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Background Healthcare-associated infections (HCAI) place a significant burden on healthcare systems globally. This systematic review and meta-analysis aimed to investigate the prevalence, risk factors, and aetiologic agents of endemic HCAI in Africa. Methods MEDLINE/PubMed, CINAHL, and Global Health databases (EBSCOhost interface) were searched for studies published in English and French describing HCAI in Africa from 2010 to 2022. We extracted data on prevalence of HCAI, risk factors, aetiologic agents, and associated antimicrobial resistance patterns. We used random-effects models to estimate parameter values with 95% confidence intervals for risk factors associated with HCAI. This study was registered in PROSPERO (CRD42022374559) and followed PRISMA 2020 guidelines. Results Of 2541 records screened, 92 were included, comprising data from 81,968 patients. Prevalence of HCAI varied between 1.6 and 90.2% with a median of 15% across studies. Heterogeneity ( I 2 ) varied from 93 to 99%. Contaminated wound (OR: 1.75, 95% CI: 1.31–2.19), long hospital stay (OR: 1.39, 95% CI: 0.92–1.80), urinary catheter (OR: 1.57, 95% CI: 0.35–2.78), intubation and ventilation (OR: 1.53, 95% CI: 0.85–2.22), vascular catheters (OR: 1.49, 95% CI: 0.52–2.45) were among risk factors associated with HCAI. Bacteria reported from included studies comprised 6463 isolates, with E. coli (18.3%, n  = 1182), S. aureus (17.3%, n  = 1118), Klebsiella spp. (17.2%, n  = 1115), Pseudomonas spp. (10.3%, n  = 671), and Acinetobacter spp. (6.8%, n  = 438) being most common. Resistance to multiple antibiotics was common; 70.3% (IQR: 50–100) of Enterobacterales were 3rd -generation cephalosporin resistant, 70.5% (IQR: 58.8–80.3) of S. aureus were methicillin resistant and 55% (IQR: 27.3–81.3) Pseudomonas spp. were resistant to all agents tested. Conclusions HCAI is a greater problem in Africa than other regions, however, there remains a paucity of data to guide local action. There is a clear need to develop and validate sustainable HCAI definitions in Africa to support the implementation of routine HCAI surveillance and inform implementation of context appropriate infection prevention and control strategies.

Bacterial bloodstream infection is a common cause of morbidity and mortality in sub-Saharan Africa, yet few facilities are able to maintain long-term surveillance. The Malawi-Liverpool-Wellcome Trust Clinical Research Programme has done sentinel surveillance of bacteraemia since 1998. We report long-term trends in bloodstream infection and antimicrobial resistance from this surveillance. In this surveillance study, we analysed blood cultures that were routinely taken from adult and paediatric patients with fever or suspicion of sepsis admitted to Queen Elizabeth Central Hospital, Blantyre, Malawi from 1998 to 2016. The hospital served an urban population of 920 000 in 2016, with 1000 beds, although occupancy often exceeds capacity. The hospital admits about 10 000 adults and 30 000 children each year. Antimicrobial susceptibility tests were done by the disc diffusion method according to British Society of Antimicrobial Chemotherapy guidelines. We used the Cochran-Armitage test for trend to examine trends in rates of antimicrobial resistance, and negative binomial regression to examine trends in icidence of bloodstream infection over time. Between Jan 1, 1998, and Dec 31, 2016, we isolated 29 183 pathogens from 194 539 blood cultures. Pathogen detection decreased significantly from 327·1/100 000 in 1998 to 120·2/100 000 in 2016 (p<0·0001). 13 366 (51·1%) of 26 174 bacterial isolates were resistant to the Malawian first-line antibiotics amoxicillin or penicillin, chloramphenicol, and co-trimoxazole; 68·3% of Gram-negative and 6·6% of Gram-positive pathogens. The proportions of non-Salmonella Enterobacteriaceae with extended spectrum beta-lactamase (ESBL) or fluoroquinolone resistance rose significantly after 2003 to 61·9% in 2016 (p<0·0001). Between 2003 and 2016, ESBL resistance rose from 0·7% to 30·3% in Escherichia coli, from 11·8% to 90·5% in Klebsiella spp and from 30·4% to 71·9% in other Enterobacteriaceae. Similarly, resistance to ciprofloxacin rose from 2·5% to 31·1% in E coli, from 1·7% to 70·2% in Klebsiella spp and from 5·9% to 68·8% in other Enterobacteriaceae. By contrast, more than 92·0% of common Gram-positive pathogens remain susceptible to either penicillin or chloramphenicol. Meticillin-resistant Staphylococcus aureus (MRSA) was first reported in 1998 at 7·7% and represented 18·4% of S aureus isolates in 2016. The rapid expansion of ESBL and fluoroquinolone resistance among common Gram-negative pathogens, and the emergence of MRSA, highlight the growing challenge of bloodstream infections that are effectively impossible to treat in this resource-limited setting. Wellcome Trust, H3ABionet, Southern Africa Consortium for Research Excellence (SACORE).

