Classes Of Integrons Research Articles

Simultaneous isolation of sulfonamide resistance gene class (sul І, П) and Integron Class I in Shigella Sonnei isolated from clinical samples in Kerman province using Multiplex-PCR

Introduction: Shigella infections caused by gram-negative bacilli intestinal has created problems in the developed and developing countries. Indiscriminate use of antibiotics, regardless of the resistance has caused the emergence of resistant strains. The aim of this study was to investigate the prevalence of sulfonamide resistance genes and class 1 integron in Shigella sonnei strains isolated from patients with diarrhea and determination of antibiotic susceptibility of the isolates. Materials &methods: A total of 60 isolates were collected out of the Shigella Sonnei bacteria isolated from fecal infection at Kerman hospitals and cultured in specific media and then confirmed by biochemical tests. Sulfonamide resistance genes were studied including sulI and sulII and intI1 by Multiplex-PCR methods. Antibiotic susceptibility was determined to 8 isolates to different antibiotics by disk diffusion method. Findings: As a result, M-PCR was found in one-sample SulI genes and gene sulII genes in 32 samples, but intI1 gene was not detected in any of the strains. The results demonstrated the greatest resistance to antibiotic of Nalidixic acid (96.6%) and the highest sensitivity to ciprofloxacin(92.1%), respectively. Conclusion & discussion: Our study proved the resistance of Shigella sonnei strains to antibiotics. Therefore, it is essential to take deep medical care and conduct an appropriate use of antibiotics to prevent the spread of resistant strains. In addition, it was found that the gene sulII was the most frequent resistance gene to sulfonamide.

Study and identify integrons class Ι, II III, Salmonella typhimurium isolated from clinical samples of Tehran Medical Centers

Study and identify integrons class Ι, II III, Salmonella typhimurium isolated from clinical samples of Tehran Medical Centers

Integrons and antimicrobial resistance in bacteria: A systematic review

Resistance to antimicrobial agents is on the rise and this phenomenon not only leads to an increase in economic burden but may also cause serious therapeutic problems. Nowadays, it is known that horizontal transfer of resistance genes is a major cause for spreading antibiotic resistance genes in microbes. The previous studies have manifested that integrons play a significant role in horizontal transfer of antibiotic resistance. Integrons are in fact natural cloning and expression systems which have the ability to spread multi drug resistance (MDR) in bacteria. They are normally motionless but can be transferred through mobile genetic elements, for example plasmids and transposons. Integrons carry divergent gene cassettes that are rearranged under antibiotic selective pressure. It is based on the sequence of the integrase gene that various classes of integrons are known. Class 1 integron is the most prevalent type among bacteria. This review highlights the need for continuous surveillance to understand the dissemination of integron and multidrug resistance among different bacteria.

Molecular analysis of integron gene cassette arrays associated multi-drug resistant Enterobacteriaceae isolates from poultry

The study investigated 110 Enterobacteriaceae isolates from broiler chickens isolated from Sharkia poultry farms and analyzed the isolates antimicrobial resistance and the presence of integrons as a potential basis for this resistance. Antibiotic susceptibilities against 12 different antibiotics were determined by the disk diffusion method. Prevalences and classes of integrons were then detected in multi-drug resistant (MDR) strains using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) followed by sequencing of the variable parts. Fifty-three isolates were MDR (resistant to three or more antimicrobial agents). High resistance was detected for rifamycin (82.7%), erythromycin (67.2%), and amoxicillin-clavulanic acid (63%). Classes 1 and 2 integrons were detected in 38 of 53 MDR Enterobacteriaceae isolates of which the most common were Salmonella species (n=19), followed by Escherichia coli (12), Klebsiella pneumoniae (3), Proteus species (3), and Citrobacter freundii (1). Three isolates only harbored class 1 integrons while the remaining 35 isolates carried class 2. All class 1 integron positive isolates exhibited the same gene cassettes arrangements: 1.) dfrA12-orfF-aadA27 (1.6 kbp); 2.) aadA23 (1.0 kbp); and 3.) dfrA15 (0.8 kbp). Moreover, four different gene cassettes were identified within class 2 integrons: 1.) dfrA1-sat2-aadA30 (2 kbp) in all isolates; 2.) sat2-aadA1 (1.7 kbp) in only one isolate; 3.) catB2 (0.9 kbp) in four isolates; and 4.) a new variant of sat2 (0.65 kbp) in three isolates. Efforts should be made to introduce surveillance programs for monitoring antimicrobial resistance that could potentially be transmitted from broiler chickens to human via integrons.

