Isolation Rate Research Articles

Epidemiology and Sensitivity to Antibiotics of Germs Isolated from Blood Cultures in the Laboratory of the National Hospital Center of Nouakchott-Mauritania

This study aims to examine the results of blood cultures carried out at the National Hospital Center (CHN) of Nouakchott over a 26-month period (2021-2023). The primary objective was to determine the positivity rate and distribution of bacterial isolates. Additionally, this retrospective analysis aimed to evaluate antibiotic resistance patterns among the identified microorganisms to guide clinical decision-making and improve therapeutic strategies. A total of 212 blood cultures were analyzed, of which 45 (21.22%) were positive. Among these, 71.12% were Gram-positive bacteria, while 26.67% were Gramnegative. The majority of affected patients were male (57%), with a sex ratio of 1.3, and pediatric cases were significantly represented. Automated blood culture systems (BACT/ALERT®) and identification by VITEK-2 facilitated pathogen detection. Antibiotic resistance was a major concern, with 44.44% of Staphylococcus aureus strains resistant to penicillin M, while Klebsiella pneumoniae exhibited multidrug resistance, including extended-spectrum beta-lactamase (ESBL) production. A notable case of candidemia was observed in a premature neonate, who presented persistent fever and sepsis unresponsive to antibiotics. Early identification of Candida spp. led to antifungal therapy with fluconazole, resulting in clinical improvement. This highlights the importance of considering fungal infections in high-risk patients. These findings emphasize the critical role of continuous surveillance of bacterial resistance patterns in optimizing empirical antibiotic therapy and infection control strategies. Strengthening antimicrobial stewardship programs and laboratory diagnostic capabilities is essential to improving patient outcomes and limiting the spread of multidrug-resistant organisms.

First report of Fusarium proliferatum causing rhizome rot on Polygonatum cyrtonema in China.

Polygonatum cyrtonema Hua (Asparagaceae) is a perennial herb widely distributed in China (Chen et al. 2021). The rhizome has antioxidant, anti-inflammatory, and immunomodulatory properties and is traditionally used to treat dizziness, diabetes, and asthma (Lu et al. 2023; Pang et al. 2022). About 3000 P. cyrtonema plants were planted in five fields at the Institute of Medicinal Plant Development (40.04°N, 116.28°E), Beijing, China, where rhizome rot was observed from June to October 2023, with an incidence rate of about 10%. Most cases occurred in low-lying, waterlogged fields. Initially, infected plants had no obvious aboveground symptoms but had brown spots on their rhizomes. In severe cases, plants exhibited aboveground withering and brown rot in rhizomes. A fungus was isolated from symptomatic plants (isolation rate 73%), and single spores were used to grow pure colonies on potato-dextrose-agar (PDA) and incubated for 5 d at 25°C in the dark. Eleven isolates with the same morphology were obtained. The upper surface of the colonies was white, with cottony mycelium and a light purple center. The lower surface of the colonies was hazel in the center. Two representative isolates, C76 and C78, were cultivated on carnation leaf agar medium. Microconidia of the isolates were aseptate, oval, elliptic or clavate, and their dimensions were 4.9 to 12.1 × 1.5 to 4.5 μm (n = 50). Macroconidia were long, slender and thin, rod-shaped or slightly curved, with one to five septa, and their dimensions were 15.3 to 44.9 × 2.7 to 4.5 μm (n = 50). The isolates were classified as Fusarium based on morphology (Leslie and Summerell 2006). To determine the species identity, we sequenced the translation elongation factor (TEF-1α) and partial RNA polymerase second largest subunit (RPB2) of two isolates (i.e., C76 and C78, GenBank access numbers: TEF-1α, PQ550044, PQ285402; RBP2, PQ550045, PQ285403, respectively) (Crous et al 2009) and compared them to other Fusarium species found at Fusarium-ID and GenBank databases. Both isolates exhibited 99.84% (TEF-1α, MT305203) and 100% (RBP2, LT841252) similarity with Fusarium proliferatum. The phylogenetic tree was constructed by combining TEF-1α, and RBP2 using MEGA6, and the two isolates clustered with F. proliferatum. To demonstrate pathogenicity, 2 mL of conidial suspension (1 × 106 conidia/mL) of the isolate of F. proliferatum designed C76 were dropped on the surface of four rhizomes without wounding. For the control, sterile water was applied on two control rhizomes. All treatments were repeated three times. Seedlings were grown at 25°C in moist soil. After 7 d, inoculated roots exhibited similar symptoms to those in the field, while control roots showed no symptoms. The same isolate was reisolated from diseased roots and was identified based on morphological characteristics, fulfilling Koch's postulates. Based on morphology and molecular biology, the isolates were identified as F. proliferatum, a ubiquitous pathogen (Li, et al 2017) that was reported to cause leaf spot on P. cyrtonema (Zhou, et al. 2021). This is the first report of F. proliferatum causing rhizome rot on P. cyrtonema. This research will help develop strategies to manage rhizome rot incited by F. proliferatum.

