The Prevalence of Campylobacter spp. in Polish Poultry Meat

The prevalence, count and molecular identification of Campylobacter spp. in Polish poultry meat were analysed. 181 samples of meat from chicken (70), turkey (47), duck (54) and goose (10) were studied. Campylobacter spp. was found in 64% of meat samples. The highest prevalence of this pathogen was detected for duck meat. On average 80% of duck samples were contaminated with Campylobacter spp. The counts of Campylobacter spp. in positive samples remained under ten colony forming units per gram of product in 59% of poultry meat. C. jejuni was more frequently detected in poultry meat than C. coli

Identification of the full set of Listeria monocytogenes penicillin-binding proteins and characterization of PBPD2 (Lmo2812)

13 páginas, 4 figuras, 7 tablas.[Background]: Bacterial penicillin-binding proteins (PBPs) can be visualized by their ability to bind radiolabeled or fluorescent β-lactam derivatives both whole cells and membrane/cell enriched fractions. Analysis of the Listeria monocytogenes genome sequence predicted ten genes coding for putative PBPs, but not all of their products have been detected in studies using radiolabeled antibiotics, thus hindering their characterization. Here we report the positive identification of the full set of L. monocytogenes PBPs and the characteristics of the hitherto undescribed PBPD2 (Lmo2812). [Results]: Eight L. monocytogenes PBPs were identified by the binding of fluorescent β-lactam antibiotic derivatives Boc-FL, Boc-650 and Amp-Alexa430 to proteins in whole cells or membrane/cell wall extracts. The gene encoding a ninth PBP (Lmo2812) was cloned and expressed in Escherichia coli as a His-tagged protein. The affinity purified recombinant protein had DD-carboxypeptidase activity and preferentially degraded low-molecular-weight substrates. L. monocytogenes mutants lacking the functional Lmo2812 enzyme were constructed and, compared to the wild-type, the cells were longer and slightly curved with bent ends. Protein Lmo1855, previously designated PBPD3, did not bind any of the antibiotic derivatives tested, similarly to the homologous enterococcal protein VanY. [Conclusions]: Nine out of the ten putative L. monocytogenes PBP genes were shown to encode proteins that bind derivatives of β-lactam antibiotics, thus enabling their positive identification. PBPD2 (Lmo2812) was not visualized in whole cell extracts, most probably due to its low abundance, but it was shown to bind Boc-FL after recombinant overexpression and purification. Mutants lacking Lmo2812 and another low molecular mass (LMM) PBP, PBP5 (PBPD1) - both with DD-carboxypeptidase activity - displayed only slight morphological alterations, demonstrating that they are dispensable for cell survival and probably participate in the latter stages of peptidoglycan synthesis. Since Lmo2812 preferentially degrades low-molecular- mass substrates, this may indicate a role in cell wall turnover.The institutional help of the Areces Foundation to CBMSO is acknowledged. Work in JAA’s lab was supported by grants BFU2006-04574 from the Spanish Ministry of Science and Innovation and HEALTH-F3-2009-223431 from the European Community.Peer reviewe

Characteristic and Antimicrobial Resistance of Bacillus cereus Group Isolated from Food in Poland

Bacillus cereus is a foodborne pathogen causing food safety issues due to the formation of difficult to eliminate spores and biofilms. The objective of this study was to investigate the occurrence of B. cereus (conducted as part of monitoring in 2017-2018) and the presence of a toxin gene in strains isolated from retail products (pastries/cakes; vegetables, spices, delicatessen products) in Poland, and to determine the susceptibility of these microorganisms to different antimicrobial agents. A total of 267 B. cereus isolates from food products were examined, of which 95.51% were found positive for the presence of at least one toxin gene, with the highest frequency of the nhe gene (91.39%). The hbl and cytK genes were detected in 53.56% and 44.19% of B. cereus strains, respectively. The lowest frequency was found for the ces gene (2.62%). The susceptibility of B. cereus isolates to 16 antimicrobials was investigated. Ampicillin and penicillin resistance was the most common resistance phenotype and was identified in 100% of the B. cereus isolates. In addition, the tested isolates exhibited resistance to: amoxicillin-clavulanic acid (96.25%), cephalothin (67.79%), ceftriaxone (64.42%), rifampicin (46.82%), trimethoprim-sulfamethoxazole (5.62%), quinupristin/dalfopristin (4.87%), chloramphenicol (3.75%), clindamycin (2.62%), teicoplanin (1.87%), erythromycin (1.87%), ciprofloxacin (0.75%), imipenem (0.75%), tetracycline (0.37%), and gentamicin (0.37%). The study results contribute to characterizing the diversity of B. cereus isolated from various food products in Poland and their impact on food safety and public health. This study delivers practical information on antibiotic resistance and the frequency of toxin genes among strains isolated from food

