Phenotypic and molecular detection of metallo-ß-lactamase-producing Pseudomonas aeruginosa isolates from patients with burns in Tehran, Iran

Abstract INTRODUCTION: Health care-associated infections caused by metallo-β-lactamase (MBL)-producing Pseudomonas aeruginosa are a significant growing concern in patients with burns worldwide. The aims of this study were to determine the antibiotic susceptibility of and detect the presence of MBLs among P. aeruginosa isolates and assess their clonal relationship using enterobacterial repetitive intergenic consensus (ERIC)-PCR. METHODS: Non-duplicated clinical isolates (160) of P. aeruginosa were collected from patients with burns at the Motahari Hospital in Tehran, Iran. All isolates were identified using standard laboratory methods and further characterized for antimicrobial susceptibility. Any carbapenem-resistant isolates were then examined for MBL production by the E-test and MBL-encoding genes were detected by PCR. The clonal relatedness of MBL-producing isolates was assessed by ERIC-PCR. RESULTS: For multidrug-resistant isolates, the highest rates of susceptibility were observed for colistin 160 (100%), polymyxin B 160 (100%), and ceftazidime 32 (20%). In total, 69 (43.7%) isolates were identified as MBL producers. Twenty-eight (17.5%) isolates were positive for the bla VIM-1 gene followed by the bla IMP-1 (15.6%) and bla SPM-1 (5.6%) genes. ERIC-PCR revealed three separate genotypes, where type A (76.8%) was the most prevalent, followed by B (20.3%), and then C (2.9%). CONCLUSIONS: Our present study found that the bla IMP-1 and bla VIM-1 genes were present at a significant frequency and also detected the bla SPM-1 gene in P. aeruginosa isolates for the first time, highlighting the need for establishing suitable infection control measures to successfully treat patients and prevent further spread of these resistant organisms among patients with burns.

High prevalence of plasmid-mediated quinolone resistance determinants in Enterobacter cloacae isolated from hospitals of the Qazvin, Alborz, and Tehran provinces, Iran

Abstract: INTRODUCTION: Plasmid-mediated quinolone resistance (PMQR) is a growing clinical concern worldwide. The main aims of this study were to detect qnr-encoding genes and to evaluate the clonal relatedness of qnr-positive Enterobacter cloacae isolates. METHODS: A total of 116 E. cloacae isolates that were not susceptible to quinolone were obtained from seven hospitals in Tehran, five hospitals in Qazvin, and two hospitals in Karaj (Iran). Bacterial identification was performed using standard laboratory methods and API 20E strips. Quinolone resistance was determined using the Kirby-Bauer disk diffusion method according to the Clinical Laboratory Standards Institute (CLSI) guidelines. PCR and sequencing were employed to detect qnrA, qnrB, and qnrS genes, and clonal relatedness was assessed using the enterobacterial repetitive intergenic consensus (ERIC)-PCR method. RESULTS: In total, 45 (38.8%) and 71 (61.2%) of isolates showed high- and low-level quinolone resistance, respectively, and qnr-encoding genes were detected in 70 (60.3%) of them. qnrB1 [45 (38.8%) isolates] was the most commonly detected gene, followed by qnrS1 [28 (24.1%) isolates] and qnrB4 [18 (15.5%) isolates] either alone or in combination with other genes. The results of the ERIC-PCR revealed that 53 (75.7%) qnr-positive isolates were genetically unrelated. CONCLUSIONS: This study describes, for the first time, the high prevalence of the qnrB1, qnrS1, and qnrB4 genes among E. cloacae isolates in Iran. The detection of qnr genes emphasizes the need for establishing tactful policies associated with infection control measures in hospital settings in Iran.

Carbapenemase genes and homology of Acinetobacter baumannii in two hospitals of Qingdao / 中国感染控制杂志

Objective To investigate antimicrobial resistance,distribution,and carriage of carbapenemase genes of Acinetobacterbaumannii(AB)from two hospitals in Qingdao.Methods 145 AB isolates collected from two hospi-tals (78 from hospital A,67 from hospital B)were performed antimicrobial susceptibility testing,carbapenemase genes were amplified by polymerase chain reaction (PCR);homology analysis were conducted with enterobacterial repetitive intergenic consensus (ERIC)-PCR.Results AB from hospital A were generally resistant to 16 commonly used antimicrobial agents,with the lowest resistant rate of 3.85% to cefoperazone/sulbactam,followed by resist-ance rate of 16.67% to minocycline,resistant rates to the other antimicrobial agents were all>73% . AB from hos-pital B were generally resistant to 23 commonly used antimicrobial agents,but the resistance rates to minocycline and tigecycline were both 0,resistance rates to amikacin and levofloxacin were 23.88% and 38.81% respectively, resistant rates to the other antimicrobial agents were all >64% . All strains carried OXA-5 1 gene,the carriage rates of OXA-23 gene in carbapenem-resistant group were 86.76% (59/68)and 56.67% (34/60)in hospital A and B re-spectively,the difference was significant(χ2= 14.53,P<0.001);OXA-58 gene was detected in 3 isolates in hospi-tal A but not detected from hospital B. 145 AB strains were classified into 8 types,the major prevalence types were type A (n= 71)and E(n= 37);the major prevalence types in hospital A were type A (46.15% )and E(41.03% ), hospital B were type A (52.24% )and C (17.91% ).Conclusion Antimicrobial resistance of clinically isolated AB is serious and prevailed in two hospitals. OXA-23 and OXA-51 genes play an important role in AB resistance to car-bapenems.