ABSTRACT
Background: Acinetobacter baumannii is usually multi-drug resistant (MDR), including third generation cephalosporins, amino glycosides and fl uoroquinolone. Resistance to these antibiotics is mediated by multiple factors such as: lactamases, effl ux pumps and other mechanisms of resistance. Pulsed-fi eld gel electrophoresis (PFGE) was then used to investigate the genetic relationships among the MDR isolates. Aim: The aim of this study was to determine MDR isolates and the existence of OXAs genes among MDR isolates of A. baumannii collected from Kermanshah hospitals in west of Iran. Materials and Methods: Forty-two MDR A. baumannii were collected from patients at Kermanshah hospitals. The isolates were identifi ed by biochemical tests and API 20NE kit. The susceptibility to different antibiotics by disk diffusion method was determined. Polymerase chain reaction (PCR) was performed for detection of blaOXA-23-like, blaOXA-24-like, blaOXA-51-like and blaOXA-58-like betalactamase genes in isolates and clonal relatedness was done by PFGE (with the restriction enzyme ApaI) and patterns analyzed by Bionumeric software. Results: This study showed high resistant to ciprofl oxacin, piperacillin, ceftazidime and also resistant to other anti-microbial agents and more spread blaOXA-23-like gene (93%) in MDR isolate. The PFGE method obtained six clones: A (10), B (9), C (5), D (4), E (11) and F (3) that clone E was outbreak and dominant in different wards of hospitals studied. Conclusion: An isolate from the emergency ward of these hospitals had indistinguishable isolates PFGE profi le and similar resistance profi le to isolates from intensive care unit (ICU), suggesting likely transmission from ICU to emergency via patient or hospital staff contact.
ABSTRACT
Background: Early detection of multidrug‑resistant tuberculosis (MDR‑TB) is essential to prevent its transmission in the community and initiate effective anti‑TB treatment regimen. Materials and Methods: High‑resolution melting curve (HRM) analysis was evaluated for rapid detection of resistance conferring mutations in rpoB and katG genes. We screened 95 Mycobacterium tuberculosis clinical isolates including 20 rifampin resistant (RIF‑R), 21 isoniazid resistant (INH‑R) and 54 fully susceptible (S) isolates determined by proportion method of drug susceptibility testing. Nineteen M. tuberculosis isolates with known drug susceptibility genotypes were used as references for the assay validation. The nucleotide sequences of the target regions rpoB and katG genes were determined to investigate the frequency and type of mutations and to confirm HRM results. Results: HRM analysis of a 129‑bp fragment of rpoB allowed correct identification of 19 of the 20 phenotypically RIF‑R and all RIF‑S isolates. All INH‑S isolates generated wild‑type HRM curves and 18 out of 21 INH‑R isolates harboured any mutation in 109‑bp fragment of katG exhibited mutant type HRM curves. However, 1 RIF‑R and 3 INH‑R isolates were falsely identified as susceptible which were confirmed for having no mutation in their target regions by sequencing. The main mutations involved in RIF and INH resistance were found at codons rpoB531 (60% of RIF‑R isolates) and katG315 (85.7% of INH‑R isolates), respectively. Conclusion: HRM was found to be a reliable, rapid and low cost method to characterise drug susceptibility of clinical TB isolates in resource‑limited settings.
ABSTRACT
BACKGROUND & OBJECTIVE: Pseudomonas aeruginosa is a common cause of nosocomial infections and exhibits innate resistance to a wide range of antibiotics. This study was undertaken to determine the resistance patterns of P. aeruginosa isolates recovered from patients at two hospitals in Tehran, to investigate the presence of plasmids and to genetically characterize them by pulsed field gel electrophoresis (PFGE). METHODS: The susceptibility of 104 isolates of P. aeruginosa to 13 different antibiotics was determined by agar disk diffusion method. The alkaline lysis method was used for plasmid extraction. PFGE technique was optimized for DNA fingerprinting of isolates. RESULTS: The isolates showed resistance to 13 different antibiotics ceftizoxime (99%), lomefloxacin (94.3%), ceftazidime (59.6%), ticarcillin (50%), ceftriaxone (44.3%), cefoperazone (37.5%), tobramycin (34.6%), piperacillin and gentamicin (33.7%), carbenicillin (25%), amikacin (22%), ciprofloxacin (15.4%) and imipenem (2.9%). Plasmids were detected in 31 isolates (29.8%) that produced 15 different patterns. In total, 84 DNA banding patterns were detected by PFGE. The dominant PFGE type, Pattern A with 14 isolates was found at both hospitals. The remaining isolates were grouped in B, C, D and PF1-PF80. The majority of isolates with the identical plasmid profiles and resistance patterns produced closely related DNA fingerprints by PFGE. INTERPRETATION & CONCLUSION: Isolates in pattern A were distributed widely at both hospitals and the environment. Absence of plasmids in majority of isolates indicated low typeability and discriminatory power of this technique.