Abstract
Objectives: Developing countries like South Africa are still faced with numerous challenges such as poor environmental sanitation, lack of clean drinking water and inadequate hygiene which have contributed largely to diarrheal infections and deaths in children. This study was aimed at investigating the prevalence of pathotypes, antimicrobial resistance and drug resistance determinants among Escherichia coli (E. coli) isolates from diarrhea stool samples within Buffalo City Municipality, Eastern Cape, South Africa. Methods: Fresh diarrheal stool samples were collected from 140 patients attending public health centres within the Municipality and presumptive E. coli isolates were obtained from the stool samples using E. coli chromogenic agar while PCR amplification methods were used to confirm the presumptive isolates as well as delineate them into pathotypes based on the presence of certain virulence genes. In addition, antimicrobial susceptibility and screening of some of the antimicrobial resistant determinants were performed on all the confirmed isolates. Results: A total of 394 presumptive E. coli isolates from 140 diarrhea stool samples were subjected to polymerase chain reaction amplification, of which 265 were confirmed positive as E. coli. Pathotypes delineation of the positive E. coli isolates validated the presence of ETEC 106 (40%), EAEC 48 (18%), DAEC 37 (14%), and EPEC 31 (11%) while no EIEC pathotype was detected. All E. coli isolates exhibited maximum susceptibility to gentamicin (95%), amikacin (91%), nitrofurantoin (91%), meropenem (90%), chloramphenicol (91%) norfloxacin (84%) and imipenem (83%). However, the isolates showed multidrug resistance to penicillin G, ampicillin, trimethoprim, tetracycline, doxycycline, and erythromycin, with over 71% of the isolates resistant to the drugs. The prevalence and distribution of the five resistance determinants assessed were as follow; sulphonamides; sulII (12%), beta lactams; [ampC (22%); blaTEM, (25%)], and tetracyclines (tetA (35%). Conclusion: The results from this study suggest the probable involvement of E. coli pathotypes as an etiologic agent of diarrhea in the study area and revealed high levels of multidrug resistance among the isolates, which could be a major health burden.
Highlights
There are six fundamentally recognized strains of diarrheagenic E. coli (DEC) that are related to diarrhea based on their different clinical features, virulence factors and serotypes grouping and they are: entero-aggregative E. coli (EAEC), enteroinvasive E. coli (EIEC), enterohemorrhagic E. coli (EHEC), enteropathogenic E. coli (EPEC), diffusely adherent E. coli (DAEC), and enterotoxigenic E. coli (ETEC) [12]
The results showed that resistance against penicillin G was 99% while 88% were resistant to ampicillin, trimethoprim (84%), tetracycline (83%), doxycycline (82%), and erythromycin (71%)
EIEC and EHEC strains were not detected among the isolates, which signifies that their role in diarrhea is limited in Buffalo City
Summary
There are six fundamentally recognized strains of diarrheagenic E. coli (DEC) that are related to diarrhea based on their different clinical features, virulence factors and serotypes grouping and they are: entero-aggregative E. coli (EAEC), enteroinvasive E. coli (EIEC), enterohemorrhagic E. coli (EHEC), enteropathogenic E. coli (EPEC), diffusely adherent E. coli (DAEC), and enterotoxigenic E. coli (ETEC) [12]. These pathotypes are categorised based on their virulence factors and the mechanisms of pathogenicity in the human gut like in diarrhea cases [12]. Other older antibiotics such as the penicillin and its derivatives, chloramphenicol, tetracycline, colistin, clindamycin, daptomycin, fosfomycin, nitrofurantoin, and tigecyclne are used in the management of bacterial infectious diseases
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