Associations between seroprevalence of Helicobacter pylori and ABO/rhesus blood group antigens in healthy blood donors in southwest Iran.

OBJECTIVE: To investigate correlations between ABO/rhesus (Rh) blood group antigens and anti-Helicobacter pylori and anti-cytotoxin-associated gene A (CagA) seropositivity in blood donors. METHODS: A total of 311 blood donors were enrolled. ABO and Rh blood groups were determined using hemagglutination tests. Specific anti-H. pylori IgG and anti-CagA IgG antibodies in sera were quantitated by enzyme-linked immunosorbent assay. Correlations between blood groups and anti-H. pylori and anti-CagA seropositivity were evaluated using the Chi-square test. RESULTS: O+ was the most frequent blood type (38%, n = 118). Anti-H. pylori IgG seropositivity was observed in 240 (77.2%) blood donors, while anti-CagA IgG seropositivity was observed in 132 (42.5%) blood donors. Although seropositivity rates for both anti-H. pylori and anti-CagA IgG were higher in individuals with blood type O, no statistically significant associations were observed between seropositivity and any ABO/Rh blood groups. CONCLUSION: Individuals with blood type O may have higher rates of H. pylori seropositivity.

Prevalence of Extended-Spectrum Beta-Lactamase-Producing Enterobacteriaceae Causing Bloodstream Infections in Cancer Patients from Southwest of Iran.

INTRODUCTION: This study aimed to evaluate the frequency rate of extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE) causing bloodstream infections (BSIs) in cancer patients referred to one of the major referral hospitals in Ahvaz city, southwest Iran. MATERIALS AND METHODS: In this study, 1700 blood cultures were collected from 610 cancer patients suspected to have BSI from October 2016 to August 2017 referred to the Shafa cancer hospital, Ahvaz, southwest of Iran. The blood culture bottles were incubated aerobically at 35-37ºC for 24 hours and then sub-cultured on routine microbiology culture media. The bacterial colonies were identified using standard tests. The antibiotic susceptibility testing was achieved by the disc-diffusion method. The phenotypic detection of ESBLs was carried out by the combination disc-diffusion test (CDDT). Finally, the polymerase chain reaction (PCR) was performed to investigate the presence of bla TEM, bla CTX, bla SHV, and bla PER genes. RESULTS: The prevalence of BSI in cancer patients was 16.4% (100/610). Gram-negative rods with rate of 74% (74/100) were the most prevalent bacteria. The frequency of Enterobacteriaceae family was 21% including Escherichia coli (n: 8), Klebsiella pneumoniae (n: 6), Enterobacter spp. (n: 5), Citrobacter freundii (n: 1), and Serratia marcescens (n: 1). All isolates were multidrug-resistant (resistance to three or more antibiotics). The results of CDDT showed that 42.8% (9/21) of Enterobacteriaceae isolates had a positive ESBL test of which 100% (9/9) indicated positive band for at least one of the ESBL genes by PCR method. The bla CTX-M and bla TEM genes were detected in 38% (8/21) and 23.8% (5/21) of isolates, respectively, while the bla SHV and bla PER were not detected in any isolates. CONCLUSION: Based on the results, surveillance, and antibiotic stewardship programs should be implemented for cancer patients to prevent the spread of more ESBL-PE that have limited therapeutically choices.

Comparison Of drrA And drrB Efflux Pump Genes Expression In Drug-Susceptible And -Resistant Mycobacterium tuberculosis Strains Isolated From Tuberculosis Patients In Iran.

