Background: Mapping the local etiology and susceptibility of common pathogens causing complicated urinary tract infection (cUTI) is important for promoting evidence-based antimicrobial prescribing. Evaluating the prevalence of extended-spectrum beta-lactamase (ESBL), AmpC beta-lactamase (AmpC), and carbapenemase-producing Enterobacterales (CPEs) is equally important as it informs treatment guidelines and empiric management. Whole genome sequencing (WGS) enhances antimicrobial resistance (AMR) surveillance by complementing phenotypic antimicrobial susceptibility testing, offering deeper insights into resistance mechanisms, transmissions, and evolutions. Integrating it into routine AMR monitoring can significantly improve global efforts to combat antimicrobial resistance. Methods: Antimicrobial susceptibility profiles of isolates from cUTI were collected from patients presenting with Sultan Qaboos University Hospital, Muscat and Suhar Hospital, Suhar, Oman. Automated systems as well as manual methods were used for detection of ESBL, AmpC, and CPE. ESBLs, AmpC β-lactamases, and CPEs were further detected by manual methods: double-disk synergy test for ESBL; disk approximation assay and D69C AmpC detection set for AmpC, and mCIM and KPC/IMP/NDM/VIM/OXA-48 Combo test kit for CPE. WGS was carried out in 11 FOX-resistant E. coli and (22 carbapenem-resistant K. pneumoniae) isolates with varying susceptibilities to identify circulating clades, AMR genes, and plasmids. Bioinformatic analysis was performed using online tools. Results: The susceptibility patterns of E. coli from cUTI were as follows: nitrofurantoin (96%), fosfomycin (100%), fluoroquinolones (44%), aminoglycosides (93%), piperacillin-tazobactam (95%), and carbapenems (98%). In comparison, susceptibility rates of K. pneumoniae were far lower: nitrofurantoin (38%), fosfomycin (89%), aminoglycosides (82%), piperacillin-tazobactam (72%), and carbapenems (83%). K. pneumoniae, however, was more susceptible to fluoroquinolones at 47% in comparison to E. coli. The prevalence of ESBL among E. coli and K. pneumoniae was 37.2% and CRE was 6.2% while the estimated prevalence of AmpC was 5.4%. It was observed that E. coli was the predominant ESBL and AmpC producer, while K. pneumoniae was the major carbapenem-resistant Enterobacterales (CREs) producer. No predominant multi-locus sequence typing (MLST) lineage was observed in AmpC-producing E. coli with nine E. coli MLST lineages being identified from eleven isolates: ST-10, ST-69, ST-77, ST-131, ST-156, ST-167, ST-361, ST-1125, and ST-2520. On the other hand, a less diverse MLST spectrum (ST-2096, ST-231, ST-147, ST-1770, and ST-111) was observed in the CRE K. pneumoniae. Among the five MLST lineages, ST-2096 (twelve isolates) and ST-147 (seven isolates) predominated. WGS revealed that DHA-1 was the predominant plasmid-mediated AmpC gene in E. coli, while OXA-232 and NDM-5 were the most common carbapenemase genes in K. pneumoniae. All E. coli DHA-1-positive isolates co-harbored the quinolone resistance gene qnrB4 and the sulfonamide resistance gene sul1 while no aminoglycoside resistance genes were detected. The majority of CPE CRE K. pneumoniae carried other β-lactamase genes, such as blaCTX-M-15, blaSHV, and blaTEM; all co-harbored the quinolone resistance gene OqxAB; and 77% carried the aminoglycoside resistance gene armA. Conclusions: Our results suggest that fosfomycin is an excellent empiric choice for treating complicated cystitis caused by both E. coli and K. pneumoniae, while nitrofurantoin is an appropriate choice for E. coli cystitis but not for K. pneumoniae. Aminoglycosides and piperacillin-tazobactam are excellent intravenous alternatives that spare carbapenems. DHA-1 was the predominant AmpC in E. coli, while OXA-232 and NDM-5 were the predominant carbapenemases in K. pneumoniae. In AmpC-producing E. coli, no MLST predominated, suggesting a significant flux in E. coli with lack of stable clades in this region. In contrast, ST-2096 and ST-147 predominated in CRE Klebsiella pneumoniae, suggesting a stable circulation of these in Oman. WGS profiling provides a deeper understanding of the genetic basis of resistance and enhances surveillance and offers comprehensive insights into pathogen evolution and transmission patterns.

Background: Non-O1, non-O139 Vibrio cholerae (NOVC) bacteraemia is an uncommon infection and could be associated with life-threatening conditions in susceptible hosts. Definitive management guidelines are lacking. Aim: To describe the clinical spectrum, treatment practices and outcome of NOVC bacteraemia. Methods: Eight patients with NOVC bacteraemia admitted to two large tertiary care hospitals in Oman were identified over a 10-year period (2010-2020). Data were extracted retrospectively from the hospital patient data management. Results: Six (75.0%) patients were male, and the median age of patients was 67.5 years. The majority of cases (87.5%) were not associated with travel and no clear sources were identified. All patients had predisposing factors including diabetes mellitus, chronic liver disease or malignancies. Gastrointestinal symptoms were the predominant manifestations in 75.0% of cases, but diarrhoea was only reported in one patient. Conclusions: Early presentation (median interval from symptom onset to presentation 1.5 days), appropriate management and highly susceptible isolates may have contributed to the favourable outcome, as there were no cases of death or severe course of infection. All patients were discharged home after a median of 9 days of hospitalization.

