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Background: The emergence of fluoroquinolone resistance in clinical isolates of Klebsiella pneumoniae is a growing concern. To investigate the mechanisms behind this resistance, we studied a total of 215 K. pneumoniae isolates from hospitals in Bushehr province, Iran, collected between 2017 and 2019. Antimicrobial susceptibility test for fluoroquinolones was determined. The presence of plasmid mediated quinolone resistance (PMQR) and mutations in quinolone resistance-determining region (QRDR) of gyrA and parC genes in ciprofloxacin-resistant K. pneumoniae isolates were identified by PCR and sequencing. Results: Out of 215 K. pneumoniae isolates, 40 were resistant to ciprofloxacin as determined by E-test method. PCR analysis revealed that among these ciprofloxacin-resistant isolates, 13 (32.5%), 7 (17.5%), 40 (100%), and 25 (62.5%) isolates harbored qnrB, qnrS, oqxA and aac(6')-Ib-cr genes, respectively. Mutation analysis of gyrA and parC genes showed that 35 (87.5%) and 34 (85%) of the ciprofloxacin-resistant isolates had mutations in these genes, respectively. The most frequent mutations were observed in codon 83 of gyrA and codon 80 of parC gene. Single gyrA substitution, Ser83→ Ile and Asp87→Gly, and double substitutions, Ser83→Phe plus Asp87→Ala, Ser83→Tyr plus Asp87→Ala, Ser83→Ile plus Asp87→Tyr, Ser83→Phe plus Asp87→Asn and Ser83→Ile plus Asp87→Gly were detected. In addition, Ser80→Ile and Glu84→Lys single substitution were found in parC gene. Conclusions: Our results indicated that 90% of isolates have at least one mutation in QRDR of gyrA orparC genes, thus the frequency of mutations was very significant and alarming in our region. [ABSTRACT FROM AUTHOR]

Background and Objectives: Klebsiella pneumoniae is an opportunistic pathogen responsible for causing nosocomial and community-acquired infections. Its pathogenicity is associated with a variety of virulence factors and antibiotic resistance. The aim of the present study was to compare virulence attributes between ESBL and non-ESBL producing isolates. Materials and Methods: A total of 113 K. pneumoniae including 56 ESBL and 57 non ESBL-producers were collected in Bushehr province, Iran, from November 2017 to February 2019. Enzymatic profile, hypermucoviscosity and biofilm formation were investigated phenotypically. In addition, the presence of rmpA, aerobactin, kfu, allS, mrkD, ybtS, entB, iutA, fimH, wabG, wcaG, K1 and K2 genes were detected by PCR and sequencing. Results: There was no statistically significant difference in enzymatic profile between ESBL and non-ESBL producers. The prevalence of the hypermocoviscosity was lower among ESBL compared to non-ESBL producers but the intensity of biofilm was higher in the ESBL producers. Among the virulence genes, K1, rmpA, iutA, and aero were observed only in non-ESBLs. Moreover, the carriage of allS, K, K2, rmpA, iutA and aero genes was higher in hypermucoviscous in comparison with non hypermucoviscous isolates. Conclusion: The identification of potentially pathogenic isolates plays an important role in preventing their spread as well as the success of their treatment. [ABSTRACT FROM AUTHOR]

