Ciprofloxacin Resistance Research Articles

Draft genome assemblies of ciprofloxacin-resistant derivatives of Bacillus cereus strain ATCC14579.

Ciprofloxacin resistance in Bacillus cereus involves diverse and understudied mechanisms. Here, we present draft genome assemblies of 95 experimentally evolved Bacillus cereus strains that exhibit increased growth in the presence of ciprofloxacin, many containing novel mutations not previously described for this phenotype.

Current Antimicrobial Susceptibility Trends and Clinical Outcomes of Typhoidal Salmonella in a Large Health Authority in British Columbia, Canada.

From 2018 to 2021, travel-related extensively drug-resistant (XDR) Salmonella Typhi was identified in Ontario, Canada. Opportunities remain to characterize typhoidal Salmonella antimicrobial susceptibility trends (including multi-drug resistance phenotypes; MDR) within a large health authority in British Columbia, Canada. This retrospective study included patients with Salmonella Typhi or Paratyphi A, B or C bacteremia identified at Fraser Health regional microbiology laboratory from 2018 to 2024. The primary outcome was the proportion of cases with MDR and XDR typhoidal Salmonella. Secondary outcomes included annual antimicrobial susceptibility for ampicillin, ceftriaxone, ciprofloxacin, trimethoprim-sulfamethoxazole, ertapenem, meropenem and azithromycin. Clinical outcomes included hospitalization length, and 30-day mortality, clinical cure and infection relapse. Among 271 patients, most were previously healthy and recently travelled. There were extended spectrum beta-lactamase (1.1%) and MDR (1.5%) typhoidal Salmonella, with no XDR cases observed. In 2024, ciprofloxacin resistance was 96% while susceptibility rates were high for other studied antimicrobials. Within 30 days, no deaths were reported; however, six patients (3%) had infection relapse. Currently, in British Columbia, MDR typhoidal Salmonella remains rare. Empiric ciprofloxacin should be avoided due to persistently high resistance rates. With ongoing travel patterns, it is beneficial for institutions to continue typhoidal Salmonella antimicrobial susceptibility surveillance, and travelers should seek pre-travel health assessments.

Genomic Characterization of Enterococcus casseliflavus Isolated from Beef Cows and Calves.

Enterococcus species are used as One Health indicators of antimicrobial resistance (AMR) in humans, animals, and the environment. A surveillance study in beef cows and calves isolated Enterococcus casseliflavus along with E. faecium, E. faecalis, and E. hirae. Given the high prevalence of E. casseliflavus, we elected to characterize this species to better understand its role in the antimicrobial resistance of enterococci in cows and calves. Almost 12% of E. casseliflavus isolates exhibited multidrug resistance with the majority being resistant to lincomycin (99%), followed by quinupristin-dalfopristin (34%), ciprofloxacin (9.6%), tylosin (4.5%), erythromycin (2.7%), tetracycline (1.8%), tigecycline (1.5%), daptomycin (0.6%), streptomycin (0.3%), and kanamycin (0.3%). All E. casseliflavus were susceptible to chloramphenicol, penicillin, streptomycin, nitrofurantoin, gentamicin, and linezolid. Whole genome antimicrobial resistance gene profiling identified vanC-type intrinsic vancomycin resistance genes in all E. casseliflavus, with the vanC4XYT gene cluster being dominant (67%) followed by vanC2XYT (31%) and vanC3XYT (1.5%). Resistance genes for erythromycin (ermB) and tetracycline (tetM) were rarely identified (2.1% and 1.2%, respectively) within E. casseliflavus genomes. No resistance genes were identified to explain either the quinupristin-dalfopristin or ciprofloxacin resistance in these isolates. A core genome phylogenetic tree revealed two clades that exhibited no distinct association with the age of the host, time of sample collection, or the farm sampled. The open nature of the E. casseliflavus pan-genome highlighted its intraspecies diversity. These findings suggest that E. casseliflavus is likely a low-risk species in terms of contributing to antimicrobial resistance in the cow-calf sector.

Epidemiological characteristics and trends of notified enteric fevers in Germany, 2001 to 2023.