Background: Mapping the local etiology and antimicrobial susceptibility profile of pathogens causing complicated urinary tract infection (cUTI) is important for promoting evidence based antimicrobial prescribing. WGS plays an important role in genomic surveillance of AMR and understanding circulating clades. Methods: Antimicrobial susceptibility profile of patients presenting with cUTI were analysed. ESBLs, AmpC β-lactamases, and CRE were detected by combined disc test (ESBL), D69C AmpC detection set (AmpC) and KPC/IMP/NDM/VIM/OXA-48 Combo test kit (CRE). Whole genome sequencing (WGS) was carried out in eleven E. coli AmpC and twenty-two K. pneumoniae CRE isolates. Bioinformatic analysis was performed using online tools. Results: The susceptibility patterns of E. coli and K. pneumoniae were as follows: nitrofurantoin (96%, 38%), fosfomycin (100%,89%), fluoroquinolones (44%, 47%), aminoglycosides (93%, 82%), piperacillin-tazobactam (95%,72% ) and carbapenems (98%, 83%). The overall prevalence of ESBL among E. coli and K. pneumoniae was 37.2%, while the estimated prevalence of AmpC was 5.4% and the prevalence of CRE was 6.2%. E. coli was the predominant ESBL and AmpC producer, whereas K. pneumoniae was the major CRE producer. Nine E. coli MLST lineages were identified: ST-10, ST-69, ST-77, ST-131, ST-156, ST-167, ST-361, ST-1125 and ST-2520, while in K. pneumoniae 5 MLST lineages were observed: ST-2096, ST-231, ST-147, ST-1770 and ST-111. ST-2096 (12 isolates) and ST-147 (7 isolates) predominated. WGS revealed DHA-1 as the predominant plasmid-mediated AmpC gene, while OXA-232 and NDM-5 as the most common carbapenemase genes. All E. coli DHA-1 positive isolates co-harboured the quinolone resistance gene qnrB4 and the sulfonamide resistance gene sul1 while no aminoglycoside resistance genes were detected. The majority of CRE K. pneumoniae carried other β-lactamase genes such as blaCTX-M-15, blaSHV, blaTEM, and all co-harboured the quinolone resistance gene OqxAB and 77% carried the aminoglycoside resistance gene armA. Conclusions: Fosfomycin is an excellent choice for treating complicated cystitis caused by multi drug resistant pathogens. Nitrofurantoin retains excellent activity against E. coli but not K. pneumoniae. Aminoglycosides and piperacillin tazobactam are alternatives which spare carbapenems. WGS results revealed DHA-1 was the predominant AmpC while OXA-232 and NDM-5 were the circulating carbapenemases. In AmpC producing E.coli no MLST predominated while in CRE Klebsiella pneumoniae ST-2096 and ST-147 predominated.

Background: Ralstonia species are environmental Gram-negative bacilli increasingly linked to healthcare-associated bloodstream infection (BSI) outbreaks from contaminated medical solutions. We describe an outbreak of Ralstonia mannitolilytica BSI in which the source was identified and withdrawn within 24 hours. Methods: Following an unusual cluster of R. mannitolilytica blood cultures on 29 September 2024 at a 700-bed tertiary-care hospital in Oman, we conducted a multidisciplinary investigation including chart review, hospitalwide surveillance, environmental and product sampling, antimicrobial susceptibility testing, and pulsed-field gel electrophoresis (PFGE) of clinical and product isolates. Results: Between 29 September and 8 October 2024, 21 patients met the case definition (median age 9 yr; 62% pediatric; 62% male; 95% immunocompromised; 86% with central venous access). Newly introduced pre-filled 10 mL 0.9% sodium chloride vials from a single manufacturer yielded R. mannitolilytica with concordant clinical and product antimicrobial susceptibility profiles. PFGE of 18 clinical isolates and one product isolate demonstrated 100% genetic relatedness, confirming a single-clone outbreak. The implicated product was withdrawn within 24 hours of cluster recognition. Thirteen of 21 patients had their central catheters removed; all received intravenous trimethoprim–sulfamethoxazole. Two patients experienced bacteremia recurrence after initial line retention; no outbreak-related deaths occurred. Conclusions: Prefilled saline vials can serve as the source of clonal R. mannitolilytica BSI outbreaks in immunocompromised patients. Laboratory-driven cluster detection, multidisciplinary coordination, and rapid product suspension enabled source identification within 24 hours and limited outbreak size and severity. Vigilance after introduction of new pharmaceutical products and prompt catheter removal in catheter-associated Ralstonia BSI are essential.