Objective(s): Production of metallo-β-lactamases (MBLs) is an important mechanism of resistance to carbapenems. This study aimed to detect the MBL-producing Pseudomonas aeruginosa clinical isolates and to investigate the presence of blaVIM, blaIMP, blaSPM, blaNDM, blaGIM, blaAIM, and blaSIM genes in these isolates in Bushehr, Iran. Materials and Methods: A total of 169 P. aeruginosa clinical isolates were collected from three hospitals in Bushehr. The modified carbapenem inactivation method (mCIM) was used for the phenotypic detection of carbapenemase production. A combination disk test (CDT) was performed for the phenotypic detection of MBL production. To investigate the presence of blaVIM, blaIMP, blaSPM, blaNDM, blaGIM, blaAIM, and blaSIM genes, PCR and sequencing was carried out. Results: Based on the results of mCIM, 40 (23.7%) of 169 isolates were carbapenemase producers. CDT revealed that 26 (15.4%) isolates were MBL producers. blaIMP, blaNDM, and blaVIM genes were found in 18 (69.2%), 8 (30.8%), and 1 (3.8%) of the MBL-producing isolates, respectively. Coexistence of blaIMP and blaNDM was observed in 2 (7.7%) MBL-producing isolates. Among all 169 P. aeruginosa isolates, 23 (13.6%) harbored blaNDM, 18 (10.6%) carried blaIMP, and 1 (0.6%) carried the blaVIM gene. blaSPM, blaGIM, blaAIM, and blaSIM were not found in the present study. Conclusion: blaNDM, blaIMP, and blaVIM genes were detected in this study, which could be a warning sign about the prevalence of these genes among P. aeruginosa clinical isolates in our region. Proper monitoring and detection of MBL-producing isolates are essential steps to prevent the spread of these isolates. [ABSTRACT FROM AUTHOR]

Background: Over the past several years our laboratories have investigated different aspects of the challenging issue of the alterations in bacterial susceptibility to antibiotics induced by physical stresses. Objective: To explore the bacterial susceptibility to antibiotics in samples of Salmonella enterica subsp. enterica serovar Typhimurium (S. typhimurium), Staphylococcus aureus, and Klebsiella pneumoniae after exposure to gamma radiation emitted from the soil samples taken from the high background radiation areas of Ramsar, northern Iran. Methods: Standard Kirby-Bauer test, which evaluates the size of the zone of inhibition as an indicator of the susceptibility of different bacteria to antibiotics, was used in this study. Results: The maximum alteration of the diameter of inhibition zone was found for K. pneumoniae when tested for ciprofloxacin. In this case, the mean diameter of no growth zone in non-irradiated control samples of K. pneumoniae was 20.3 (SD 0.6) mm; it was 14.7 (SD 0.6) mm in irradiated samples. On the other hand, the minimum changes in the diameter of inhibition zone were found for S. typhimurium and S. aureus when these bacteria were tested for nitrofurantoin and cephalexin, respectively. Conclusion: Gamma rays were capable of making significant alterations in bacterial susceptibility to antibiotics. It can be hypothesized that high levels of natural background radiation can induce adaptive phenomena that help microorganisms better cope with lethal effects of antibiotics. [ABSTRACT FROM AUTHOR]

Objectives. In 2013, Clermont classified E. coli strains into eight phylogenetic groups using a new quadruplex PCR method. The aims of this study were to identify the phylogenetic groups of E. coli based on this method and to assess their antibiotic resistance patterns in Bushehr, Iran. Methods. In this cross-sectional study, 140 E. coli isolates were subjected to phylogenetic typing by a quadruplex PCR method. Antimicrobial susceptibility testing was performed by disk diffusion method. Results. Phylogenetic group B2 was most predominant (39.3%), followed by unknown (27.1%), E (9.3%), C and clade I (each 6.4%), B1 (5%), F and D (each 2.9%), and A (0.7%). The most common antibiotic resistance was related to amoxicillin (82.1%) and the least to meropenem (0.7%). 82.14% of isolates were multiple drug resistant (MDR). Antibiotic resistance was mainly detected in group B2 (50%). Conclusions. Our findings showed the high prevalence of MDR E. coli isolates with dominance of group B2. About 25% of E. coli isolates belong to the newly described phylogroups C, E, F, and clade I. Such studies need to be done also in other regions to provide greater understanding of the antibiotic resistance pattern and the prevalences of different phylogenetic groups. [ABSTRACT FROM AUTHOR]