Detection of AdeAB, TetA, and TetB efflux pump genes in clinical isolates of tetracycline-resistant Acinetobacter baumannii from patients of Suez Canal University Hospitals

BackgroundAcinetobacter baumannii is an opportunistic bacteria associated primarily with hospital-acquired infections. Its tendency to acquire or donate resistance genes to neighboring bacteria is a major concern. Tetracyclines have shown promise in treating A. baumannii infections, but tetracycline resistance is growing globally in A. baumannii isolates.ObjectivesThe study aimed to study (1) the prevalence of multidrug-resistant (MDR) A. baumannii infections at Suez Canal University Hospitals, (2) the distribution of efflux pump genes AdeA &B, TetA, and TetB, and (3) the effect of efflux pump inhibitor (CCCP) on tetracycline-resistant isolates.MethodsClinical samples (457) were collected (blood, urine, sputum, ETA, pus, and pleural fluid), followed by A. baumannii isolation and identification, PCR detection of efflux pump genes, and detection of tetracycline susceptibility and its MIC before and after treatment with the efflux pump inhibitor (CCCP).ResultsA total of 31 A. baumannii isolates were recovered (6.78%). The highest rate of isolation was from the ICU (48.3%) from the ET aspirate samples (48.3%). The efflux system AdeA and TetB genes were distributed in 100% of isolates, whereas AdeB was found in 93.5% of isolates and the TetA gene in 87.1% of isolates. All A. baumannii isolates were MDR showing resistance to three or more classes of antibiotics. 45% of the isolates showed a 4-fold reduction of MIC and 12.9% showed a 2-fold reduction in the MIC.ConclusionsEfflux pump is an important mechanism for tetracycline resistance among A. baumannii isolates.

Characterization of non-typhoidal Salmonella reveals the highly prevalent mcr-1-positive S. 1,4,[5],12:i:- within eggs are derived from chickens.

Salmonella is one of the most common foodborne pathogens. Antimicrobial-resistant Salmonella isolates, especially those resistant to colistin, pose a significant threat to public health worldwide. However, data about the prevalence of mcr-positive Salmonella in animals was few and the dissemination of mcr-positive Salmonella from animals to food, especially eggs, has not been fully addressed. The role of houseflies in the Salmonella transmission has also not been clarified. Here, we analyzed the prevalence and resistance characteristics of mcr-positive Salmonella in 1707 samples of animals (commercial laying hens, broilers, waterfowls and swine), eggs and flies from 23 farms in four cities of China between July 2021 and October 2022. Pulsed-field gel electrophoresis (PFGE) and whole-genome sequencing (WGS) analyses of Salmonella from different sources were further performed. Among animals, waterfowls had the highest isolation rate of Salmonella (18.1%, 35/193), followed by swine (6.1%, 23/377), laying hens (4.2%, 21/505) and broilers (1.4%, 7/489). Two of the 53 flies (3.8%) carried Salmonella. The detection rate of Salmonella in eggs from farms was 26.7%. All mcr-1-positive Salmonella isolates were S. 1,4,[5],12:i:- and were only found in hens (0.2%) and eggs (11.1%). PFGE and WGS analyses showed that the mcr-1-positive S. 1,4,[5],12:i:- from commercial laying hens and eggs in the same farm had no single nucleotide polymorphism (SNP) variation, indicating that the mcr-1-positive S. 1,4,[5],12:i:- in eggs were derived from hens. The phylogenomic analysis also showed that the mcr-1-positive S. 1,4,[5],12:i:- isolates from hens and eggs were closely related to previously reported mcr-1-positive Salmonella from human in China, further confirming that such mcr-1-positive Salmonella in animals could transmit to humans via the food chain. Furthermore, the blaCTX-M-1G-positive S. Kentucky isolates from broiler and flies in the same farm had a limited number of variations (5-7 SNPs), proving the clonal transmission of Salmonella between broilers and flies. The S. Kentucky isolates carrying blaCTX-M-1G from broilers were also closely related to the S. Kentucky isolates from chicken meats and humans. Our findings suggest that Salmonella including those carrying mcr-1 in animals could transmit to eggs/meats and potentially trigger human infections. The houseflies can play an important role in the Salmonella transmission within farms. Salmonella carrying mcr in animals and animal products should be monitored regularly and control measures are urgently needed to reduce the dissemination of such pathogens.

Nodular-bronchiectatic pattern in pulmonary nocardiosis: Immune status and treatment outcomes in a multicenter retrospective study.

Pulmonary nocardiosis is a rare opportunistic infection, with approximately 15% of patients being immunocompetent. The isolation rate of Nocardia spp. has recently increased, indicating rising clinical concern. This study aimed to summarize computed tomography (CT) findings, evaluate treatment outcomes, and improve disease recognition. We retrospectively analyzed 12 pulmonary nocardiosis cases recorded over 10 years in three hospitals, excluding two unclear cases. All pathogens were detected on smears and isolated from respiratory specimens. The mean age was 73.0±12.9 years, with 9 men and 6 smokers. Among the included patients, 8 had underlying pulmonary diseases, 4 had non-pulmonary diseases, and 3 were on steroids. The most common species were N. cyriacigeorgica and N. nova. CT findings included cavitary, consolidation/infiltrative, and nodular-bronchiectatic (NB) patterns. The NB pattern, particularly common in immunocompetent patients, was associated with significantly better treatment outcomes than non-NB patterns (Fisher's exact test, p=0.0476). All isolates were susceptible to trimethoprim/sulfamethoxazole. Eight patients recovered with appropriate antimicrobial therapy, while two patients died. Pulmonary nocardiosis presented three CT patterns, with the NB pattern being the most frequent and showing favorable treatment outcomes, especially in immunocompetent patients. While Nocardia spp. can develop in patients with preexisting bronchiectasis, it may also independently cause bronchiectasis. Nocardia infection should be considered as a differential diagnosis in patients exhibiting the NB pattern, resembling that of nontuberculous mycobacterial pulmonary diseases.

