Resistance Profiles Research Articles

Role of metabolism, resistance, and/or antagonism as drivers of endomicrobiomes assemblage in Origanum heracleoticum L

The understanding of selective forces driving the compartmentalization of microbiota in plants remains limited. In this study, we performed a phenotypic characterization of bacterial endophytes isolated from the medicinal plant Origanum heracleoticum, together with the determination of the antibiotic resistance profiles and the antagonistic interactions of communities within and across different plant organs. Results revealed organ-related differences in the metabolic capabilities of bacteria, with those associated with stems displaying the highest metabolic activity for carbon sources. Contrarily, the patterns of antibiotic resistance appeared closely aligned with the taxonomical classification of the endophytes. The presence of antagonistic interactions, likely spurred by resource limitations, favor bacteria exhibiting greater metabolic plasticity. In conclusion, this research advances our comprehension of the intricate dynamics between plants and their associated microbiota, indicating that its composition is mainly influenced by forces contributing to the selection of distinct functions and phenotypic traits.

Risk factors associated with mortality and pathogen characteristics of bloodstream infection-induced severe sepsis in the pediatric intensive care unit: a retrospective cohort study

BackgroundBloodstream infection (BSI)-induced severe sepsis is a common cause of mortality, frequently resulting in septic shock and multiple organ dysfunction syndrome (MODS). This study aimed to analyze mortality risk factors and summarize pathogen characteristics associated with BSI-induced severe sepsis in the pediatric intensive care unit (PICU).MethodsThis retrospective study was conducted at a tertiary pediatric hospital between January 2015 and December 2023, encompassing children with BSI-induced severe sepsis in the PICU. Clinical characteristics, laboratory parameters, pathogen characteristics, and drug resistance profiles of the patients were collected. Clinical and laboratory indicators along with pathogen characteristics were summarized. Logistic regression analysis was employed to identify independent risk factors associated with 28-day mortality.ResultsA total of 192 patients with bloodstream infection (BSI)-induced severe sepsis were identified, with a 28-day in-hospital mortality rate of 36.98% (71/192). The incidence of septic shock (42.1% vs. 69%, P < 0.001) and AKI (14% vs. 31%, P = 0.005) was significantly lower in the survival group compared to the non-survival group. In multivariate analysis, independent risk factors for 28-day mortality were the pediatric sequential organ failure assessment (pSOFA) score (OR 1.176; 95% CI: 1.046-1.321, p = 0.007) and the P/F value (OR 0.994; 95% CI: 0.991-0.997, P < 0.001). Double organism growth was detected in 8 cultures, and a total of 200 pathogenic bacteria were isolated from all blood cultures. Of these, 110 strains (55.0%) were Gram-negative bacteria, 88 strains (44.0%) were gram-positive bacteria, and 2 strains (1.0%) were Candida albicans. The most commonly isolated pathogens were Staphylococcus aureus, Coagulase-negative Staphylococcus, and Escherichia coli. The detection rate of carbapenem resistance (CR) in Acinetobacter baumannii (66.7%) was higher than that in Pseudomonas aeruginosa (15.4%). The detection rates of extended-spectrum cephalosporin resistance (ECR) and fluoroquinolone resistance (FQR) in Escherichia coli (E. coli) were higher than those in Klebsiella pneumoniae.ConclusionIn the PICU, higher mortality was observed in children with BSI-induced severe sepsis who presented with elevated pSOFA scores and low P/F values. Acinetobacter baumannii exhibited the highest levels of CR and FQR, while Escherichia coli demonstrated the highest level of ECR.

Prevalence and Characterization of Staphylococcus aureus Isolated from Meat and Milk in Northeastern Italy.

Staphylococcus aureus is a pathogenic microorganism often found in animal-derived foods and is known for its ability to readily develop resistance to antibiotic treatments. This study was designed to determine the prevalence of S. aureus strains in raw milk and meat in Italy and to evaluate their antibiotic resistance profiles and biofilm production. Among the meat isolates, 41.67% were resistant to ampicillin, and 25% were methicillin-resistant S. aureus (MRSA). In milk, 20% of the isolates were resistant to gentamycin, while 5.71% were MRSA. The prevalence of multidrug-resistant strains was higher in meat (16.67%) compared to milk (5.71%). The biofilm formation capability was assessed in most of the isolates (80% in milk and 100% in meat). Representative strains exhibiting different antibiotic resistance profiles were all negative for the enterotoxin genes sea, seb, sec, sed, and see, but harbored potential virulence factors such as hemolytic activity, high pigmentation, low cell envelop permeability, charged and hydrophobicity. Finally, the interaction of representative strains with human Caco-2 intestinal cell line showed that most strains had an adhesion capacity. Our findings reveal that foodborne isolates of S. aureus present a considerable threat to consumers due to their production of virulence factors, which enhance their pathogenicity and increase the likelihood of antibiotic treatment failures.

