Journal of Global Antimicrobial Resistance

To characterise temporal changes in antimicrobial resistance (AMR) among clinically important bacterial pathogens in Iraq during 2021-2024 and examine their implications for empirical antimicrobial therapy and stewardship. We conducted a retrospective longitudinal analysis of aggregated national AMR surveillance data for Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Staphylococcus aureus. Annual resistance proportions were evaluated across clinically relevant antimicrobials. Temporal change was characterised using absolute percentage-point changes and exploratory linear regression. Resistance trajectories were interpreted in relation to empirical treatment options and antimicrobial stewardship. The analysis included 92,338 organism records: 40,496 (43.9%) E. coli, 24,621 (26.7%) S. aureus, 18,223 (19.7%) K. pneumoniae and 8,998 (9.7%) P. aeruginosa. In 2024, ceftriaxone resistance reached 82.9% in E. coli and 65.2% in K. pneumoniae, while ciprofloxacin resistance was 55.4% and 57.9%, respectively. Meropenem resistance reached 37.4% in K. pneumoniae and 62.3% in P. aeruginosa. Conversely, resistance declined for amoxicillin-clavulanate in E. coli (83.5% in 2021 to 57.2% in 2024) and piperacillin-tazobactam in P. aeruginosa (46.4% to 32.9%). Several pathogen-antimicrobial combinations showed marked year-to-year variation, and no temporal trend remained statistically significant after false discovery rate correction. Resistance to several agents central to empirical therapy remains high in Iraq, while substantial carbapenem resistance constrains reliance on carbapenem escalation when resistance to other {beta}-lactams is suspected. Heterogeneous trajectories indicate that empirical recommendations should not rely on single-year national antibiograms alone and support regular integration of national and local resistance surveillance into empirical treatment and antimicrobial stewardship strategies.

Sepsis is a global health problem. Patients in the Intensive Care Unit (ICU) are at risk of having sepsis because of their vulnerability and use of invasive medical devices. Emerging antimicrobial-resistance complicates treatment. Understanding bacterial profiles and antibiotic sensitivity patterns in the ICU plays an important role in managing sepsis, optimizing antimicrobial use, and improving patient outcomes. The aim of this study was to show bacterial profiles and antibiotic sensitivity patterns among patients who were admitted to the ICU at Mbeya Zonal Referral Hospital for 12 months. This was a prospective cross-sectional study among 187 sepsis-suspected patients. Data analysis was performed using SPSS Version 27. Categorical data were summarized by frequency and percentage. Fishers exact test, chi-square test, and modified Poisson regression were used to show the association between patients clinical variables and culture positivity at a 95% CI. Statistical significance was set at a p-value < 0.05. Out of 187 samples, 41.7% were culture positive. Gram-negative bacteria were commonly isolated (65.4%, with Klebsiella pneumoniae and Escherichia coli being commonly isolated. Commonly isolated Gram-positive bacteria were Coagulase-negative Staphylococcus species (19%). 100% of gram-positive bacteria and 96% of gram-negative bacteria were Multi-Drug Resistant (MDR), respectively. In multivariable analysis, patients who were intubated and mechanically ventilated (aPR = 2.208, 95% CI: 1.133-4.305, p = 0.020) and post-laparotomy patients (aPR = 3.241,95% CI: 1.320-7.958, p = 0.010) independently had a higher proportion of Gram-negative bacteria. The study reveals a high level of resistance to commonly used antimicrobials in our setting, necessitating strengthening of the antimicrobial stewardship program and routine surveillance of antimicrobial resistance patterns.

