Etiological agents of diarrhea in hospitalized pediatric patients with special emphasis on diarrheagenic Escherichia coli in North India

Epidemiology of multidrug-resistant zoonotic E. coli from beef processing and retail points in Delta State, Nigeria: Public health implications

Some sorbitol non-fermenting E. coli (SN-F E. coli) and all E. coli O157 are zoonotic. Contamination of beef with zoonotic E. coli at the processing or retail point is a significant public health problem. Despite the public health importance of these organisms, there is no published data on the prevalence and antimicrobial resistance (AMR) of zoonotic E. coli from Delta State, Nigeria. Consequently, this study determined the prevalence and AMR of SN-F E. coli and E. coli O157 isolates from meat contact surfaces at the processing and retail points in the study area. The isolation, biochemical and serological characterisations and AMR status of the isolates were performed following standard microbiological methods. Overall prevalence of SN-F E. coli and E. coli O157 were 13.8% (56/406) and 1.5% (6/406), respectively. Majority of the 56 SN-F E. coli (64.3%, 36/56) and all the six E. coli O157 (10.7%, 6/56) detected in this study were found at the meat processing points. Most of the SN-F E. coli were isolated at the slaughterhouse floor (31%), meat hooks (17.2%) and meat sellers' knives (17.2%). The SN-F E. coli exhibited greater AMR to ampicillin (67.9%), gentamycin (64.3%) and tetracycline (50%) than other antimicrobial agents tested. No isolate was resistant to aztreonam. All six E. coli O157 isolates were resistant to enrofloxacin. Overall, 23 AMR patterns, comprised 14 from meat processing points and nine from meat retailing points, were observed from the 56 antimicrobial-resistant SN-F E. coli isolates. All the six E. coli O157 and 73.2% (41/56) of the SN-F E. coli isolates were multidrug-resistant. An overall mean multiple antimicrobial resistance index of 0.6 was recorded. Multidrug-resistant zoonotic E. coli were detected at meat processing and retail points in Delta State, Nigeria. The findings warrant the adoption of One Health control approach, "farm to fork" principle of food safety and prudent use of antimicrobial agents in animal agriculture. These may help to limit beef contamination with multidrug-resistant zoonotic E. coli at the processing and retailing points, for public health safety.

RB49-like Bacteriophages Recognize O Antigens as One of the Alternative Primary Receptors

The power of most of the enterobacterial O antigen types to provide robust protection against direct recognition of the cell surface by bacteriophage receptor-recognition proteins (RBP) has been recently recognized. The bacteriophages infecting O antigen producing strains of E. coli employ various strategies to tackle this nonspecific protection. T-even related phages, including RB49-like viruses, often have wide host ranges, being considered good candidates for use in phage therapy. However, the mechanisms by which these phages overcome the O antigen barrier remain unknown. We demonstrate here that RB49 and related phages Cognac49 and Whisky49 directly use certain types of O antigen as their primary receptors recognized by the virus long tail fibers (LTF) RBP gp38, so the O antigen becomes an attractant instead of an obstacle. Simultaneously to recognize multiple O antigen types, LTFs of each of these phages can bind to additional receptors, such as OmpA protein, enabling them to infect some rough strains of E. coli. We speculate that the mechanical force of the deployment of the short tail fibers (STF) triggered by the LTF binding to the O antigen or underneath of it, allows the receptor binding domains of STF to break through the O polysaccharide layer.

Antibody therapy against antibiotic-resistant diarrheagenic Escherichia coli: a systematic review

Over four billion episodes of diarrhea occur annually in developing countries with diarrheagenic Escherichia coli (DEC) outbreaks also being reported, until now bacterial diarrhea is conventionally addressed by the antibiotic treatment regimes. In recent decades, the emergence of antimicrobial-resistant strains has become a major obstacle in diarrheal treatment; hence, novel and ideal therapeutics are needed. Notably, 80% of DEC is resistant to first-class antibiotics. Among the existing strategies, passive immunization is considered as an alternative to combat drug-resistant bacteria. Antibodies specific to an antigen can be used for prophylactic and therapeutic purposes. In this review, we have systematically discussed the effect of passive immunotherapy to combat DEC and explored the types and advancements in antibodies used against antibiotic-resistant DEC.

New Insights into the Antimicrobial Action of Cinnamaldehyde towards Escherichia coli and Its Effects on Intestinal Colonization of Mice

Escherichia coli is responsible for cases of diarrhea around the world, and some studies have shown the benefits of cinnamaldehyde in the treatment of bacterial disease. Therefore, the objective of this study was to evaluate the effects of cinnamaldehyde in mice colonized by pathogenic E. coli, as well as to provide more insights into its antimicrobial action mechanism. After determination of minimum inhibitory (MIC) and minimum bactericidal (MBC) concentrations, the interference of cinnamaldehyde in macromolecular pathways (synthesis of DNA, RNA, protein, and cell wall) was measured by incorporation of radioisotopes. The anti-adhesive properties of cinnamaldehyde towards E. coli 042 were evaluated using human epithelial type 2 (HEp-2) cells. Intestinal colonization was tested on mice, and the effect of cinnamaldehyde on Tenebrio molitor larvae. Cinnamaldehyde showed MIC and MBC values of 780 μg/mL and 1560 μg/mL, respectively; reduced the adhesion of E. coli 042 on HEp-2 cells; and affected all the synthetic pathways evaluated, suggesting that compost impairs the membrane/cell wall structure leading bacteria to total collapse. No effect on the expression of genes related to the SOS pathway (sulA and dinB1) was observed. The compound did not interfere with cell viability and was not toxic against T. molitor larvae. In addition, cinnamaldehyde-treated mice exhibited lower levels of colonization by E. coli 042 than the untreated group. Therefore, the results show that cinnamaldehyde is effective in treating the pathogenic E. coli strain 042 and confirm it as a promising lead molecule for the development of antimicrobial agents.

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.