ABSTRACT
The majority of cystic fibrosis (CF) patients suffer from chronic respiratory infection with the opportunistic bacterial pathogen Pseudomonas aeruginosa. The virulence of P. aeruginosa is associated with the presence of various extracellular factors, like alginate, elastase, alkaline protease which contribute tissue destruction and assist bacterial invasion. Virulence factor production of P. aeruginosa strains isolated from 46 CF patients followed in two cities in Turkey was detected. Strains were compared genotypically by arbitrarily primed PCR. Antimicrobial susceptibilities to 12 antibiotics were determined by broth microdilution method. Evaluation of virulence factor results revealed that 95.8% of the strains were alginate, 71.7% elastase and 52.1% alkaline protease producers. AP-PCR analysis revealed 35 genotypes indicated almost a complete discrepancy among the strains. The most effective drugs were penems and quinolones. Among aminoglycosides amikacin was the most effective one and a high level resistance to beta lactams was observed. Alginate is the most important virulence factor in the chronic colonisation of CF patients with P. aeruginosa. No evidence for cross infection between patients and for relationship between phenotypes and genotypes of the strains was found.
Subject(s)
Cystic Fibrosis/microbiology , Pseudomonas Infections/microbiology , Pseudomonas aeruginosa/classification , Alginates/metabolism , Bacterial Proteins/metabolism , DNA, Bacterial/chemistry , DNA, Bacterial/genetics , Humans , Metalloendopeptidases/metabolism , Microbial Sensitivity Tests , Polymerase Chain Reaction , Pseudomonas aeruginosa/enzymology , Pseudomonas aeruginosa/genetics , Turkey , VirulenceABSTRACT
OBJECTIVE: To determine the most frequently occurring individual and combined resistance mechanisms in Gram-negative bacteria resistant to any of the clinically available aminoglycosides in Turkey, and to compare these mechanisms with those found in smaller, earlier studies. METHODS: Aminoglycoside resistance mechanisms in Gram-negative isolates resistant to either gentamicin, tobramycin, netilmicin or amikacin collected in different regions of Turkey were evaluated both phenotypically and genotypically using 12 aminoglycosides and up to 22 aminoglycoside resistance gene probes. RESULTS: Among 696 aminoglycoside-resistant Gram-negative bacteria, resistance rates were very high for gentamicin (94.5%), tobramycin (82.4%), netilmicin (53.6%), and amikacin (49.7%). Although isepamicin was the most active aminoglycoside against Gram-negative bacteria, increased resistance (29.7%) was found and resistance rates were higher than those in most of the other countries surveyed in earlier studies. The most common aminoglycoside resistance mechanisms (AAC(3)-II (GTN), AAC(6')-I (TNA), and ANT(2")-I (GT)) in the earlier studies were also found in the present isolates of Klebsiella spp., Enterobacter spp. and Escherichia coli, with increased complexity. In addition to these old mechanisms, two new aminoglycoside resistance mechanisms, namely AAC(6')-III (TNAI) and AAC(6')-IV (GTNA), were also found at significant frequencies (11.9% and 26.9%, respectively) in these isolates of Enterobacteriaceae (n = 435). Among the isolates of Pseudomonas spp. (n = 150), in addition to the increased complexity of enzymatic resistance mechanisms (AAC(3)-I (16.6%), AAC(6')-II (29.3%), AAC(6')-III (19.3%), ANT(2")-I (40%)), permeability resistance seemed to be responsible for the high rates of resistance to aminoglycosides. CONCLUSION: The results of this study indicated increased resistance to clinically available aminoglycosides, including isepamicin, even though it was the most active, as a result of both the presence of new aminoglycoside resistance mechanisms and the increased complexity of all mechanisms, including permeability resistance, particularly in Pseudomonas in Turkey.
Subject(s)
Anti-Bacterial Agents/pharmacology , Gram-Negative Bacteria/drug effects , Gram-Negative Bacterial Infections/drug therapy , Aminoglycosides , Anti-Bacterial Agents/metabolism , Drug Resistance, Bacterial , Drug Resistance, Multiple, Bacterial , Genotype , Humans , Microbial Sensitivity Tests , Phenotype , TurkeyABSTRACT
Resistance of Streptococcus pneumoniae (750) to penicillin, erythromycin, chloramphenicol and trimethoprim/sulfamethoxazole isolated in 4 Turkish hospitals between 1996 and 1999 was evaluated according to year of isolation, patients' age groups and specimen. Penicillin susceptibility was determined by E-test strips and the other antibiotics were tested by disk diffusion test following the NCCLS guidelines in each center. Overall high and intermediate resistance to penicillin was 3% and 29%, respectively. There was a significant difference (p<0.001) between the centers with regard to penicillin resistance. However, there was no significant increase in resistance by year. Penicillin resistance varied significantly among children and adults (36% versus 25%) and according to the specimen. Highest rate of penicillin resistance was observed in respiratory specimens (36%) followed by ear exudates (33.5%). In blood isolates, resistance to penicillin was 28.6%. Overall resistance to erythromycin was 8%, to chloramphenicol 5% and to trimethoprim-sulfamethoxazole 47%. Although overall penicillin resistance in these Turkish S. pneumoniae isolates is high, resistance rates vary in each center and have not increased from 1996 to 1999.