BackgroundMethicillin-resistant Staphylococcus aureus (MRSA) is one the most common cause of post-surgical infections in Malawi and poses a significant public health challenge due to resistance to commonly used antibiotics. We isolated and evaluated the stability and lytic activity of a MRSA-specific bacteriophage (Staphylophage) from Mzuzu Central hospital (MZCH) sewage against MRSA strains isolated from surgical wards. MethodsA prospective in vitro experimental study was conducted using 56 pus swabs collected from post-surgical patients at Mzuzu Central Hospital (MZCH), Malawi. Standard microbiological methods and VITEK analysis were used for bacterial isolation, identification and antimicrobial susceptibility testing of Staphylococcus aureus and MRSA according to the 2024 EUCAST guidelines. A lytic Staphylophage was isolated and purified from sewage wastewater using filtration, enrichment, and double-layer agar techniques. The purified Staphylophage was evaluated for its lytic activity through host range testing and stability under ultraviolet (UV) exposure (up to 60 minutes), different pH levels (2-12), and temperatures (4{degrees}C, -20{degrees}C, and -80{degrees}C). ResultsOut of 56 bacterial isolates, 18 (32.1%) were S. aureus, of which 11 (61.1%) were MRSA. The isolated Staphylophage showed lytic activity against 87% of Staphylococcus species tested. The phage remained stable at temperatures between -80{degrees}C and 4{degrees}C and across a pH range of 2- 12. It also retained viability after UV exposure for up to 15 minutes, although a reduction in phage titre was observed after 30 minutes. ConclusionsA lytic Staphylophage isolated from hospital sewage at MZCH demonstrated activity against Staphylococcus species, including MRSA strains from post-surgical wound infections. These findings illustrate the feasibility of generating candidate phages for alternative therapeutic approaches in a central hospital setting in Malawi.

Morganella morganii is an opportunistic pathogen with intrinsic and acquired antimicrobial resistance, but its genomic epidemiology remains poorly characterized in Bangladesh. We sequenced and compared genomes of 47 stool-derived M. morganii isolates from hospital (n = 29) and community (n = 18) participants in urban Dhaka. Susceptibility testing showed frequent resistance to imipenem (70.2%) and cefuroxime (97.9%), while all isolates were resistant to colistin. Resistance to meropenem (6.4%) and ertapenem (2.1%) was uncommon. Based on acquired non-susceptibility across tested antimicrobial categories, 18/47 (38.3%) isolates were multidrug-resistant, including 15/29 (51.7%) hospital-derived and 3/18 (16.7%) community-derived isolates. Genomic analysis identified 17 {beta}-lactamase alleles including Morganella-associated chromosomal {beta}-lactamases and acquired resistance determinants, with blaOXA-1, blaDHA-21, blaCTX-M-15, and blaTEM-1 predominating. However, no recognized acquired carbapenemase genes were detected. Among 44 non-{beta}-lactam resistance genes, tetB was most frequent. Phylogenomic and average nucleotide identity analyses classified 31 isolates as M. morganii subsp. morganii and 16 as the subsp. intermedius lineage. Considerable population diversity was observed, with 33 distinct sequence types among the 47 isolates and no clear clustering by hospital or community origin. The subsp. intermedius isolates showed greater genomic heterogeneity than subsp. morganii, with a minimum within-group average nucleotide identity of 94.2%. Single nucleotide variant (SNV) analysis identified several closely related isolate groups, including an ST1 pair differing by 10 SNVs and collected three days apart within the same hospital, although direct transmission could not be established. Virulence-associated gene profiles differed between subspecies, with hemolysin- and toxin-associated genes predominantly detected among subsp. morganii isolates and largely absent from subsp. intermedius. Overall, these findings reveal substantial genomic diversity, a considerable burden of multidrug resistance, and subspecies-associated differences in virulence gene content among M. morganii circulating in Dhaka, while the frequent imipenem-non-susceptible but carbapenemase-negative phenotype highlights the need to investigate alternative carbapenem resistance mechanisms.