Characterization of novel mutations involved in the development of resistance to colistin in Salmonella isolates from retail pork in Shanghai, China.

Salmonella is an important foodborne pathogen that poses a significant threat to food safety. This study aims to assess the prevalence, genomic features, and colistin-resistant mechanisms of Salmonella isolates collected from 118 retail pork samples from January 2021 to January 2022 in Shanghai, China. Overall, 46 (39.0%, 46/118) Salmonella isolates were collected, which were identified as 12 serotypes by genomic analysis, including Salmonella Typhimurium (n=17) and Salmonella London (n=6). Antimicrobial resistance profiling revealed that the resistance rate of these isolates to colistin was 13.0% (6/46), while 60.9% (28/46) exhibited multidrug-resistant. It was found that there were 51 distinct antimicrobial resistance genes in these 46 isolates, which were predominantly associated with resistance to aminoglycosides, fluoroquinolones, and β-lactams. More importantly, among six colistin-resistant isolates, two isolates (Salmonella Schwarzengrund and Salmonella Indiana) were found to carry the mcr-1 gene. The mechanism of resistance in the remaining four colistin-resistant isolates was further studied, and it was found that there were nine amino acid substitutions in PmrAB. It was demonstrated by site-directed mutagenesis that novel substitutions G53W in PmrA and I83V in PmrB led to colistin resistance in Salmonella (MIC=2 or 4μg/mL). Analysis results by real-time quantitative PCR and mass spectrometry indicated that the mutants PmrAG53W and PmrBI83V displayed higher expression levels of the gene pmrE than in the parental strain. This upregulation resulted in an increase in the production of 4-amino-4-deoxy-l-arabinose (L-Ara4N) that modified lipid A, thereby conferring resistance to colistin. These findings demonstrated that there was a high prevalence of MDR Salmonella isolates in retail pork in Shanghai, and the substitution G53W in PmrA and I83V in PmrB were independent factors contributing to the development of resistance to colistin in Salmonella via modification of lipid A with L-Ara4N.

Bacterial assessment, thermal resilience and antibiotic resistance profiles of bacterial contaminants in retail fish and meat

Bacterial assessment, thermal resilience and antibiotic resistance profiles of bacterial contaminants in retail fish and meat

Integrated assessment of mucilage impact on human health using the One Health approach: Prevalence and antimicrobial resistance profiles of Escherichia coli and Clostridium perfringens in the Marmara Sea, Türkiye

Integrated assessment of mucilage impact on human health using the One Health approach: Prevalence and antimicrobial resistance profiles of Escherichia coli and Clostridium perfringens in the Marmara Sea, Türkiye

Detections of antimicrobial resistance phenotypes and extended-spectrum beta-lactamase (ESBL)- producing Salmonella spps and Escherichia coli O157:H7 in raw vegetables and fruits from open markets in Jimma town, Ethiopia and evaluation of hygiene and handling practices of vendors

