Phylogenetic Aspects of Antibiotic Resistance and Biofilm Formation of P. aeruginosa Isolated from Clinical Samples.

Introduction: Biofilm production and drug resistance phenomenon play a critical role in P. aeruginosa infections. Several genes, including psl, pel, brlR, and mex, are involved in the phenomenon. The aim of this study was to find the relationship between the mentioned genes and the sources of P. aeruginosa infections. Materials and Methods: Fifty-nine P. aeruginosa isolates detected from clinical specimens were used to determine antibiotic susceptibility patterns, prevalence of the genes using PCR, biofilm formation, biofilm eradication concentration assay (MBEC), and epidemiological characteristics using pulsed-field gel electrophoresis (PFGE). Results: The results showed that 35.6% and 16.94% of all the samples were isolated from urine and wounds, 81.33% of the isolates were biofilm producers, 27.11% were multidrug-resistant (MDR), and 100% of the main biofilm former genes belonged to pslA. 94.91% of the isolates possessed brlR and mexA, and 91.5% of them expressed pslA. It was also indicated that neither ciprofloxacin nor imipenem could eradicate the formed biofilms. Moreover, we could identify 81.4% distinctive restriction profiles among the isolates, using an 80% similarity cutoff point; brlR and pel genes were significantly (P=0.032; P=0.044) related to phylogenetic pulsotypes. Comparison of the dendrogram in the isolates revealed that the detected isolates from urine were present in 12 different pulsotypes. Conclusion: It was found that there was a relationship between MDR, biofilm production, and brlR and pel genes among the isolates. It is distinguished there were similar genetic patterns between detected isolates from urine and could be concluded that the urinary tract played a critical role in maintaining and transferring biofilm drug-resistant genes of P. aeruginosa in clinical sites. The study highlights the importance of urine in distribution of clinical biofilm formation and drug-resistant P. aeruginosa isolates.

Treatment Failure in Urinary Tract Infections: A Warning Witness for Virulent Multi-Drug Resistant ESBL- Producing Escherichia coli.

BACKGROUND: Global increase in the prevalence of virulent extended-spectrum beta-lactamase (ESBL)-producing uropathogenic Escherichia coli (UPEC), which is also multi-drug resistant (MDR), leads to increase in severity of urinary tract infections (UTIs), decrease in the efficacy of the first-line antibiotics, and therefore increase in the morbidity and mortality rates. METHODS: We investigated the distribution of ESBL-producing UPEC in 78 E. coli isolates from community-acquired UTI patients in southern Iran. The prevalence of three major ESBL genes, antimicrobial resistance patterns against 15 conventional antibiotic disks, and the presence of 11 important virulence genes that involve in the development and progression of UTIs were evaluated in these isolates. RESULTS: Of the UPECs, 34.6% were ESBL-positive and 96.3% of the ESBL-producers were MDR. Among the ESBL-producers, 100% harbored bla CTX-M, 63% harbored bla SHV, and 11.1% harbored bla TEM genes. ESBL-producers showed a higher level of resistance to the tested cephalosporins, fluoroquinolones, trimethoprim-sulfamethoxazole, and tetracycline than non-ESBL producers. All isolates were resistant to the tested penicillins. Prevalence of resistance to about two-third of the tested antibiotics was higher than 50% and 93.6% of the isolates were MDR. High prevalence of virulence factors particularly the adhesins (82.1% csgA, 73.1% fimH genes) and siderophore (73.1% sitA gene) was seen in the UPECs. But fortunately in MDR isolates, the virulence score and prevalence of hemagglutinin (tsh), hemolysin toxin (hlyD) and invasin (ibeA) genes were lower than in non-MDR UPECs. Shockingly, among the 15 common antibiotics, only nitrofurantoin (<20% resistance) could be recommended as an appropriate drug for the treatment of UTIs due to our ESBL-producer UPECs. CONCLUSION: The alarming level of virulent MDR ESBL-producer E. coli strains in this study necessitates the performing of an antibiotic stewardship program, regional screening of ESBL-producers and their virulence properties to select appropriate antibiotic, or designing new therapeutic methods for UTIs by inactivation of the essential virulence factors of UPECs.

Dissemination Pattern of Multidrug Resistant Carbapenemase Producing Klebsiella pneumoniae Isolates Using Pulsed-Field Gel Electrophoresis in Southwestern Iran.