Investigating Classes of Integrons in Salmonella infantis Isolated from Clinical Samples and their Antibiotic Resistance Profile

Investigating Classes of Integrons in Salmonella infantis Isolated from Clinical Samples and their Antibiotic Resistance Profile

Diversity and Antimicrobial Resistance Genotypes in Non-Typhoidal Salmonella Isolates from Poultry Farms in Uganda.

Non-typhoidal Salmonella (NTS) are foodborne pathogens of global public health significance. The aim of this study was to subtype a collection of 85 NTS originating from poultry farms in Uganda, and to evaluate a subgroup of phenotypically resistant isolates for common antimicrobial resistance genes and associated integrons. All isolates were subtyped by pulsed-field gel electrophoresis (PFGE). Phenotypically resistant isolates (n = 54) were screened by PCR for the most relevant AMR genes corresponding to their phenotypic resistance pattern, and all 54 isolates were screened by PCR for the presence of integron class 1 and 2 encoding genes. These genes are known to commonly encode resistance to ampicillin, tetracycline, ciprofloxacin, trimethoprim, sulfonamide and chloramphenicol. PFGE revealed 15 pulsotypes representing 11 serotypes from 75 isolates, as 10 were non-typable. Thirty one (57.4%) of the 54 resistant isolates carried at least one of the seven genes (blaTEM-1, cmlA, tetA, qnrS, sul1, dhfrI, dhfrVII) identified by PCR and six (11%) carried class 1 integrons. This study has shown that a diversity of NTS-clones are present in Ugandan poultry farm settings, while at the same time similar NTS-clones occur in different farms and areas. The presence of resistance genes to important antimicrobials used in human and veterinary medicine has been demonstrated, hence the need to strengthen strategies to combat antimicrobial resistance at all levels.

Colistin-Resistant Klebsiella pneumoniae: Prevalence of Integrons and Synergistic Out Turn for Colistin-Meropenem

Background: Klebsiella pneumoniae has the potential to disseminate at speed among the hospital environment, hence included as a major nosocomial pathogen cause of severe infections. This work mainly focused on finding out the prevalence of different classed of integrons in colistin-resistant Klebsiella pneumoniae and to analyze the efficacy of colistin-meropenem in combination. Methods: For this cross-sectional study, random non-biased sampling technique was followed and non-repetitive, Klebsiella pneumoniae clinical isolates were collected (Jan 2015 - Jan 2016) from 2 diagnostic centers located at Chennai and Trichy in Tamil Nadu, India. Isolates were identified as Klebsiella pneumoniae using the VITEK identification system. All the 24 isolates collected were studied for resistance using disk diffusion and minimal inhibitory concentration (MIC). Integrons (class 1, 2, 3) and mcr-1/2 genes were screened for all the isolates. Synergism for colistin-meropenem was tested using checkerboard, time-kill, and modified time-kill analysis. Results: Klebsiella pneumoniae isolates (n = 24) that were resistant to colistin were studied, and MIC50, as well as MIC90 values for colistin, were 64 µg/mL and 16 µg/mL, respectively. Whereas the gene mcr-1/2 was absent in all the isolates tested. Our results revealed the prevalence of class 1 integron among 10/24 isolates (41.6%) and its integron gene cassette in 60% of the isolates with a pattern of variable regions ranging between 700 bp to 2000 bp. The combination of colistin-meropenem implies that by the checkerboard method 86% (21/24) of the isolates, by time-kill analysis 76% (16/21), and by modified time-kill analysis 94% (15/16) of the colistin-resistant isolates showed synergism. Conclusions: This study reveals that the prevalence of integrons might have an impact in spreading colistin resistant Klebsiella pneumoniae among hospital environment, which is a major threat for clinicians. The combination of colistin with meropenem had bactericidal effect against colistin- resistant Klebsiella pneumoniae.

