Pakistan is experiencing the first known outbreak of extensively drug-resistant (XDR) Salmonella enterica serotype Typhi (resistant to third-generation cephalosporins). The outbreak originated in Hyderabad in 2016 and spread throughout the Sindh Province. Whereas focus has remained on Sindh, the burden of XDR typhoid in Punjab, the most populous province, and the rest of the country is understudied. Using laboratory data from Shaukat Khanum Memorial Cancer Hospital and Research Centre in Lahore (Punjab Province) and its network of more than 100 collection centers across the country, we determined the frequency of blood culture–confirmed XDR typhoid cases from 2017 to 2019. We observed an increase in XDR typhoid cases in Punjab, with the percent of ceftriaxone resistance among Salmonella Typhi cases increasing from no cases in 2017, to 30% in 2018, and to 50% in 2019, with children bearing the largest burden. We also observed spread of XDR typhoid to the two other provinces in Pakistan. To assess prevailing knowledge and practices on XDR typhoid, we surveyed 321 frontline healthcare workers. Survey results suggested that inappropriate diagnostic tests and antibiotic practices may lead to underdiagnosis of XDR typhoid cases, and potentially drive resistance development and spread. Of those surveyed, only 43.6% had heard of XDR typhoid. Currently, serological tests are more routinely used over blood culture tests even though blood culture is imperative for a definitive diagnosis of typhoid fever. We recommend stronger liaisons between healthcare providers and diagnostic laboratories, and increased promotion of typhoid vaccination among healthcare workers and the general population.

: Antimicrobial resistance (AMR), largely driven by irrational use of antimicrobials, is a global, multifaceted problem calling for a complete understanding of all contributory factors for effective containment. In conflict settings, war-wounds and malnutrition can combine with existing social determinants to increase demand for antibiotics, compounding irrational use. In this study, we focus on Yemen, a low-income country with active conflict for the last 5 years, and analyze the current status of awareness and stewardship efforts regarding AMR. We performed a survey of prescribers/physicians and pharmacists to describe perceptions of AMR prevalence, antibiotic use practices, and stewardship in Yemen, supported by a nonsystematic scoping literature review and a key informant interview. Participants (96%, N = 54) reported a perceived high AMR prevalence rate. Prescribers (74%, 20/27) reported pressure to prescribe broad-spectrum antibiotics. In the majority of cases (81%, 22/27), antimicrobial sensitivity tests (AST) were not performed to inform antibiotic choice. The main barrier to AST was cost. Most pharmacists (67%, 18/27) sold antibiotics without prescriptions. Amoxicillin (including amoxicillin-clavulanate) was the most-commonly prescribed (63%, 17/27) or dispensed (81%, 22/27) antibiotic. AST was rated the least important solution to AMR in Yemen. While there was awareness of a high AMR rate, stewardship is poor in Yemen. We note that barriers to the use of AST could be addressed through the deployment of reliable, affordable, quality rapid diagnostics, and AST kits. Compulsory continuing education emphasizing the use of AST to guide prescribing and patients’ awareness programs could help avoid irrational use.

Infections caused by Acinetobacter baumannii, a Gram‐negative opportunistic pathogen, are difficult to eradicate due to the bacterium's propensity to quickly gain antibiotic resistances and form biofilms, a protective bacterial multicellular community. The A. baumannii DNA damage response (DDR) mediates the antibiotic resistance acquisition and regulates RecA in an atypical fashion; both RecA^Low and RecA^High cell types are formed in response to DNA damage. The findings of this study demonstrate that the levels of RecA can influence formation and dispersal of biofilms. RecA loss results in surface attachment and prominent biofilms, while elevated RecA leads to diminished attachment and dispersal. These findings suggest that the challenge to treat A. baumannii infections may be explained by the induction of the DDR, common during infection, as well as the delicate balance between maintaining biofilms in low RecA cells and promoting mutagenesis and dispersal in high RecA cells. This study underscores the importance of understanding the fundamental biology of bacteria to develop more effective treatments for infections.

: Typhoid fever, caused by Salmonella enterica serovar Typhi (S. Typhi), is a life-threatening bacterial infection. Recently, an outbreak of a new sublineage of extensively drug resistant (XDR) S. Typhi emerged in Pakistan in the province of Sindh. This sublineage had both a composite multidrug resistance transposon integrated on the chromosome and an acquired IncY plasmid carrying the extended spectrum beta-lactamase, blaCTX-M-15, which conferred resistance to third-generation cephalosporins. We observed previously that XDR typhoid had spread beyond the originating southern Sindh Province. Thus, we sought to determine the genetic diversity of 58 ceftriaxone-resistant S. Typhi clinical isolates by whole genome sequencing collected across Pakistan from November 2018 to December 2020 to provide insights into the molecular epidemiology of the evolving outbreak. We identify multiple novel genomic integrations of the extended spectrum beta-lactamase gene into the chromosome in S. Typhi, revealing the existence of various XDR typhoid variants circulating in the country. Notably, the integration of the IncY plasmid bearing antibiotic resistance genes may allow for subsequent plasmid acquisition by these variants, potentially leading to further plasmid-borne multidrug resistance. Our results can inform containment initiatives, help track associated outcomes and international spread, and help determine how widespread the risk is.

Introduction Antibiotic resistance (AR) is among the most pressing global health challenges. Fluoroquinolones are a clinically important group of antibiotics that have wide applicability in both humans and animals. While many drivers of AR are known, the impact of medicine quality on AR remains largely unknown. The aim of this review is to systematically evaluate the evidence of the impact of in vitro subinhibitory antibiotic exposure, a major tenet of substandard antibiotics, on the development of AR and mutagenesis, using fluoroquinolones as a case study. Methods and analysis EMBASE, Web of Science and PubMed will be systematically searched for primary experimental in vitro studies, from earliest available dates within each database (1947, 1965 and 1966, respectively) through 2018, related to subinhibitory fluoroquinolone exposure and AR. A specifically developed non-weighted tool will be used to critically assess the evidence. Subgroup analyses will be performed for different variables and outcomes. Ethics and dissemination Ethical approval is not required as no primary data are to be collected. The completed systematic review will be disseminated through conference meeting presentations and a peer-reviewed publication.

Changing climate may contribute to increased antimicrobial resistance (AMR), particularly in wastewater which acts as a reservoir for resistant bacteria. Here, we determined how applying climate dependencies to our previously published model, rooted in theory, impacts computational simulations of AMR in wastewater. We found AMR levels were reduced at lower temperatures but increased with lower precipitation. The impact of precipitation on AMR was more pronounced at higher temperatures compared to lower temperatures. To validate our model, we investigated associations between total AMR gene abundance in wastewater from the Global Sewage Surveillance project and mean temperature and rainfall values extracted from European Centre for Medium-Range Weather Forcasts Reanalysis v5 (ERA5) reanalysis. We observed similar trends between the simulations and observations. Observations and simulations from our study can inform experiments to determine causal relationships as well as help identify other key drivers. We also discuss study challenges given the complex nature of AMR in the environment.