Identification of the full set of <it>Listeria monocytogenes </it>penicillin-binding proteins and characterization of PBPD2 (Lmo2812)

Abstract Background Bacterial penicillin-binding proteins (PBPs) can be visualized by their ability to bind radiolabeled or fluorescent β-lactam derivatives both whole cells and membrane/cell enriched fractions. Analysis of the Listeria monocytogenes genome sequence predicted ten genes coding for putative PBPs, but not all of their products have been detected in studies using radiolabeled antibiotics, thus hindering their characterization. Here we report the positive identification of the full set of L. monocytogenes PBPs and the characteristics of the hitherto undescribed PBPD2 (Lmo2812). Results Eight L. monocytogenes PBPs were identified by the binding of fluorescent β-lactam antibiotic derivatives Boc-FL, Boc-650 and Amp-Alexa430 to proteins in whole cells or membrane/cell wall extracts. The gene encoding a ninth PBP (Lmo2812) was cloned and expressed in Escherichia coli as a His-tagged protein. The affinity purified recombinant protein had DD-carboxypeptidase activity and preferentially degraded low-molecular-weight substrates. L. monocytogenes mutants lacking the functional Lmo2812 enzyme were constructed and, compared to the wild-type, the cells were longer and slightly curved with bent ends. Protein Lmo1855, previously designated PBPD3, did not bind any of the antibiotic derivatives tested, similarly to the homologous enterococcal protein VanY. Conclusions Nine out of the ten putative L. monocytogenes PBP genes were shown to encode proteins that bind derivatives of β-lactam antibiotics, thus enabling their positive identification. PBPD2 (Lmo2812) was not visualized in whole cell extracts, most probably due to its low abundance, but it was shown to bind Boc-FL after recombinant overexpression and purification. Mutants lacking Lmo2812 and another low molecular mass (LMM) PBP, PBP5 (PBPD1) - both with DD-carboxypeptidase activity - displayed only slight morphological alterations, demonstrating that they are dispensable for cell survival and probably participate in the latter stages of peptidoglycan synthesis. Since Lmo2812 preferentially degrades low-molecular- mass substrates, this may indicate a role in cell wall turnover.</p

Generation of Inducible BCL11B Knockout in TAL1/LMO1 Transgenic Mouse T Cell Leukemia/Lymphoma Model

The B-cell CLL/lymphoma 11B gene (BCL11B) plays a crucial role in T-cell development, but its role in T-cell malignancies is still unclear. To study its role in the development of T-cell neoplasms, we generated an inducible BCL11B knockout in a murine T cell leukemia/lymphoma model. Mice, bearing human oncogenes TAL BHLH Transcription Factor 1 (TAL1; SCL) or LIM Domain Only 1 (LMO1), responsible for T-cell acute lymphoblastic leukemia (T-ALL) development, were crossed with BCL11B floxed and with CRE-ER/lox mice. The mice with a single oncogene BCL11Bflox/floxCREtg/tgTAL1tg or BCL11Bflox/floxCREtg/tgLMO1tg were healthy, bred normally, and were used to maintain the mice in culture. When crossed with each other, >90% of the double transgenic mice BCL11Bflox/floxCREtg/tgTAL1tgLMO1tg, within 3 to 6 months after birth, spontaneously developed T-cell leukemia/lymphoma. Upon administration of synthetic estrogen (tamoxifen), which binds to the estrogen receptor and activates the Cre recombinase, the BCL11B gene was knocked out by excision of its fourth exon from the genome. The mouse model of inducible BCL11B knockout we generated can be used to study the role of this gene in cancer development and the potential therapeutic effect of BCL11B inhibition in T-cell leukemia and lymphoma