Plasmid-Mediated Class 1 and 2 Integron Carriage in Drug-Resistant Nosocomial Isolates of Acinetobacter baumannii

Background: Acinetobacter baumannii is an opportunistic multidrug-resistant pathogen associated with nosocomial infections in critically ill patients. Antibiotic resistance genes are often encoded by class 1 and 2 integrons and located on plasmids that can facilitate their horizontal transfer among bacteria. Objectives: The aim of this research was to study the correlation between plasmid carriage and presence of class 1 and 2 integrons in nosocomial isolates of A. baumannii. Methods: Fifty isolates collected between October 2014 and March 2015 from Imam Hussein hospital in Tehran were examined. Bacterial identification was carried out by biochemical identification as well as detection of the blaOXA-51 gene among the isolates. Susceptibility to 18 antibiotics was determined by disc diffusion method. Class 1 and 2 integrons were detected in total DNA extracts as well as in isolated plasmids using specific primers and PCR. Results: All isolates were extremely drug-resistant (XDR). Integron carriage was observed in 32 isolates (64%). Seventeen isolates (34%) carried plasmids with molecular sizes of > 20 kbp. Among them, six (35.4%) carried class 1, three (17.6%) harbored class 2, four (23.5%) had both integron classes, and four isolates (23.5%) carried no integrons. Of the plasmid negative isolates, 14 (42.4%) had no integron, 10 (30.3%) carried integron 2, five (15.2%) harbored integron 1 and interestingly, four (12.1%) carried both integron classes. Conclusions: No correlation was found between antibiotic resistance profiles and integron carriage. Class 1 integron was significantly associated with plasmid carriage showing its role in the dissemination of drug resistance in A. baumannii. No association was observed between class 2 integrons and plasmid carriage suggesting their chromosomal location.

A Microfluidic Quantitative Polymerase Chain Reaction Method for the Simultaneous Analysis of Dozens of Antibiotic Resistance and Heavy Metal Resistance Genes

This study developed, optimized, and demonstrated a microfluidic quantitative polymerase chain reaction (MF-qPCR) method for the simultaneous quantification of 39 antibiotic resistance genes (ARGs), five heavy metal resistance genes, three genes encoding the integrase of three different classes of integrons, and 16S rRNA genes (used as a measure of total bacterial biomass). Because the volume of the template is much smaller with MF-qPCR (a few nanoliters) than with conventional qPCR, a preamplification step was needed to improve the sensitivity and the limits of quantification of the MF-qPCR method to be similar to those of conventional qPCR. The MF-qPCR method was successfully demonstrated on untreated municipal wastewater, treated municipal wastewater, and drinking water samples. The treated municipal wastewater samples had higher concentrations of all genes compared to those in the drinking water samples. Similarly, the untreated municipal wastewater samples had higher concentrations for all but one of...

Polyclonal Distribution of blaOXA-23 Gene Among Acinetobacter baumannii Isolated from Intensive Care Unit Patients in Tehran; Pulsed-Field Gel Electrophoresis Analysis

Background: Despite a relatively low virulence of Acinetobacter baumannii isolates, emerging multidrug-resistant (MDR) strains to pose a formidable threat to patients, particularly in ill patients in intensive care unit (ICU). Objectives: The aim of the present study was to determine the genetic relatedness and antimicrobial susceptibility patterns in the endemic clones of A. baumannii isolated from patients in the ICU. Methods: Fifty-five non-repetitive A. baumannii isolates were examined for antimicrobial susceptibility, oxacillinase genes, class 1 integrons and genetic relationships by PFGE. Results: Antibiotic susceptibility testing showed that 21.8%) 12 isolates) were resistant to all tested antibiotics. Resistant to carbapenems were up to 85%. OXA-23, OXA-24 and OXA-58 genes were detected in 81.81%, 16.36% and 1.81% isolates respectively. The ISAba1 element upstream of blaOXA-51 was detected in 18 (32%) isolates, and 22 (40%) isolates had an ISAba1 insertion sequence upstream of the blaOXA-23. Integron class 1 was detected in 25 (55.5%) OXA-23 carrying isolates, 2 (22.2%) in OXA-24 positive isolates and in one OXA-58 carrying isolate. PFGE analysis resolved 50 distinct pulsotypes, Most of the isolates were scattered throughout across the dendrogram and a few grouped as clusters. Conclusions: No significant association has been found between the pulsotype of each isolate and MDR patterns and the presence of carbapenemase genes, however, highly resistant blaOXA-23 gene carrying endemic clones of A. baumannii disseminated in the ICU of two hospitals. Therefore, active surveillance and health policies are urgently needed for the detection and control the dissemination of such organisms.