BackgroundEnteric fevers (EF) are caused by infections with Salmonella Typhi (STY) or Salmonella Paratyphi (SP) A-C (except the SPB enteric pathovar) and exhibit increasing antimicrobial resistance (AMR). Notification is mandatory in Germany.AimTo describe characteristics and trends of notified EF cases in Germany.MethodsWe analysed German EF notifications 2001-2023 fulfilling the case definition. We calculated numbers of imported EF cases per 100,000 air travellers by country of exposure 2012-2023.ResultsIn 2001-2023, 2,670 confirmed EF cases were notified: 56% (1,498/2,670) STY, 44% (1,172/2,670) SP, with seasonal peaks in April-May and August-September. Aside from years with COVID-19-related travel restrictions, STY notifications were stable, while SP notifications decreased. Median age of EF cases was 26 years (range: 0-93) and 55% (1,458/2,663) were male. Of cases with information, 93% (2,491/2,670) had fever, 71% (1,906/2,670) diarrhoea, 78% (2,033/2,607) were hospitalised (STY: 85% (1,234/1,459) vs SP: 70% (799/1,148), p < 0.001) and four died (two STY, one SPA, one SPB). Of STY cases, 7% (88/1,221) reported vaccination. Overall, 86% (2,251/2,613) of cases acquired EF abroad, most commonly in India, Pakistan and Türkiye. Ciprofloxacin resistance was reported for 50/59 STY and 16/18 SPA cases and cefotaxime resistance for 10/57 STY cases (exposure: Pakistan (9/10), India (1/10)) with information since 2017. We also report outbreaks and incidence among travellers.ConclusionsMost cases were imported and had high hospitalisation rates and AMR. Typhoid vaccination was underutilised, highlighting that additional ways to reach at-risk travellers with information and vaccination offers are needed.

Enhancing activity and overcoming ciprofloxacin resistance via multifunctional nanostructured lipid carriers

Enhancing activity and overcoming ciprofloxacin resistance via multifunctional nanostructured lipid carriers

Salad Vegetables as a Reservoir of Antimicrobial-Resistant Enterococcus: Exploring Diversity, Resistome, Virulence, and Plasmid Dynamics.

This study investigates the occurrence, antimicrobial resistance (AMR) profiles, virulence factors, and plasmid composition of Enterococcus species isolated from salad ingredients in the United Arab Emirates (UAE). Four hundred salad vegetable items collected from local markets, over ten months through 2023, were screened, yielding an Enterococcus detection rate of 85.5% (342/400). E. casseliflavus was the most commonly identified species (50%), followed by E. faecium (20%) and E. faecalis (16%). Among 85 Enterococcus isolates tested for antimicrobial susceptibility, 55.3% displayed resistance to at least one agent, with 18.8% classified as multidrug-resistant (MDR). All isolates were not resistant to ampicillin, linezolid, teicoplanin, tigecycline, and high-level gentamicin. Intrinsic phenotypic resistance to vancomycin was found in E. gallinarum and E. casseliflavus, while low-level (<5%) ciprofloxacin and erythromycin resistance was sporadically detected in E. faecium and E. faecalis. Whole-genome sequencing (WGS) of 14 isolates (nine E. faecium, four E. faecalis, and one E. casseliflavus) unveiled a complex resistome. We report the first detection in salad vegetables of vancomycin resistance genes (vanC, vanXY-C2) in a vancomycin-susceptible E. faecalis isolate. Identifying tetM, ermB, and optrA genes in the studied isolates further underscored emerging resistance to tetracyclines, macrolides, and oxazolidinones. Concurrently, virulence gene analysis revealed 74 putative virulence factors, with E. faecalis harboring a higher diversity of biofilm-related and exoenzyme-encoding genes. One E. faecalis strain carried the cytolysin cluster (cylI, cylS, cylM), highlighting its pathogenic potential. Plasmid profiling identified 19 distinct plasmids, ranging from 3845 bp to 133,159 bp. Among the genome-sequenced isolates, mobilizable plasmids (47.3%) commonly carried AMR genes, especially tet(L) and tet(M), whereas conjugative plasmids (10.5%) did not harbor resistance determinants. These findings highlight that salad vegetables can still harbor and potentially transmit Enterococcus strains with clinically relevant resistance determinants and virulence traits. Enhancing foodborne AMR surveillance with WGS and targeted interventions is key to controlling its spread in the food.

