Prevalence of EHEC O157:H7 in patients with diarrhoea in Lagos, Nigeria

Prevalence, antibiotic resistance, and virulence gene profile of Escherichia coli strains shared between food and other sources in Africa: A systematic review

Background and Aim

Foodborne diseases caused by Escherichia coli are prevalent globally. Treatment is challenging due to antibiotic resistance in bacteria, except for foodborne infections due to Shiga toxin-producing E. coli, for which treatment is symptomatic. Several studies have been conducted in Africa on antibiotic resistance of E. coli isolated from several sources. The prevalence and distribution of resistant pathogenic E. coli isolated from food, human, and animal sources and environmental samples and their virulence gene profiles were systematically reviewed.

Materials and Methods

Bibliographic searches were performed using four databases. Research articles published between 2000 and 2022 on antibiotic susceptibility and virulence gene profile of E. coli isolated from food and other sources were selected.

Results

In total, 64 articles were selected from 14 African countries: 45% of the studies were conducted on food, 34% on animal samples, 21% on human disease surveillance, and 13% on environmental samples. According to these studies, E. coli is resistant to ~50 antimicrobial agents, multidrug-resistant, and can transmit at least 37 types of virulence genes. Polymerase chain reaction was used to characterize E. coli and determine virulence genes.

Conclusion

A significant variation in epidemiological data was noticed within countries, authors, and sources (settings). These results can be used as an updated database for monitoring E. coli resistance in Africa. More studies using state-of-the-art equipment are needed to determine all resistance and virulence genes in pathogenic E. coli isolated in Africa.

Prevalence of integrons in multidrug-resistant Escherichia coli isolates from waters and vegetables in Nsukka and Enugu, Southeast Nigeria

Irrigation of fresh produce with poorly treated wastewater or contaminated freshwater sources can lead to produce contamination and foodborne illnesses, as well as the dissemination of antimicrobial resistance determinants. In this study, we assessed the presence of integrons in multidrug-resistant Escherichia coli isolated from the University of Nigeria, Nsukka Wastewater Treatment Plant effluent, tap water, vegetables from irrigated gardens and vegetables sold in selected markets from Nsukka and Enugu cities. E. coli was isolated following standard laboratory procedure and confirmed through beta-glucuronidase (uidA)-targeted polymerase chain reaction (PCR). The antibiotic resistance of the isolates was determined using Bauer-Kirby disk diffusion assay, and multiplex PCR was used to determine the presence of class 1 and 2 integrons. Our result revealed a total of 188 E. coli isolates from WWTP effluent (n = 41), tap water (n = 10) and vegetables from greenhouse (n = 46), farms (n = 55) and market (n = 36). Multidrug resistance was detected in all the isolates, ranging from three-drug resistance in a single isolate to 7-drug resistance patterns in two different isolates. Of the total isolates, class 1 integrons were abundantly detected in 175 (93.1%) and class 2 in 5 (2.7%). All the class 2 integrons were found in isolates that were positive for class 1. The abundance of multidrug-resistant E. coli harbouring class 1 integrons in the effluent and vegetable samples is a potential public health risk. Therefore, the appropriate measures for the safe use of poorly treated wastewater for vegetable farm irrigation are required to be put in place to reduce the microbial load of the discharged effluent. Also, education of farmers and the community on the dangers of wastewater effluent-grown plants and proper methods for cleaning harvested vegetable is recommended.

The frequency of virulent genes and antimicrobial resistance patterns of diarrheagenic Escherichia coli isolated from stools of children presenting with diarrhea in a tertiary hospital in Abakaliki, Nigeria

Aim: This study was aimed to determine the virulent genes and antibiotic resistance patterns among circulating diarrheagenic Escherichia coli (DEC) pathotypes in a tertiary care health center in east of Nigeria. Materials and Methods: Diarrheal stool samples were obtained from 80 children under 5 years and E. coli was isolated and identified using standard biochemical and molecular methods. Multiplex polymerase chain reaction (PCR) was used to detect eight virulent genes of DEC. Disk diffusion method was used to determine the antibiotic susceptibility of DEC. Results: DEC infection was observed in 54 (68%) children among which ial gene for enteroinvasive E. coli (EIEC) (40% [n=22]) was commonly detected followed by eltA/eltB for enterotoxigenic E. coli (ETEC) (30% [n=16]), pCVD for enteroaggregative E. coli (EAEC) (20% [n=11]), and eaeA/bfpA for typical enteropathogenic E. coli (EPEC) (10% [n=5]). The DEC isolates phenotypically exhibited resistance for ampicillin (AMP) (44 [81%]), followed by ciprofloxacin (CIP)/ levofloxacin (LEV) (28 [52%]), cefoxitin (FOX) (11 [20%]), and amoxicillin-clavulanic acid (AMC) (6 [11%]). About 60% isolates of stable toxins-ETEC were resistant to AMC, CIP, and LEV while all the labile toxin-ETEC exhibited resistance to AMP. About 60% (n=6) resistance were seen in EAEC against ampicillin, AMC, FOX, CIP, and LEV. In EIEC, all the isolates (n=22) were resistant to AMP while 50% (n=11) were resistant to both CIP and LEV. All EPEC (n=5) were resistant to AMP, FOX, CIP, and LEV. Conclusion: High frequency of virulent ial and eltA/eltB genes for EIEC and ETEC, respectively, suggests that they are the primary etiological agents of diarrhea in children among DEC pathotypes. Resistance of DEC to more than two classes of antibiotics indicate possible emergence of multidrug resistance.