P-298. Treatment of Carbapenem-Resistant Gram Negative Bacteremia based on Polymixin MIC

Abstract Background Recent studies from India have noted increasing resistance against ceftazidime- avibactam in enterobacteriacea and non-fermenters and hence, polymixins are mainstay in the treatment of carbapenem-resistant gram negative (CRGN) infections. There is no susceptible breakpoint for polymixins in view of concerns with clinical outcome and therefore, guidelines recommend combination therapy. However, studies have failed to show the superiority of polymixin combination therapy over monotherapy. Invitro data shows ≥ 90% PK-PD target attainment for isolates with colistin MIC ≤ 0.5 mg/L, but lower success rates in isolates with higher MICs. Aim of the study is to evaluate if the choice of treatment of CRGN infections can be guided by polymixin MIC. Methods We retrospectively evaluated critically-ill patient with CRGN bacteremia with intermediate in vitro susceptibility to colistin (MIC ≤ 2 mg/L; as per CLSI) at a tertiary care hospital in India from January 2022- June 2023. Patients who received treatment for the CRGN bacteremia for <48 h were excluded. Based on polymixin MIC, patients were grouped into two study groups: those that received polymixin monotherapy and those that received polymixin in combination with another agent susceptible in vitro. Chi-square test was used for categorical data and student’s t-test for continuous data. Analysis was performed using SPSS v28 and statistical significance was defined as p < 0.05. Results Of the 114 patients with CRGN bacteremia, 64 (56%) had an MIC of ≤ 0.5 and 50 (44%) had MIC ≥ 1. There was no statistically significant difference in the ICU mortality between monotherapy and combination therapy arms (16% vs 15%; P = 0.9778) for polymixin MIC ≤ 0.5. However, when the MIC was ≥ 1, a higher mortality was observed in the polymixin monotherapy arm (82% vs 39%; P = 0.0029). Conclusion Isolates with MIC ≤ 0.5 can be treated with polymixin monotherapy alone while isolates with MIC ≥ 1 require a combination therapy of polymixin with another antibiotic suseptible invitro. However, this is a single centre retrospective study and further clinical trials are required to ascertain the feasibility of polymixin MIC guided treatment of CRGN infections. Disclosures All Authors: No reported disclosures

P-762. Prevalence and/or Recurrence of Non-Tubercular Mycobacterial Pulmonary Disease in Structural and Airway Lung Disease

Abstract Background Nontuberculous mycobacterial pulmonary disease (NTM-PD) frequently remains undetected, especially among patients with preexisting respiratory conditions who are prone to develop the disease. This study aims to explore the prevalence, species diversity, and outcomes of NTM-PD in India, an uncharted topic. Methods We conducted a prospective observational study, enrolling 69 patients with symptomatic chronic respiratory diseases or a history of Tuberculosis (TB). These patients underwent thorough clinical assessment, chest computed tomography scans, and either a single bronchoscopic sample or three sputum samples for microbiological analysis, along with relevant biochemical investigations. Diagnosis of NTM-PD followed the ATS 2020 diagnostic criteria. The growth of the organism was compared using patented indigenous media with or without p-nitrobenzoic acid. Results The prevalence of NTM-PD was 17.4%, with TB affecting 31.9% of cases. Baseline clinical symptoms and their duration showed no statistically significant differences, except NTM-PD patients with hemoptysis had significantly shorter symptom durations than other groups. Isolation rates were notably higher with the patented indigenous media compared to the mycobacterial growth indicator tube for both NTM (100% vs. 33.3%, p < 0.001) and Mycobacterium tuberculosis (M.Tb) (57.1% vs. 47.6%, p < 0.001). NTM-PD patients exhibited a significantly higher proportion of fibro-cavitary disease compared to other groups when comparing radiological findings. After monitoring NTM-PD patients following treatment, one patient (20%) experienced a recurrence of symptoms within six months, rest continue to be under follow-up. Conclusion In a high-burden TB setting, clinical suspicion and effort to look for NTM-PD is often low. Our study highlights the high prevalence of NTM-PD in individuals with chronic lung conditions/past history of TB. Patients with NTM-PD show higher rates of fibro-cavitary disease, possibly allowing the NTM to form biofilms and hence lead to relapses. Diagnosis of NTM-PD is thus important, to ensure desired treatment for the recommended duration and a thorough and prolonged post-treatment monitoring due to higher relapse risk. Disclosures All Authors: No reported disclosures

P-244. Antibiotic Prescribing Patterns in Ventilator Associated Pneumonia and their Effect on Carbapenem Resistant Organism Colonisation in Asian Hospitals