Antimicrobial resistance and integrons of ESBL-producing thermotolerant coliforms from a water reservoir in Tai'an, China.

The contamination of water environments by extended-spectrum β-lactamases-producing thermotolerant coliforms (ESBL-TC) has aroused public concern. However, little epidemiological data on ESBL-TC isolates from water reservoirs is available in China. This study was designed to investigate antibiotic resistance, bla gene types, and the presence of integrons (class 1, 2, and 3) and gene cassettes in ESBL-TC isolated from the Huangqian Reservoir of Tai'an, China. A total of 96 non-duplicate ESBL-TC were obtained in this study and the ESBL genes included blaCTX-M-14 (n = 47), blaCTX-M-15 (n = 27), blaCTX-M-55 (n = 18), blaSHV-12 (n = 4), blaCTX-M-3 (n = 3), and blaCTX-M-123 (n = 1). Eighty-three of the ninety-six ESBL-TC contained class 1 integrons (86.5%), and 2 isolates harbored class 2 integrons. The sizes of gene cassette regions within integrons were ranged from 0.2 kb to 3.2 kb. The findings of this study indicated the widespread presence of ESBL-TC strains in the Huangqian Reservoir and spotlighted the potential role of water bodies as reservoirs for antibiotic resistant genes.

Significant spread of extensively drug-resistant Acinetobacter baumannii genotypes of clonal complex 92 among intensive care unit patients in a university hospital in southern Iran.

Infections associated with Acinetobacter baumannii represent an increasing threat in healthcare settings. Therefore, we investigated the epidemiological relationship between clinical isolates of A. baumannii obtained from patients in a university hospital in Bandar Abbas in southern Iran. Sixty-four consecutive non-duplicate clinical isolates collected during 2014-2015 were subjected to susceptibility testing, clonal relationship analysis using PFGE, multilocus variable-number tandem-repeat analysis (MLVA) and multilocus sequence typing (MLST), and examined for the presence of carbapenemases and integrons. Almost all A. baumannii isolates were extensively drug-resistant (XDR; 98 %) and carried an OXA carbapenemase gene (blaOXA-23-like; 98 %) and class 1 integrons (48 %). PFGE and MLST analysis identified three major genotypes, all belonging to clonal complex 92 (CC92): sequence type 848 (ST848) (n=23), ST451 (n=16) and ST195 (n=8). CC92 has previously been documented in the hospital setting in northern Iran, and ST195 has been reported in Arab States of the Persian Gulf. These data suggest national and global transmission of A. baumannii CC92. This report demonstrates the occurrence and potential spread of closely related XDR genotypes of A. baumannii CC92 within a university hospital in southern Iran. These genotypes were found in the majority of the investigated isolates, showed high prevalence of blaOXA-23 and integron class 1, and were associated with stay in the intensive care unit. Very few treatment options remain for healthcare-adapted XDR A. baumannii, and hence effective measures are desperately needed to reduce the spread of these strains and resultant infections in the healthcare setting.

Characterization of multidrug-resistant Acinetobacter ssp. strains isolated from medical intensive care units in Cali - Colombia.