ObjectivesDespite of the health benefits of consumption of fresh vegetables and fruits, this product could be associated with food-borne bacterial pathogens, including infections with antibiotic-resistant strains especially in developing countries due to limited in knowledge, and hygienic practices. This study was conducted to provide evidence data on the rates of Salmonella spp. and E. coli O157:H7 contamination, the antimicrobial resistance profile, and extended-spectrum β-lactamase (ESBL)-producing strains in fresh vegetables and fruits sold in open-air markets at Jimma town, southwest Ethiopia. In addition, this study provided data on the hygiene and handling practices of vendors, which can help as impute to improve food safety and safeguard public health. A total of 242 salad samples were collected from three different kebeles and examined for the presence of Salmonella spp. and E. coli O157:H7 in the microbiology laboratory of Jimma University by using conventional microbiological techniques.ResultsOut of 242 samples tested, 12.8% (31/242) were contaminated with Salmonella spp. and E. coli O157. Of these, Salmonella spp. was detected in 10.7% (26/242) of the tested samples, whereas Escherichia coli O157:H7 was found in 2.1% (5/242) of samples. Fifty-three-point-8% of Salmonella spp. were resistant to ampicillin, 42.3% to co-trimoxazole, 46.2% to tetracycline, and 26.9% resistance was observed against each of ceftriaxone and cefotaxime. 40% of E. coli O157:H7 isolates were resistant against ampicillin, amoxicillin-clavulanic acid, and co-trimoxazole. Only one isolate was resistant to ceftriaxone and cefotaxime, and no resistance was observed against ceftazidime, gentamicin, ciprofloxacin, chloramphenicol, and meropenem. Four Salmonella spp. and one E. coli O157:H7 isolate with a total of 5/31 (16.1%) isolates were confirmed as the ESBL producers. Multidrug resistance (MDR) was detected in 23.1% of Salmonella and 20.0% of E. coli O157:H7. Hygienic and handling practices of vendors were poor, which could contribute to contamination of vegetables and fruits in the area.ConclusionsContamination of fresh salad vegetables with pathogenic bacteria could be a food safety concern in the study area. Hence, this finding suggests the need for attention by the concerned bodies to prevent the emergence and transmission of food-borne pathogens and antimicrobial-resistant strains through these food items in the study area.

Evaluation of multi-drug resistance, virulence factors, and antimicrobial resistance genes of non-typhoidal Salmonella isolated from ruminants as a potential human health threat in Razavi Khorasan, northeastern Iran.

Non-typhoidal Salmonella (NTS) is a significant foodborne pathogen that poses a threat to human health by causing infections and potentially acquiring antibiotic resistance. We evaluated thirty-five Salmonella serovars previously isolated from cattle, sheep, goats, and their retail meat in Razavi Khorasan Province, Iran. The isolates were confirmed with Salmonella polyvalent antiserum. Furthermore, PCR was used to identify the Salmonella Enteritidis, Salmonella Typhimurium, and the host-adapted serovars Salmonella Dublin and Salmonella Abortusovis. Additionally, the antimicrobial susceptibility of the serovars was evaluated using the disk diffusion method. Subsequently, the occurrence of antimicrobial resistance genes and virulence factors was evaluated using the PCR technique. Molecular typing revealed that 20% of the isolates were S. Typhimurium, 11.4% were S. Dublin, 8.6% were S. Enteritidis, 5.7% were S. Abortusovis, and 54.3% (19 isolates) were classified as non-typed serovars. Salmonella isolates showed high susceptibility to ciprofloxacin (91.4%), colistin (88.6%), gentamicin (88.6%), and cefotaxime (85.7%) while exhibiting high resistance to others such as ampicillin (88.6%), streptomycin (74.3%), and tetracycline (51.4%). The most prevalent resistance genes in non-typhoidal Salmonella (NTS) are blaTEM (91.4%), sul1 (65.7%), and aadA (54.3%). Additionally, twenty-five isolates (71.4%) showed multi-drug resistance profiles. The most frequent virulence genes are stn (100%), iroN (100%), and pefA (42.9%). The current study has revealed that Salmonella serovars isolated from sheep and goats, like those from cattle, exhibit multi-drug resistance and harbor antimicrobial resistance genes. Additionally, they possess diverse virulence factors that can threaten human health by spreading diseases and developing drug resistance, leading to antibiotic treatment failure.

Rapid karstification process with evaporite-driven sinkholes in Southern Kohat Basin, NW Pakistan

Sinkholes are small karstic features in soluble rocks that play an essential role in karstification and cause severe environmental hazards. The Karak region of the Himalaya foothills showcases one of the best exposures of karstification landforms, given their highly soluble nature and salt dissolution activities. The well-developed sinkholes are unique worldwide, yet have not been investigated. Here, we apply Interferometric Synthetic Aperture Radar (InSAR), resistivity profiles, and field observations to study the karstification process in this region. InSAR detects numerous localized subsiding zones reflecting rates up to 29 mm/year from 2014 to 2023. Resistivity profiles and field observations catalog them as cover collapse, bedrock collapse, and bedrock sagging sinkholes, carrying distinctive evaporite-driven dissolution features controlled by faulting activity. The results enhance our understanding of the linkages between sinkhole development, subsidence, and subsurface structures, emphasizing the need for comprehensive planning to mitigate future hazards in this less-representative yet populated region.

