Background: Escherichia coli O157 is an emerging foodborne pathogen of great public health concern. It has been associated with bloody diarrhoea, haemorrhagic colitis and haemolytic uremic syndrome in humans. Most human infections have been traced to cattle and the consumption of contaminated cattle products. In order to understand the risk associated with the consumption of cattle products, this study sought to investigate the prevalence and identify virulence genes in E. coli O157 from cattle in Cameroon. Method: A total of 512 rectal samples were obtained and analysed using conventional bacteriological methods (enrichment on modified Tryptone Soy Broth and selective plating on Cefixime-Tellurite Sorbitol Mac-Conkey Agar) for the isolation of E. coli O157. Presumptive E. coli O157 isolates were confirmed serologically using E. COLIPRO^TM O157 latex agglutination test and molecularly using PCR targeting the rfb gene in the isolates. Characterisation of the confirmed E. coli O157 strains was done by amplification of stx1, stx2, eaeA and hlyA virulence genes using both singleplex and multiplex PCR. Results: E. coli O157 was detected in 56 (10.9%) of the 512 samples examined. The presence of the virulence genes stx2, eaeA and hylA was demonstrated in 96.4% (54/56) of the isolates and stx1 in 40 (71.4%) of the 54. The isolates exhibited three genetic profiles (I-III) with I (stx1, stx2, eaeA and hlyA) being the most prevalent (40/56; 71.4%) while two isolates had none of the virulence genes tested. Conclusion: A proportion of cattle slaughtered in abattoirs in Buea are infected with pathogenic E. coli O157 and could be a potential source of human infections. We recommend proper animal food processing measures and proper hygiene be prescribed and implemented to reduce the risk of beef contamination.

Research papers on the pathogenesis, diagnosis, and treatment of infectious diseases

The growing global threat of antimicrobial resistance is reaching a crisis point as common bacterial infections, including those caused by pathogenic Neisseria species, are becoming increasingly untreatable. This is compelling the scientific community to search for new antimicrobial agents, taking advantage of computational mining and using whole genome sequences to discover natural products from the human microbiome with antibiotic effects. In this study, we investigated the crude extract from a Rothia dentocariosa strain with demonstrated antimicrobial activity against pathogenic Neisseria spp. by spot-on-lawn assay. The genomic DNA of the R. dentocariosa strain was sequenced, and bioinformatic evaluation was performed using antiSMASH and PRISM to search for biosynthetic gene clusters (BGCs). The crude extract with potential antimicrobial activity was run on Tricine-SDS-PAGE, and the putative peptides were characterised using liquid chromatography–tandem mass spectrometry (LC-MS). The crude extract inhibited the growth of the pathogenic Neisseria spp. Six BGCs were identified corresponding to non-ribosomal peptide synthases (NRPSs), polyketide synthases (PKSs), and ribosomally synthesised and post-translationally modified peptides. Three peptides were also identified corresponding to Actinorhodin polyketide putative beta-ketoacyl synthase 1. These findings serve as a useful reference to facilitate the research and development of NRPS and PKS as antimicrobial products against multidrug-resistant N. gonorrhoeae.

With increasing incidence of pathogenic Neisseria infections coupled with emerging resistance to antimicrobials, alternative approaches to limit the spread are sought. We investigated the inhibitory effect of oropharyngeal microbiota on the growth of N. gonorrhoeae and N. meningitidis and the impact of the essential oil-based mouthwash Listerine Cool Mint^® (Listerine). Oropharyngeal swabs from 64 men who have sex with men (n = 118) from a previous study (PReGo study) were analysed (ClinicalTrials.gov, NCT03881007). These included 64 baseline and 54 samples following three months of daily use of Listerine. Inhibition was confirmed by agar overlay assay, and inhibitory bacteria isolated using replica plating and identified using MALDI-TOF. The number of inhibitory isolates were compared before and after Listerine use. Thirty-one pharyngeal samples (26%) showed inhibitory activity against N. gonorrhoeae and/or N. meningitidis, and 62 inhibitory isolates were characterised. Fourteen species belonging to the genera Streptococci and Rothia were identified. More inhibitory isolates were observed following Listerine use compared to baseline, although this effect was not statistically significant (p = 0.073). This study isolated and identified inhibitory bacteria against pathogenic Neisseria spp. and established that daily Listerine use did not decrease their prevalence. These findings could provide a new approach for the prevention and treatment of pharyngeal Neisseria infections.

Background: Escherichia coli O157, a Shiga toxin-producing serotype of E. coli implicated in severe foodborne diseases, is a major public health concern worldwide. Most human infections are attributed to the consumption of infected beef and contaminated bovine products. The burden of E. coli O157 disease is compounded by the extensive use of antibiotics in the animal production line which might lead to the selection for antibiotic resistance. The aim of this study was to describe the antibiotic resistance patterns of E. coli O157 isolates from cattle in Cameroon. Methods: Fifty-six E. coli O157 isolates previously obtained were subjected to antibiotic susceptibility testing using the Kirby-Bauer disc diffusion technique. Polymerase chain reaction was used to screen the isolates for the presence of eight antibiotic resistance genes. Results: Antibiotics susceptibility profiling of the 56 isolates showed ofloxacin was the most active drug (55; 98.2%), followed by gentamicin (51; 91.1%). Ampicillin was the least active drug with only 7 (12.5%) isolates susceptible. Multidrug resistance was a common phenomenon exhibited by 33 isolates comprising 17 phenotypic profiles (A8-A24). The most frequent phenotypic profile was TET^RSTR^RAMP^RTRI^RERY^R (tetracycline, streptomycin, ampicillin, trimethoprim, and erythromycin resistance) which accounted for 17.0% of the resistant strains. All the 8 resistance genes investigated were observed in one or more isolates and genotypic resistance was generally consistent with the resistant phenotypes observed. The most commonly observed resistance genes were tetA (73.2%) and aac(3)-IV (57.1%). Five isolates had none of the resistance genes investigated while 25 carried at least three different resistance determinants. Conclusions: Cattle in Cameroon are infected with multidrug-resistant E. coli O157 and are a potential risk to consumers. Hence adequate animal food production measures should be prescribed and implemented to minimize the development and spread of antibiotic resistant E. coli O157.