ABSTRACT
Enterococcus species isolated from poultry sources were characterized for their resistance to antibiotics, plasmid content, presence of van genes and their diversity by randomly amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR). The results showed that all isolates were multi-resistance to the antibiotics tested. Ampicillin (15/70) followed by chloramphenicol (37/70) were the most active antibiotics tested against the Enterococcus spp. isolates, while the overall resistant rates against the other antibiotics were between 64.3% to 100%. All vancomycin-resistant E. faecalis, E. durans, E. hirae and E. faecium isolates tested by the disk diffusion assay were positive in PCR detection for presence of vanA gene. All E. casseliflavus isolates were positive for vanC2/C3 gene. However, none of the Enterococcus spp. isolates were positive for vanB and vanC1 genes. Plasmids ranging in sizes between 1.1 to ca. 35.8 MDa were detected in 38/70 of the Enterococcus isolates. When the genetic relationship among all isolates of the individual species were tested by RAPD-PCR, genetic differences detected suggested a high genetic polymorphisms of isolates in each individual species. Our results indicates that further epidemiological studies are necessary to elucidate the role of food animals as reservoir of VRE and the public health significance of infections caused by Enterococcus spp.
Subject(s)
Bacterial Proteins/genetics , Carbon-Oxygen Ligases/genetics , Enterococcus/genetics , Gram-Positive Bacterial Infections/veterinary , Peptide Synthases/genetics , Poultry Diseases/microbiology , Animals , Anti-Bacterial Agents/pharmacology , DNA, Bacterial/analysis , Drug Resistance, Microbial , Drug Resistance, Multiple , Enterococcus/classification , Enterococcus/isolation & purification , Genotype , Gram-Positive Bacterial Infections/microbiology , Malaysia , Microbial Sensitivity Tests , Plasmids/analysis , Poultry , Random Amplified Polymorphic DNA TechniqueABSTRACT
Eighteen Bifidobacterium strains were tested for their susceptibility to a range of antimicrobial agents. All the strains tested, including the reference culture Lactobacillus acidophilus CH2, were susceptible to several groups of antimicrobial agents, they were cephalosporin (cefamandole, cefazolin, cefaperazone, cefoxitin), polypeptide (bacitracin), macrolide (erythromycin), penicillin (amoxicillin), phenicol (chloramphenicol) and beta-lactam (imipenem). Fourteen strains were resistant to more than 10 antibiotics. The reference culture was resistant to only three antibiotics. The results showed that bifidobacteria are resistant to a wide range of antimicrobial agents.
Subject(s)
Anti-Bacterial Agents/pharmacology , Bifidobacterium/drug effects , Drug Resistance, Microbial , Lactobacillus acidophilus/drug effects , Microbial Sensitivity TestsABSTRACT
The growth and culturability of Campylobacter jejuni NCTC 11351 and other campylobacters were examined in media having different osmolalities at a range of temperatures (4, 25, and 42 degreesC). The medium osmolalities used ranged from the osmolality of full-strength nutrient medium (modified campylobacter broth having an osmolality of around 254 mosmol) down to 96 mosmol. The following two methods were used to produce media having different osmolalities: dilution of the nutrient medium with distilled water and reformulation of the medium such that the concentrations of various osmolytes were altered while the nutrient content of the medium was unchanged. The results obtained with the two experimental methods were similar, indicating that there was an osmotic threshold effect, such that none of the campylobacters examined (C. jejuni NCTC 11351 and ATCC 33291, Campylobacter lari, and Campylobacter coli) grew in media having osmolalities around 130 mosmol and at temperatures below at 42 degreesC. Conversely, growth occurred in media having osmolalities of around 175 mosmol and above. Osmolar concentrations can be expressed in terms of osmolarity or osmolality. Osmolality is easier to evaluate, is the more commonly used term, and was used in the current study. In nutrient media having low osmolalities (i.e., 130 mosmol and below), the number of CFUs per milliliter declined rapidly regardless of the temperature, and no cells were recovered after 24 h. However, at nongrowth temperatures (25 and 4 degreesC) in higher-osmolality media (175 mosmol and above) a significant population was recovered throughout the experiment (up to 96 h). In low-osmolality nutrient media, the cellular morphology was principally coccoid, while in the early stages of growth in full-strength media the morphology was predominantly rodlike. We propose that the formation of coccoid cells in these experiments was the result of osmotic stress in low-osmolality media. This osmotic effect was apparent regardless of the osmolyte used to reformulate the medium (NaCl, KCl, Na2SO4, NH4Cl, and glucose were used).