Introduction: The extensive use of antibiotics has led to the emergence of multi-resistant strains in some species of the genus Acinetobacter.Objective: To investigate the molecular characteristics of multidrug-resistant of Acinetobacter ssp. strains isolated from 52 patients collected between March 2009 and July 2010 in medical intensive care units in Cali - Colombia.Methods: The susceptibility to various classes of antibiotics was determined by disc diffusion method, and the determination of the genomic species was carried out using amplified ribosomal DNA restriction analysis (ARDRA) and by sequencing of the 16s rDNA gene. Also, the genes of beta-lactamases as well as, integrases IntI1 and IntI2 were analyzed by PCR method.Results: The phenotypic identification showed that the isolates belong mainly to A. calcoaceticus- A. baumannii complex. All of them were multi-resistant to almost the whole antibiotics except to tigecycline and sulperazon, and they were grouped into five (I to V) different antibiotypes, being the antibiotype I the most common (50.0%). The percent of beta-lactamases detected was: blaTEM (17.3%), blaCTX-M (9.6%), blaVIM (21.2%), blaIMP (7.7%), blaOXA-58 (21.2%), and blaOXA-51 (21.2%). The phylogenetic tree analysis showed that the isolates were clustering to A. baumannii (74.1%), A. nosocomialis (11.1%) and A. calcoaceticus (7.4 %). Besides, the integron class 1 and class 2 were detected in 23.1% and 17.3% respectively.Conclusion: The isolates were identified to species A. baumanii mainly, and they were multiresistant. The resistance to beta-lactams may be by for presence of beta-lactamases in the majority of the isolates.

Integron Digestive Carriage in Human and Cattle: A “One Health” Cultivation-Independent Approach

Objectives: Dissemination of antimicrobial resistance (AMR) is a global issue that requires the adoption of a “One-Health” approach promoting integration of human and animal health. Besides culture-dependent techniques frequently used for AMR surveillance, cultivation-independent methods can give additional insights into the diversity and reservoir of AMR genetic determinants. Integrons are molecular markers that can provide overall and reliable estimation of AMR dissemination. In this study, considering the “One-Health” approach, we have analyzed the integron digestive carriage from stools of humans and cattle living in a same area and exposed to different antibiotic selection pressures.Methods: Three collections of human [general population (GP) and intensive care unit patients (ICUs)] and bovine (BOV) stool samples were analyzed. The three main classes of integrons were detected using a multiplex qPCR both from total DNA extracted from stools, and from Gram-negative bacteria obtained by culture after an enrichment step.Results: With the cultivation-independent approach, integron carriage was 43.8, 52.7, and 65.6% for GP, ICU, and BOV respectively, percentages being at least twofold higher to those obtained with the cultivation-dependent approach. Class 1 integrons were the most prevalent; class 2 integrons seemed more associated to cattle than to humans; no class 3 integron was detected. The integron carriage was not significantly different between GP and ICU populations according to the antibiotic consumption, whatever the approach.Conclusion: The cultivation-independent approach constitutes a complementary exploratory method to investigate the integron digestive carriage of humans and bovines, notably within subjects under antibiotic treatment. The high frequency of carriage of integrons in the gut is of clinical significance, integrons being able to easily acquire and exchange resistant genes under antibiotic selective pressure and so leading to the dissemination of resistant bacteria.

Molecular screening of antibiotic-resistant determinants among multidrug-resistant clinical isolates of Proteus mirabilis from SouthWest Nigeria.

Globally, and particularly in developing countries, the menace of anti-microbial resistance is an accelerating problem. In Nigeria, increase in bacterial resistance has been phenotypically established but due to high cost, few molecular studies have been reported. This study screened for presence of transferable resistance genes and mobile genetic elements (MGEs) such as integron among multi-drug resistant (MDR) P. mirabilis. A total of 108 P. mirabilis strains collected from five tertiary hospitals in SouthWest Nigeria were subjected to antibiotic susceptibility study using disc-diffusion method. Transferable resistance genes and MGEs were amplified using Polymerase chain reaction (PCR) analysis and amplicons sequenced. Varied resistance was observed against all the antibiotics tested. About 56% of the isolates were MDR including those from 0-12 years old children. PCR analysis revealed the presence of aac(6')-Ib (33.3%), plasmid mediated quinolone resistance (PMQR) genes [qnrA (36.7%), acc(6')-Ib-cr (5%)], TEM (48.3%), CTX-M (6.7%) and integrons class 1 (58.3%) and class 2 (26.7%). Sequencing analysis revealed blaTEM-1, blaCTX-M-15 associated with ISEcp1 and eight different arrays of gene cassettes: aadA1, aadA1-qacH, aadB-aadA2, aadA5, dfrA7, dfrA15, dfrA17, dfrA17-aadA5. Transferable resistance genes in association with MGEs are present in Nigerian P. mirabilis thus their potential in disseminating resistance.

Characterization of extended spectrum β-lactamase (ESBL)-producing Escherichia coli in Asi (Orontes) River in Turkey.