Purpose: Vancomycin-resistant Gram-positive organisms represent a potential therapeutic challenge in endophthalmitis. To evaluate alternative treatment options, the FDA-approved oxazolidinones linezolid (LZD) and tedizolid (TZD) were tested against a collection of Gram-positive bacterial endophthalmitis isolates. Methods: Minimum inhibitory concentrations (MICs) were determined using epsilometers (Etest strips) for coagulase negative staphylococci (CoNS, n=20), Staphylococcus aureus (n=18), Bacillus species (n=10), Enterococcus species (n=5), and Streptococcus pneumoniae (n=1). Available CLSI and EUCAST breakpoints were applied to determine susceptibility. Results: TZD exhibited a >5-fold reduction in median MIC compared with LZD across all organisms tested (p<0.0001). MIC90 values for CoNS were 2.0 /ml for LZD and 0.25 /ml for TZD. For S. aureus, MIC90 values were 1.5 /ml (LZD) and 0.19 /ml (TZD). For Bacillus spp., MIC90 values were 1.0 /ml (LZD) and 0.25 /ml (TZD). Among Enterococcus species, the MIC range was 0.5-4.0 /ml (LZD) and 0.064-0.75 /ml (TDZ). The single S. pneumoniae strain had a MIC of 0.5 for LZD and 0.064 for TZD. All isolates were susceptible to TZD. One Enterococcus isolate was non-susceptible to LZD; the remaining isolates were susceptible. Conclusions: LZD and TZD demonstrated in vitro activity against Gram-positive bacterial endophthalmitis isolates, with TZD displaying consistently lower MICs than LZD. These findings suggest that oxazolidinones may represent potential alternatives when vancomycin cannot be used, including infections caused by vancomycin-resistant Gram-positive organisms. Given their excellent oral bioavailability, favorable safety profile, and reported anti-virulence effects in certain pathogens, further evaluation of oxazolidinones for the treatment of intraocular infections is warranted.

Co-administration of phages and antibiotics has been proposed as a therapeutic approach against antibiotic-resistant bacteria. The relationship, however, between antibiotic resistance and phage resistance in clinical isolates is unclear. Here, we examine associations between phage and antibiotic resistance profiles across a panel of Pseudomonas aeruginosa clinical isolates from the Centers for Disease Control (CDC) and Food and Drug Administration (FDA) Antimicrobial Resistance Isolate (ARI) Bank comprising 55 clinical strains with full genome sequences and antibiotic susceptibility testing (AST) data for 11 clinically relevant antibiotics. As phages in this study, we use three well-characterized, morphologically distinct phages, OMKO1, Luz19, and PAML31-1. We screen for phage resistance using a growth suppression assay, then conduct statistical analysis against antibiotic MIC (Minimum Inhibitory Concentration) data provided by the CDC to define association patterns across this dataset. We find multiple significant susceptibility correlations between pairs of antibiotics and phages, and a positive overall association between average phage resistance and antibiotic resistance across the 55 strains, even controlling for phylogenetic associations (=0.358, p<0.005). We conclude that phage and antibiotic resistance are positively associated across this clinical isolate collection, suggesting that the two resistance phenotypes are not independent in P. aeruginosa. These findings have implications for the development of phage-antibiotic cocktails.

Macrolides remain the first-line antimicrobial treatment for pertussis, primarily caused by Bordetella pertussis. Emergence of macrolide-resistant B. pertussis in Australia and globally presents a growing concern for clinical management. As molecular diagnosis predominates for pertussis, limited numbers of cultures are available for antimicrobial susceptibility testing. The A2037G mutation in the 23S rRNA gene is most commonly associated with macrolide resistance in B. pertussis, yet no commercial molecular assay is available for its detection. In this study, we adapted and validated a previously published real-time PCR assay as a laboratory developed test (LDT) on the Panther Fusion(R) system using Open Access functionality to detect the macrolide resistance-associated mutation in B. pertussis from culture isolates and clinical specimens. Total turnaround time was ~2.5 h for the first result and 2-3 min for subsequent results in the same batch, with an estimated cost of AUD 18 per sample, excluding labour. A total of 30 samples were included in the validation panel to assess assay performance. All isolates and clinical specimens in the validation panel produced results concordant with the expected mutation status, demonstrating 100% accuracy, sensitivity and specificity. The assay demonstrated a limit of detection of 1.5 x 103 CFU/mL (22 CFU/reaction). This Panther Fusion(R) LDT provides a rapid and fully automated approach for molecular detection of the targeted mutation associated with macrolide resistance in B. pertussis. Its integration into routine molecular workflows as a reflex test following identification of B. pertussis may facilitate timely identification of resistant infections.