Abstract Background Ventilator-associated pneumonia (VAP) is associated with prolonged hospitalisation, excessive antibiotic use and high mortality. Antibiotic regimens used for VAP and their effect on development of carbapenem resistant (CR) organisms (CRO) have not been well characterised, especially in Asia.Table 1.Antibiotics used for index episode of VAP caused by carbapenem resistant organisms, and overall carbapenem use Methods The REGARD-VAP study was a randomised trial conducted in 39 intensive care units in Nepal, Singapore and Thailand. Adults aged ≥18 years with VAP (defined by the US CDC and Prevention National Healthcare Safety Network criteria), who had been mechanically ventilated for ≥48 hours, and received culture-directed antibiotics were enrolled. In culture-negative cases, antibiotics were prescribed as per local hospital antibiograms. We analysed the antibiotics prescribed in VAP and their association with CRO acquisition. We also assessed the effect of CRO colonisation on 60-day mortality and VAP recurrence.Table 2.Factors associated with new carbapenem-resistant organism (CRO) isolation in microbiological samples in a multivariable logistic regression model Carbapenem use for index episode of VAP was independently associated with higher odds ratio of new CRO colonization when adjusted for duration of antibiotics, and length of hospital stay. Duration of ICU stay was not included in this model due to high collinearity with length of hospital stay. Results The study enrolled 460 participants and the majority (47.4%) of VAP was caused by Gram-negative non-fermenters (VAPnf). Amongst participants with CR VAPnf, 56 (45.5%) received colistin-based regimens and 48 (39.0%) received beta-lactams. Amongst those with CR Enterobacterales, 11 (44.0%) received either a colistin-based regimen or beta-lactams. 52 different antibiotic regimens were used to treat CR VAP, and only one participant received a novel beta-lactam/beta-lactamase inhibitor (Ceftazidime-avibactam). 45.9% of all antibiotic regimens included carbapenems which was independently associated with new acquisition of CRO during the study period (OR 1.80, 95% CI 1.10 – 2.93, p=0.019). In a Cox regression model, CRO colonization (n=176, 38.3%) was associated with higher 60-day mortality (HR 1.66 (95%CI 1.21 – 2.28), p=0.002) and VAP recurrence (HR 8.37 (95% CI 4.28 – 16.38), p< 0.001) when adjusted for demographic factors, disease severity, comorbidities, antibiotic duration, and VAPnf.Figure 1.Cox-Regression Survival analysis showing 60-day mortality (left) and 60-day VAP recurrence (right) in participants with or without Carbapenem Resistant Organism (CRO) colonization. 60-day mortality and VAP recurrence was adjusted for demographic factors (patient age and gender), disease severity (qSOFA score and inotropic requirement at VAP diagnosis), comorbidities (Charlson comorbidity index and presence of congestive cardiac failure, acute coronary syndrome, chronic obstructive pulmonary disease, chronic kidney disease, cirrhosis, cancer, diabetes), duration of antibiotics prescribed for index episode of VAP, use of appropriate empiric antibiotics to which the organism was susceptible prior to switching to culture-directed antibiotics and cause of VAP (presence/ absence of Gram-negative non-fermenter). Participants with CRO colonization had increased hazards ratio of mortality and VAP recurrence. Conclusion In lower, middle- and high-income countries in Asia, variable antibiotic regimens were used for the treatment of VAP, majority consisting of colistin and carbapenem based regimens, with the latter being associated with higher rates of new CRO isolation. There is a need for better treatment options for these difficult to treat pathogens across the income spectrum in Asia. Disclosures Paul Tambyah, MBBS (S'pore), Diplomate, American Board of Internal Medicine and Infectious Diseases, Moderna: Grant/Research Support|Sanofi-Pasteur: Grant/Research Support

P-1754. An Antimicrobial Stewardship Program (ASP) Without Antibiotic Restrictions - Performance Update

Abstract Background In 2011, University Medical Center of Southern Nevada (UMC) in Las Vegas presented introductory results of a simple, yet effective ASP program with the unique strategy of not restricting antibiotics. Since this time, ASP has continued to strive towards appropriate antimicrobial use in an attempt to improve patient care and minimize development of resistance. This project is an update of the progress of this ASP program in terms of resistance, antibiotic use and costs. Methods ASP started January 2008 with minimal resources. Baseline activities included targeted medication use evaluation (MUE), duration regulation, expansion of infection prevention and education. In contrast to many ASP programs our program did not restrict antibiotics – formulary agents were available for any practitioner. Over time activities were adjusted, reporting technologies advanced although personnel resources remained limited. ASP modifications:Added MUE agentsTiered sensitivity reportingReduce duration to 7 daysExpand service to 6 days per week Deviating from initial procedures, in 2015 we implemented restriction of 5 “last-line” antimicrobials to UMC employed Infectious Disease Physicians (table 1) using the EHR. Markers of ASP progress was monitored by rates of organism isolation per 1000 patient days and antimicrobial in days of therapy per 1000 patient days. Financial implications were based on antibiotic expenditures per adult patient day. Results Monitored bacterial pathogens decreased 65 – 94% (table 2). The largest reduction was with Acinetobacter sp. followed by carbapenem resistant P. aeruginosa. Antibiotic use also improved (table 3). Overall use was decreased 71.3 ± 14.7% with the largest changes with fluoroquinolones and piperacillin/tazobactam. Of note, not all antibiotics reported are MUE, and use of these agents still improved. Despite expanding formulary, and cost monitoring activities, antibiotic expenditures decreased 47% per adult patient day. Conclusion ASP at UMC has demonstrated that simple programs, with limited resources, can decrease the use of unnecessary antimicrobial agents and isolation of specific bacterial pathogens. Additional benefits include a decrease in hospital costs without requiring significant restriction of antimicrobial agents. Disclosures Kimberly D. Leuthner, PharmD, FIDSA, AbbVie Inc.: Advisor/Consultant|AbbVie Inc.: Honoraria|Basilea Pharamceutica: Advisor/Consultant|La Jolla Pharmaceutical Company: Honoraria|Merck: Advisor/Consultant|Merck: Honoraria|Shionogi, Inc: Honoraria

