Evaluation of mechanisms of colistin resistance in Klebsiella pneumoniae strains isolated from patients with urinary tract infection in ICU

Background and Objectives: One of the major causes of urinary tract infections is Klebsiella pneumoniae. Currently, few studies investigated the mechanisms of resistance to colistin in Iran. The current study aimed to determine the prevalence of plasmid and chromosome-mediated resistance to colistin in K. pneumoniae isolates. Materials and Methods: 177 urine samples were collected from patients with urinary tract infections hospitalized in the intensive care unit (ICU) of hospitals in the city of Qazvin. K. pneumoniae isolates were identified by standard biochemical methods, resistance to colistin among K. pneumoniae isolates were tested by disk diffusion and microbroth dilution methods. The chromosomal mutation and presence of the mcr genes in colistin-resistant K. pneumoniae were evaluated by PCR. Results: Out of 177 samples, 65 K. pneumoniae were obtained from patients in the ICU. Six colistin-resistant isolates were isolated with MIC values ≥4 μg/mL, none of them was positive for mcr1-5. In 4 isolates, missense mutation in mgrB gene resulted in amino acid substitutions and in one isolate of mgrB gene was found intact mgrB gene. Conclusion: The results suggest that mgrB mutation was the main mutation among colistin-resistant isolates and plasmid-borne colistin resistance was not expanded among strains

Phenotypic Identification and Genotypic Characterization of Plasmid‑Mediated AmpC β‑Lactamase‑Producing Escherichia coli and Klebsiella pneumoniae Isolates in Iran

One of the mechanisms of Klebsiella pneumoniae and Escherichia coli resistance to β-lactam antibiotics is the production of β-lactamase enzymes. Among these are the AmpC β-lactamases, which confer resistance to a class of antibiotics. However, little is known about the AmpC β-lactamases of K. pneumoniae and E. coli clinical isolates in Qazvin, Iran. This study was designed to assess the AmpC β-lactamases-producing strains and also identify the prevalence of AmpC β-lactamases genes. Antimicrobial susceptibility tests were performed on 435 K. pneumoniae and E. coli isolates using disk difusion technique. Plasmid-mediated AmpC genes were studied using a multiplex PCR assay. The AmpC β-lactamase-producer isolates were studied by employing cefoxitin disk difusion test, AmpC induction test, AmpC cefoxitin-EDTA test, and boronic acid disk test. Our results showed that of 46 (18.4%) cefoxitin-insensitive E. coli isolates, 10 (21.7%) were positive for AmpC β-lactamase genes, among them 4 (8.69%) isolates were positive for blaDHA genes and 6 (13%) for blaCIT genes. Of 57 (30.4%) cefoxitin-insensitive K. pneumoniae isolates, 10 (17.5%) were positive for AmpC gene with 4 (6.34%) and 6 (9.5%) isolates positive for blaDHA and blaCIT genes, respectively. However, no MOX, ACC, FOX, or EBC genes were detected in the isolates. Considering the results of diferent confrmatory phenotypic tests, the AmpC cefoxitin-EDTA test showed a higher discriminatory power for detecting AmpC β-lactamase-producing strains. The specifcity and sensitivity of AmpC cefoxitin-EDTA were 77%, 100% for K. pneumonia and 70%, 90% for E. coli higher than the other two tests, respectively. Also, the authors demonstrated high prevalence rate for resistance to certain antibiotics, such as cefuroxime, trimethoprim-sulfamethoxazole, ampicillin, and cefotaxime. In conclusion, our study provided valuable information regarding the plasmid-mediated AmpC β-lactamase gene content, antibiotic resistance, and confrmatory phenotypic tests for AmpC β-lactamases in E. coli and K. pneumoniae isolates from clinical sources

Stability of SARS-CoV-2 in Different Environments and the Effect of Disinfectants on its Survival

In December 2019, the prevalence of a pneumonia with unknown cause was reported in China which was later named Coronavirus Disease 2019 (COVID-19) caused by a virus called SARS-CoV-2. One of the most important ways of COVID-19 transmission is contaminated surfaces. In this review study, we investigated the stability of SARS-CoV-2 in air and on surfaces and the methods of preventing its spread Reported in studies conducted from 2003 to April 2020 which were searched in PubMed, Scopus, Embace, and Google Scholar databases using keywords including Coronavirus, COVID-19, SARS-CoV-2, disinfection, transmission and surfaces. Out of 118 articles identified in the initial search, 73 were remained after screening their titles and abstracts. By applying inclusion and exclusion criteria, 51 articles were finally selected for review. The novel coronavirus epidemic in humans is more widespread than previous coronaviruses, indicating the high infectivity and environmental stability of the virus. The SARS-CoV-2 can stay active for up to 28 days at low temperatures (4°C). Currently, due to the lack of effective treatment and vaccines, the best ways to deal with this disease is to avoid contamination, use disinfectants, and prevent its spread by protective measures

فراوانی و ویژگی های مولکولی مقاومت به کلیستین با واسطه ژن پلاسمید mcr-1,2 در ایزوله های کلبسیلا و انتروباکتر جداشده از نمونه های کلینیکی

