Resistance-Gene Cassettes Associated With Salmonella enterica Genotypes

In silico characteristics for re-emerging possibility of Vibrio cholerae genotypes in Iran

Epidemic cholera has been registered several times within recent years in Iran. The dominant genotype was Ogawa until 2011, but this gradually changed to Inaba. However, in 2015, the re-appearance of a previous Ogawa genotype was detected by the Iranian CDC. This raised worries because no evidence was found for its origin abroad. The aim of the present study was to identify clearly the source of this outbreak. Pulsed field gel electrophoresis (PFGE) was used to compare the recently detected Vibrio cholerae strains with those isolated from 2011 to 2015. We selected one strain per PFGE pattern, and compared the distinct patterns. BioNumerics software was applied, which enables interpretation of phenotypic and genotypic differences. In total, we studied 33 V. cholerae Ogawa strains. Analysis showed that strains could be discriminated on the basis of annual clusters but with a similarity of more than 80%. The highest homology was observed among those isolated each year from 2011 to 2014. In contrast, strains isolated in 2015 also exhibited close correlation with each other but were located in distinct clusters. The analysis also proved genetic variations among some strains. All 2015 strains showed differences with regard to previous genotypes despite some similarities. The new genotypes were probably imported into Iran from neighbouring countries such as Iraq by travellers or contaminated food sources since 2015. However, more investigations are required to identify the exact source of the 2015 outbreak.

Molecular Epidemiology and Surveillance Program in Iran: Present Status and Future Prospect

Background and aims: The food-borne pathogens appear to be a reemerging and endless problem in the human community all over the world. Hence, all the outbreaks should be constantly monitored for pandemic strains and new mutant genotypes. The main purpose behind the molecular typing methods is the comparison of bacterial isolates to obtain genomic relatedness regarding epidemiological aspects. One of these methods that have been recently reported in several Iranian studies is pulse field gel electrophoresis (PFGE). The aim of this study was to review and discuss the current situation and difficulties, and also the necessity of planning for tracking new and re-emerging food-borne pathogens investigating PFGE future status in Iran as a molecular epidemiology tool. Results: According to the results, it was found that this technique requires high investments in both fields of required equipment and software some of which are now available in many research centers. In addition, investigations on various medical search engines revealed that hundreds of studies have been published after 2010 in Iran. These reports indicated that most of these studies were not able to provide an efficient epidemiological analysis of the outbreaks and prevention of future events, except for a few exceptions. Conclusion: A review of the capabilities available in the country in this respect led the researchers to infer that it may be the best time to make a plan on the existence of a general network of collecting and analyzing the results, as well as integrating them into the international databases. It is expected that these responsible institutions to make the required design in this field.

Heterogeneity of Multidrug-Resistant Salmonella enterica Isolates with Increasing Frequency of Resistance to Ciprofloxacin During a 4-Year Period in Iran

BACKGROUND

The study was conducted to assess the trend of antimicrobial resistance among Salmonella enterica strains during a period of 4 years and to compare the effectiveness of three genotyping methods, including flagellin polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP), enterobacterial repetitive intergenic consensus (ERIC)-PCR, and pulsed-field gel electrophoresis (PFGE), and to determine the most efficient method for S. enterica genotyping.

METHODS AND RESULTS

About 50 S. enterica isolates were isolated from 5,064 stool samples. All of the isolates harbored fliC gene, 29 of which (58%) showed diphasic characteristic with a fliC⁺/fljB⁺ genotype. Simpson diversity index (Di) for RFLP analysis of fliC and fljB genes was calculated as 0.71 and 0.82, respectively. Strains were differentiated into 40 ERIC genotypes and 27 pulsotypes. All isolates with identical pulsotypes belonged to common serogroups which depict their correlation in a good manner. The Di calculated for ERIC-PCR and PFGE analysis was 0.99 and 0.94, respectively. The frequency of multidrug resistance (MDR) was dramatically increased from 25% in 2009-2010 to 63% in 2011-2012 with the emergence of 10% ciprofloxacin resistance in the latter period.

CONCLUSION

About 44% increase in MDR phenotype among S. enterica isolates during a 4-year period and concomitant appearance of ciprofloxacin resistance is a traumatic situation for health professionals in Iran. PFGE profiles offered a satisfactory discriminatory power, which was positively correlated with S. enterica serogrouping. The current study marks the superiority of PFGE method over other conventional molecular techniques in epidemiological investigations; however, their limitations need to be addressed for further refinement.