In this study, the presence of extended spectrum β-lactamase (ESBL)-producing Escherichia coli in aquatic environments (the Orontes River and an urban wastewater) was investigated. Fifty-four E. coli strains resistant to cefotaxime were isolated from the river waters and nearby waste water treatment plant and screened for ESBL gene variants, different classes of integrons and sulfonamide resistance genes. The ESBL-producing E. coli strains were further characterized by PhP-typing system, phylogenetic grouping and antimicrobial susceptibility testing. Of the 54 ESBL-producing strains, 14 (25.9%) belonged to four common PhP types and the remaining were of single types. CTX-M type ESBL genes were identified in 68% of the isolates. The most predominant specific CTX-M subtype identified was blaCTX-M-15 (n = 36), followed by blaCTX-M-1 (n = 1). None of the isolates were SHV and OXA positive. Most of the ESBL positive isolates (n = 37; 68.5%) were harboring sul gene. This study indicates a widespread distribution of CTX-M-15 producing E. coli strains in the surface waters in part of Turkey, suggesting an aquatic reservoir for ESBL genes.

Dissemination of Classes 1, 2, and 3 Integrons in Acinetobacter baumannii Strains Recovered from Intensive Care Units Using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism

Background: Acinetobacter baumannii as the most important nosocomial pathogen can cause various types of clinical infections. Multidrug resistance in A. baumannii strains has significantly limited the choice of available therapeutic options for treatment of patients and is a serious threat to hospitalized patients, especially those in intensive care units. Objectives: The present study was performed to investigate the frequency of classes 1, 2, and 3 integrons in A. baumannii strains isolated from selected hospital ICUs. Methods: A total of 105 A. baumannii isolates were collected between October 2015 and April 2016 from 4 medical centers located in different regions of Tehran, Iran. The resistance rate to different classes of antimicrobial agents was assessed using Epsilometer test. Conventional PCR was performed for the detection of blaOXA-51-like gene and integrase gene. Restriction Fragment Length Polymorphism technique using RsaI and HinfI restriction enzymes was used to detect integron classes. Results: All the isolates were observed to be susceptible to colistin and polymixin B and inhibited at similar minimum inhibitory concentration (MIC) 50 (MIC50) and MIC90 1 µg/mL. All the tested A. baumannii isolates were multidrug resistant. The rate of extensive drug-resistance among these clinical isolates was 71.4%. The highest and the lowest levels of resistance were observed to be related to ciprofloxacin (96.2%) and netilmicin (40%), respectively. Resistance rates to other antibiotics tested were between 43.8% and 80%. The prevalence of classes 1 and 2 integrons was found to be 66.7% and 20%, respectively. Class 3 integron was reported, for the first time, in three A. baumannii strains (2.9%) isolates from Tehran, the capital of Iran. Conclusions: The results revealed that the dissemination of multi-drug resistance among A. baumannii isolates may be associated with the presence of integrons. The findings highlighted the need for continuous surveillance to monitor integrons among A. baumannii strains.

Genetic Determinants of Antibiotic Resistance in Hospital and Community Isolates of Klebsiella pneumoniae and Escherichia coli

Background: Multi-drug resistant Escherichia coli and Klebsiella pneumoniae with various resistance determinants are a major con- cern in hospital and community acquired infections around the world. Objectives: To describe the presence of blaCTX-M, blaTEM, blaPER, blaVEB, and integrons class 1, 2, 3 and extended spectrum β lactamase (ESBL) phenotype in E. coli and K. pneumoniae isolates from clinical samples of inpatients and outpatients. Methods: One hundred and eighty six E. coli and fifty-eight K. pneumoniae were collected. Antimicrobial susceptibility test was performed by disk diffusion method. Extended-spectrum beta-lactamase phenotype were screened by phenotypic confirmatory test. PCR assay was performed for blaTEM, blaCTX-M, blaPER and blaVEB and class 1, 2, 3 integrase genes. Statistical analysis was performed by chi-squared test. Results: Extended-spectrum beta-lactamase phenotype was detected in 49 (26.3%) E. coli and 19 (32.8%) K. pneumoniae isolates. BlaVEB gene in 32 (17.2%) E. coli and 5 (8.6%) K. pneumoniae isolates. BlaPER gene in 4 (2.1%) E. coli and 0 (0%) K. pneumoniae isolates. BlaCTX-M gene in 113 (60.7%) E. coli and 34(58.6%) K. pneumoniae isolates. BlaTEM gene in 106 (57%) E. coli and 25 (43.1%) K. pneumoniae isolates. One hundred and nine (58.6%) of E. coli and 33 (56.9%) of K. pneumoniae were carrying Class 1 integron and 18 (9.7%) of E. coli and 3 (5.2%) of K. pneumoniae were carrying Class 2 integron. Class 3 integron was not detected. Conclusions: High prevalence of ESBLs in E. coli and K. pneumoniae isolated from the community and hospital acquired infections could lead to the wide spread of multi-drug resistance clones that also contain new mechanism of resistance.