Prophages are infrequently associated with antibiotic resistance in Pseudomonas aeruginosa clinical isolates.

Lysogenic bacteriophages can integrate their genome into the bacterial chromosome in the form of a prophage and can promote genetic transfer between bacterial strains in vitro. However, the contribution of lysogenic bacteriophages to the incidence of antimicrobial resistance (AMR) in clinical settings is poorly understood. Here, in a set of 186 clinical isolates of Pseudomonas aeruginosa collected from respiratory cultures from 82 patients with cystic fibrosis, we evaluate the links between prophage counts and both genomic and phenotypic resistance to six anti-pseudomonal antibiotics: tobramycin, colistin, ciprofloxacin, meropenem, aztreonam, and piperacillin-tazobactam. We identified 239 different prophages in total. We find that P. aeruginosa isolates contain on average 3.06 ± 1.84 (SD) predicted prophages. We find no significant association between the number of prophages per isolate and the minimum inhibitory concentration for any of these antibiotics. We then investigate the relationship between particular prophages and AMR. We identify a single lysogenic phage associated with phenotypic resistance to the antibiotic tobramycin and, consistent with this association, we observe that AMR genes associated with resistance to tobramycin are more likely to be found when this prophage is present. However, we find that they are not encoded directly on prophage sequences. Additionally, we identify a single prophage statistically associated with ciprofloxacin resistance but do not identify any genes associated with ciprofloxacin phenotypic resistance. These findings suggest that prophages are only infrequently associated with the AMR genes in clinical isolates of P. aeruginosa.IMPORTANCEAntibiotic-resistant infections of Pseudomonas aeruginosa (Pa), a leading pathogen in patients with cystic fibrosis (CF), are a global health threat. While lysogenic bacteriophages are known to facilitate horizontal gene transfer, their role in promoting antibiotic resistance in clinical settings remains poorly understood. In our analysis of 186 clinical isolates of P. aeruginosa from CF patients, we find that prophage abundance does not predict phenotypic resistance to key antibiotics but that specific prophages are infrequently associated with tobramycin resistance genes. In addition, we do not find antimicrobial resistance (AMR) genes encoded directly on prophages. These results highlight that while phages can be associated with AMR, phage-mediated AMR transfer may be rare in clinical isolates and difficult to identify. This work is important for future efforts on mitigating AMR in CFCF and other vulnerable populations affected by Pa infections and advances our understanding of bacterial-phage dynamics in clinical infections.

Mechanisms of mepA Overexpression and Membrane Potential Reduction Leading to Ciprofloxacin Heteroresistance in a Staphylococcus aureus Isolate.

Heteroresistance has seriously affected the evaluation of antibiotic efficacy against pathogenic bacteria, causing misjudgment of antibiotics' sensitivity in clinical therapy, leading to treatment failure, and posing a serious threat to current medical health. However, the mechanism of Staphylococcus aureus heteroresistance to ciprofloxacin remains unclear. In this study, heteroresistance to ciprofloxacin in S. aureus strain 529 was confirmed by antimicrobial susceptibility testing and population analysis profiling (PAP), with the resistance of subclonal 529_HR based on MIC being 8-fold that of the original bacteria. A 7-day serial MIC evaluation and growth curves demonstrate that their phenotype was stable, with 529_HR growing more slowly than 529, but reaching a plateau in a similar proportion. WGS analysis showed that there were 11 nonsynonymous mutations and one deletion gene between the two bacteria, but none of these SNPs were directly associated with ciprofloxacin resistance. Transcriptome data analysis showed that the expression of membrane potential related genes (qoxA, qoxB, qoxC, qoxD, mprF) was downregulated, and the expression of multidrug resistance efflux pump gene mepA was upregulated. The combination of ciprofloxacin and limonene restored the 529_HR MIC from 1 mg/L to 0.125 mg/L. Measurement of the membrane potential found that 529_HR had a lower potential, which may enable it to withstand the ciprofloxacin-induced decrease in membrane potential. In summary, we demonstrated that upregulation of mepA gene expression and a reduction in membrane potential are the main heteroresistance mechanisms of S. aureus to ciprofloxacin. Additionally, limonene may be a potentially effective agent to inhibit ciprofloxacin heteroresistance phenotypes.

