterococcus faecalis was the predominant species (360 strains), followed by E. faecium (35 isolates), and small numbers of others. The highest level of resistance was observed to lincomycin, tetracycline, quinupristin/dalfopristin (Synercid), erythromycin, kanamycin, streptomycin, chloramphenicol, and tylosin. Single strains were resistant to vancomycin and ciprofloxacin. All isolates were sensitive to daptomycin. E. faecalis presented a higher level of resistance in comparison to E. faecium, except to nitrofurantoin.
Conclusion: The results showed frequent occurrence of enterococci in mastitic cow’s milk and confirmed the high rate of their antimicrobial resistance.
The aim of study was the preliminary evaluation of the occurrence of methicillin-resistant Staphylococcus aureus (MRSA) and extended spectrum ß-lactamases (ESBL) - producing Escherichia coli in 650 milk and inflammatory secretions from cows with clinical or subclinical mastitis. One millilitre of the sample was added to Mueller-Hinton broth supplemented with 6.5% NaCl, Tryptone Soya Broth with cefoxitin and aztreonam, and then to MRSA ID agar. Presumptive MRSA colonies were analysed for the presence of mecA gene. Parallel to MRSA identification, the samples were incubated in buffered peptone water, lauryl tryptose broth and McConkey agar supplemented with cefotaxim for ESBL-producing E. coli isolation. These bacteria were identified using API Rapid 32 E and the ability of ESBL production was initially established using disc test D68C and confirmed by MIC technique using Sensititre ESBL plates. The primers (blaCTX, blaTEM, blaSHV, and blaCMY-2-group) for the detection of some of the genes encoding ESBL production were used. The 45 strains of S. aureus with mecA gene and 41 strains of E. coli with blaTEM gene were detected.
The aim of the study was the evaluation of the antimicrobial resistance of Enterococcus faecalis strains isolated from cattle, pig, and poultry meat. A test was performed on 111 strains using the minimum inhibitory concentration technique. The highest number of isolates (94 strains) were resistant to lincomycin, the second-highest resistance was to quinupristin/dalfopristin (88 strains), tetracycline followed (65 strains), and erythromycin resistance was also notable (40 strains). All isolates tested were sensitive to daptomycin, nitrofurantoine, and tigecycline, whereas only few strains were resistant to ciprofloxacin, gentamicin, penicillin, and vancomycin. The obtained results showed that meat may be a source of antimicrobial resistant enterococci which may be transferred to humans