An investigation of virulence factors of Legionella pneumophila environmental isolates

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. (C) 2017 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda

Determination of Multiple Antibiotic and Heavy Metal Resistance of the Bacteria Isolated from the Kucukcekmece Lagoon, Turkey

One hundred strains of Gram-negative bacteria were isolated from a brackish water Lagoon, Kucukcekmece in Istanbul-Turkey. Identification studies showed that 31% of the isolated bacteria were Escherichia colt, 28% were Citrobacter, and 12% were Enterobacter. Antibiotic and heavy metal resistances exhibited by these bacteria were evaluated. In antibiotic susceptibility tests, 68% of the isolates appeared to be resistant to vancomycin, while 38% was resistant to erythromycin, 23% to penicilin G, 19% to ampicillin, 13% to nalidixic acid and streptomycin, 7% to chloramphenicol, 5% to amikacin, 2% to gentamycin, and 1% to kanamycin. Most of the isolates tolerated various concentrations of heavy metals, and the minimum inhibitory concentrations (MIC) ranged from 20 mu g/ml to >5000 mu g/ml. In terms of heavy metal sensitivity, 98% of the isolates were resistant to Fe, 95% to Cd, 85% to Co, 83% to Cu and Zn, and 74% to Ni. When antibiotic-heavy metals multiresistance index was examined, it was determined that the multiple heavy metal resistance (MHMR) index was remarkably high for the bacteria, while the multiple antibiotic resistance (MAR) index was low according to heavy metal resistance

EFFECT OF BIOCIDES ON DIFFERENT SEROGROUPS OF LEGIONELLA PNEUMOPHILA

Cooling towers are potential sources for the amplification and dissemination of legionellae. Public health risks posed by legionellae may be eliminated via preventive methods. Biocide application in cooling towers is the most common and critical prevention strategy against legionellae. Successful results may be achieved by pre-determining microbial inhibitory concentration and minimum contact time for a given biocide. In the current study, efficacy of various biocides was evaluated in terms of dosage and contact time, against various Legionella pneumophila strains, in vitro. Results indicated that quaternary ammonium compounds were effective at lower dosages than those recommended by the manufacturer. K4 kloran, an oxidizing agent, was the least effective biocide. It was found that the efficacy of biocides was directly related to applied dosages and the origin of the target strains (standard or environmental)

Efficacy of Colloidal Silver-Hydrogen Peroxide and 2-Bromo-2-nitroporopane-1,3-diol Compounds Against Different Serogroups of Legionella pneumophila Strains

Cooling towers are considered as amplifier and disseminator sources for Legionella spp. despite preventive treatments. Information which was obtained from biocidal tests could improve the effectiveness of treatments. Therefore, the choice of appropriate biocides and the applying of biocides in correct dosages and contact times are important. Various oxidizing and non-oxidizing biocides have been investigated in vitro for their effectiveness against legionellae. Colloidal silver-hydrogen peroxide (CSHP) and 2-bromo-2-nitroporopane-1,3-diol (BNPD) biocides were selected as an example for oxidizing and non-oxidizing agents, respectively, in view of bactericidal action against different serogroups of L. pneumophila strains [ serogroup 1 (S1) and serogroup 2-14 (S2)] which are isolated different cooling towers in the vicinity of Istanbul, Turkey and reference strain. In the current study, oxidizing biocide was found more effective than non-oxidizing biocide in terms of contact times, log reductions and recommended dosages. At the recommended concentrations for cooling towers (100 ppm), while CSHP compound killed all strains in 3 h contact time, BNPD compound killed S2 and reference strain in the same contact time, S1 strain after 6 h contact time. The results of the present study showed that effective biocide applications can be achieved by pre-determining minimum inhibitory concentration (MIC) and minimum contact time of different biocides to kill target bacteria