Understanding the pattern of resistance in multi-drug resistant clinical isolates of Acinetobacter baumannii based on metabolomics approach.

Understanding the pattern of resistance in multi-drug resistant clinical isolates of Acinetobacter baumannii based on metabolomics approach.

Dynamic association of antimicrobial resistance in urinary isolates of Escherichia coli and Klebsiella pneumoniae between primary care and hospital settings in the Netherlands (2008-2020): a population-based study.

Dynamic association of antimicrobial resistance in urinary isolates of Escherichia coli and Klebsiella pneumoniae between primary care and hospital settings in the Netherlands (2008-2020): a population-based study.

Heavy metals promote the formation of multidrug-tolerant Staphylococcus aureus and Escherichia coli persisters.

Heavy metals promote the formation of multidrug-tolerant Staphylococcus aureus and Escherichia coli persisters.

Widespread dissemination of Salmonella, Escherichia coli and Campylobacter resistant to medically important antimicrobials in the poultry production continuum in Canada.

The Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS) monitors Escherichia coli, Salmonella and Campylobacter and their resistance to antimicrobials in broiler chickens at the farm and slaughter plant levels. In response to many years of CIPARS' observations and farmers' data, the Chicken Farmers of Canada implemented a strategy to reduce antimicrobial use in 2014. As resistance genes can be transmitted vertically from parents to their offspring, a study was conducted in broiler breeder flocks to assess the frequency of target bacteria, their antimicrobial resistance (AMR) and to obtain a comprehensive picture of AMR in poultry production. Spent breeder flocks slaughtered between 2018 and 2021 were sampled and data from broiler flocks at the farm and slaughter plants were assessed. Salmonella was most frequently detected in farm broiler chickens (46%), while Campylobacter was most frequently detected in broiler breeders (73%). In Campylobacter, high levels (20-24%) of ciprofloxacin resistance were found across the three production stages, and was highest in farm broiler chickens (24%). In E. coli, an indicator organism, low-level ceftriaxone resistance and occasional isolates that were non-susceptible to ciprofloxacin were noted. Using the indicator, fully susceptible E. coli, broiler breeders had the highest frequency (54%) compared to farm (36%) and slaughtered (35%) broiler chickens. In Salmonella broiler breeders had the highest resistance to most antimicrobials tested.Fully susceptible Salmonella was lowest in broiler breeders (16%) compared to farm (42%) and slaughtered (42%) broiler chickens. Salmonella serovars differed between the production stages, but S. Kentucky was the most predominant. Resistance to critically important antimicrobials in human medicine and regional variations in resistance profiles were observed. This study suggests that broiler breeders carry foodborne bacteria resistant to antimicrobials used in human medicine, demonstrating their role in the maintenance of AMR in poultry and the need to adopt a harmonized sector-wide AMU strategy.

The CRISPR System and MepA Multidrug Efflux Pump Linked to Antibiotic Resistance in Staphylococcus aureus.

Staphylococcus aureus (S. aureus) is a major zoonotic pathogen. To investigate CRISPR carriage in S. aureus isolates from cows with mastitis and the role of the CRISPR system and efflux pumps in antibiotic resistance. We analyzed antibiotic resistance genes and CRISPR loci, sequenced spacers, and assessed correlations between CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) presence and antibiotic resistance in 234 S. aureus isolates. The changes in CRISPR sequences were examined by continuous passage of 360 generations without antibiotic pressure. Subsequently, variations in CRISPR loci and transcript levels were measured under ciprofloxacin (CIP) exposure. In addition, an S. aureus-25-mepA was constructed to evaluate changes in antimicrobial sensitivity and mepA transcript levels in both planktonic and biofilm states. Our results revealed a CRISPR loci detection rate of 7.69% among the 234 S. aureus isolates, with significantly lower rates of the antibiotic resistance genes gyrA, grlA, norA, and tet(M) in CRISPR-positive isolates compared to those in CRISPR-negative isolates (p < 0.05). CIP-resistant strains exhibited loss of repeat and spacer sequence in CRISPR loci, and the transcript abundance of these loci gradually decreased under CIP pressures, indicating that CRISPR loci deletion or transcript level downregulation under antibiotic stress may be a potential regulatory mechanism of antibiotic resistance. Correlation analysis linked CIP resistance in both planktonic and biofilm S. aureus to mepA transcript levels and biofilm integrity. Our study provides insight into the mechanism by which S. aureus develops antibiotic resistance via the CRISPR system and the MepA efflux pump, offering a theoretical foundation for monitoring the prevalence and resistance of pathogenic bacteria.

