Integrons In Strains Research Articles

Integron distribution and relationship to antimicrobial resistance in E. coli isolated from blood culture

PurposeThe aim of this study was to evaluate the distribution of integrons in strains of E. coli isolated from blood culture and the relationship between integrons and antimicrobial resistance. MethodsThe study included 100 E. coli strains sent to the Medical Microbiology Laboratory from different clinics between September 2022 and June 2023. Antibiotic susceptibility was evaluated according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST). The presence of integrons was determined by the inhouse polymerase chain reaction (PCR). ResultsIntegron positivity was detected in 45 (45%) of isolates, and class 1 integrons were found in 41 (41%), class 2 integrons in 2 (2%), and both class 1 integrons and class 2 integrons in 2 (2%). Class 3 integron positivity was not detected. In total, 63 cases of community origin and 37 cases of hospital origin were identified. When antibiotic resistance was evaluated, the highest sensitivity was noted for amikacin (1%), meropenem (5%), imipenem (6%), and the highest resistant antibiotics were ampicillin (82%), cepfuroxime sodium (65%), and amoxicillin/clavulanate (62%), respectively. Of the 16 antimicrobial substances evaluated, 10 had an antibiotic resistance rate of over 45%. In class 1 integron-positive samples, ampicillin resistance and trimethoprim/sulfamethoxazole resistance were higher than in negative samples (p = 0.02, p = 0.0001, respectively). Fifty-one (51%) samples were found to have multiple drug resistance (MDR). In total, 59.5% of hospital-acquired isolates and 46% of community-acquired isolates were considered to be MDR. The class 1 integron positivity in MDR samples was high (p = 0.038). ConclusionThe high MDR rates in both hospital-acquired and community-acquired isolates are alarming. In particular, class 1 integron monitoring is very important to prevent the spread of MDR isolates.

Yoğun Bakım Ünitesinden Alınan Alt Solunum Yolu Örneklerinde Üretilen Acinetobacter baumannii İzolatlarında Antibiyotik Direnci ve İntegron Gen Kasetleri

Objective: The spread of antibiotic resistance genes among bacteria causes serious problems in the treatment of infectious diseases. Recently, it has been shown that these resistance genes are also found in integrons. This study investigated the class 1, 2 integrons and the antibiotic-resistant genes in the infection agent Acinetobacter baumannii produced in respiratory tract samples.Material and Methods: The study involved 86 A. baumannii strains isolated from lower respiratory tract samples collected between March 2014 and March 2015 in the Intensive Care Units. Identification and antibiograms of the isolates were made using conventional methods and Vitek 2 Compact systems. The presence of integrons in strains was investigated by polymerase chain reaction method using specific primer pairs for class 1and class 2 integrase regions. All samples in which integron amplification was carried out were subjected to DNA sequence analysis both by cloning and as a PCR product. The resistance genes were screened by polymerase chain reaction. Results: Isolates were obtained from specimens including tracheal aspirates (33.7%), bronchoalveolar lavage (29.1%), sputum (22.1%), bronchial washing fluid/bronchial brushing (4.7%), transbronchial biopsy (4.7%), pleural fluid (3.4%) and lung aspirates/abscess (2.3%). While resistance to imipenem, meropenem, ampicillin-sulbactam, ceftazidime, and piperacillin-tazobactam was determined in all isolates, resistance rates to ciprofloxacin, levofloxacin, gentamicin, amikacin and tigecycline were 97.7%, 93.0%, 60.5%, 53.5%and 9.3%, respectively. Colistin was the only antibiotic to which all strains were susceptible. The positivity rates of integrase I and II genes were 45.4%and 9.3%, respectively. Class 1 and 2 integron positivity rates in all isolates were 31.4%and 8.1%, respectively. blaTEM, blaSHV, blaCTX-M1, blaCTX-M2, blaOXA23, blaOXA40, blaOXA58 were 70.9%, 2.3%, 4.7%, 7.0%, 95.3%, 5.8%and 3.5%, respectively. Conclusion: Increasing association of multi drug resistant strains and integron resistant genes in A. baumannii infections will lead to the failure of antibiotic treatment strategies.

