ANTONIO MASTROIANNI

Whether, or under what conditions? A configurational approach to AI-supported antimicrobial stewardship in sub-Saharan Africa

Abdulrasheed Ibrahim

Ceftriaxone-by-default in surgical prophylaxis across the East African community: a measurement problem

Samar Rashid Abdullahi, Nathan Mugenyi, Lucy Ochola, Jamal Abade Mohamed, Hussein Iman Sigat, Abdirizak Ali Yusuf, Wigilya P. Mikomangwa, Armstrong Ndihokubwayo, David Majuch Kunjok, Schifra Uwamungu, Nathan Banzi, Barbra Tuhamize

Surgical antibiotic prophylaxis across the East African Community is dominated by ceftriaxone, a WHO Access, Watch, and Reserve (AWaRe) Watch-group third-generation cephalosporin not recommended for routine prophylaxis. The practice recurs across regional point prevalence surveys, yet consumption surveillance cannot distinguish prophylactic from therapeutic use. Drawing on antimicrobial-use surveys, surgical-prophylaxis studies, resistance surveillance, and medicine-availability reports, we argue that four interacting failure modes sustain it: substitution of first-line agents, prolongation of postoperative prophylaxis, unnecessary combination, and empirical spillover from ward prescribing. Resistance among surgical-site isolates is already high enough to threaten the value of prophylaxis itself. Prophylaxis is measured for duration, documented indication, and guideline concordance, and agent choice is captured in point-prevalence surveys, but none of this reaches the national consumption totals that govern procurement, and no indicator records the supply constraint determining the agent or the resistance it selects. We propose four measures, one requiring routing rather than building and three genuinely absent, that would convert an ungoverned practice into a governable one.

Genomic insights into multidrug and extensively drug-resistant Klebsiella pneumoniae from bloodstream infections at three Zambian tertiary hospitals

Joseph Yamweka Chizimu, Harvey Kakoma Kamboyi, Maisa Kasanga, Taona Sinyawa, Misheck Shawa, Ruth Nakazwe, Steward Mudenda, Joseph Njung’e, Susan Kiiru, Mungunsar Chuluun, Chileshe Lukwesa, Zoran Muhimba, Victor Daka, Dianah Tibatemwa, Everlyn Wesangula, O-Tipo Shikanga, Sandra Diana Mwadetsa, Nchimunya Machila, Veronica Chuchu, Zachariah Mupila, Peter Clement Lasuba, Yasuhiko Suzuki, Flavien Nsoni Bumbangi, Roma Chilengi

Klebsiella pneumoniae is a leading cause of hospital-associated infections and a major contributor to antimicrobial resistance (AMR) worldwide. Despite its importance and prioritisation in Zambia’s National Action Plan on AMR, genomic surveillance information in sub-Saharan Africa remains limited. This study investigated the population structure, determinants of AMR, and plasmid diversity of K. pneumoniae isolates from three tertiary hospitals in Zambia. Thirty archived K. pneumoniae blood isolates collected between December 2023 and May 2025 from University Teaching Hospitals (UTH), Ndola University Teaching Hospital (NUTH), and Livingstone University Teaching Hospital (LUTH) and subjected to antimicrobial susceptibility testing (AST) and whole-genome sequencing (Illumina NextSeq 2000). Sequence types (STs), plasmid replicons, and antimicrobial resistance genes (ARGs) were identified using MLST, PlasmidFinder, and the Comprehensive Antibiotic Resistance Database, respectively. Twenty-eight isolates (93%) were multidrug-resistant, of which seven (25%) were extensively drug-resistant (XDR), exhibiting resistance across eight antibiotic classes, including carbapenems. Whole-genome sequencing identified 18 sequence types (STs), including two novel STs, and globally disseminated high-risk clones such as ST11, ST15, ST101, ST307, ST377, and ST607, which are circulating across hospitals. UTH exhibited the highest diversity of STs. The seven XDR K. pneumoniae isolates, six (85%) were from UTH, while the remaining isolate was from NUTH. Among the XDR isolates, five belonged to clinically dominant clones, comprising ST377 (two isolates) and single representatives of ST101, ST307, and ST607. The other two were ST13 and ST831, which have not been reported to have an XDR profile. All isolates carried multiple ARGs, dominated by those encoding β-lactamases (bla CTX-M-15: 93%, bla TEM: 70%), aminoglycoside-modifying enzymes (aac(6’)-Ib-cr5: 77%, aac(3)-IIe: 64%), and efflux pump genes (emrD: 100%). The carbapenemase-encoding gene, bla NDM-5, was present in 13% of the isolates. This first genomic survey of K. pneumoniae in Zambia reveals extensive clonal diversity dominated by global high-risk lineages carrying plasmid-mediated ESBL and carbapenemase genes. The detection of XDR strains, particularly at UTH, underscores the urgent need to strengthen laboratory surveillance across all tertiary hospitals in Zambia and improve infection prevention programmes.

Environmental occurrence and dissemination of colistin resistance in contaminated aquatic systems: a systematic review of eight observational studies

Alisha Sinha, Jogesh Murmu, Shreya Singh, Aditi Pal, Utkalika Mallick, Poonamrani Mishra, Krushna Chandra Sahoo, Mahesh Chandra Sahu, Sanghamitra Pati

Colistin is a last-resort antibiotic used against multidrug-resistant Gram-negative bacterial infections. The emergence of plasmid-mediated colistin resistance, particularly mcr genes, has raised concerns about the environmental persistence and dissemination of resistance determinants. Aquatic environments may serve as reservoirs and dissemination pathways for colistin resistance; however, the available evidence remains fragmented. This systematic review aimed to synthesize evidence on the occurrence, resistance mechanisms, and environmental and potential public health implications of colistin resistance in contaminated aquatic systems. A systematic literature search was conducted in five electronic databases up to December 2024 in accordance with PRISMA guidelines. Studies investigating colistin resistance in wastewater, surface water, aquaculture systems, and related aquatic environmental matrices were eligible for inclusion. Following screening and eligibility assessment, eight observational studies were included. Owing to substantial methodological and outcome heterogeneity, a narrative synthesis was performed. Isolate-level phenotypic resistance, sample- or site-level molecular positivity, and metagenomic relative gene abundance were analyzed as separate, non-comparable outcome strata. A total of 26,740 records were retrieved, of which 20,691 unique records were screened after removal of duplicates. Eight studies met the predefined eligibility criteria. The studies investigated diverse aquatic environments, including slaughterhouse effluents, municipal wastewater, urban rivers, aquaculture systems, and wastewater-associated bioaerosols. Plasmid-mediated mcr genes were identified across several environmental settings and frequently occurred alongside other antimicrobial resistance determinants. Chromosomal mechanisms of colistin resistance were also reported. The reported resistance measures varied substantially between studies, ranging from isolate-level phenotypic resistance and sample/site-level molecular detection to metagenomic relative abundance. The available evidence indicates that contaminated aquatic environments can harbor colistin resistance determinants and may contribute to their environmental dissemination. However, the limited number of eligible studies and substantial methodological heterogeneity prevent direct quantitative comparison or estimation of a common environmental prevalence. Standardized surveillance approaches integrating culture-based methods, molecular detection, and genomic/metagenomic characterization are needed to improve comparability and clarify the environmental pathways of colistin resistance within a One Health framework. https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42024613277.

Editorial: Innovations and impacts of antimicrobial stewardship in primary care and proximity settings

Elmien Bronkhorst