Australian Gonococcal Surveillance Programme Annual Report, 2023.

The Australian Gonococcal Surveillance Programme (AGSP) has continuously monitored antimicrobial resistance in Neisseria gonorrhoeae for more than 40 years. In 2023, a total of 10,105 isolates from patients in the public and private sectors, in all jurisdictions, were tested for in vitro antimicrobial susceptibility by standardised methods. Nationally, in 2023, the AGSP captured antimicrobial susceptibility data for 25% of all gonococcal infection notifications. The current treatment recommendation for gonorrhoea, for the majority of Australia, continues to be dual therapy with ceftriaxone and azithromycin. In 2023, of N. gonorrhoeae isolates tested, 0.22% (22/10,105) met the WHO criterion for ceftriaxone decreased susceptibility (DS), defined as a minimum inhibitory concentration (MIC) value ≥ 0.125 mg/L. Resistance to azithromycin was reported in 4.5% of N. gonorrhoeae isolates, proportionally stable since 2019. There were 27 isolates (0.27%) with high-level resistance to azithromycin (MIC value ≥ 256 mg/L) reported in Australia: Victoria (13), New South Wales (11), non-remote Western Australia (2) and Queensland (1). This is the highest number ever detected and reported in a twelve-month period by the AGSP. In 2023, penicillin resistance was found in 30.7% of gonococcal isolates, and ciprofloxacin resistance in 60.3%, although there was considerable variation by jurisdiction. In some remote settings, penicillin remains recommended as part of an empiric therapy strategy. However, in 2023, in remote Northern Territory, five penicillin-resistant isolates were reported; and in remote Western Australia, 14.1% of gonococcal isolates (10/71) were penicillin resistant. In addition, there were eight ciprofloxacin-resistant isolates reported from remote Northern Territory; ciprofloxacin resistance rates have increased in remote Western Australia (16/71; 22.5%). This increase in penicillin-resistant Neisseria gonorrhoeae in the Northern Territory has effected a change in gonococcal treatment recommendations.

Comparative Genomic Analysis of Livestock-Derived Campylobacter jejuni: Antimicrobial Resistance, Virulence, Mobile Genetic Elements, and Genetic Relatedness.

Campylobacter jejuni is a major cause of foodborne illnesses, and its increasing antimicrobial resistance (AMR) poses serious public health risks. Owing to their high genetic diversity and frequent intraspecific recombination, understanding the virulence traits of Campylobacter remains challenging. We elucidated the resistance and virulence mechanisms of C. jejuni in livestock using comparative genomic and phenotypic analyses. We analyzed C. jejuni strains isolated from chicken meat, chicken slaughterhouses, and dairy cattle farms. High resistance rates were observed for nalidixic acid, ciprofloxacin, and tetracycline. The chicken-derived strains showed significantly higher tetracycline resistance and marginally higher nalidixic acid resistance, whereas the cattle-derived strains showed marginally higher ciprofloxacin resistance. The key AMR determinants included gyrA and tet(O), which were correlated with resistance phenotypes. Ten virulence factor families were identified with prevalences exceeding 90%. Biofilm formation was observed in 31.9% of strains and correlated with flagella-associated virulence factors. Eighteen plasmid types were detected, primarily in the pTet family, which carried various AMR genes and components of the Type IV secretion system, potentially facilitating the co-transfer of resistance and virulence traits. Conjugation experiments confirmed the horizontal transfer of two pTet plasmid types into the wild-type C. jejuni strain. Further, our analyses revealed over 95% genetic similarity with European C. jejuni strains in a public database-supporting the hypothesis of zoonotic transmission via global food chains-and the zoonotic risks of livestock-derived Campylobacter jejuni. These findings emphasize the need for extended global surveillance to mitigate the risk of zoonotic transmission.