Background: Bovine respiratory disease (BRD) is a major cause of antimicrobial use in cattle, raising concerns about antimicrobial resistance (AMR). This systematic review estimated pooled AMR proportions in BRD pathogens: Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni, and assessed temporal and geographic trends in resistance. Methods: Five antimicrobials commonly used for BRD treatment were evaluated: penicillin G (PEN), tetracycline (TET), florfenicol (FLO), tulathromycin (TUL), and enrofloxacin (ENR). Following PRISMA guidelines, 1,097 records were screened and 24 studies met inclusion criteria. Study quality and risk of bias were assessed, and random-effects meta-analyses estimated pooled proportions of resistant isolates by antimicrobial, continent and period. Results: A total of 13,949 bacterial isolates were analysed including P. multocida (5,615), M. haemolytica (5,585), and H. somni (2,749). TET resistance was highest across all pathogens (12-30%), followed by TUL (6-11%), PEN (4-12%), FLO (0.5-1.6%) and ENR (0.2-1.1%). TET resistance in M. haemolytica and P. multocida, and FLO resistance in P. multocida were significantly more frequent in North America than in Europe (p[&le;]0.05). TUL resistance increased significantly in P. multocida after 2013 (p=0.038), with similar non significant trends in M. haemolytica and H. somni. FLO resistance decreased significantly in H. somni after 2013 (p=0.013). Egger's test identified significant funnel plot asymmetry for ENR resistance in H. somni and PEN resistance in M. haemolytica, suggesting possible small study effects. Conclusion: These results offer insights into distribution of phenotypic resistance across pathogens and regions, informing BRD antimicrobial treatment guidelines and One-Health antimicrobial stewardship aimed at preserving the effectiveness of medically important antimicrobials.

Invasive candidiasis has become more common in recent decades, particularly within ICUs. Identifying specific Candida spp., and testing their sensitivity to antifungal drugs is crucial for effective treatment that helps healthcare providers to detect potential treatment challenges early. This study aimed to identify Candida spp. at their spp. level present in blood, assess their susceptibility to antifungal agents, and apply a random forest classifier to predict the best antifungal drug for a given species. The isolates were classified at the species complex level through MALDI-TOF MS. The strains' susceptibility to antifungal agents such as AMB, FLZ, VOZ, ITZ, POZ, CAS, MFN, and ANF was assessed using CLSI guidelines. Out of the 354 Candida spp. isolated from blood, C. utilis was found to be the predominant species, followed by C. tropicalis, and C. albicans. This study demonstrated that MFN and ANF exhibited high potency, with an impressive MIC90 of 0.12 {micro}g/mL against all isolates, surpassing CAS, which had a slightly higher overall MIC90 of 0.25 {micro}g/mL. FLZ exhibited the highest MIC90 value among the azoles at 16 {micro}g/mL, while VOZ, ITZ, and POZ all had MIC90 values of 0.5 {micro}g/mL. AMB MIC90 values were 2 {micro}g/mL against all isolated Candida species. The Random Forest AI/ML model showed perfect overall prediction, with the actual and predicted best antifungal drugs matching for all fungal species. This study is particularly essential because rare Candida spp. becoming more common and exhibiting higher MICs to AMB and FLZ and required suitable remedies for controlling the infection.

Carbohydrate inducible promoters on expression plasmids are widely used for biotechnology and basic science research. However, using carbohydrates for inducers has drawbacks including influencing bacterial metabolism, the inducer being used as a carbon source by the bacteria, high background expression, and only a subset of cells experiencing promoter activation. Furthermore, some bacteria including the pathogen Acinetobacter baumannii currently lack good carbohydrate-inducible promoters. To address this issue, a tetracycline-inducible promoter, PtetB, isolated from A. baumannii was cloned and evaluated in a number of important bacteria: Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Pseudomonas fluorescens, and Serratia marcescens. A highly sensitive luxCDABE reporter was used to evaluate promoter activity. S. marcescens strains with elevated and reduced cyclic-AMP levels were used to evaluate the impact of cAMP on PtetB function. The PtetB promoter was induced over 800-fold in A. baumannii and 10-750-fold inducible in the other tested species. Background expression was lower from PtetB in the pseudomonads than previously described carbohydrate inducible promoters. Data indicated that the PtetB promoter system may be a useful tool for future basic science research with the tested bacteria.