The occurrence of antimicrobial resistance and class 1 integrons among commensal Escherichia coli isolates from infants and elderly persons

BackgroundThe aim of our study was to compare the presence of the intI1 gene and its associations with the antibiotic resistance of commensal Escherichia coli strains in children with/without previous antibiotic treatments and elderly hospitalized/healthy individuals.MethodsOne-hundred-and-fifteen intestinal E. coli strains were analyzed: 30 strains from 10 antibiotic-naive infants; 27 from 9 antibiotic-treated outpatient infants; 30 from 9 healthy elderly volunteers; and 28 from 9 hospitalized elderly patients. The MIC values of ampicillin, cefuroxime, cefotaxime, gentamicin, ciprofloxacin, and sulfamethoxazole were measured by E-test and IntI1 was detected by PCR.ResultsOut of the 115 strains, 56 (49%) carried class 1 integron genes. Comparing persons without medical interventions, we found in antibiotic-naive children a significantly higher frequency of integron-bearing strains and MIC values than in healthy elderly persons (53% versus 17%; p < 0.01). Evaluating medical interventions, we found a higher resistance and frequency of integrons in strains from hospitalized elderly persons compared with non-hospitalized ones. Children treated with antibiotics had strains with higher MIC values (when compared with antibiotic-naive ones), but the integron-bearing in strains was similar. In most cases, the differences in resistance between the groups (integron-positive and negative strains separately) were higher than the differences between integron-positive and negative strains within the groups.ConclusionThe prevalence of integrons in commensal E. coli strains in persons without previous medical intervention depended on age. The resistance of integron-carrying and non-carrying strains is more dependent on influencing factors (hospitalization and antibiotic administration) in particular groups than merely the presence or absence of integrons.

Characterization of antibiotic resistance genes linked to class 1 and 2 integrons in strains of Salmonella spp. isolated from swine

The aim of this study was to characterize the antibiotic resistance profiles, the integron-associated resistance determinants, and the potential ability of transferring these determinants by conjugation in Salmonella enterica isolated from swine. Fifty-four strains of Salmonella spp. were isolated from healthy swine. The percentages of resistance, determined by the plate dilution method were as follows: oxytetracycline (41%), streptomycin (39%), sulphamethoxazol+trimethoprim (19%), enrofloxacin-ciprofloxacin (13%), and amoxicillin (0%). The most important resistance serovars were Salmonella Branderburg, Salmonella Derby, Salmonella Typhimurium, and Salmonella Heidelberg. The oxytetracycline-resistant strains amplified the genes tetA (36%), tetB (64%); and the strains resistant to streptomycin and trimethoprim amplified the genes aadA1 (100%) and dfrA1 (100%), respectively. None of the fluoroquinolone-resistant strains amplified the gene qnr. Ten strains amplified the class 1 integron harboring the cassette aadA1. Six strains amplified the class 2 integron harboring the cassettes dfrA1, sat1, and aadA1. The conjugation assays showed that 2 strains transferred the tetA and aadA1 genes and the class 1 integron to a recipient strain. Taken together, the results obtained in this study show a high percentage of resistance in and the presence of integrons in strains of S. enterica isolated from swine. This information should support the implementation of regulations for the prudent use of antimicrobial agents in food-producing animals.

Incidence of class 1 integrons in multiple antibiotic-resistant Gram-negative copiotrophic bacteria from the River Torsa in India

The presence of class 1 integrons in multiple-antibiotic-resistant (MAR) Gram-negative copiotrophic bacteria from the River Torsa in India was detected using a polymerase chain reaction (PCR)-based screening method. Among 100 isolates that were resistant to at least five of the twelve antibiotics tested, 40 carried class 1 integrons, with inserted DNA regions of 0.7–3.2 kb. Carriage of integrons in strains of higher MAR index was found to be statistically significant. DNA sequencing was used to identify the genetic content of the integron-variable regions. In addition to the identification of gene cassettes dfrA1, dfrA5, dfrA7, dfrA17 and a variant of dfrA12 for trimethoprim, aac( 6′) -Ib for amikacin and tobramycin and aadA1 and aadA6 for streptomycin and spectinomycin resistance, a novel ORF predicted from a sequence of Morganella sp. TR 90 bearing homology with the Vibrio cholerae dfrA1 gene cassette was characterized. To our knowledge, this is the first report of the incidence and abundance of class 1 integrons in copiotrophic river water bacteria from India.