Trends in insecticide resistance in natural populations of Culex quinquefasciatus and its impact on mosquito fitness in Dschang, West Cameroon

Specific information about the dispersion of Culex quinquefasciatus from Dschang in western Cameroon is scarce, and evidence-based interventions are needed. Common use of larvicides and adulticides conduct to the development of vectors resistance which can lead to deep biological changes, including fitness costs. We assessed the profile of insecticide resistance in field populations of Cx. quiquefasciatus and its potential fitness cost in a lineage selected for deltamethrin and permethrin resistance in the laboratory for two generations. The resistance intensity of the Cx. quinquefasciatus population was moderated when the population was exposed to deltamethrin at 10 × . Preexposure to PBO led to the restoration of full susceptibility to both deltamethrin and permethrin. Compared with that of the control group, female fecundity rates, egg hatchability, and pupation rates were significantly lower in the insecticide exposed groups. Larval development time and adults emergence rates were comparable between insecticide-exposed groups and the control. Insecticide-exposed adults lived longer than control adults did. Our findings suggest that the mechanisms selected for pyrethroid resistance are associated with negative impacts on different life-trait parameters and support the hypothesis that insecticide resistance is related to a high fitness cost.

Detection and antimicrobial resistance profiles of Salmonella enterica recovered from house fly intestinal tracts and environments of selected broiler farms in Texas.

The entry of drug-resistant Salmonella enterica into the food supply is a challenge to public health and food safety. One emerging concern is the role of synanthropic insects for moving microbial pathogens throughout poultry production systems, where insects commonly thrive. We investigated the presence and phenotypic antimicrobial susceptibility of Salmonella enterica from insect and environmental samples from broiler farms. Insects were collected throughout the broiler house and adjacent compost barn. Environmental samples (poultry feed, drinking water, fresh litter, feces) were collected simultaneously (n=80). Insect gastrointestinal tracts were dissected and pooled (n=57). Recovered Salmonella isolates were serotyped and subjected to antimicrobial susceptibility testing against 14 medically important antimicrobials. Overall, six isolates were recovered from 137 total samples (4.4%): 3.5% (2/57) from adult house flies (Musca domestica), 15% (3/20) from poultry feed, and 4.8% (1/21) from litter. Salmonella Montevideo (16.7%; 1/6)), Typhimurium (33.3%; 2/6), and Kentucky (50%, 3/6) were identified. All but one Salmonella isolate (83.3%; 5/6) demonstrated resistance to at least one antimicrobial. Further research should investigate movement patterns between broiler operations and food processing facilities to establish efficient biosecurity measures to prevent any instances of foodborne pathogen transmission into human food systems.

Prevalence of antimicrobial resistance phenotypes and genes in stable fly- and manure-derived bacterial isolates from clinically relevant taxa in dairy settings.

This study aimed to characterize and compare the antimicrobial resistance (AMR) profiles of clinically relevant bacterial taxa isolated from biting stable flies (Stomoxys spp.) and bovine manure samples collected at a dairy research facility over the course of an entire fly breeding season. The presence of extended-spectrum beta-lactamase (ESBL) and other antimicrobial resistance genes (ARGs) was also examined. A total of 606 fly- and 180 manure-derived strains were tested via disk diffusion for susceptibility to commonly administered antibiotics used in veterinary and human medicine. A small percentage of Enterobacterales exhibited resistance to the tested antimicrobials, including ceftiofur and other beta-lactam antibiotics. Extended spectrum beta-lactamase genes (TEM, CTX, OXA, CMY) were detected by PCR amplification in ceftiofur-resistant Escherichia coli, Klebsiella and Enterobacter spp. isolates. We additionally identified pirlimycin-resistant Staphylococcus and Mammaliicoccus spp. isolates encoding lnuA, a lincosamide resistance gene found primarily on small mobilizable plasmids. These findings highlight the significance of stable flies in the carriage of antimicrobial-resistant bacterial strains and plasmid-associated ARGs on dairy farms.

