Genetic profiling of Klebsiella pneumoniae: comparison of pulsed field gel electrophoresis and random amplified polymorphic DNA

In this study, the discriminatory power of pulsed field gel electrophoresis (PFGE) and random amplified polymorphic DNA (RAPD) methods for subtyping of 54 clinical isolates of Klebsiella pneumoniae were compared. All isolates were typeable by RAPD, while 3.6% of them were not typeable by PFGE. The repeatability of both typing methods were 100% with satisfying reproducibility (≥ 95%). Although the discriminatory power of PFGE was greater than RAPD, both methods showed sufficient discriminatory power (DI > 0.95) which reflects the heterogeneity among the K. pneumoniae isolates. An optimized RAPD protocol is less technically demanding and time consuming that makes it a reliable typing method and competitive with PFGE.

Integron mediated multidrug resistance in extended spectrum beta-lactamase producing clinical isolates of Klebsiella pneumoniae

The present study describes integron mediated multiple antibiotic resistance in extended-spectrum β-lactamase producing clinical isolates of Klebsiella pneumoniae. One hundred and four clinical isolates of K. pneumoniae from two Iranian hospitals were screened for extended-spectrum β-lactamase production and susceptibility of the extended-spectrum β-lactamase producing isolates was determined to 17 antibiotics by disc diffusion. Presence of integron classes 1, 2 and 3 was detected by PCR and integrase specific primers. Isolates harboring class 1 integron were then screened for variable regions using PCR. Fifty isolates (48%) produced extended-spectrum β-lactamases among which, 22 (44%) harbored class 1, 3 (6%) carried class 2 and none contained class 3 integons. Integron carriage was significantly associated with higher rates of multiple antibiotic resistance in extended-spectrum β-lactamase producing clinical isolates of K. pneumoniae. Integron harboring isolates were more resistant to aztreonam (51.3%), ceftazidime (42.6%), cefotaxime (43.3%), cefepime (24.6%), kanamycin (43.2%), tobramycin (30.7%), norfloxcacin (32%) and spectinomycin (25.6%) compared to the organisms without integrons. On the other hand, resistance to nitrofurantoin and streptomycin was significantly higher among the integron negative isolates. PCR amplification of class1 integron variable regions revealed 9 different sized DNA fragments and isolates with similar profiles for class 1 integron variable regions showed the same antibiotic resistance phenotypes.

A survey on pulmonary pathogens and their antibiotic susceptibility among cystic fibrosis patients

OBJECTIVE:This study was performed to investigate frequency and antimicrobial susceptibility of pulmonary pathogens in cystic fibrosis (CF) patients. METHODS: 129 pediatric patients with CF were enrolled in this cross-sectional study. Microbiological cultures were performed based on sputum or pharyngeal swabs. Antibiotic susceptibilities of the isolated bacteria were determined by the disk diffusion method. RESULTS: The main infecting pathogens were Pseudomonas aeruginosa (38.8%), Klebsiella pneumoniae (11.6%) and Staphyloccus areus (9.3%), respectively. The most active antibiotics included rifampin (91.7% susceptibility), vancomycin (85%) and imipenem (83.5%). Emerging resistance against aminoglycosides was observed. CONCLUSION: Regarding in vitro susceptibility results, cyclic treatment of long-term oral azithromycin and inhaled tobramycin could prophylactically be applied, and during exacerbations, imipenem or ceftazidime in combination with an aminoglycoside such as amikacin could be considered the drugs of choice.