P-841. Empiric Antimicrobial Treatment of Sepsis in Canadian Emergency Rooms: Analysis of Pathogens Causing Bacteremia and Their Susceptibility Rates

Abstract Background An alarming increase in the frequency of ESBL-producing organisms has been reported in Canada, raising concerns about whether empiric regimens used for the treatment of sepsis remain sufficient to cover ER patients with potentially undiagnosed bloodstream infections. Using data from the CANWARD study, we report on the epidemiology of bloodstream infections in Canadian emergency rooms and estimate the susceptibility rate of these pathogens to empiric regimens commonly used for the treatment of sepsis. Rate of ESBL production in blood culture isolates of Escherichia coli (ER patients, CANWARD 2007-2022). Methods As part of the CANWARD national surveillance study, sentinel hospitals across Canada submitted the first 10 clinically significant isolates recovered from blood cultures each month. Isolates underwent antimicrobial susceptibility testing using the broth microdilution method and susceptibility to antibiotics was determined whenever MICs and CLSI breakpoints were available. For Streptococcus and Enterococcus, where piperacillin-tazobactam breakpoints were not available, susceptibility was inferred from penicillin and ampicillin MICs as per EUCAST standards. Rate of ceftriaxone susceptibility in blood culture Escherichia coli isolates (ER patients, CANWARD 2007-2022). Results From 2007 to 2022, 9,178 blood culture isolates were collected from patients presenting to Canadian emergency rooms. The most common organisms isolated were: 1. Escherichia coli (31.7%) 2. Staphylococcus aureus (16.8%) 3. Klebsiella pneumoniae (7.8%) 4. Streptococcus pneumoniae (6.8%) 5. Streptococcus pyogenes (2.9%) There has been a marked increase in the rate of ESBL production in E. coli (Figure 1). This is associated with a decrease in the susceptibility rate of E. coli to ceftriaxone (Figure 2). Despite these changes, isolates from blood cultures of ER patients remain susceptible to piperacillin-tazobactam more than 90% of the time and remain susceptible to piperacillin-tazobactam plus vancomycin more than 95% of the time (Table 1). Susceptibility rates of blood culture isolates from ER patients to commonly prescribed empiric antimicrobial regimens. Conclusion Isolates causing bloodstream infections in Canadian ER patients remain susceptible to piperacillin-tazobactam more than 90% of the time. The susceptibility rate to ceftriaxone is less than 85% and ceftriaxone should be used with caution in sepsis when the source of infection is unclear. Individual centers should perform their own assessments based on the most common pathogens causing bacteremia and their local susceptibility rates. Disclosures All Authors: No reported disclosures

P-278. Emerging Threat: Rising Incidence and Antimicrobial Resistance of Serratia marcescens in a Guatemalan Intensive Care Unit

Abstract Background Serratia marcescen, a gram-negative bacillus, is an important pathogen associated with hospital acquired infections. It ranks as the 5thmost common Gram-negative organism in Intensive Care Units infections globally. With a global case-mortality of 2.8%, Serratia marcescens poses a substantial threat to healthcare systems. The use of broad-spectrum antibiotics has led to increased antimicrobial resistance among Serratia strains. Rates of ESBL-producing isolates of Serratia have been reported ranging from 6-24% of all strains, in low- and middle-income countries. This study evaluates the incidence and resistance patterns of Serratia isolates in Guatemala City. Methods An ecological study was conducted at an intensive care unit from a third-level reference hospital in Guatemala City from 2022 to 2023. All microbiologic isolates of Serratia Marcescens were included, and antimicrobial resistance was determined through the use VITEK® MS (Maldi Tof) and VITEK® 2 systems. Antimicrobial resistance patterns were identified according to the Clinical and Laboratory Standard Institute (CLSI) guidelines. GyrA/ParC phenotype was inferred through resistance to fluoroquinolones. Results A total of 20 isolates of Serratia were identified in 2022 and 49 in 2023. The majority of strains were isolated from respiratory samples (81.15%). There was a significant increase in Serratia positivity rates (4.72 vs 9.06 per 1000 cultures) and incidence of Serratia isolates (24.75 vs. 94.59 per 1000 admissions) from 2022 to 2023. An increase in antimicrobial resistance was observed between 2022 and 2023. In 2022, 70% of strains where susceptible, and 20% showed only one mechanism of resistance. Conversely, in 2023, only 6% of strains where susceptible and over 57% presented more than one mechanism of resistance. An increase in inferred GyrA/ParC (5% vs 83.6%) and confirmed ESBL (0% vs 36.7%) phenotypes were observed. Conclusion An increased use of antimicrobials in the ICU may be associated with the sudden and alarming rise in resistance in Serratia isolates. The clinical impact of these ecological changes is yet to be determined. The escalating incidence and resistance of S. marcescen in Guatemala City highlights the urgency for enhanced surveillance and antimicrobial stewardship programs. Disclosures All Authors: No reported disclosures