BACKGROUND: Klebsiella pneumoniae is an important cause of healthcare-associated infection. Carbapenemases have increasingly been reported in Enterobacteriaceae, especially in K. pneumoniae. PROPOSE: The objective of this study was to determine antibiotic resistance patterns, and the molecular epidemiology of multidrug resistant K. pneumoniae isolates, obtained from hospitalized patients in Shiraz, Iran. METHODS: In this study, 60 K. pneumoniaeisolates were collected from Nemazee and Faghihi referral hospitals. Antibiotic susceptibility testing and MIC were performed by disk diffusion test and Epsilometer (E)-test strips, respectively. Carbapenemase genes were identified by polymerase chain reaction and sequencing. Then, clonal relationships were analyzed, using PFGE. RESULTS: Thirty-three out of 60 K. pneumoniae isolates were resistant to carbapenems. Among the isolates, 86.6% were multidrug resistant (MDR). Polymyxin B (18.3%) and tigecycline (23.3%) were shown to be the most active agents against K. pneumoniae isolates. In our study, the high prevalence of bla NDM (45%) and bla OXA-48 (10%) was detected. CONCLUSION: The results of this study revealed the widespread carbapenemase gene between different wards in hospitals as a risk factor for treatment options. PFGE analysis showed 11 clusters and 3 singletons based on an 80% similarity level. Also, PFGE analysis showed that there were similar genetic patterns among K. pneumoniae isolates and these patterns were responsible for the distribution of infection in hospitals.

Clonal Relatedness, Phylotyping and Antimicrobial Susceptibility of Extended- spectrum-beta-lactamase Producing Uropathogenic Escherichia coli Isolates from Outpatients and Inpatients.

OBJECTIVES: Antibiotic resistance, phylogenetic groups and Pulsed-Field Gel Electrophoresis (PFGE) patterns were evaluated in urinary tract infection (UTI) Escherichia coli (E. coli) isolates from outpatients and inpatients. METHODS: In this study, antibiotic resistance to E. coli isolated from non-hospitalized and hospitalized patients (153 outpatients and 147 inpatients ) was evaluated in Shiraz County, Iran. Phylogenetic groups and Pulse Field Gel Electrophoresis (PFGE) patterns of 143 ESBLs-producing E. coli were also assessed. RESULTS: The prevalence of ESBL-producing E. coli was shown to be 46.4% and 49% in the outpatient and inpatient UTI E. coli isolates, respectively. Most ESBL-producers were detected on patients hospitalized in clinical surgery units (66.7%) and intensive care units (62.5%). Phylogenetic group D was the dominant group in both the outpatient and inpatient isolates (67.6% and 61.1%, respectively) and also in internal, clinical surgery and ICU units. PFGE results showed more relatedness (>80% similarity) among inpatient isolates. PFGE analysis of 49 ESBL-producing inpatient E.coli in hospital units revealed 17 different pulsotypes, consisting of 11 clones and 6 single patterns. There were no clonal patterns in outpatient isolates, and similarity among the outpatient isolates and also between inpatient and outpatient isolates was less than 80% (75% and 66%, respectively). CONCLUSION: The results showed extreme genomic diversity among the ESBL-producing E. coli isolates in terms of the community and multiclonal dissemination of ESBL-producing E. coli isolated from hospital units.

Isolation and identification of Legionella spp. from different aquatic sources in south-west of Iran by molecular &culture methods.

Legionella pneumophila, the causative agent of Legionnaires' diseases (LD) is usually transmitted to humans via inhalation of aerosols from contaminated natural and manmade water sources. These organisms may become fatal especially in immunocompromised patients and LD is the one of the important disease from a public health perspective. This survey investigated the frequency of Legionella spp. including L. pneumophila, in some cold and warm water systems in South-West of Iran by culture and PCR methods. Thirty four water samples were collected from diverse water supply systems. After acid and heat treatments of samples, inoculated onto buffered charcoal yeast extract agar. Isolated colonies were confirmed by morphological and biochemical tests. Then the isolates were examined for icmO, sidA and lidA genes by PCR assay. This study showed that frequency of L. pneumophila was 4 by culture and 14 by PCR. PCR method to be efficient and sensitive test for rapid detection of these organisms in environmental water sources. This study emphasizes the need for effective infection control and prevention strategies to minimize the risk from exposure to potential pathogens such as Legionella spp. and to create a safe working environment.