Comparison of stool samples and rectal swabs with and without pre-enrichment for the detection of third-generation cephalosporin-resistant Enterobacterales (3GCREB)

Optimized methods for the targeted surveillance of extended-spectrum beta-lactamase-producing Escherichia coli in human stool

Understanding transmission pathways of important opportunistic, drug-resistant pathogens, such as extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli, is essential to implementing targeted prevention strategies to interrupt transmission and reduce the number of infections. To link transmission of ESBL-producing E. coli (ESBL-EC) between two sources, single-nucleotide resolution of E. coli strains, as well as E. coli diversity within and between samples, is required. However, the microbiological methods to best track these pathogens are unclear. Here, we compared different steps in the microbiological workflow to determine the impact different pre-enrichment broths, pre-enrichment incubation times, selection in pre-enrichment, selective plating, and DNA extraction methods had on recovering ESBL-EC from human stool samples, with the aim to acquire high-quality DNA for sequencing and genomic epidemiology. We demonstrate that using a 4-h pre-enrichment in Buffered Peptone Water, plating on cefotaxime-supplemented MacConkey agar and extracting DNA using Lucigen MasterPure DNA Purification kit improves the recovery of ESBL-EC from human stool and produced high-quality DNA for whole-genome sequencing. We conclude that our optimized workflow can be applied for single-nucleotide variant analysis of an ESBL-EC from stool.IMPORTANCEDrug-resistant infections are increasingly difficult to treat with antibiotics. Preventing infections is thus highly beneficial. To do this, we need to understand how drug-resistant bacteria spread to take action to stop infection and transmission. This requires us to accurately trace these bacteria between different sources. In this study, we compared different laboratory methods to see which worked best for detecting extended-spectrum beta-lactamase (ESBL)-producing E. coli, a common cause of urinary tract or bloodstream infections, from human stool samples. We found that enriching stool in a nutrient broth for 4 h, then plating the bacterial suspension on antibiotic-selective MacConkey agar, and finally extracting DNA from the bacteria using a specific DNA purification kit resulted in improved recovery of ESBL E. coli and high-quality DNA. Sequencing multiple isolates from stool allowed us to distinguish unambiguously and at high resolution between different variants of ESBL E. coli present in stool.

ESBL-producing Enterobacteriaceae in a rural Rwandan community: Carriage among community members, livestock, farm products and environment

OBJECTIVES

Extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE) are spreading globally. However, respective data from African communities including livestock and environmental specimens are rare. In a rural community of southern Rwanda, we assessed intestinal carriage of ESBL-PE among residents and livestock as well as presence in household specimens and examined associated factors.

METHODS

Samples of humans and livestock (both rectal swabs), soil, water, vegetables and animal products were collected within 312 community households in Sovu, Southern Rwanda. Specimens were screened for ESBL-PE on chromogenic agar, and susceptibility to common antibiotics was determined by disc diffusion assays. Socio-demographic information was collected with questionnaires focusing on the socio-economic background, alimentation, living conditions, hygiene measures and medical history of the participants.

RESULTS

Data and specimens from 312 randomly selected households including 617 human beings, 620 livestock and of approximately each 300 kitchen vegetables, animal products, soil and drinking water were analysed. Overall, 14.8% of 2508 collected samples were positive for ESBL-PE; figures were highest for humans (37.9%) and livestock (15.6%), lower for vegetables (3.8%) and animal products (3.3%), and lowest for soil (1.6%) and water (0.6%). Most detected ESBL-PE were Escherichia coli (93.5%) in addition to Klebsiella pneumoniae (6.5%). Cross-resistance to ampicillin-sulbactam, ciprofloxacin and co-trimoxazole was common. Logistic regression identified increasing age, another ESBL-PE positive household member, prolonged time for fetching water, current diarrhoea and the ability to pay school fees as independent predictors of intestinal ESBL-PE carriage among community members.

CONCLUSIONS

ESBL-PE carriage is common in a rural Rwandan farming community. Carriage in livestock is not associated with human carriage. Associated factors suggest few addressable risk factors. The data indicate that in southern Rwanda, ESBL-PE are no longer primarily hospital-based but circulate in the community.

First-Day-of-Life Rectal Swabs Fail To Represent Meconial Microbiota Composition and Underestimate the Presence of Antibiotic Resistance Genes

The human gut microbiome plays a vital role in health and disease. In particular, the first days of life provide a unique window of opportunity for development and establishment of microbial community. Currently, stool samples are known to be the most widely used sampling approach for studying the gut microbiome. However, complicated sample acquisition at certain time points, challenges in transportation, and patient discomfort underline the need for development of alternative sampling approaches. One of the alternatives is rectal swabs, shown to be a reliable proxy for gut microbiome analysis when obtained from adults. Here, we compare the usability of rectal swabs and meconium paired samples collected from infants on the first days of life. Our results indicate that the two sampling approaches display significantly distinct patterns in microbial composition and alpha and beta diversity as well as detection of resistance genes. Moreover, the dissimilarity between the two collection methods was greater than the interindividual variation. Therefore, we conclude that rectal swabs are not a reliable proxy compared to stool samples for gut microbiome analysis when collected on the first days of a newborn's life. IMPORTANCE Currently, there are numerous suggestions on how to ease the notoriously complex and error-prone methodological setups to study the gut microbiota of newborns during the first days of life. Especially, meconium samples are regularly failing to yield meaningful data output and therefore have been suggested to be replaced by rectal swabs as done in adults as well. We find this development toward a simplified method to be producing dramatically erroneous results, skewing data interpretation away from the real aspects to be considered for neonatal health during the first days of life. We have put together our knowledge on this critical aspect with careful consideration and identified the failure of rectal swabs to be a replacement for sampling of meconium in term-born newborns.

Detection of Multidrug-Resistant Enterobacterales-From ESBLs to Carbapenemases

Multidrug-resistant Enterobacterales (MDRE) are an emerging threat to global health, leading to rising health care costs, morbidity and mortality. Multidrug-resistance is commonly caused by different β-lactamases (e.g., ESBLs and carbapenemases), sometimes in combination with other resistance mechanisms (e.g., porin loss, efflux). The continuous spread of MDRE among patients in hospital settings and the healthy population require adjustments in healthcare management and routine diagnostics. Rapid and reliable detection of MDRE infections as well as gastrointestinal colonization is key to guide therapy and infection control measures. However, proper implementation of these strategies requires diagnostic methods with short time-to-result, high sensitivity and specificity. Therefore, research on new techniques and improvement of already established protocols is inevitable. In this review, current methods for detection of MDRE are summarized with focus on culture based and molecular techniques, which are useful for the clinical microbiology laboratory.