Insights into incompatible plasmids in multidrug-resistant Raoultella superbugs

The emergence of multidrug-resistant (MDR) Raoultella isolates is linked to the acquisition of antibiotic resistance genes (ARGs) with plasmids playing a pivotal role in this process. While plasmid-mediated transmission of ARGs in Raoultella has been extensively reported, limited attention has been given to genetically dissecting the modular structures of plasmids. This study aims to elucidate the genomic features of novel incompatible plasmids in MDR Raoultella by presenting 13 complete plasmid sequences from four isolates, along with an analysis of 16 related plasmids from GenBank. These 29 plasmids were classified into five distinct groups: IncFII single-replicon plasmids, dual-replicon plasmids containing the IncFII replicon, IncHI plasmids, IncR plasmids, and IncX8 plasmids. A new incompatible group, IncFIIp23141−CTXM, was identified, alongside five newly designated Inc groups based on previously determined sequences, namely IncFIIpKPC2_EC14653, IncFIIpCP020359, IncFIIpCP024509, IncFIIpKOX−137, and IncFIIpKDO1. Furthermore, this research marks the first report of four Inc groups of plasmids within Raoultella, namely IncFIIp23141−CTXM plasmid, IncFIIpKPC2_EC14653 plasmid, IncX8 plasmid, and IncFIIpCP020359: IncFIB-7.1 dual-replicon plasmid. Moreover, novel mobile genetic elements, including two unit transposons (Tn6806 and Tn6891), one IS-based transposition unit (Tn6561), and four insertion sequences (ISRor6, ISRor7, ISRor8, and ISRor9) were discovered. Notably, this is the first report of mcr-9 in clinical Raoultella strains. At least 49 ARGs conferring resistance against 11 different categories of antimicrobials were identified on these 13 plasmids. Overall, this research deepens the understanding of incompatible plasmids in Raoultella, serving as a reference for exploring antibiotic resistance profiles and plasmid diversity in MDR Raoultella.

The continued evolution of the L2 cephalosporinase in Stenotrophomonas maltophilia: a key driver of beta-lactam resistance.

The Stenotrophomonas maltophilia L2 cephalosporinase is one of two beta-lactamases that afford S. maltophilia beta-lactam resistance. With the overuse of beta-lactams, selective pressures have contributed to the evolution of these proteins, generating proteins with an extended spectrum of activity. Variant L2 cephalosporinases have been detected, as has their distribution into two main clades (clades 1 and 2). Comprehensive analysis of six L2 variants, cloned into pET41a(+) and expressed in Escherichia coli BL21(DE3) cells, revealed that clade 1 variants exhibited higher ceftazidime resistance compared to clade 2. Notably, the Sm5341 L2 variant, carrying a Phe72Ile variation, displayed a significantly reduced resistance profile across all substrates tested, suggesting a key role of Phe72 in enzymatic activity. An Ile72Phe substitution in the pET41a(+) based Sm5341_L2 variant resulted in a gain-of-function for this protein, confirming the role of Phe72 in the activity of L2. Furthermore, residue interaction network analysis elucidated a pi-cation interaction between Tyr272 and Arg244, which may potentially be stabilizing the enzyme and its binding site. The presence of Tyr272 in clade 1 variants correlates with higher ceftazidime affinity, contrasting Asp272 in clade 2 variants. Displaying lower Km values and higher kcat/Km ratios, clade 1 L2 enzymes demonstrated a higher binding efficiency and greater catalytic efficiency for most of the substrates assessed. These results indicate that L2 enzymes are continuing to evolve and adapt to a selective environment fuelled by the overuse of beta-lactams. This adaptation may signal the beginning of an evolutionary process yielding variant L2 cephalosporinases with extended substrate profiles.

