Nine Legionella pneumophila strains isolated from cooling towers and a standard strain (L. pneumophila serogroup 1, ATCC 33152, Philadelphia 1) were analyzed and compared in terms of motility, flagella structure, ability to form biofilms, enzymatic activities (hemolysin, nucleases, protease, phospholipase A, phospholipase C, acid phosphatase, alkaline phosphatase and lipase), hemagglutination capabilities, and pathogenicity in various host cells (Acanthamoeba castellanii ATCC 30234, mouse peritoneal macrophages and human peripheral monocytes). All the isolates of bacteria appeared to be motile and polar-flagellated and possessed the type-IV fimbria. Upon the evaluation of virulence factors, isolate 4 was found to be the most pathogenic strain, while 6 out of the 9 isolates (the isolates 1, 2, 3, 4, 5, and 7) were more virulent than the ATCC 33152 strain. The different bacterial strains exhibited differences in properties such as adhesion, penetration and reproduction in the hosts, and preferred host type. To our knowledge, this is the first study to compare the virulence of environmental L. pneumophila strains isolated in Turkey, and it provides important information relevant for understanding the epidemiology of L. pneumophila.

Among the 21 different species of the Listeria genus, Listeria monocytogenes is the most common and listeriosis agent in humans. The mortality rate of L. monocytogenes infection is higher than the other common foodborne pathogens such as Salmonella Enteritidis, Campylobacter and Vibrio species. In the current study, it is aimed to determine the presence of L. monocytogenes bacteria in minced meat samples sold in Istanbul province by using the culture method of the USDA-FSIS. In this study, 100 minced meat samples purchased from different butchers in 11 districts of Istanbul between December 2018 and November 2019 were examined for the presence of L. monocytogenes. The bacteria identified also molecularly verified according to the presence of iap and hlyA gene regions by the polymerase chain reaction (PCR) method. When antibiotic susceptibility tests of 21 strains, identified as L. monocytogenes through biochemical tests, it was found to be resistant to Amoxicillin/Clavulanic acid (14.28%), penicillin (9.52%), cefaclor (9.52%), vancomycin (9.52%), ciprofloxacin (9.52%) and trimethoprim-sulfamethoxazole (9.52%) and susceptible to ampicillin (100%) and tetracycline (100%). In terms of iap and hlyA gene regions, only 16 of 21 isolates, identified as L. monocytogenes as a result of biochemical tests, were found to be L. monocytogenes. In our study with minced meat offered for sale in Istanbul, although, the L. monocytogenes isolation rate (17%) and the incidence of antibiotic resistance of the isolated L. monocytogenes bacteria are low, it was concluded that minced meat may pose a public health risk.

Production of the beta-lactamase enzymes is the primary resistance mechanism caused by uncounscious consumption of the beta-lactam group of antibiotics in Enterobacteriaceae. Combined disc tests were performed for extended-spectrum beta-lactamase (ESBL) confirmation (n = 15) and class C beta-lactamase (AmpC) confirmation (n = 6) after the disc diffusion test was applied in total of 27 Enterobacteriaceae strains from Western Black Sea, Lake Manyas and Lake Iznik. Plasmid-mediated blaTEM, blaSHV, blaCTX-M , blaIMP genes, CIT, MOX, FOX gene groups and chromosomal bla AmpC gene of E. cloacae were investigated with polimerase chain reaction (PCR). Three E. coli strains were shown to produce ESBL while one E.coli and three E. cloacae strains were confirmed for AmpC production by disc tests. blaTEM (n = 2), blaSHV (n = 4), blaCTX-M (n = 2), blaTEM + blaSHV (n = 1), blaCTX-M + CIT (n = 1), blaSHV + CIT (n = 1) genes and/or gene groups were detected in eleven E. coli isolates; while blaSHV (n = 3) was observed in three Klebsiella strains (two K.oxytoca and one K.pneumoniae). With this study, aquatic environments of Turkey were proved to be the reservoirs of antibiotic resistance determinants of plasmid-mediated beta-lactamases in environmental wild-type bacteria transmitted by horizontal gene transfer.

Özet: Enterobacteriaceae üyesi olan Salmonella cinsi bakteriler, insanlarda gastroenterit, bakteriyemi ve enterik ateş gibi enfeksiyonlara neden olmaktadır. Salmonella bakterilerinin patojenitesinin belirlenmesi için bu bakterilerin virülans özelliklerinin araştırılması gereklidir. Klinik örneklerden izole edilen Salmonella bakterilerinin virülans faktörlerini belirlemeye yönelik birçok çalışma olmasına rağmen, hem gıda ve çevresel örneklerden izole edilen bakterilerin patojenitesinin bir arada araştırıldığı hem de standart bakterilerle kıyaslandığı kapsamlı bir çalışmaya rastlanmamıştır. Bu nedenle çalışmamızda kıyma, deniz suyu ve klinik örneklerden izole edilen Salmonella bakterilerinin ve standart bakterilerin (Salmonella enterica serovar Typhimurium ATCC 14028; Salmonella enterica serovar Enteritidis ATCC 13076) virülans faktörleri incelenerek patojenitelerinin değerlendirilmesi amaçlanmıştır. Çalışma kapsamında, bakterilerin serumun antimikrobiyal etkisine karşı direnci, antibiyotik direnci, hemolizin aktiviteleri, hemaglütinasyon yetenekleri, fimbriya tipleri, biyofilm oluşturma kapasitesi ve bakterinin dış ortamdan demir alımını sağlayan siderofor moleküllerinin üretim özellikleri incelenmiştir. Ortalama toplam virulans oranları (%29) değerlendirildiğinde, kıyma örneklerinden izole edilen Salmonella bakterilerinin diğer kaynaklardan izole edilenlere göre daha patojen olduğu, en patojen bakterinin ise %38 virulans değeriyle ZS-4 izolatı olduğu belirlenmiştir. Bakterilerin serum direnci, antibiyotik direnci, hemoliz oluşturma yetenekleri, hemaglütinasyon özellikleri, biyofilm oluşturma ve siderofor üretme kapasitelerinin izole edildikleri kaynağa göre farklılık gösterdiği belirlenmiştir.

In this study, 119 feta cheese samples taken from different vendors in Istanbul were examined for the presence of Listeria monocytogenes. Isolates were confirmed by the PCR method using iap and hlyA primers, and the antibiotic susceptibility of the identified strains was performed by the Kirby-Bauer protocol. Seven Listeria spp. were isolated from three (2.52%) of 119 cheese samples analyzed. The seven Listeria spp. obtained from these three samples were found to contain the iap gene region but not the hlyA gene region. As a result of the sequence analysis using the 16S rRNA gene region, it was determined that these isolates were L. seeligeri. As a result of antibiotic susceptibility tests, it was observed that L. seeligeri isolates showed ciprofloxacin (85.71%) and penicillin (42.85%) resistance. All strains were susceptible to amikacin, amoxicillin/clavulanic acid, chloramphenicol, rifampin, gentamicin, cefaclor, ampicillin, trimethoprim-sulfamethoxazole, tetracycline, vancomycin, and clarithromycin antibiotics. The detection of Listeria spp. isolates in feta cheese samples made with pasteurized milk revealed that packaging, distribution, and storage practices following the pasteurization process should be followed more strictly. It is recommended to apply controls at each stage to prevent contamination.