Phenotypic and Molecular Characteristics of Escherichia coli Isolated from Aquatic Environment of Bangladesh

Abstract

Diarrhea continues to be one of the most common causes of morbidity and mortality among infants and children in the developing world (45). Escherichia coli, a gram-negative bacillus, is among the normal microbial flora that exists in the healthy human intestine (11). However, some of the E. coli serotypes cause diarrhea or food poisoning, mostly in infants and children. Following the recognition of certain pathotypes of E. coli as human diarrheagenic pathogens and the establishment of a serotyping system, serovars associated with diarrheal diseases have gained increasing interest (47). At coli strains revealed 47%, 30%, and 6% to belong to EPEC, ETEC, and EHEC pathotypes, respectively. The majority of the 160 strains tested were resistant to commonly used antimicrobial agents. Plasmid profiling showed a total of 17 different bands ranging from 1.3 to 40 kb. However, 35% of the strains did not contain any detectable plasmid, implying no correlation between plasmid and drug resistance. Although virulence gene profiling revealed 97 (61%) of the strains to harbor the gene encoding heat-stable enterotoxin (ST), 2 for the gene encoding Shiga toxin (Stx), and none for the gene for heat-labile enterotoxin (LT), serotype-based pathotyping of E. coli was not fully supported by this gene profiling. A dendrogram derived from the PFGE patterns of 22 strains of three predominant serogroups indicated two major clusters, one containing mainly serogroup O55 and the other O8. Three strains of identical PFGE profiles belonging to serogroup O55 were isolated from three distinct areas, which may be of epidemiological significance. Finally, it may be concluded that serotype-based pathotyping may be useful for E. coli strains of clinical origin; however, it is not precise enough for reliably identifying environmental strains as diarrheagenic. Phenotypic and Molecular Characteristics of

Multi-Drug Resistance Pattern of Escherichia coli Isolated from Hospital Effluent and Determination of Tetracycline Resistance Gene

“…Interestingly, aminoglycosides (gentamycin and neomycin) were highest sensitive in present study which was contradictory to the findings of Katouli et al (2012). But it showed close agreement with the findings of Ahaduzzaman et al (2014) and Alam et al (2006).…”

“…The study revealed that the percentage of E. coli in untreated hospital effluent was 100%. Many of the previous studies indicated that the prevalence of E. coli varies widely based on type of environmental samples and it was ranging from 44% to 100% in different environmental samples such as sewage, sludge, recreational water, dairy surface water and ground water (Anastasi et al, 2010;Li et al, 2014;Blaak et al, 2014).…”

Phenotypic and Genotypic Analysis of Enterotoxigenic Escherichia coli in Samples Obtained from Egyptian Children Presenting to Referral Hospitals

“…was identified. The observation of severe diarrhea markers (e.g., dehydration, the number of stools per day, and the volume of stool) in some study children may be attributed to the presence of strains that are more virulent because of the presence of additional virulence attributes (4). On the other hand, the elaboration of severe diarrhea symptoms may also be the result of an immunologically naive child's first encounter with an ETEC pathogen.…”

Comparison between O Serotyping Method and Multiplex Real-Time PCR To Identify DiarrheagenicEscherichia coliin Taiwan

“…The DEC reference strains used as positive controls in this study were CCRC 15376 (an EHEC isolate) containing eae, stx 1 Serotyping O and H antigens. The O serotyping method was used to identify the isolates belonging to O serogroups defined commercially.…”

“…The serotype-based method has been widely used in clinical laboratories with commercial antisera or antisera prepared in-house. Although several serotypes are predominantly found by the use of serotyping and correlated with specific categories of DEC, not all of the isolates belonging to those serotypes are truly pathogenic (1,7,17). In addition, serotypic markers themselves do not confer pathogenicity but sometimes correlate very closely with pathogenicity.…”