P-279. An Online Registry of Carbapenemase Producing Gram Negative Organisms for Evaluating the Clinical Profile, Outcomes and Mechanisms of Resistance in Two Tertiary Level Hospitals (ORiGiN Study): An Interim Analysis

Abstract Background Infections with gram-negative carbapenem-resistant organisms (CRO) are an emerging global problem, but little is known about CRO in the Philippines. This study aims to build a registry and describe the clinical profile and molecular mechanisms of resistance of carbapenem-resistant infections. Methods This prospective study will enroll patients from two tertiary-level hospitals from 01/01/2023 to 12/31/2025. Admitted patients >18 years old with documented CRO infection confirmed by phenotypic resistance and molecular testing are included in this year-1 analysis. Results 150 patients were enrolled in the first year. Around half (79/150, 54.7%) were female. Median age was 60 (range 21-94) years. Many had at least one comorbidity -- hypertension (90/150 65.2%), diabetes mellitus (45/150, 32.6%), and congestive heart failure (42/150, 30.4%). Most patients experienced CR infection only once (123/150, 82%), while a few (27/150,18%) had two or more. Infections originated from respiratory (63.3%), blood (22.6%), or urinary (16.4%) sites. Higher mortality was seen among patients who received three or more antibiotics (119/150, 57.1%) or had prolonged treatment ( >15 days) during admission (53.1%). Resistance to fluoroquinolones (ORadjusted=4.32 (95% CI: 1.11, 16.81); p=0.035) and older tetracyclines (ORadjusted=5.49 (95% CI: 1.08, 27.93); p=0.040) were significantly associated with mortality in the adjusted models. Only 9 out of 169 (5.32%) were Extended Spectrum Beta Lactamase (ESBL) producing. 40/169 (23.7%) were tested for carbapenem resistance genes and the two most common antimicrobial resistance genes were blandm (n= 17) and blaoxa51 (n=20). Conclusion The study provides initial data on the local epidemiology and molecular mechanisms of resistance of gram-negative CRO. Interim results show that CR infections affect the older population and are mainly respiratory in origin. Multiple antibiotics, prolonged therapy, and the use of fluoroquinolones and tetracyclines were all associated with higher mortality. Class D (OXA-51) and Class B (NDM) beta-lactamases were most frequently isolated. Disclosures All Authors: No reported disclosures

P-426. Antimicrobial Resistance Focus in French ICU: A national surveillance network analysis on ventilator acquired pneumonia

Abstract Background The aim of this study was to perform a characterization of patients who underwent mechanical ventilation, the incidence rate of ventilator acquired pneumoniae (VAP) as well as identification of the pathogens involved, their resistance profiles, and the associated clinical outcomes. This group will be scrutinized for patterns and outcomes specifically associated with ventilator use. Cumulative incidence of VAP Methods Adult patients undergoing mechanical ventilation hospitalized in France for at least 48 hours in ICU participating to REA-REZO surveillance network between 2018 and 2021 were included in this cohort. To estimate the cumulative incidence of VAP, extubation and death were considered as competing event. Description of the cohort Results In this cohort, 98 047 patients were included. Among them, 12 251 (12.5%) had a VAP; the incidence rate for 1000 ventilation days was 18.9 cases per 1000 ventilation days. The median age of the cohort is 66 [55-75] years old with a male predominance (63.0 %). The SAPS score is 49 [36-63], the mortality is 24.4 % and the median ICU length of stay is 7 [4-15] days. Ventilated patients are more frequently admitted for medical (63.0 %) compared to surgical (37.0%) reason. At day 30, the attributable mortality associated with ventilator-associated pneumonia (VAP) was estimated at 4.9% (3.7% - 6.2%). Out of 15,575 diagnosed cases of VAP, there were 4,695 instances of polymicrobial VAP, which constitutes 30.1% of the cases. Non-fermenting Gram-negative bacteria were a significant group, contributing to 25.4% of the VAP cases, with Pseudomonas aeruginosa being the most significant contributor (3 924 cases, 76.2% of non-fermenters) Description of the microbial ecology of VAP Conclusion The development of VAP is frequent, especially in patients admitted for medical reasons, with high severity and appears to be associated with an increased use of medical devices, like urinary and central venous catheters, reflecting the complexity of their clinical management. Disclosures Xavier Bourge, PharmD, MSD France: Employee Arnaud Friggeri, MD, MSD France: Advisor/Consultant Alain Lepape, MD, MSD France: Grant/Research Support Claire Prevot, n/a, MSD France: Employee Anais Machut, n/a, MSD France: Grant/Research Support Charles-Hervé Vacheron, MD, MSD France: Grant/Research Support

P-1038. Clinical Analysis of Nosocomial Candidemia: Species Profile, Resistance Patterns and Mortality Determinants