Recent data re-affirm antimicrobial resistance (AMR) as a One Health problem, particularly in low- and middle-income countries. Transdisciplinary and intersectoral collaboration are required if we are to improve environmental hygiene, addressing both AMR and a range of aligned development challenges. Antimicrobial resistance is a One Health problem that impacts humans, animals, and the environment. In this Comment, the authors discuss evidence for antimicrobial resistance transmission to humans, highlighting contrasting pictures between high- and low/middle-income settings.

Infections caused by carbapenemase-producing enterobacteria (CPE) are a major concern in clinical settings worldwide. Two fundamentally different processes shape the epidemiology of CPE in hospitals: the dissemination of CPE clones from patient to patient (between-patient transfer), and the transfer of carbapenemase-encoding plasmids between enterobacteria in the gut microbiota of individual patients (within-patient transfer). The relative contribution of each process to the overall dissemination of carbapenem resistance in hospitals remains poorly understood. Here, we used mechanistic models combining epidemiological data from more than 9,000 patients with whole genome sequence information from 250 enterobacteria clones to characterize the dissemination routes of a pOXA-48-like carbapenemase-encoding plasmid in a hospital setting over a 2-yr period. Our results revealed frequent between-patient transmission of high-risk pOXA-48-carrying clones, mostly of Klebsiella pneumoniae and sporadically Escherichia coli . The results also identified pOXA-48 dissemination hotspots within the hospital, such as specific wards and individual rooms within wards. Using high-resolution plasmid sequence analysis, we uncovered the pervasive within-patient transfer of pOXA-48, suggesting that horizontal plasmid transfer occurs in the gut of virtually every colonized patient. The complex and multifaceted epidemiological scenario exposed by this study provides insights for the development of intervention strategies to control the in-hospital spread of CPE. Modelling combined with epidemiological and genomic data analysis from a hospital in Spain reveals frequent transmission of high-risk pOXA-48-carrying enterobacteria clones between patients and horizontal transfer of pOXA-48 plasmid within patients.

Infections with Enterobacterales (E) are increasingly difficult to treat due to antimicrobial resistance. After ceftriaxone replaced chloramphenicol (CHL) as empiric therapy for suspected sepsis in Malawi in 2004, extended-spectrum beta-lactamase (ESBL)-E rapidly emerged. Concurrently, resistance to CHL in Escherichia coli and Klebsiella spp. decreased, raising the possibility of CHL re-introduction. However, many phenotypically susceptible isolates still carry CHL acetyltransferase ( cat ) genes. To understand the molecular mechanisms and stability of this re-emerging CHL susceptibility we use a combination of genomics, phenotypic susceptibility assays, experimental evolution, and functional assays for CAT activity. Here, we show that of 840 Malawian E. coli and Klebsiella spp. isolates, 31% have discordant CHL susceptibility genotype–phenotype, and we select a subset of 42 isolates for in-depth analysis. Stable degradation of cat genes by insertion sequences leads to re-emergence of CHL susceptibility. Our study suggests that CHL could be reintroduced as a reserve agent for critically ill patients with ESBL-E infections in Malawi and similar settings and highlights the ongoing challenges in inferring antimicrobial resistance from sequence data. In this work, authors probe the molecular mechanism of re-emerging CHL susceptibility in Malawian Enterobacterales isolates, where they identify a stable truncation of resistance genes by insertion sequences.

Pathogenic Salmonella strains that cause gastroenteritis are able to colonize and replicate within the intestines of multiple host species. In general, these strains have retained an ability to form the rdar morphotype, a resistant biofilm physiology hypothesized to be important for Salmonella transmission. In contrast, Salmonella strains that are host-adapted or even host-restricted like Salmonella enterica serovar Typhi, tend to cause systemic infections and have lost the ability to form the rdar morphotype. Here, we investigated the rdar morphotype and CsgD-regulated biofilm formation in two non-typhoidal Salmonella (NTS) strains that caused invasive disease in Malawian children, S. Typhimurium D23580 and S. Enteritidis D7795, and compared them to a panel of NTS strains associated with gastroenteritis, as well as S. Typhi strains. Sequence comparisons combined with luciferase reporter technology identified key SNPs in the promoter region of csgD that either shut off biofilm formation completely (D7795) or reduced transcription of this key biofilm regulator (D23580). Phylogenetic analysis showed that these SNPs are conserved throughout the African clades of invasive isolates, dating as far back as 80 years ago. S. Typhi isolates were negative for the rdar morphotype due to truncation of eight amino acids from the C-terminus of CsgD. We present new evidence in support of parallel evolution between lineages of nontyphoidal Salmonella associated with invasive disease in Africa and the archetypal host-restricted invasive serovar; S. Typhi. We hypothesize that the African invasive isolates are becoming human-adapted and 'niche specialized' with less reliance on environmental survival, as compared to gastroenteritis-causing isolates.

