Background The aim of this study was to evaluate the antimicrobial resistance and genetic basis for metronidazole (Mtz) and clarithromycin (Cla) resistance in strains of Helicobacter pylori , isolated from patients with gastroduodenal disorders. Patients and methods A total of 157 H . pylori isolates (from 22 gastric cancer, 38 peptic ulcer disease, and 97 non-ulcer dyspepsia patients) were analyzed for drug susceptibility to Mtz and Cla, by gradient diffusion test (E-test, MAST). The PCR and sequence analysis of the rdxA and frxA for Mtz-resistant strains and the 23S rRNA for Cla-resistant strains were used to determine the genetic basis of drug resistance in H. pylori strains. Increased expression of TolC homologous genes ( hefA ) that upregulates efflux pump activity was determined in multidrug-resistant (MDR) strain of H. pylori by real-time PCR technique. Results Among 157 H . pylori isolates, 32 (20.4%) strains were resistant to at least one of the antimicrobial agents. The highest resistance rate was attributed to Mtz (n=69, 43.94%). Among the resistant strains of H. pylori , 15 cases (9.55%) were detected as MDR. Mutations in the rdxA (85.5%) and A2143G point mutations (63.1%) in the 23S rRNA were the most common cause of resistance to Mtz and Cla in strains of H. pylori , respectively. In MDR strains, the rdxA mutation and A2143G-point mutation in the 23S rRNA were the most abundant mutations responsible for drug resistance. The relative expression of hefA in MDR strains (mean 3.706) was higher than the susceptible strains (mean 1.07). Conclusion Mutational inactivation and efflux pump overexpression are two mechanisms that increase the resistance to H. pylori antimicrobial agents and the rate of MDR strains. In Iran, the mutations of rdxA and frxA in Mtz-resistant strains and A2143G and A2142G of the 23S rRNA in Cla-resistant strains were significant. The screening for these mutations could help to prevent antibiotic resistance, and to determine the most effective anti- H. pylori drugs.
Background: Different Escherichia coli phylogenetic groups, such as A, B1, B2, and D, have four functional groups – adhesins, microcins, toxins, and capsules – which can cause urinary tract infections (UTIs). A phylogenetic group with a high virulence content becomes a worldwide health concern. Resistance to antimicrobial agents increasingly complicates the management of E. coli extraintestinal infections, as a major source of illness, death, and increased health care costs. The aim of this study was to determine the virulence content and the antimicrobial susceptibility pattern of different uropathogenic E. coli (UPEC) phylogenetic groups in Ahvaz, Iran. Methods: Phylogenetic groups, virulence-associated genes (VAGs), and antimicrobial susceptibility tests were detected by molecular and phenotypic methods in a total of 232 clinically well-characterized E. coli strains, isolated from two collections of patients with hospital-acquired (HA) and community-acquired (CA) UTIs. Results: Our results revealed that among 232 UPEC strains, the most frequent phylogenetic group was phylogroup D (58%) with the greatest content in virulence factors, including kpsM (23%), neuA (76.3%, capsule), cnf (29.6%, toxin), and Pap (54.8%, adhesin). Phylogroups D and, to a lesser extent, B2 were the most drug-resistant phylogroups. In addition, phylogroup D was responsible for the majority of HA (64.7%) and CA (48.4%) infections. Conclusion: Among UPEC strains causing UTIs, different phylogroups, through different VAGs, could cause severe infection. Knowledge about the distribution of the four functional groups and VAGs belonging to these phylogroups would significantly help to confine and prevent the development of lethal infection caused by these strains.
Background and Purpose:Root canal therapy is the primary method for the treatment of an infected pulp in modern dentistry. The main aim of endodontic treatment is the elimination of bacteria and their products from infected root canals. In this study, we attempted to investigate the antimicrobial activity of three root canal sealers against oral pathogens.Materials and Methods:The antimicrobial effectiveness of three endodontic sealers with different chemical compositions, namely resin (AH 26), zinc oxide eugenol (ZOE), and mineral trioxide aggregate (MTA), against Candida albicans, Streptococcus sanguis, Streptococcus salivarius, Streptococcus mutans, and Lactobacillus casei was assayed by agar well diffusion method (AWDM). The tested sealers were prepared according to the manufacturer’s instructions and poured in the prepared wells of agar plates; diluted inocula (105 and 106 CFU/ml) of the tested microorganism strains were also used. The minimum inhibitory concentration (MIC) values of the selected canal sealers ranged between 3.12 and 50 mg.ml-1 against the employed microorganism strains. All the plates were incubated at 37°C under anaerobic condition for bacteria and at 30°C for C. albicans. After three days, the inhibition zones were measured. Results:In this investigation, AH 26 exhibited strong activity against C. albicans with the minimum inhibitory concentration of 12.5 mg.ml-1, but ZOE and MTA did not act against C. albicans. ZOE sealer had the highest antimicrobial activity against the tested bacteria, while MTA showed the lowest antimicrobial activity. Conclusion:The ascending sequence of microbial growth inhibition zones was as follows AH 26 > ZOE > MTA.
IntroductionCoagulase-negative staphylococci (CoNS) are normal inhabitants of human skin and mucous membranes. However, CoNS represent one of the major nosocomial pathogens, especially in immunocompromised patients. The increasing incidence of CoNS and mainly methicillin-resistant strains underlines the need for an accurate identification of Staphylococcus isolates at the species level. Analysis of the tuf gene proved to be an accurate tool for the species identification of CoNS. The aims of this study were to identify the CoNS species by tuf gene-based polymerase chain reaction method and sequencing, and to determine the frequency of CoNS clinical isolates resistant to methicillin (MRCoNS) and other antibiotics.MethodsA total of 200 staphylococci isolates were collected from various clinical samples. Phenotyping methods were used for initial identification followed by polymerase chain reaction amplification of tuf gene with subsequent sequencing. The phylogenetic relationships among species were analyzed using the neighbor-joining method based on the partial gene sequence of tuf. Microbroth dilution test was used for screening methicillin resistance, and disk diffusion susceptibility testing was performed for evaluation of antibiotic resistance among the isolates.ResultsIn the present study, 125 isolates were identified as CoNS; among them, Staphylococcus epidermidis 54(43.2%) and Staphylococcus haemolyticus 50 (40.0%) were demonstrated as the most prevalent species. Resistance to methicillin was detected in 54.4% of the CoNS based on microbroth dilution method. In disk diffusion susceptibility testing, the greatest resistance of CoNS was demonstrated for cefoxitin (65.4%), cotrimethoxazole (54.4%), and clindamycin (49.6%), while daptomycin (87.2%) and linezolid (83.2%) showed the greatest effectiveness for CoNS isolates.ConclusionOur results confirmed the predominance of S. epidermidis and S. haemolyticus among CoNS isolates. The high prevalence of MRCoNS strains is a serious concern and strongly suggests the need for control program measures in our hospitals in order to reduce MRCoNS infections, especially in immunocompromised patients.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.