Abstract Background Candidemia has become one of the commonest nosocomial blood stream infection (BSI) secondary to infected central venous catheters or surgical site infections. Prompt diagnosis followed by early treatment is needed to reduce the high mortality associated with it. Hence this study was conducted to analyse the epidemiology, clinical characteristics, species distribution, resistance profile, outcome and factors related to outcome in nosocomial candidemia. Methods It was a retrospective observational analysis done for the period of 1 year in a tertiary health care centre of western Rajasthan from 1st July 2022 to 30th June 2023. All adult patients admitted in multispeciality intensive care unit (ICU) for more than 48 hours and developing candidemia were included and those patients with a single blood fungal culture positive from the sample obtained from indwelling central venous catheter were excluded as colonisers. Data was collected by regular AMS rounds and was analysed using SPSS version 20. Results Out of total 76 cases of candidemia,61 were included in the study. As shown in figure 1, the most common species isolated was Candida tropicalis followed by Candida parapsilosis.both were associated with high mortality. Clinicoepidemiological characters are described in table1. Overall, all cause 28th day mortality was 63.9 %. Highest resistance was found for the azoles. As depicted in table 2, on univariate and multivariate analysis infection with Candida tropicalis, use of inotropes, ventilator use, and high SOFA scores were the independent factors affecting mortality in candidemia. Conclusion Candidemia is a nosocomial infection with very high mortality which needs to be diagnosed early. Candida tropicalis being the most frequent species isolated in our ICU setup with a significantly high mortality. Disclosures All Authors: No reported disclosures

Serotyping and antimicrobial resistance of Actinobacillus pleuropneumoniae isolates from fattening pigs in Poland from 2019 to 2024

BackgroundActinobacillus pleuropneumoniae is a prevalent respiratory pathogen causing substantial economic losses in swine production worldwide. The bacterium's ability to rapidly develop antimicrobial resistance (AMR) poses a significant challenge to effective treatment and control. In Poland, limited data on A. pleuropneumoniae serotype distribution and AMR patterns hinder evidence-based treatment strategies. This study examined the serotype diversity and AMR patterns of A. pleuropneumoniae isolates from porcine pleuropneumonia outbreaks in northeastern Poland between 2019 and 2024, providing crucial information for regional veterinary practices and antimicrobial stewardship efforts.ResultsAnalysis of 119 isolates from 67 farms demonstrated the predominance of serotype 2 (65.5%), followed by serogroups 3, 6, 8 (18.5%) and 1, 9, 11 (15.1%). This distribution differs from recent trends in other European countries, suggesting regional epidemiological variations. High resistance rates were observed for tylosin (55.5%), gentamicin (36.1%), doxycycline (32.8%), and sulfamethoxazole/trimethoprim (26.1%). Multidrug resistance fluctuated between 14.3% and 21.9% over the study period, with no clear linear trend. From 2022 onwards, strains exhibiting resistance to seven or more antimicrobials, including cephalosporins, emerged, marking a significant shift in resistance profiles. Temporal analysis revealed diverse resistance patterns, with significant increases in some antimicrobials (e.g., sulfamethoxazole/trimethoprim, p = 0.001) and stability in others (e.g., tetracycline, p = 0.890). Notably, several antimicrobials, including florfenicol and colistin, maintained 100% efficacy against all isolates throughout the study period.ConclusionsThe findings highlight the dynamic nature of AMR development in A. pleuropneumoniae and underscore the need for ongoing surveillance in the region. The emergence of highly resistant strains, particularly those resistant to cephalosporins, raises concerns about future treatment options. These results can guide evidence-based treatment strategies and enhance antimicrobial stewardship efforts in regional swine production. Furthermore, the study emphasizes the importance of local AMR data in guiding antimicrobial use policies and the need for a coordinated approach to combat AMR in veterinary medicine.