Little is currently known about the regulation of PL fimbriae produced by some pathogenic E. coli strains. We identified PlfB, a transcriptional regulator of the PapB family, as a negative regulator of PL fimbriae (Plf). Deletion of plfB significantly increased plfA transcription and Plf production. PlfB bound specifically to the plfA promoter region. Using a PplfA-lux reporter system, the deletion of plfB caused sustained and increased expression across serial passages. Global regulatory genes such as lrp, argR, and hns were also implicated in regulation of plf expression. Loss of lrp or argR decreased plf expression, suggesting these regulators positively regulate PL fimbriae. By contrast, loss of hns increased levels of plf expression, supporting its role as a negative regulator. Interestingly, loss of plfB significantly increased bacterial colonization in the lung of 6-day-old turkey poults. Further, complementation of plfB restored plf fimbrial expression and colonization of turkey lungs to wild-type levels. This further supports an important role for PL fimbriae for colonization of turkey lungs, since loss of plfB which resulted in increased plf gene expression in turkey lungs also correlated with higher bacterial numbers in the lungs. Taken together, these results indicate that PlfB acts as a negative regulator to reduce levels of PL fimbrial expression, under some conditions, but that it is not required for plf expression. This contrasts with the role the PapB regulator, which has been shown to play an essential role in expression of P fimbriae in uropathogenic E. coli strains.

Importance: Nirsevimab, a monoclonal antibody against RSV, was implemented in France in September 2023. Recently, rare resistance-associated substitutions were described in RSV but the effectiveness according to lineages remains unclear. Objective: We aimed to estimate the effectiveness of nirsevimab against hospitalization for RSV bronchiolitis according to RSV lineages. Design: We conducted a multicenter test-negative case-control study from October 15, 2023 to March 15, 2025. Setting: This study was based on data from three national multicentric prospective studies. The 12 participating centers were secondary or tertiary hospital with a pediatric department located in France. Participants: We included all children younger than 12 months who were hospitalized for RSV bronchiolitis in one of the participating centers in France during the two first RSV epidemic seasons following the implementation of nirsevimab (from October 15, 2023 to February 29, 2024, and from October 10, 2024 to March 15, 2025). Main outcomes and measures: The main outcome of the study was the RSV test result of bronchiolitis cases. RSV whole-genome sequencing was performed using a tiled amplicon approach covering the complete viral genome, as previously described in the POLYRES studies. We estimated the effectiveness of nirsevimab by a multivariable logistic regression model adjusted for potential confounders. We estimated the adjusted risk of immunization failure for each lineage by calculating relative odds ratio to a reference lineage. A range of sensitivity analyses were conducted. Results: We included 3019 infants with bronchiolitis among which 2273 had a positive RSV test (case patients) and 746 had a negative RSV test (control patients). Overall, 373/2273 (16.4%) case patients were immunized by nirsevimab versus 423/746 (56.7%) control patients. The adjusted effectiveness of nirsevimab against hospitalization for bronchiolitis was 88.4% (95% CI, 84.5-91.4) with RSV-B and 79.4% (95% CI, 73.7-83.8) with RSV-A. The risk of immunization failure was 3.2-fold (95% CI 1.8-5.7) higher for lineages derived from A.D.3 than for lineages derived from B.D.4.1. Conclusion and relevance: In this multicentric case-control study, we observed that nirsevimab effectiveness was variable across RSV lineages, with a lower effectiveness against A.D.3 lineages compare to others. Further surveillance is needed to confirm these findings and assess their implication on RSV lineages epidemiology as nirsevimab use expands.

Objective Heme-dependent metronidazole (MTZ) resistance has emerged in Clostridioides difficile and is primarily mediated by a T-to-G single-nucleotide polymorphism (SNP) in the promoter of nimB (PnimBG). We aimed to develop a CRISPR-Cas12a-based assay for rapid detection of the PnimBG mutation associated with MTZ resistance. Methods A series of primers and CRISPR RNAs (crRNAs) were designed and optimized to identify the most effective combination for discriminating between PnimBG (MTZ-resistant) and PnimBT (MTZ-susceptible) alleles. Detection was evaluated by visual fluorescence using blue-light and UV imaging systems, as well as by quantitative fluorescence measurements. Results The CRISPR-Cas12a assay accurately differentiated PnimBG and PnimBT alleles in C. difficile. In a collection of clinical isolates, the assay correctly identified all 11 MTZ-susceptible isolates carrying the PnimBT allele and all 10 MTZ-resistant isolates carrying the PnimBG allele. Fluorescence signals were readily detected both visually and quantitatively. Furthermore, colony PCR using crude colony lysates yielded results comparable to those obtained with purified genomic DNA, enabling rapid colony-based detection without conventional DNA extraction. Conclusions The CRISPR-Cas12a assay enables rapid molecular detection of the PnimBG mutation associated with heme-dependent MTZ resistance in C. difficile. This approach could complement conventional susceptibility testing for MTZ resistance detection.