Diverse salmonellae have the potential to cause disease and may be carried asymptomatically within the intestine of many vertebrate species. The relative contribution of human, animal, and environmental hosts to the transmission of Salmonella is unknown within and between households in low-income settings, especially where humans and animals may live in close contact and sanitary infrastructure is often inadequate. Between November 2018 and December 2019, we isolated Salmonella spp. from thirty households in urban and rural locations in Malawi, sampling at three time points from the stool of humans, animals, and their household environment. Using whole genome sequencing and fine-resolution bioinformatic and phylogenetic analyses we found evidence of sharing of Salmonella species and strains between humans, animals and the environment, both within and between households. The intricate web of interconnected salmonellae within this ecosystem underscores the importance of adopting a multi-faceted ‘One Health’ strategy when considering control of Salmonella in low-intensity agricultural systems. In this work, Wilson et al., examined sharing of Salmonella between humans, animals and the environment using household samples from Malawi. They revealed an interconnected web of Salmonella circulation, underscoring the importance of the One Health concept.

For 475 ESBL-producing Escherichia coli (ESBL-Ec), and 171 ESBL-producing Klebsiella pneumoniae (ESBL-Kp) collected from human carriers, the human-polluted (hp)-environment, and food: (i) to compare the antimicrobial resistance gene (ARG) content, and (ii) to assess clonal relationships between human and non-human isolates. Two prospective multicenter cohorts were assessed: colonized hospitalized index-subjects and household contacts, and long-term care facility (LTCF) residents. Additionally, linked hp-environment and food samples were collected. Presence of ARGs were assessed using pairwise comparisons and proportional similarity index (PSI). Clonal relationships were assessed using cgMLST distance visualizations and maximum likelihood phylogeny. ESBL-Ec and ESBL-Kp co-occurred in 14/65 households, 3/6 LTCFs, and in 33/202 of ESBL-positive participants. Thirty-nine percent of detected ARG types were found in both species (36/93). Frequencies of beta-lactamase, ESBL, aminoglycoside, and sulfonamide ARG types from human ESBL-Ec and ESBL-Kp overlapped considerably: PSIs 0.59-0.75, and were equal or higher compared to the overlap between ESBL-Ec from humans and food isolates: PSIs 0.33-0.72. Isolates from humans and the hp-environment were frequently clonally related, indicating human contamination of the environment. Links with food isolates were observed less frequently. For ESBL-Ec both interregional and regional clonal dissemination were observed, while for ESBL-Kp clonal dissemination was mainly regional. ESBL-Ec and ESBL-Kp from human carriage showed considerable overlap in ARG content. Furthermore, clonal links were observed frequently between humans and hp-environment, and with lower frequency between humans and food. These findings are consistent with human-to-human transmission as an important driver of ARG spread in humans.

To determine the duration of carbapenemase-producing Enterobacteriaceae (CPE) carriage, we studied 21 CPE carriers for »1 year. Mean carriage duration was 86 days; probability of decolonization in 1 year was 98.5%, suggesting that CPE-carriers' status can be reviewed yearly. Prolonged carriage was associated with use of antimicrobial drugs.

Salmonella enterica encompasses over 2,600 serovars, including several commonly associated with severe infection in humans. Salmonella is a major cause of sepsis in Africa; however, diagnosis requires clinical microbiology facilities. Environmental surveillance has the potential to play a role in Salmonella surveillance. We undertook water-based environmental surveillance in Blantyre, Malawi, from 2018-2020, taking samples from rivers (87.9%), a sewage plant (8.85%) and other water sources (3.24%), isolating and storing 1,042 non-typhoidal Salmonella (NTS) isolates in this period. Of these, 341 NTS isolates were whole genome sequenced, genome quality was checked, duplicate genomes from any given sample were removed and core genome phylogeny was reconstructed. AMRFinder, PathogenWatch and SISTR were used to further investigate serovar, sequence type and antimicrobial resistance determinants. After quality checks, and removal of duplicate genomes, 270 NTS genomes remained for further analysis. Multiple Salmonella serovars associated with human infection were detected, of which S. Typhimurium (55/270 isolates) was the most common, including 44 of Sequence Type (ST) 313, a serovar commonly associated with severe invasive disease (iNTS). Six lineage 2 ST313 genomes possessed AMR genes predicting multidrug resistance (MDR), while 29 lineage 3 isolates contained no AMR predictive genes. PCR based detection of staG has been proposed as a diagnostic marker of S. Typhi; however, all eight genomes that contained staG identified as Salmonella enterica serovar Orion, raising concerns about the specificity of this marker as a monoplex for environmental surveillance of S. Typhi. The study identified diverse Salmonella serovars in the environment, including those reported to cause invasive disease, emphasizing the complex but potentially valuable contribution of implementing environmental surveillance for Salmonella in high burden areas lacking diagnostic microbiology capacity.