P-1082. Antimicrobial Susceptibility of Enterobacterales Causing Infection in the Elderly: Focus on Aztreonam-avibactam and Recently Approved β-Lactamase Inhibitor Combinations

Abstract Background Infections account for about 1/3 of all deaths in people 65 years and older and this population has a higher risk of exposure to antimicrobial-resistant bacteria. We evaluated the antimicrobial susceptibility of Enterobacterales (ENT) causing infection in elderly patients in United States (US) medical centers. Activity of β-lactamase inhibitor combinations against Enterobacterales from elderly patients Methods Clinical isolates (1/patient) were consecutively collected from 72 US medical centers in 2021-2023 and susceptibility tested by broth microdilution. Results for 10,574 ENT isolates from elderly patients (≥65 years old) were analyzed and compared to 9,793 isolates from adult patients (age 18-64). Results were stratified by infection type and resistant subsets. Cefiderocol was only tested against carbapenem-resistant ENT (CRE). ATM-AVI was tested with AVI at fixed 4 mg/L and a PK/PD susceptible (S) breakpoint of ≤8 mg/L was applied for comparison. CRE isolates were screened for carbapenemases (CBase) by whole genome sequencing. Comparator agents included ceftazidime-avibactam (CAZ-AVI), meropenem-vaborbactam (MEM-VAB), imipenem-relebactam (IMI-REL), and cefiderocol (CRE only), among others. Results All elderly isolates were inhibited at ATM-AVI MIC of ≤8 mg/L. CAZ-AVI (99.7% S) and MEM-VAB (99.8% S) were very active against ENT overall but exhibited limited activity against CRE (71.6% and 70.4% S, respectively; Table). The most active agents against CRE were ATM-AVI (100.0% inhibited at ≤8 mg/L) and cefiderocol (96.3% S). Multidrug-resistant (MDR; non-S to ≥3 classes) and ESBL phenotypes were observed in 19.8% and 12.3% of isolates, respectively, and ceftolozane-tazobactam (TOL-TAZ) and piperacillin-tazobactam (PIP-TAZ) showed limited activity against these organisms. Susceptibility to TOL-TAZ, PIP-TAZ, and ceftriaxone were lower among elderly isolates from pneumonia than BSI or UTI. The most common CBase were KPC (56.8% of CRE) and NDM (22.2%). A metallo-β-lactamase was identified in 24.7% of isolates. In general, susceptibility rates of isolates from the elderly were comparable (+/- < 2%) to those from the adult population. Conclusion ATM-AVI demonstrated complete activity (100.0% S) against ENT causing infection in the elderly, including CRE and isolates with ESBL or MDR phenotypes. Disclosures Rodrigo E. Mendes, PhD, GSK: Grant/Research Support Marisa Winkler, MD, PhD, Element Iowa City (JMI Laboratories) was contracted to perform services in 2023 for > 30 biotech and pharmaceutical companies: Grant/Research Support

Prevalence and Antibiotic Susceptibility Pattern of Bacteria Isolated from Nigerian Currency Note in Enugu State, Nigeria

Background: Nigerian currency notes act as fomites and thus can transmit pathogenic microorganisms from one person to another. Aim: This study was conducted to evaluate the prevalence and antibiotic susceptibility pattern of bacteria isolated from Nigerian currency notes circulating in Enugu East local government area of Enugu State. Methods: Isolation, characterization and antibiotic sensitivity tests were done using standard methods. Results: A total of 632 bacterial strains comprising 13 different bacterial species were isolated and identified from the Nigerian currency notes. The respective isolation rates of the isolates were Staphylococcus aureus(35.3%), E.coli (15.0%), Pseudomonas aeruginosa (2.5%), Bacillus sp (13.6%), Salmonella sp (2.8%), Klebsiella sp (10.1%), Streptococcus sp (7.3%), Acinetobacter sp (1.6%), Serratia marcescens (1.7%), Proteus mirabilis (3.8%), Enterococcus faecalis (2.8%), Citrobacter sp (3.0%) and Actinomycete sp (0.3%). The Gram positive and Gram negative bacteria showed resistance to cloxacilline (87%) and amoxicillin (84%). Further, 93.4% of all the bacterial isolates had a multi-antibiotic resistance index (MARI) >2 and the rest of the isolates (6.5%) had a MARI < 2. Conclusion: Nigerian currency notes harbour bacteria. Many of these bacteria are multidrug resistant organisms.

