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Background: Infections caused by Pseudomonas aeruginosa or Acinetobacter baumannii are of greatest concern for hospitalized patients, particularly those in intensive care units (ICUs). The aims of this study were to investigate the prevalence of integrons and biofilm formation among P. aeruginosa and A. baumannii isolates collected from ICU and non-ICU inpatients.
Materials and Methods: A total of 90 P. aeruginosa and 90 A. baumannii isolates were recovered from patients admitted into diverse units of Shahid Mohammadi hospital in Bandar Abbas from January to December 2014. Bacterial identification was carried out by phenotypic methods and PCR. Antibiotic susceptibility was measured by disk diffusion assay. The presence of Class 1, 2, and 3 integrons were evaluated by multiplex-PCR. Biofilm quantification was done by microtiter method.
Results: The highest number of isolates (48%) were recovered from ICU patients. 81% of P. aeruginosa isolateswere sensitive to piperacillin/tazobactam and ticarcillin, while 60% were resistant to third generation of cephalosporins. In case of A. baumannii, all the isolates were sensitive to colistin, but 98% were resistant to other antibiotics (p≤0.05). Susceptibility to ceftazidime, ticarcillin, imipenem, and piperacillin/tazobactam were higher among isolates obtained from non-ICU patients. Class 1 integron was detected in 13.3% of the P. aeruginosa and 40% of the A. baumannii isolates, while Class 2 integron was harbored by 7 and 6.6% of the isolates, respectively. Furthermore, 23% of the A. baumannii and 12% of the P. aeruginosa isolates showed strong biofilm activity.
Conclusion: Class 1 integron-positive isolates were resistant to three classes of antibiotics and predominantly observed in specimens collected from ICU patients showing strong biofilm.

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Background: Integrons are considered as to play a significant role in the evolution and spread of antimicrobial resistance genes.
Materials and Methods: A total of 120 clinical isolates of Pseudomonas aeruginosa (collected from Zanjan hospitals between March 2015 and February 2016) were investigated for molecular characterization of MBLs and Class I and II integrons. Antimicrobial susceptibility testing was also performed based on the CLSI guidelines. The frequency of MBL producing isolates and the susceptibility to various antimicrobial agents were investigated.
Results: Based on the obtained results, Bla_IMP was the most frequently detected metallo-β-lactamase. The frequency of bla_VIM, blaSPM, and bla_SIM, in MBL producing isolates was 17.1, 57.1, and 14.1%, respectively. No bla_GIM harboring isolate was detected in our study. We detected two (5.7%) multidrug resistant P. aeruginosa strains isolated from the urine and sputum samples, which harbored bla_NDM-1. These isolates also contained bla_IMP and bla_SPM. Class I integron was detected in 94.3% of the MBL positive isolates while 8.5% of the isolates contained Class II integrons. Of five different gene cassettes identified in Class I and II integrons, cassette encoding resistance to trimethoprim (dfr) was found to be predominant.
Conclusion: These results indicate that Class I integrons are widespread among the MBL producing P. aeruginosa isolates. Therefore, appropriate surveillance and control measures are essential to prevent the further spread of MBL and integron producing P. aeruginosa in hospitals.­­

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Background: This study aimed to evaluate the prevalence of tet genes and Class I and 2 integrons in Enterobacter cloacae strains isolated from patients with urinary tract infections (UTIs).
Materials & Method: A total of 50 E. cloacae isolates were collected. Antimicrobial susceptibility pattern and tetracycline MIC were determined. The presence of tet genes (tetA, tetB, tetC, tetD) and Class 1 and 2 integrons and the content of Class 1 integron were determined.
Findings: Tetracycline MIC pattern classified 36 % of the E. cloacae isolates as resistant. The most common tet gene was tetC (22%), followed by tetD, tetA, and tetB.  Class 1 integron was detected in 64% of the isolates. Class 1 integron content analysis showed two variable gene cassettes (aadA1 and aadA5/dfrA17 genes). The frequency of aadA5/dfrA17 was 18.75%, which was more common than aadA1 gene (6.25%).
Conclusion: The most important genetic markers for tetracycline resistance in E. cloacae isolates were tetC and Class 1 integron. Harboring Class 1 integron and resistance to streptomycin and ciprofloxacin were significantly correlated.

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Backgrounds: The global spread of carbapenemase-producing Enterobacteriaceae represents a public health concern. This study aimed to investigate the prevalence of carbapenem resistance and the presence of some oxacillinase types and class 1-3 integrons among Enterobacter clinical isolates from an Iranian inpatient population.
Materials & Methods: Ninety Enterobacter isolates from hospitalized patients were diagnosed by microbiological methods. Antibiogram pattern was also determined. The presence of class 1-3 integrons and four types of oxacillinase genes was assessed using PCR.
Findings: Among 90 Enterobacter isolates, the most common species was E. aerogenes, (45.6%), followed by E. cloacae (30%). The highest resistance rate was against ampicillin (96.7%). Multi-drug resistance (MDR) was substantial (93%). Carbapenemase-producers were detected in 96% of carbapenem-resistant isolates by mCIM test. The frequency of evaluated genes was as follows: intI1 = 50 (55.6%), intI2 =12 (13.3%), bla_oxa-1 =6 (6.7%), bla_oxa-2 =5 (5.6%), bla_oxa-10 =18 (20%), and bla_oxa-48 =18 (20%).
Conclusion: Determinants of class 1 integron along with OXA-10 and OXA-48 like carbapememases are responsible for relatively considerable carbapenem resistance among isolates. This is the first report about the presence of OXA-10 and OXA-48-producing Enterobacter spp. in Iran, indicating that the prevalence of oxacillinases in the country might be on the rise.    

 

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Background: The prevalence of carbapenem-resistant Enterobacteriaceae (CRE) is a growing global public health concern due to the significant morbidity and mortality associated with infections caused by these bacteria. The main objective of this study was to determine the prevalence of class I integron in CRE isolates collected from patients in teaching hospitals affiliated to Mazandaran University of Medical Sciences (MAZUMS).
Materials & Methods: A total of 100 Enterobacteriaceae isolates were collected during March 2022 to March 2023 from MAZUMS teaching hospitals using a consecutive sampling technique. The isolates were distinguished using standard microbiological methods. The antibiotic resistance of the isolated strains to carbapenem was subsequently detected using antibiotic discs including imipenem and meropenem. Using the disc diffusion method, 73 carbapenem-resistant isolates were identified and subsequently investigated by genetic analysis using polymerase chain reaction (PCR).
Findings: Among the 73 carbapenem-resistant isolates, the most commonly found bacterial isolates were Klebsiella pneumoniae (39.72%), Escherichia coli (30.13%), and Serratia rubidaea (12.32%), respectively. Also, 100% of the isolates were resistant to meropenem, while these isolates showed lower resistance to imipenem (70%). Also, out of the 73 isolates, 64.38% were positive for the intI1 gene. K. pneumoniae isolates had the highest prevalence of the intI1 gene (89.65%).
Conclusion: The prevalence of class I integron among patients in MAZUMS educational hospitals is relatively high, exceeding 50%. Therefore, it is crucial to implement effective infection prevention measures and identify this gene in hospitals to hinder the rapid dissemination of these hazardous organisms.