Importance: Antibiotic-resistant infections in neonates often arise from the infant's own colonizing bacteria harboring antibiotic resistance genes (ARG). This study evaluates ARG that impact antibiotic selection and drive resistance-related mortality, termed clinically important antibiotic resistance genes (CI-ARG). Objective: To determine differences in gut CI-ARG abundance in children from birth through 3 years old, stratified by neonatal intensive care unit (NICU) admission and antibiotic (abx) exposure in the first two months Design: Cohort study (sequencing, analysis completed 2025-2026) using shotgun metagenomic sequencing of stool samples from infants in two studies: Neonatal Intestinal Microbiome (+NICU groups, 2015-2022), The First 1000 Days of Life and Beyond (-NICU groups, 2018-2021). Infants grouped into four cohorts: +NICU/+abx, +NICU/-abx, -NICU/-abx, and -NICU/+abx. Prespecified CI-ARG abundance compared longitudinally among groups. Setting: NICU, well-baby nursery, Inova Fairfax Hospital, Virginia Participants: +NICU criteria: admission to the NICU, anticipated length of stay (LOS) of at least five days, maternal age at least 18 years. -NICU: parents with good general health and age at least 18 years enrolled prior to infant birth. Stool samples: adequate stool processing volume, at least one stool sample from before one month and after one year of age, 7-day minimum between serial samples. Exposures: NICU versus well-baby nursery; antibiotics versus none in first two months of corrected age Main Outcomes and Measures: Predefined primary outcome- longitudinal CI-ARG abundance by group, compared using linear mixed effects models with adjustment for multiple comparisons (Benjamini-Hochberg procedure). Predefined secondary outcomes- differences in overall microbiota and resistome composition. Results: 1000 serial stool samples, 179 infants (birth-39 months). Longitudinal abundance significantly differed among cohorts for 11 CI-ARG (p < 0.05); often higher in the +NICU groups in early life, with or without antibiotic exposure. Abundance of ARG conferring resistance to aminoglycosides, macrolides, and fluoroquinolones later decreased below -NICU levels. mecA, which often drives methicillin resistance in Staphylococcus, was detected only in +NICU infants during premature period. Conclusions: This longitudinal study demonstrates significant longitudinal CI-ARG differences in children grouped by early-life NICU status and/or antibiotic exposure. Future studies should explore the mechanisms driving these CI-ARG changes and evaluate their impact on infection risk and community spread.

Antimicrobial resistance is a global One Health threat connecting antimicrobial use in human health, animal husbandry, and companion animal health with concern for persistence in environmental reservoirs. Complicating this threat is the gap that exists in our understanding of the intersection of antimicrobial resistance among humans and our companion and food production animals. This study applies a visual and statistical approach to further understand antimicrobial resistance characteristics and relatedness of Escherichia coli found in humans, dogs and cattle. The primary study collection included third-generation cephem resistant (3GCR) E. coli isolates recovered from human, dog, and cattle gastrointestinal specimens and secondarily human and dog isolates recovered from infection sources, primarily urinary tract infections. We previously reported on the transferable gene targets encoding for 3GCR in colonizing isolates and here further identified the familial-like clonal group of each resistant isolate using a novel clonotype diagnostic (septatyping). Together, this approach identified distinct genetic signatures among these 3GCR isolates, many of which are peculiar to their respective host species. We found that the overlap measured by the correlation in abundance of shared clonotypes of resistant E. coli among hosts revealed statistically greater similarity between dogs and humans than between cattle and humans. Yet, the reservoir of AMR genes was highest in cattle and secondarily dogs. While these findings demonstrate that clonotypes of 3GCR E. coli in humans, dogs and cattle display significant host specificity, transient colonization from a host enriched with resistant strains may still pose considerable risk of horizontal transfer of resistance genes between hosts living in proximity to each other.