Isolation, Characterization and Plasmid Profiling of Multi-drug Resistant Bacteria Isolated from Automated Teller Machines (ATM devices) in Enugu State, Nigeria

Background: Due to high frequency of use, many kinds of microbes may contaminate the ATM device resulting in the emergence and spread of infectious agents especially multi-antibiotic resistant (MAR) bacteria. Aim: This study was conducted to isolate and phenotypically characterize bacteria isolates from ATM devices in Enugu State, Nigeria. Study Design: This is a prospective, cross-sectional study involving 30 different ATM devices. Place and Duration: The research was conducted in Enugu State from January 2024 to August 2024. Methodology: The isolation, phenotypic characterization and plasmid profiling of the test bacteria were carried out using standard methods. Results: A total of one hundred and twelve (112) bacteria were isolated and they include Klebsiella spp, Pseudomonas aeruginosa, Enterobacter spp, Serratia marcescens, Escherichia coli, Streptococcus spp, Staphylococcus aureus and coagulase negative Staphylococcus spp (CoNS). In the study, CoNS had the highest isolation rate of 20.5 % and Serratia marcescens had the lowest isolation rate of 1.8 %. A total of 20 plasmids with molecular weight ranging from 2322 – 23130 bp were detected from the bacteria tested. The MAR index of the isolates fell within 0.2 to 0.8 indicating a high risk source of contamination where antibiotics misuse exist by the users in this study area. Conclusion: Therefore, it is high time people started adopting the culture of washing and sanitizing hands before and after using the ATM devices as hand transmission is a major source of MAR infectious agents that can contaminate ATM surfaces.

Mental Distress Posed by the Co-Experience of Elder Mistreatment and Social Isolation: A Study with Older Korean Americans

ABSTRACT This study examined the concurrent effects of social isolation and elder mistreatment on mental distress in older Korean Americans (n= 2,122, Mean age = 73.4). Approximately 44% experienced mistreatment, with 32% exposed to a single type and 12% to multiple types (polyvictimization). Social isolation and mental distress rates were about 24% and 30%, respectively. Both factors independently affected mental distress, with a significant interaction observed. The odds of experiencing mental distress were substantially greater when polyvictimization occurred in social isolation. These findings underscore the importance of targeted interventions to support for those who are mistreated and lack social protection.

Carbapenemase-Producing Enterobacterales: An Increasing Threat to Australian Liver Transplant Recipients.

Carbapenemase-producing Enterobacterales (CPE) are associated with increased morbidity and mortality in liver transplant recipients (LTRs). There is a paucity of data regarding CPE colonization and infection in Australian LTRs. A single-center retrospective cohort study of CPE was performed in LTRs from 2015 to 2024. LTRs underwent targeted screening and a period of enhanced screening to evaluate the incidence of CPE colonization. CPE infections were identified via clinical samples. All CPE isolates underwent whole genome sequencing. CPE isolation rates in LTRs were compared to the general hospital population and trends over time were analyzed. There were 31 episodes of CPE isolation (5 community acquired, 26 healthcare associated) from 28 LTRs. Nine episodes of CPE infection were found: urinary tract (n = 3), bloodstream (n = 3), wound/abscess (n = 2), and Salmonella gastroenteritis (n = 1). The remaining 22 episodes represented new CPE colonization. CPE Klebsiella pneumoniae was the most common bacterial species (n = 12) with the New Delhi metallo-β-lactamase (n = 13), the most common CPE gene detected. CPE isolation rates in LTRs increased over the study period (p = 0.06). The overall rate of CPE infection was significantly higher in LTRs than the general hospital population (1.92vs. 0.30 per 10 000 occupied bed days, p = 0.04). Enhanced CPE screening identified an additional eight episodes of CPE colonization in 415 patients screened (1.9%). CPE is an emerging threat for Australian LTRs and there is an urgent need to optimize strategies to prevent CPE colonization and infection in LTRs.

Repeat Procedures After Pulsed Field Ablation for Atrial Fibrillation: MANIFEST-REDO Study.

Initial clinical studies of pulsed field ablation (PFA) to treat atrial fibrillation (AF) indicated a >90% durability rate of pulmonary vein isolation (PVI). However, these studies were largely conducted in single centers and involved a limited number of operators. The electrophysiological findings and outcomes in patients undergoing repeat ablation after an initial PF ablation for AF are incompletely understood. In the MANIFEST-REDO study, we investigated patients who underwent repeat ablation due to clinical recurrence - AF or atrial tachycardia (AT) - following first-ever PVI with a pentaspline PFA catheter (Farawave; Boston Scientific Inc). At 22 centers, 427 patients (age 64±11 years; 37% female) were included. Of note, the recurrent arrhythmia leading to the repeat ablation was paroxysmal AF (51%), persistent AF (30%), or AT (19%). At the repeat procedure, the PV reconnection rates were: 30% (LSPV), 28% (LIPV), 33% (RSPV) and 32% (RIPV). In 45% of patients all PVs were durably isolated at the beginning of the repeat procedure, with the previous use of any imaging or mapping modality being univariately associated with durable PVI. After a post-redo follow-up period of 284 [90-366] days, the primary effectiveness endpoint (freedom from documented AF/AT lasting ≥30s after 3-month blanking without class I/III antiarrhythmic drugs or symptoms) was achieved in 65% of patients, with significant differences between groups (PAF 65% vs. PersAF 56% vs. AT 76%; p=0.04). Persistent AF as recurrent arrhythmia after the initial PFA ablation predicted AT/AF recurrence after repeat ablation (HR 1.241 (95% CI 1.534-1.005 CI); p=0.045). The procedural complication rate was 2.8%. In repeat procedures for AF/AT performed after an index procedure with PFA for AF, PV reconnections are not uncommon. Repeat procedures can be performed safely and with an acceptable subsequent success rate.

Prevalence, Characterization, and Proteomic Relatedness Among β-Lactam-Resistant Bacteria Throughout the Poultry Production Chain in Greece.