Streptococcus pneumoniae is an important causative agent for bacteremia. Fluorescent in situ hybridization (FISH) is a helpful molecular technique for the rapid identification of S. pneumoniae in positive blood cultures. There are many reports concerning the application of an enzymatic treatment with lysozyme in the FISH procedure for partial cell wall digestion of S. pneumoniae. However, this study was aimed to test the FISH procedure without enzymatic treatment for the identification of S. pneumoniae in blood culture specimens. Seventy-seven positive blood culture specimens containing Gram-positive cocci were examined by both the conventional laboratory methods and FISH. Detection of S. pneumoniae was performed by two FISH procedures: one procedure was performed with an enzymatic treatment step and the other one was done without enzymatic treatment. In addition, the specimens were tested by the FISH procedure with enzymatic treatment to detect Streptococcus pyogenes and Enterococcus. The specificity of FISH in comparison with conventional culture methods was 100%. The sensitivity of the FISH procedure with enzymatic treatment for the detection of S. pneumoniae was 90%, whereas, the sensitivity of the FISH procedure without enzymatic treatment was 100%. In fact, by omission of enzymatic treatment, detection of S. pneumoniae was improved in 6 specimens. The results of the FISH and culture methods for the detection of S. pyogenes and Enterococcus were compatible. Altogether, FISH procedure without enzymatic treatment step seems to improve the detection of S. pneumoniae in some cases. Thus, for successful detection of S. pneumoniae, we suggest the application of both FISH procedures (the procedure with enzymatic treatment and the procedure without enzymatic treatment) for each blood culture specimen.

Background: The establishment of Helicobacter pylori in the stomach and duodenum is associated with gastritis, peptic ulcers, and gastric cancer. Application of suitable methods, including molecular techniques, for an accurate detection of H. pylori can lead to the administration of appropriate drugs and successful therapy. In this study, fluorescent in situ hybridization (FISH) was compared with histology for the diagnosis of H. pylori in gastric biopsy specimens., Material/methods: Flourescently labeled oligonucleotdie probes that target ribosomal RNA were utilized in the FISH procedure. Ninety-one gastric biopsy specimens were tested by FISH and by histology using hematoxylin-eosin (H-E) and Geimsa stains. Furthermore, clarithromycin resistance in 39 of the 91 specimens was examined by FISH., Results: The sensitivity and specificity of FISH for the detection of H. pylori were 97.9% and 100%, respectively. Of the 39 samples that were tested for clarithromycin resistance, 19 were FISH positive for H. pylori, of which 15 and 4 specimens were infected with clarithromycin-susceptible and clarithromycin-resistant strains, respectively. There were coccoid forms of H. pylori in a few of the specimens., Conclusions: FISH is a highly sensitive and specific technique for the diagnosis of H. pylori infection. It can be a method of identification when a patient is infected with coccoid forms of H. pylori. The ability of FISH for determination of clarithromycin resistance is a considerable advantage of this method over histology.

Background: Peptic ulceration following infection of the stomach with H. Pylori is a common disease. Accurate and rapid detection of the bacteria can lead to the implementation of appropriate treatment and recovery. Chronic infection of the gastric milieu with H. Pylori may lead to gastric carcinoma. Routine detection of this bacterium in peptic ulcer is based on the urease test and culture of peptic biopsies. Unfortunately, the sensitivity and specificity of both tests are not satisfying. Molecular techniques have been successfully applied for the rapid and accurate detection of bacterial agents in clinical samples. This study was undertaken to evaluate the sensitivity and specificity of fluorescent in situ hybridization (FISH) in the detection of H. Pylori in patients suffering from dyspepsia., Material/methods: One hundred gastric biopsy samples taken by endoscopy from the antrum and corpus of the stomach were tested by FISH and compared with the conventional culture method complemented by biochemical tests., Results: FISH detected H. Pylori in 48 clinical samples, while the conventional method detected 42 samples. The sensitivity and specificity of FISH for the detection of H. Pylori were calculated as 98% and 100%, respectively., Conclusions: The findings of this study suggest that FISH is a highly suitable and rapid method for diagnosing H. Pylori. Especially when the samples are taken from the antrum and the corpus of the stomach, this technique potentially can be applied routinely for the detection of this bacterium in clinical samples.