BACKGROUND: Among different resistance mechanisms in Mycobacterium tuberculosis (MTB), efflux pumps may have a role in drug-resistance property of MTB. So, the aim of this study was to compare the relative overexpression of two important efflux pump genes, drrA and drrB, among MTB isolates from TB patients. METHODS: A total of 37 clinical isolates of confirmed MTB isolates were analyzed. Drug susceptibility testing (DST) was performed using the conventional proportional method. Real-time semiquantitative PCR profiling of the efflux pump genes of drrA and drrB was performed for clinical isolates. The receiver operating curve (ROC) analysis for differentiation of resistant from susceptible isolates on the basis of efflux pump expression fold changes was also performed. RESULTS: According to DST, 16 rifampin (RIF) monoresistant, 3 isoniazid (INH) monoresistant, 5 multidrug-resistant (MDR) and 13 pan-susceptible isolates of MTB were evaluated for gene expression. The highest values of drrA and drrB gene expression fold changes were seen in MDR isolates, which were significant in comparison with susceptible isolates and H37Rv reference strain. By using comparative ROC analysis, the obtained cutoff point for drrA and drrB gene overexpression was the folds of >1.6 and >2.3, respectively. CONCLUSION: The results of the present study confirm the role of DrrA-DrrB efflux pump in antibiotic resistance in clinical MTB isolates. As the large number of efflux pumps are located in the cell envelope of MTB, we cannot correlate a single efflux pump overexpression to the drug-resistance phenotype, unless all the pumps simultaneously investigated.

Characterization of the most common embCAB gene mutations associated with ethambutol resistance in Mycobacterium tuberculosis isolates from Iran.

INTRODUCTION: Ethambutol (Emb) is one of the first-line drugs in the standard combination therapy for tuberculosis; however, due to the rapid increase in Emb resistance among clinical isolates of Mycobacterium tuberculosis (MTB), early detection of Emb resistance is desirable. As the embCAB operon is considered involved in resistance to Emb, this study aimed to analyze the most common mutations within the embCAB operon among MTB isolates from Iran to find any correlations of these mutations with Emb resistance. METHODS: A total of 307 clinical isolates of MTB were screened for Emb resistance by phenotypic drug-susceptibility testing. PCR amplification was performed on extracted DNA from all Emb-resistant and randomly selected Emb-susceptible isolates using sets of primers for various gene loci of embC, embA, and embB, followed by sequencing for the detection of most common alterations. RESULTS: In total, ten isolates showed resistance to Emb by phenotypic susceptibility testing (3.25%). The mutation rate in ten Emb-resistant MTB strains was 20% (n=2), comprising one mutation in embB (10%), at codon 306 Met-Val and one in embC (10%) at codon 270 Thr-Ile. A nonsynonymous mutation in the embA gene in one of the randomly selected Emb-susceptible isolates located in codon 330 Leu-Leu was also noticed. CONCLUSION: The majority of our Emb-resistant isolates (n=8, 80%) did not demonstrate the sequences investigated within the embCAB operon. As such, these mutations solely are insufficient for the development of complete resistance to Emb in MTB isolates. Additional mechanisms of resistance other than mutations in these sequences studied within the embCAB operon should also be considered.

Molecular detection of rifampin, isoniazid, and ofloxacin resistance in Iranian isolates of Mycobacterium tuberculosis by high-resolution melting analysis.