Evaluation of the Allplex NG & DR assay for molecular prediction of ciprofloxacin and azithromycin resistance in Neisseria gonorrhoeae

PurposeMolecular methods to detect antimicrobial resistance in Neisseria gonorrhoeae (Ng) are increasingly needed worldwide to improve diagnostic tests and enable individualized patient treatments. The Allplex™ NG & DR Assay (NG & DR assay) was assessed for its ability to detect Ng and its antimicrobial resistance. The assay predicts ciprofloxacin resistance and susceptibility by targeting the molecular antimicrobial resistance (AMR) determinant gyrA S91F. The AMR determinants 23 S rRNA A2059G and C2611T were investigated to predict azithromycin wild-type and nonwild-type genotypes.MethodsAfter antimicrobial susceptibility testing, 153 Ng isolates were evaluated with the NG & DR assay. Furthermore, 394 clinal specimens, including 76 with corresponding antimicrobial susceptibility results, were analyzed simultaneously by the NG & DR assay and the in-house SYBR-Green assay.ResultsThe NG & DR assay predicted ciprofloxacin resistance and susceptibility with a sensitivity and specificity of 98.2% and 100.0%, respectively, and the results were consistent with those of the SYBR-Green assay for the detection of S91F. For the prediction of azithromycin nonwild-type and wild-type genotypes, the NG & DR assay demonstrated a sensitivity and specificity of 50.0% and 100.0%, respectively.ConclusionThe NG & DR assay demonstrated promising results for the molecular prediction of ciprofloxacin resistance and susceptibility, expanding the potential diagnostic tool kit for individualized patient treatment. Furthermore, it might serve as a surveillance tool for azithromycin nonwild-type strains.

Pathogen Distribution, Drug Resistance, and Postoperative High-Quality Nursing Intervention Effectiveness in Knee Osteoarthritis Patients After Knee Arthroplasty With Postoperative Infection.

To analyze the distribution and drug resistance of pathogens in patients with postoperative infection following knee arthroplasty (TKA) for knee osteoarthritis (KOA) and to explore the effectiveness of high-quality nursing interventions postoperatively. A retrospective analysis was conducted on clinical data from 87 KOA patients who underwent TKA and developed postoperative wound infections (infection group) at the first Affiliated Hospital of Harbin Medical University from July 2022 to September 2024. Another 87 patients without postoperative infection during the same period were selected as the control group. Deep wound exudate samples were collected from the infection group for pathogen culture, isolation, and identification. Drug susceptibility testing was performed using the K-B disk diffusion method. Additionally, venous blood samples were collected from both the infection and control groups one week after surgery, and serum levels of inflammatory markers [interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), procalcitonin (PCT)] were measured using enzyme-linked immunosorbent assay (ELISA). According to the type of nursing interventions received, the infection group was divided into the conventional care group (n=43, receiving standard orthopedic perioperative care) and the high-quality care group (n=44, receiving comprehensive high-quality care based on routine care). The pain levels [Visual Analog Scale (VAS) scores], knee joint function [Hospital for Special Surgery (HSS) knee scores], activities of daily living (modified Barthel index), and patient satisfaction [Newcastle Satisfaction with Nursing Service (NSNS) scale] were compared between the two groups. Among the 87 KOA patients with postoperative infection after TKA, 83 patients had a single pathogen infection, and 4 patients had mixed infections with two pathogens, resulting in the cultivation and isolation of 91 pathogens. Of these, 63 (69.23%) were Gram-positive bacteria, primarily Staphylococcus aureus (29.67%) and Staphylococcus epidermidis (17.58%). There were 25 (27.47%) Gram-negative bacteria, primarily Escherichia coli (9.89%) and Pseudomonas aeruginosa (6.59%). Three (3.30%) fungal strains were isolated, all identified as Candida albicans. Gram-positive bacteria showed high resistance to penicillin, benzylpenicillin, ampicillin, erythromycin, clindamycin, ciprofloxacin, and gentamicin, but low resistance to gatifloxacin, and no resistance to vancomycin or teicoplanin. Gram-negative bacteria showed high resistance to ciprofloxacin, levofloxacin, gentamicin, and tobramycin, but low resistance to cefepime, imipenem, meropenem, gatifloxacin, and amikacin. The infection group had significantly higher serum levels of IL-6, TNF-α, and PCT compared to the control group (P<0.05). The VAS scores at 24hours, 3 days, and 7 days postoperatively were significantly lower in the high-quality care group compared to the conventional care group (P<0.05). The HSS scores and modified Barthel index scores at 3 months postoperatively were higher than preoperative values in both groups, with a greater improvement observed in the high-quality care group (P<0.05). The satisfaction rate in the high-quality care group (93.18%) was significantly higher than in the conventional care group (74.42%) (P<0.05). The primary pathogens causing postoperative wound infections in KOA patients after TKA are Gram-positive bacteria, with Staphylococcus aureus and Staphylococcus epidermidis being predominant. Serum levels of inflammatory markers are significantly higher in infection patients compared to non-infection patients. High-quality nursing interventions can effectively alleviate postoperative pain, promote recovery of knee joint function, enhance activities of daily living, and improve patient satisfaction.