Integron occurrence is linked to reduced biocide susceptibility in multidrug resistant Pseudomonas aeruginosa

Objective: Integrons are gene acquisition systems commonly found in bacterial genomes that play a major role in the dissemination of resistance to antibiotics. This work aimed to study the relationship between the presence of integrons and the reduced susceptibility of multidrug-resistant (MDR) Pseudomonas aeruginosa isolates towards different groups of biocides.Methods: The antimicrobial susceptibility patterns of 104 clinical isolates were determined against different antibiotics by the disk diffusion method. The isolates were also tested for their susceptibility to six biocides (glutaraldehyde, benzalkonium chloride, cetrimide, chlorhexidine gluconate, chlorocresol and gluconate, and phenyl mercuric nitrate) by agar dilution. The presence of integrons and resistance genes in MDR isolates were detected by polymerase chain reaction.Results: Thirty-six Pseudomonas isolates were MDR, and the majority of these isolates showed reduced susceptibility to biocides. In the MDR isolates, Class I integron was detected in 22 isolates (61.1%), while Class II and III integrons were identified in only four isolates (11.1%), In addition, aacA4 and qacE genes were detected in 22 (61.1%) and 11 (30.5%) isolates, respectively. Integron I-positive isolates showed reduced susceptibility to tested biocides.Conclusions: The current study reveals the presence of different classes of integrons, with class I being predominant. Class I integron may be responsible for generating MDR P. aeruginosa isolates with reduced susceptibility to biocides. This linkage between integrons and biocide resistance in MDR-Pseudomonas isolates is notable and could be clinically important. Strict antibiotic prescription policies and the adequate use of biocides could help in controlling this problem.

Sources and Pollution Characteristics of Antibiotic Resistance Genes and Conditional Pathogenic Bacteria in Concentrated Poultry Feeding Operations

Concentrated animal feeding operations (CAFOs) is considered a source of airborne human pathogens and antibiotic resistance genes. This study collected fecal samples and corresponding air samples from inside and outside atmospheric environments of layer and broiler feeding operations. We detected the types of 61 genes including five classes of antibiotics antibiotic resistance genes (23 genes of ampicillin, 23 genes of tetracycline, 5 genes of quinolones, 5 genes of sulfonamides and 2 genes of erythromycin), five conditional pathogenic bacteria (Enterococcus, Escherichia coli, Staphylococcus, Campylobacter and Clostridium perfringens) and class1 integron. Quantitative real time PCR was used to analyze concentrations of typical genes with relatively high detection rates. The results indicated that the detection rates of antibiotic resistance genes were 8,7,2,3 and 2. At the same time, two kinds of pathogenic bacteria were detected. The detection rates of the target genes in the air were lower than those of the fecal sample. The total bacterial gene (16S rDNA) concentration in the air of layer and broiler was 106 copies·m-3, and that of the other typical genes was about 104copies·m-3. And the outdoor concentration was much lower than the indoor concentration. The proportions of antibiotic resistance genes and conditional pathogenic bacteria in the air were higher than those in the fecal samples and the outdoor proportions were lower than the indoor proportions. Preliminary results of this study indicated that feces was an important source of antibiotic resistance genes, conditional pathogenic bacteria and class1 integron. Aerosolization degrees of genes in feces were different. This study will provide the basic data for both source tracking of antibiotic resistance genes and pathogens from CAFOs and risk assessment of pollution of CAFOs in the surrounding air environment.