P-1296. Community-acquired methicillin-resistant Staphylococcus aureus infections: 1 year of surveillance in 6 pediatric centers

Abstract Background Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infections is emerging in the world and can have a serious evolution. The objective of this study were to study the hospitalization rate, the clinical-epidemiological and bacteriological pattern and the case fatality risk factors of CA-MRSA infection. Methods Cross-sectional observational epidemiological study, with prospective data capture. All patients ≤ 15 years of age with community-acquired Staphylococcus aureus (CA-SA) infection hospitalized in 6 pediatric sentinel units, between January and December 2023, were included. The rate of CA-MRSA cases per 10,000 hospital discharges was calculated. with 95 % confidence interval (95 % CI). Results Of a total of 201 patients with CA-SA infection, 131 (65.2 %) were CA-MRSA. The global hospitalization rate for CA-MRSA cases was 27.8 (23.3-32.9), with a higher rate in < 2 years 37,7 (27,9-49,8). Of the 131 cases: 56.5 % were male, median age 48.8 months (IQR 16.4-90.4), ≥ 2 years 64.9%, complete vaccination card 77.0 %, low socioeconomic level 54.2 %, overcrowding 15.3 %, underlying disease 29.0 %, passive smoking 24.4 %. The clinical presentations were (n; %): skin and soft tissue infection (SSTI 101; 77.1 %), arthritis (17; 13.0 %), osteomyelitis (12; 9.2 %), pneumonia (16; 12.2 %; 14 with pleural effusion and 3 necrotizing), sepsis (11; 8.4 %), bacteremia (4; 3.1 %), meningitis (1; 0.8 %). Conventional microbiological diagnosis was performed in 130 cases and molecular diagnosis in one. 4 cases had coinfection with group A beta hemolytic Streptococcus. Antibiotic resistance was for erythromycin 43.1 %, clindamycin 26.0 %, gentamicin 19.9 %, TMP-SMX 1.5 %. All strains were susceptible to vancomycin. Fatality rate: 1.5 % (2/131). No deceased case had an underlying disease. 18.2 % (2/11) of sepsis cases died (2-tailed Fisher exact p 0.006), however, there was no significant association in the multivariate analysis. Conclusion The high burden of CA-MRSA infection, the most common clinical form of SSTI, and the high profile of antibiotic resistance, highlight the importance of continuous clinical surveillance and alert for these infections. Disclosures All Authors: No reported disclosures

P-283. Epidemiology, clinical, phenotypic, and genotypic characteristics of multidrug, extensive and pan-drug resistant Acinetobacter baumannii from Qatar

Abstract Background Multidrug-resistant Acinetobacter baumannii-calcoaceticus complex is associated with significant morbidity and mortality with limited treatment options. The outlined study aimed to evaluate the epidemiology , clinical , phenotypic and genotypic characteristics of multidrug resistant (MDR) Acinetobacter species from Qatar between 2017-2020 . Methods A prospective study was conducted between 2017-2020 for all clinical isolates of Acinetobacter species. Microbial identifications and antimicrobial susceptibility tests were performed using automated MALDI-TOF MS and BD PhoenixTM system according to the manufacturer’s recommendations while additional ASTs were performed with E test . Genomic tests were performed using whole genome sequence Results Out of 536 isolates, 62 (11.5%) resistant isolates were identified showing decremental trend over the study period with dominance of sequence types: ST2 (71 %), ST 25 % (8%) and ST 164 (8%). Main age of acquisition was 64 year (38-70). Isolate sites were urinary (42 %), respiratory (29%), bloodstream (16%), skin and soft tissues (13%) mainly acquired at hospitals (97 %). Existing multiple comorbidities and previous antimicrobial exposure were present in most cases. Multiple antimicrobial regimes for management were dominated by colistin, meropenem, amikacin, cotrimoxazole and tigecycline with 30-day mortality of 16 %. Microbiological evaluation demonstrated extensive resistance ranging between 85-100 % for active agents including meropenem and ampicillin-sulbactam at 97.4 % as well as for novel agents: ceftazidime-avibactam (100%), ceftolozane-tazobactam, meropenem-vaborbactam and imipenem- relebactam at 97.4 %. All ST2 isolates carried class D blaOXA-23 and blaOXA-51 family, that confer resistance to carbapenems, as well 7 isolates carried class B MBL blaNDM-1. Conclusion Acquisition of resistant Acinetobacter baumannii is infrequent with decremental trend dominated by ST 2, mainly isolated from the elderly with multiple comorbidities and risk factors. Predominant isolation sites are urinary, respiratory, bloodstream, skin and soft tissues. Extensive resistance profiles limit treatment options for conventional and novel agents pointing towards urgent needs for alternative therapy. Disclosures All Authors: No reported disclosures