Evaluation of Mex A' Mex B Efflux Pump Gene in Pseudomonas aeruginosa Isolated from Milk in Qom Province, Iran

Background: Pseudomonas aeruginosa is an opportunistic pathogen protected from antibiotics' harmful effects by various mechanisms. One of the most important mechanisms is the activation of exudation systems. Therefore, identifying such targets in food contaminating bacteria can help us target them and eliminate bacteria resistant to several drugs, making food safe. Therefore, the present study aimed to trace Mex A and Mex B efflux pump genes in Pseudomonas aeruginosa isolated from dairy products in Qom City, Iran. Methods: 300 samples of raw milk, 30 samples of pasteurized milk, and 30 samples of local cream were collected. After a 24-hour culture on nutrient agar and blood agar and performing warm staining, confirmatory biochemical tests were performed to identify bacteria. The disk method was used according to CLSI guidelines to determine the antibiotic sensitivity pattern. Then Mex A and Mex B efflux pump genes were detected using specific primers with PCR technique. Results: 117 strains of Pseudomonas aeruginosa were isolated from 300 raw milk samples, and 7 strains were resistant to ciprofloxacin. Out of 117 Pseudomonas aeruginosa isolates, 51 isolates (43.5%) had Mex A gene and 10 isolates (8.5%) had Mex B gene. Three isolates had both Mex A and Mex B genes. Among the strains with resistance to ciprofloxacin (7 isolates), 4 isolates did not have any of the genes. One isolate had Mex A and Mex B genes; 2 isolates were Mex A positive and Mex B negative, and Mex B positive and Mex A negative isolates were not observed. Conclusions: Based on the results, among the studied isolates, the Mex A gene was more abundant. In addition, no significant relationship was found between the existence of Mex A and Mex B genes and ciprofloxacin resistance.

P-812. Not Little Adults: Key Differences in Antimicrobial Resistance in Australian Bloodstream Isolates between Children and Adults, 2020-2021