BACKGROUND: The emergence of drug resistance among Mycobacterium tuberculosis (MTB) strains is a serious health concern worldwide. The development of rapid molecular diagnostic methods in recent years has a significant impact on the early detection of resistance to major anti-TB drugs in MTB isolates, which helps in employing appropriate treatment regimen and prevents the spread of drug-resistant strains. This study was designed to evaluate the efficacy of real-time PCR and high-resolution melting (HRM) curve analysis for the determination of resistance to rifampin (RIF), isoniazid (INH), and ofloxacin (OFX) in MTB isolates and to investigate their resistance-related mutations. METHODS: HRM analysis was performed to screen 52 (32 drug-resistant and 20 fully susceptible) MTB clinical isolates for mutations in rpoB, katG, mab-inhA, and gyrA genes. The HRM results were then confirmed by DNA sequencing. RESULTS: In total, 32 phenotypically resistant isolates, comprising 18 RIF-, 16 INH-, and five OFX- resistant strains, were investigated. HRM analysis successfully identified 15 out of 18 mutations in rpoB, 14 out of 16 mutations in katG and mab-inhA, and four out of five mutations in gyrA conferring resistance to RIF, INH, and OFX, respectively. The obtained sensitivity and specificity, respectively, for HRM in comparison with phenotypic susceptibility testing were found to be 83.3% and 100% for RIF, 87.5% and 100% for INH, and 80% and 100% for OFX. In five resistant strains (12.8%), no mutation was detected by using HRM and DNA sequencing. CONCLUSION: HRM assay is a rapid, accurate, and cost-effective method possessing high sensitivity and specificity for the determination of antibiotic resistance among MTB clinical isolates and screening of their associated mutations. This method can generate results in a shorter period of time than taken by the phenotypic susceptibility testing and also allows for timely treatment and prevention of the emergence of possible MDR strains.

Antibiotic resistance pattern and molecular characterization of extended-spectrum ß-lactamase producing enteroaggregative Escherichia coli isolates in children from southwest Iran.

INTRODUCTION: Enteroaggregative Escherichia coli (EAEC) has been implicated as an emerging cause of traveler's diarrhea, persistent diarrhea among children, and immunocompromised patients. The present study aimed to investigate the prevalence of antibiotic resistance, extendedspectrum ß-lactamase (ESBL) production, and virulence factors of EAEC isolates obtained from Iranian children suffered from diarrhea. MATERIALS AND METHODS: In this cross-sectional study, from March 2015 to February 2016, 32 EAEC isolates were collected from fecal samples of children aged <12 years with diarrhea in southwest of Iran. All EAEC isolates identified using phenotypic and molecular methods and the cell line adhesion assay. Antimicrobial susceptibility testing was determined using disk diffusion method. The presence of virulence factors and ESBL resistance genes were determined by polymerase chain reaction. RESULTS: Overall, 28.1% (9/32) of the isolates were positive for at least one of virulence genes. The most frequent gene was aap with a frequency of 96.9%. Neither aafA nor aggA gene was detected among all of the EAEC isolates. Antimicrobial susceptibility testing revealed the highest resistance rate to ampicillin (100%) and co-trimoxazole (100%), followed by ceftriaxone (81.3%). Further analysis revealed that the rate of ESBLs-producing isolates was 71.9% (23/32). Polymerase chain reaction screening revealed that 87.5% and 65.5% of EAEC isolates were positive for blaTEM and blaCTX-M genes, respectively, and 17 (53.1%) of isolates contained both blaTEM and blaCTX-M genes. CONCLUSION: The high detection rate of ESBL-producing EAEC isolates accompanied with virulence genes highlights a need to restrict infection control policies in order to prevent further dissemination of the resistant and virulent EAEC strains.

Assessing the role of the RND efflux pump in metronidazole resistance of Helicobacter pylori by RT-PCR assay.

INTRODUCTION: Metronidazole is a significant antibiotic used for eradication of Helicobacter pylori infections and it is of notice that metronidazole-resistant clinical isolates have been found in high rates worldwide. While the RND family of efflux pumps plays a central role in drug resistance among Gram-negative bacteria, this is questionable for H. pylori. METHODOLOGY: To understand whether TolC homologues of RND pumps contribute to metronidazole resistance in H. pylori isolates, expression of four TolC homologous genes of five resistant clinical isolates exposed to varying concentrations of metronidazole were evaluated by RT-PCR and transcriptional analysis. RESULTS: The results indicate that excess amounts of metronidazole are able to increase the expression level of these genes at the transcriptional stage. CONCLUSIONS: Therefore, it may be hypothesized that use of metronidazole in H. pyori infection can induce metronidazole resistance. Furthermore, the RND family of efflux pumps may contribute to metronidazole resistance in clinical isolates of H. pylori.