A probabilistic assessment of the contribution of wastewater-irrigated lettuce to Escherichia coli O157:H7 infection risk and disease burden in Kumasi, Ghana

Wastewater use for vegetable production is widespread across the cities of many developing countries. Studies on the microbial health risks associated with the practice have largely depended on faecal indicator organisms with potential underestimation or overestimation of the microbial health risks and disease burdens. This study assessed the Escherichia coli O157:H7 infection risk and diarrhoeal disease burden measured in disability-adjusted life years (DALYs) associated with the consumption of wastewater-irrigated lettuce in Kumasi, Ghana using data on E. coli O157:H7 in ready-to-harvest, wastewater-irrigated lettuce. Two exposure scenarios - best case and worst case - associated with a single consumption of wastewater-irrigated lettuce were assessed. The assessment revealed wastewater-irrigated lettuce is contributing to the transmission of E. coli O157:H7 in Kumasi, Ghana. The mean E. coli O157:H7 infection risk and DALYs in the wet and dry seasons, irrespective of the exposure scenario, were above the World Health Organization tolerable daily infection risk of 2.7 × 10⁻⁷ per person per day and 10⁻⁶ DALYs per person per year. It is recommended that legislation with clear monitoring indicators and penalties is implemented to ensure that farmers and food sellers fully implement risk mitigating measures.

Multidrug resistance and plasmid patterns of Escherichia coli O157 and other E. coli Isolated from diarrhoeal stools and surface waters from some selected sources in Zaria, Nigeria

We have assessed the prevalence of Escherichia coli O157 in diarrhoeal patients and surface waters from some selected sources in Zaria (Nigeria), evaluating the antibiotic susceptibility and plasmid profiles of 184 E. coli isolates, obtained from 228 water samples and 112 diarrhoeal stool specimens (collected from children aged <15 years), using standard methods. The detection rate of E. coli O157 in surface waters was 2.2% and its prevalence in children with diarrhoea was 5.4%. The most active antibiotics were gentamicin, chloramphenicol and fluoroquinolones. Seventy-nine (42.9%) of 184 E. coli isolates were resistant to four or more antibiotics. Multidrug resistance (MDR) was higher amongst aquatic isolates than the clinical isolates. Out of 35 MDR isolates (20 of which were O157 strains), 22 (62.9%) harboured plasmids all of which were no less than 2.1 kb in size. Amongst the 20 E. coli O157 strains, only seven (35.0%) contained multiple plasmids. An aquatic O157 isolate containing two plasmids was resistant to seven drugs, including ampicillin, cefuroxime, ciprofloxacin, cotrimoxazole, nalidixic acid, nitrofurantoin and tetracycline. Loss of plasmid correlated with loss of resistance to antibiotics in cured (mutant) strains selected in tetracycline (50 μg/mL)-nutrient agar plates. Our findings revealed that plasmids were prevalent in both the aquatic and clinical isolates, and suggest that the observed MDR is plasmid-mediated. The occurrence of plasmid-mediated multidrug resistant E. coli O157 in surface waters used as sources for drinking, recreation and fresh produce irrigation heightens public health concern.

Outbreaks where food workers have been implicated in the spread of foodborne disease. Part 4. Infective doses and pathogen carriage

In this article, the fourth in a series reviewing the role of food workers in foodborne outbreaks, background information on the presence of enteric pathogens in the community, the numbers of organisms required to initiate an infection, and the length of carriage are presented. Although workers have been implicated in outbreaks, they were not always aware of their infections, either because they were in the prodromic phase before symptoms began or because they were asymptomatic carriers. Pathogens of fecal, nose or throat, and skin origin are most likely to be transmitted by the hands, highlighting the need for effective hand hygiene and other barriers to pathogen contamination, such as no bare hand contact with ready-to-eat food. The pathogens most likely to be transmitted by food workers are norovirus, hepatitis A virus, Salmonella, Shigella, and Staphylococcus aureus. However, other pathogens have been implicated in worker-associated outbreaks or have the potential to be implicated. In this study, the likelihood of pathogen involvement in foodborne outbreaks where infected workers have been implicated was examined, based on infectious dose, carriage rate in the community, duration of illness, and length of pathogen excretion. Infectious dose estimates are based on volunteer studies (mostly early experiments) or data from outbreaks. Although there is considerable uncertainty associated with these data, some pathogens appear to be able to infect at doses as low as 1 to 100 units, including viruses, parasites, and some bacteria. Lengthy postsymptomatic shedding periods and excretion by asymptomatic individuals of many enteric pathogens is an important issue for the hygienic management of food workers.

Prevalence of Escherichia coli O157:H7 among diarrhoeic HIV/AIDS patients in the Eastern Cape Province-South Africa

This study investigated the prevalence of Escherichia coli O157:H7 in the stool of confirmed and non-confirmed diarrhoeic HIV/AIDS patients. Escherichia coli O157:H7 was isolated by culture-based and immunomagnetic separation from three hundred and sixty stool swabs. Identification was by conventional IMViC, 20E API and molecular techniques. Confirmed and non-confirmed diarrhoeic HIV/AIDS patients had 56.5% (74/131) and 43.5% (57/131) respectively of E. coli O157:H7. Molecular results indicated that the prevalence of E. coli O157:H7 was 12.16% (9/74) and 8.77% (5/57) from stool swabs of confirmed and non-confirmed diarrhoeic HIV/AIDS patients. Antimicrobial resistance was higher for E. coli O157:H7 isolates from stools of confirmed HIV/AIDS than it was for non-confirmed HIV/AIDS patients. Escherichia coli O157:H7 might be a silent cause of diarrhoea in HIV/AIDS patients. It is recommended that HIV/AIDS patients with diarrhoea should be screened for E. coli O157:H7 and surveillance programmes for these bacteria should be established in both urban and rural areas of South Africa.