Background Neonatal sepsis remains a major cause of neonatal morbidity and mortality, particularly in low- and middle-income countries. Its management is increasingly complicated by antimicrobial resistance (AMR), while limited facility-specific data on causative bacterial pathogens and susceptibility patterns often necessitate empirical antibiotic treatment. This study assessed the prevalence of neonatal sepsis, bacterial pathogens and antimicrobial resistance patterns, and maternal, neonatal and clinical factors associated with neonatal sepsis among neonates admitted to the Neonatal Intensive Care Unit (NICU) at Livingstone University Teaching Hospital (LUTH), Zambia. Methods A retrospective cross-sectional record review was conducted among neonates admitted to the NICU at LUTH from 2020 to 2025. A total of 150 neonatal records were analysed. Neonatal, maternal, clinical, blood culture and antimicrobial susceptibility data were analysed using descriptive statistics, chi-square tests and logistic regression. Missing information was treated as missing and was not imputed; denominators were reported according to the records available for each analysis. Results Neonatal sepsis was identified in 52/150 neonates, giving a prevalence of 34.7% (95% CI: 27.5%-42.6%). Among the 52 sepsis cases, 20 had positive blood cultures, corresponding to a culture positivity rate of 38.5% (95% CI: 26.5%-52.0%); this represented 13.3% of the full study sample. Maternal fever during labour (aOR=6.822; 95% CI: 2.032-22.905; p=0.002) and caesarean delivery (aOR=2.245; 95% CI: 1.050-4.801; p=0.037) were independently associated with neonatal sepsis, while increasing birth weight was protective (aOR=0.891 per 100 g; 95% CI: 0.817-0.973; p=0.010). Escherichia coli was the most frequent isolate (5/20; 25.0%), followed by Klebsiella pneumoniae (4/20; 20.0%) and Staphylococcus aureus (4/20; 20.0%). Resistance was highest to ampicillin (15/19; 78.9%), followed by gentamicin and ceftriaxone (10/19; 52.6% each), while all 19 isolates tested against meropenem were susceptible. Conclusion The findings indicate that empirical management of neonatal sepsis at LUTH should be informed by local microbiological surveillance rather than reliance on historical first-line susceptibility assumptions. Routine blood culture and susceptibility testing, a regularly updated facility antibiogram, strengthened infection prevention and antimicrobial stewardship are required to improve treatment decisions and preserve effective antibiotics. Interpretation should consider the retrospective single-centre design, incomplete routine records and the small number of culture-positive isolates.

Methicillin-resistant Staphylococcus aureus (MRSA) is non-susceptible to beta-lactams. Blockade of cell wall biosynthesis is a potential target for beta-lactam enhancement but requires further investigation. A butyrolactone derivative enhanced beta-lactams against MRSA strains by reducing the availability of D-Ala-D-Ala. Unlike D-cycloserine, it did not inhibit D-Ala-D-Ala ligase (Ddl). Nor did it show an additive or synergistic effect when combined with cycloserine, indicating a unique mechanism for blocking cell wall precursor production that does not involve the traditional Lipid II pathway. Notably, beta-lactam potentiation by our chemical or D-cycloserine was highly dependent on the intrinsic autolytic ability of the tested MRSA strains. Strains that resisted lysis upon Triton X-100 exposure showed a minimal increase in beta-lactam susceptibility, whereas highly autolytic strains showed significant changes in their beta-lactam MICs. We have thus identified autolytic ability as the Achilles Heel in the strategy of targeting cell wall biosynthesis for beta-lactam potentiation.