Extended-spectrum-β-lactamase (ESBL) and carbapenemase-producing Escherichia coli, Klebsiella pneumoniae and Acinetobacter spp. are associated with hospital-acquired infections and are commonly isolated across the poultry food production chain. Comprehensive data regarding the prevalence, spatiotemporal variations, and characterization of β-lactam-resistant bacteria in poultry farms and slaughterhouses is scarce. This study examines the prevalence and characteristics of β-lactam-resistant E. coli, K. pneumoniae, and Acinetobacter spp. isolated from poultry farms, slaughterhouses, and associated personnel in Greece. Strains were selectively isolated and identified via MALDI-TOF MS, which was also employed to identify possible relatedness. E. coli isolates were further classified into phylogenetic groups. The prevalence of β-lactam-resistant strains in farm and slaughterhouse environments was 15.0% (n = 15 strains)/57.3% (n = 71 strains) for E. coli, 11.0% (n = 11 strains)/1.6% (n = 2 strains) for K. pneumoniae, and 1.0% (n = 1 strain)/25.8% (n = 38 strains) for Acinetobacter spp., respectively. The prevalence of Acinetobacter spp. and E. coli on farmers' skin was 16.7% (n = 2 strains) and 8.3% (n = 1 strain), correspondingly. Significantly higher E. coli isolation rates were observed in warmer seasons. All strains were multidrug-resistant and most carried ESBL/AmpC genes. Most E. coli isolates belonged to phylogroups A (41.4%, n = 36) and B1 (24.1%, n = 21). Proteomic analysis indicated relatedness among strains from different regions and seasons. Thus, poultry farms and slaughterhouses may serve as significant reservoirs of β-lactam-resistant strains of E. coli, K. pneumoniae, and Acinetobacter spp.

Associations Between Peak Expiratory Flow and Community Mobility Loss Among Older Adults in the United States.

Community mobility is a vital patient-centered outcome for older adults living in the community. These deficits in mobility are linked to social isolation, increased hospitalizations, and higher mortality rates. Impaired pulmonary function may be a modifiable risk factor for mobility decline, with existing inequities in lung health potentially contributing disproportionately to mobility loss among Black older adults. A cohort of 4742 community-dwelling older adults (weighted n = 29,180,893) with self-reported ability to walk 3 or more blocks in their community was drawn from the National Health and Aging Trends Study (NHATS). Pulmonary function was measured by PEF in NHATS. Community mobility loss was defined as self-reported inability to walk ≥ 3 blocks in the 1-year follow-up assessment. Hierarchical multivariable logistic regression was used and adjusted for demographics, comorbidities, pain, and assistive device use. Overall, 73.7% of the sample had normal PEF, 18.6% had moderate impairment, and 7.7% had severe impairment. Those with severe impairment were more likely to be male and identify as Black. In unadjusted analyses, 8.8% of older adults with normal PEF experienced mobility loss, compared with 12.7% of those with moderate impairment, and 19.7% with severe impairment. Odds of mobility loss were 111% higher for those with severe PEF impairment as compared to those with normal PEF (OR = 2.1, 95% CI 1.2-3.7) in fully adjusted models, with weaker relationships being observed for those with moderately impaired PEF (OR = 1.2, 95% CI 0.8-1.8). Nearly 8%, or an estimated 1 million community-ambulating U.S. older adults, had severe impairments in peak expiratory flow in 2015; these older adults have a substantially higher risk of losing the ability to ambulate community distances over the subsequent year.

Optimized workflow with hybrid (very) high-power short-duration radiofrequency ablation renders point-by-point pulmonary vein isolation as fast and effective as cryoballoon ablation.

A hybrid approach with very high-power short-duration (vHPSD) posteriorly and ablation-index guided HPSD (50 W) anteriorly seems to be an optimal balance between efficiency and effectiveness for point-by-point pulmonary vein isolation (PVI). The aim of the current study is to compare vHPSD/HPSD ablation to cryoballoon ablation (CBA) in patients with symptomatic atrial fibrillation (AF). In this retrospective single-center study, we identified 110 consecutive patients who underwent their first PVI with either vHPSD/HPSD (n = 54) or CBA (n = 56). We compared procedural efficacy, efficiency, safety, and long-term outcomes. Baseline characteristics of both groups were comparable; however, patients in the vHPSD/HPSD group had larger left atrial volume index (35, IQR 27-45 vs. 28, IQR 21-36ml/m2, P = 0.005). Complete PVI was achieved in all patients except two CBA cases (100% vs. 96.4%, P = 0.50). First-pass isolation rate was 79.6% in the hybrid group. Procedure times were similar between groups (53, IQR 47-63 vs. 55, IQR 49-65min, P = 0.35), but fluoroscopy time was shorter in the vHPSD/HPSD group (3.9 [2.7, 5.6] vs. 11.9 [9.3, 14.9] min, P < 0.001). There were 3 temporary phrenic nerve palsies (5.4%) in the CBA group which resolved within 1year. The 1-year freedom from any atrial tachyarrhythmias after a single procedure was similar between groups (68.5% vs. 73.2%, P = 0.56). During repeat procedure, the durability of PVI was comparable. The use of vHPSD/HPSD ablation renders point-by-point PVI as fast and effective as CBA. Furthermore, it has lower radiation exposure compared to CBA.