Zali, M. R. | bioRxiv Science

bioRxiv2019

High prevalence of antibiotic resistance in Helicobacter pylori isolates from Iran: importance of functional and mutational analysis of resistance genes and virulence genotyping

The high prevalence of antibiotic resistance in Helicobacter pylori has become a great challenge in Iran. The genetic mutations that contribute to the resistance have yet to be precisely identified. This study aimed to investigate the prevalence of antibiotic resistance and virulence markers in Iranian H. pylori isolates and to analyze if there is any association between resistance and genotype. Antibiotic susceptibility patterns of 33 H. pylori isolates were investigated against metronidazole, clarithromycin, amoxicillin, rifampicin, ciprofloxacin, levofloxacin and tetracycline by the agar dilution method. The frxA, rdxA, gyrA, gyrB and 23S rRNA genes of the isolates were sequenced. The virulence genotypes were also determined using PCR. Metronidazole resistance was present in 81.8% of the isolates, followed by clarithromycin (36.4%), ciprofloxacin (36.4%), amoxicillin (30.3%), rifampicin (30.3%), levofloxacin (27.3%) and tetracycline (6.1%). Most of the metronidazole-resistant isolates carried frameshift mutations in both frxA and rdxA genes, and premature termination was occurred in positions Q5Stop and Q50Stop, respectively. Amino acid substitutions M191I, G208E, and V199A were predominantly found in gyrA gene of fluoroquinolone-resistant isolates. A2143G and C2195T mutations of 23S rRNA were found in four isolates. Interestingly, significant associations were demonstrated between intact cagPAI and resistance to rifampicin (P = 0.027), and between susceptibility to amoxicillin and cagPAI intactness (P = 0.016). The prevalence of H. pylori antibiotic resistance is high in our region, particularly that of metronidazole, clarithromycin, ciprofloxacin and multidrug resistance. Occurrence of mutations in resistance genes were involved in the development of resistance, especially in less virulent isolates.

microbiology↗

bioRxiv2018

Bayesian adjustment for trend of colorectal cancer incidence in misclassified registering across Iranian provinces

One of the problems in cancer registry of developing countries is misclassification error. This error leads to overestimation and underestimation of cancer rate in different provinces. The aim of this study is to use Bayesian method to correct for misclassification in registering cancer incidence in neighboring provinces of Iran. Incidence data of colorectal cancer were extracted from Iranian annual of national cancer registration reports 2005 to 2008 And Eighteen of the thirty Iranian provinces were selected to enter the Bayesian model and to correct their misclassification. Always a province with appropriate medical facilities is comparable to its neighbor or neighbors. Between years of 2005 and 2008, on the average, 28% misclassification was estimated between the province of East Azarbaijan and West Azarbayjan, 56% between the province of Fars and Hormozgan, 43% between the province of Isfahan and Charmahal and Bakhtyari, 46% between the province of Isfahan and Lorestan, 58% between the province of Razavi Khorasan and North Khorasan, 50% between the province of Razavi Khorasan and South Khorasan, 74% between the province of Razavi Khorasan and Sistan and Balochestan, 43% between the province of Mazandaran and Golestan, 37% between the province of Tehran and Qazvin, 45% between the province of Tehran and Markazi, 42% between the province of Tehran and Qom, 47% between the province of Tehran and Zanjan. Correcting the regional misclassification and obtaining the correct rates of cancer incidence in different regions is necessary for making cancer control and prevention programs and in healthcare resource allocation.

epidemiology↗