BackgroundFebrile neutropenia requires rapid empirical antibiotic therapy, with regimen selection shaped by local prescribing practice and pathogen patterns. We described starting treatment, later drug changes, microbiological findings, and inpatient outcomes. MethodsThis ambispective cohort comprised 96 episodes from 90 patients admitted to a tertiary-level teaching hospital. Treatment and outcome analyses used each episode as the unit of observation. Recorded variables included the starting antibiotics, later regimen modification, microbiology, hospitalization length, invasive fungal infection (IFI) as captured in study records, and disposition. Comparisons based on escalation status were exploratory. ResultCefoperazone-sulbactam appeared in 62/96 initial regimens (64.6%), amikacin in 42 (43.8%), teicoplanin in 28 (29.2%), and meropenem in 14 (14.6%). Eighteen episodes (18.8%) required a change that broadened or substituted antibacterial therapy. Among 31 microbiologically documented infections, 22 (71.0%) yielded Gram-negative organisms and 9 (29.0%) were polymicrobial. Median length of admission was 18.5 days in the escalation group and 9 days in the remainder (p<0.001). Mortality was 27.8% (5/18) with escalation and 5.1% (4/78) without it (p=0.011), with nine inhospital deaths overall (9.4%). ConclusionAntibacterial management differed within this cohort, with treatment escalation required in 18 of 96 episodes. Gram-negative organisms comprised most microbiologically confirmed infections. Escalation marked a clinically complex course with prolonged hospitalization and greater observed mortality; the observational design does not establish comparative efficacy or causation.

GeneCapture is developing a novel, point-of-care, rapid AST technique that, when fully automated, can accomplish AST within 2 hours directly from a raw sample, representing a significant advancement in diagnostic capabilities. For this study, a panel of uropathogen isolates was collected from clinical specimens positive for urinary tract infection from various laboratories in the southern US. A selection of these isolates were then spiked into fresh clean-catch urine samples to produce mock samples covering a variety of antibiotic responses. Testing was performed on 20 strains of Escherichia coli, the cause of over 80% of UTIs, and 6 strains each of Klebsiella pneumoniae and Proteus mirabilis, the next most common causes. Each strain was tested against the susceptible, intermediate and resistant (S-I-R) breakpoints of up to 5 appropriate antibiotics including Amoxicillin-Clavulanate, Cefpodoxime, Ciprofloxacin, Nitrofurantoin and Trimethoprim-Sulfamethoxazole. The new method uses a phenotypic assessment of bacterial growth, comparing responses from bacteria treated with antibiotics at S-I-R breakpoint concentrations to untreated controls as the metric for determining susceptibility. Exposure to the drugs for only 90 minutes gave a Categorical Agreement of 98% to gold standard culture results across the resulting 247 bacteria/antibiotic pairs. Testing on separate days of nine of these strains in triplicate gave a reproducibility of 97%. The sequential steps of this novel AST - sample processing, growth, labeling, and counting - can readily be performed on an automated cartridge that is currently under development. The presented work, which took place in a laboratory setting, demonstrates the efficacy of the assay.

Linezolid is a key component of the bedaquiline, pretomanid, linezolid (BPaL) regimen for rifampin-resistant tuberculosis, but dose- and duration-dependent mitochondrial toxicity frequently limits its use. TBD09 (formerly MK-7762) is a novel oxazolidinone developed to maintain antitubercular potency comparable to linezolid while reducing related adverse events. We evaluated the contribution of TBD09 to the bactericidal and sterilizing activities of BPa-based regimens in a murine tuberculosis model. BALB/c mice were aerosol-infected with Mycobacterium tuberculosis H37Rv and treated starting 2 weeks post-infection. In Experiment 1, dose-ranging bactericidal activity of TBD09 (50, 100, 200 mg/kg) was assessed alone and in combination with BPa, with comparison to linezolid and sutezolid. In Experiment 2, the sterilizing activity of TBD09 (200 mg/kg) in combination with BPa and BPa plus moxifloxacin (M) was assessed by evaluating relapse after treatment durations of 4-22 weeks. TBD09 monotherapy was bacteriostatic, similar to linezolid over the first 4 weeks of treatment. The addition of TBD09 to BPa significantly enhanced bactericidal activity comparable to the addition of linezolid. In relapse assessments, BPa+TBD09 resulted in significantly fewer relapses compared to BPa alone after 14 weeks of treatment, and BPaM+TBD09 resulted in significantly fewer relapses compared to BPaM after 10 weeks. Model-based analysis estimated the treatment duration to 95% cure for BPa+TBD09 at 2.7 weeks, compared to 3.2 weeks for BPaL, although the time to 50% cure was similar. These results demonstrate that TBD09 provides bactericidal and sterilizing activity similar to linezolid in combination with BPa(M), supporting further clinical development of TBD09 for tuberculosis.