Abstract Background The incidence, risks and organisms causing bloodstream infections (BSI) differ between children and adults due to distinct comorbidities, procedures and antibiotic exposures. Age-specific data are required to inform targeted interventions, empiric treatment and guideline development. We aimed to compare the incidence, risk factors and resistance patterns of bacteria causing BSI in children and adults (2020-21). Methods The Australian Group on Antimicrobial Resistance (AGAR) is a national hospital-based BSI surveillance program reporting on Staphylococcus aureus, Enterococcus spp. and key gram-negative pathogens. Results Data from 25,958 isolates were assessed (children: 1,679; adults: 24,279). The most common organisms in children and adults were Escherichia coli (20.9 vs 39.1%) and S. aureus (36.2 vs 20.9%). E. faecalis and non-typhoidal Salmonella spp. were more frequent in children (7.3% and 4.4% of surveyed organisms in children vs 5.1% and 0.5% in adults). BSI were more often community onset (69.0% children; 76.4% adults). 30-day mortality was significantly lower in children (3.3% vs 9.8%). Enterobacterales resistance was more common in children: e.g. to gentamicin/tobramycin (11.6% of child isolates; 8.5%, adult isolates; rate ratio [RR]: 1.4 [95%CI: 1.1-1.7]) and piperacillin-tazobactam resistance (11.2%; 8.6%; RR: 1.3 [1.0-1.6]). However, there was no difference observed in Enterobacterales resistance to cephalosporins, ciprofloxacin, meropenem or multi-drug resistance status. AMR prevalence in Pseudomonas and Acinetobacter spp isolates were also similar between children and adults. Methicillin-resistant S. aureus isolates were less common in children (13.2 vs 17.7%; RR: 0.7 [0.6-0.9]). Rates of clindamycin and cotrimoxazole resistance in S. aureus were similar to adults. Children had a lower proportion of E. faecium infections (24.1 vs 39.8%) and the rate of vancomycin-resistant E. faecium in children was half that in adults (19.5 vs 37.2%; RR; 0.5, [0.2-1.0]). Conclusion Analysis of national AMR data identifies unique trends in children. Ongoing clinical surveillance, targeted prevention, antimicrobial stewardship strategies and research to evaluate AMR drivers in children are required. Disclosures All Authors: No reported disclosures

P-1299. Epidemiology of Invasive Meningococcal Disease in the United States: Review of Recent Data and Identified Risk Factors

Abstract Background Although relatively rare, invasive meningococcal disease (IMD) is distinguished by its unpredictable epidemiology, rapid clinical progression, and often severe or fatal outcomes. IMD risk peaks in infants and young children, with secondary peaks in adolescents/young adults and sometimes older adults. Overall IMD has been declining in the United States and elsewhere since the year 2000, with historic lows during the COVID-19 pandemic; however, widespread post-pandemic rebounds stress the ongoing public health threat of IMD. In the United States, IMD is a notifiable condition tracked by the Centers for Disease Control and Prevention (CDC) in part using the National Notifiable Diseases Surveillance System (NNDSS). A comprehensive enhanced meningococcal disease surveillance (EMDS) program was implemented in 2015. Presa_Figure N/A Methods We compiled annual NNDSS and EMDS data and searched published literature for analyses of US IMD data to review recent IMD epidemiology and associated risk factors. Results The NNDSS and EMDS reported similar numbers of IMD cases during 2016‒2021, with EMDS providing more updated serogroup information (Figure). NNDSS data indicate more cases in 2023 than in any of the 7 years prior, with this rebound intensifying thus far in 2024; the CDC estimates there will be more cases in 2024 than the 422 seen in 2023 (35% serogroup Y). Serogroup Y ciprofloxacin and/or penicillin resistance rose from 22.8% in 2019 to 65.4% in 2021. Surveillance data and additional analyses point to increased IMD incidence associated with college vs no college attendance (1.6- to 3.1-fold during 2016‒2019), Black vs White race (1.1- to 2.4-fold, 2016‒2020), Medicaid vs commercial insurance (1.8- to 3.0-fold, 2016‒2019), homelessness vs non-homelessness (13.8- to 30.2-fold, 2016‒2019), men having vs not having sex with men (5.4-fold, 2015‒2016), and HIV vs no HIV infection (6.2-fold; 2009‒2019). Conclusion US IMD is rebounding after major COVID-associated declines. Established risk factors (eg, smoking, sharing food, dormitory living) and related behaviors (eg, vaping, overnight camp attendance) may be influencing IMD surges as post-COVID socialization increases. Comprehensive understanding of US epidemiology is crucial for optimizing vaccination strategies. Funding: Pfizer. Disclosures Jessica Presa, MD, Pfizer: Employee|Pfizer: Stocks/Bonds (Public Company) Daniel Spitz, PharmD, Pfizer Inc: Employee Paul Palmer, PhD, Pfizer Inc: Employee Vincenza Snow, MD, Pfizer: Employee|Pfizer: Stocks/Bonds (Public Company) Kathleen Dooling, MD, Pfizer: Employee|Pfizer: Stocks/Bonds (Public Company)