چکیده فارسی( Abstract) سابقه و هدف : یکی از علل اصلی عفونت های بیمارستانی باکتری های خانواده انتروباکتریاسه هستند. مطالعات کمی در خصوص باکتری های کلبسیلا و انترو باکتر در خصوص مقاومت به کلیستین ، که به عنوان آخرین خط درمانی در باکتری های MDR محسوب می شود، انجام شده است. مطالعه حاضر با هدف تعیین شیوع مقاومت کروموزومی و وابسته به پلاسمید کلیستین در ایزوله های کلبسیلا و انتروباکتر جداشده از بیمارستان های شهر قزوین انجام شد. روش بررسی : 384 ایزوله کلبسیلا و انتروباکتر از بخش های مختلف بیمارستان های شهر قزوین جمع آوری شدند. تمامی ایزوله ها با روش های استاندارد بیوشیمیایی تعیین هویت شدند و جهش های کروموزومی و حضور ژن هایmcr-1 تا mcr-5 مقاوم به کلیستین مورد مطالعه قرار گرفت. یافته ها: در تمامی 280 ایزوله کلبسیلا و 100 ایزوله انتروباکتر به دست آمده، ژن های پلاسمیدی mcr-1 تا mcr-5 مقاوم به کلیستین مشاهده نشد.در مطالعه انجام شده بر روی ژن های کروموزومی مقاومت به کلیستین، از بین 26 ایزوله مقاوم به کلیستین ایزوله های کلبسیلا مطابق MIC بدست آمده ، در 5 ایزوله ادراری ، موتاسیون در ژن mgrB علت ایجاد مقاومت به کلیستین شناخته شد و در 3 ایزوله تنفسی مقاوم به کلیستین، ژن mgrB دست نخورده گزارش شد. بحث و نتیجه گیری: همانند دیگر مطالعات انجام شده در ایران، در هیچ ایزوله کلبسیلا و انتروباکتر، مقاومت به کلیستین با واسطه پلاسمید مشاهده نشد. نتایج ما نشان داد که تغییرات ایجاد شده در ژن mgrB همانند سایر مطالعات، مکانیسم اصلی در مقاومت ایزوله های مطالعه شده بود. کلید واژه ها: کلیستین، مقاومت آنتی بیوتیک، کلبسیلا، انتروباکتر، ژنmcr-1، ژنmgrB ایمیل استاد راهنما : دکتر فرهاد نیکخواهی [email protected]

Phenotypic Identification and Genotypic Characterization of Plasmid-Mediated AmpC beta-Lactamase-Producing Escherichia coli and Klebsiella pneumoniae Isolates in Iran

One of the mechanisms of Klebsiella pneumoniae and Escherichia coli resistance to β-lactam antibiotics is the production of β-lactamase enzymes. Among these are the AmpC β-lactamases, which confer resistance to a class of antibiotics. However, little is known about the AmpC βlactamases of K. pneumoniae and E. coli clinical isolates in Qazvin, Iran. This study was designed to assess the AmpC β-lactamases-producing strains and also identify the prevalence of AmpC β-lactamases genes. Antimicrobial susceptibility tests were performed on 435 K. pneumoniae and E. coli isolates using disk diffusion technique. Plasmid-mediated AmpC genes were studied using a multiplex PCR assay. The AmpC β-lactamase-producer isolates were studied by employing cefoxitin disk diffusion test, AmpC induction test, AmpC cefoxitin-EDTA test, and boronic acid disk test. Our results showed that of 46 (18.4%) cefoxitin-insensitive E. coli isolates, 10 (21.7%) were positive for AmpC β-lactamase genes, among them 4 (8.69%) isolates were positive for blaDHA genes and 6 (13%) for blaCIT genes. Of 57 (30.4%) cefoxitin-insensitive K. pneumoniae isolates, 10 (17.5%) were positive for AmpC gene with 4 (6.34%) and 6 (9.5%) isolates positive for blaDHA and blaCIT genes, respectively. However, no MOX, ACC, FOX, or EBC genes were detected in the isolates. Considering the results of different confirmatory phenotypic tests, the AmpC cefoxitin-EDTA test showed a higher discriminatory power for detecting AmpC β-lactamase-producing strains. The specificity and sensitivity of AmpC cefoxitinEDTA were 77%, 100% for K. pneumonia and 70%, 90% for E. coli higher than the other two tests, respectively. Also, the authors demonstrated high prevalence rate for resistance to certain antibiotics, such as cefuroxime, trimethoprim-sulfamethoxazole, ampicillin, and cefotaxime. In conclusion, our study provided valuable information regarding the plasmid-mediated AmpC βlactamase gene content, antibiotic resistance, and confirmatory phenotypic tests for AmpC βlactamases in E. coli and K. pneumoniae isolates from clinical sources

First detection of mobilized colistin resistance mcr-1 gene in Escherichia coli isolated from livestock and sewage in Iran

Currently, few studies have investigated the mechanisms of resistance to colistin in Iran. The aim of this study was to investigate mcrharbouring Escherichia coli dissemination in livestock and sewage in Iran. A total of 115 samples from cows (n = 38), chickens (n = 47) and urban sewage samples (n = 30) were collected. The presence of genes including mcr1–6 and ampC β-lactamase (blaMOX, blaCIT, blaDHA, blaACC, blaEBC, blaFOX) for colistin-resistant isolates was investigated by multiplex PCR method. Genetic association of colistinresistant strains was also evaluated by ERIC PCR. Sixty-five isolates were identified as E. coli. Meaningless were resistant to colistin. The highest (26.1%) and lowest (3.07%) resistance were shown to ampicillin and meropenem respectively. Among the three colistin-resistant isolates, 2 (66%) were multidrug resistant, with one of them being mcr-1 positive and the other one positive for DHA ampC β-lactamase gene. No mcr2–6 genes were found. Minimum inhibitory concentration of mcr-producing isolate was 4 mg/L by microbroth dilution. This study reports, first the detection of mcr-1 in E. coli from farm animals in Iran, a finding that is indicative of a global distribution of this plasmidic element and threatning the use of colistin as a last resort antibiotic. No clonal relationship was observed between the colistinresistant E. coli isolates by ERIC-PCR. Monitoring the presence of these strains in animal sources help as to controlling the spread of resistance genes from animal to human is vital. © 2021 The Authors. Published by Elsevier Ltd