Community-associated Infections Research Articles

Molecular Epidemiology of Clostridioides difficile Colonization in Families With Infants.

Community-associated Clostridioides difficile infection is a major public health hazard to adults and older children. Infants frequently excrete toxigenic C difficile asymptomatically in their stool, but their importance as a community reservoir of C difficile is uncertain. Families of healthy infants were recruited at the baby's 4-month well child visit and were followed longitudinally until the baby was approximately 9 months old. Babies and mothers submitted stool or rectal swabs every 2 weeks that were cultivated for C difficile; fathers' participation was encouraged but not required. Clostridioides difficile isolates were strain-typed by fluorescent polymerase chain reaction ribotyping and by core genome multilocus sequence typing, and the number of families in whom the same strain was cultivated from >1 family member ("strain sharing") was assessed. Thirty families were enrolled, including 33 infants (3 sets of twins) and 30 mothers; 19 fathers also participated. Clostridioides difficile was identified in 28 of these 30 families over the course of the study, and strain sharing was identified in 17 of these 28. In 3 families, 2 separate strains were shared. The infant was involved in 17 of 20 instances of strain sharing, and in 13 of these, the baby was identified first, with or without a concomitantly excreting adult. Excretion of shared strains usually was persistent. Clostridioides difficile strain sharing was frequent in healthy families caring for an infant, increasing the likelihood that asymptomatically excreting babies and their families represent a reservoir of the organism in the community.

The Distribution of Carbapenem-Resistant Acinetobacter Species and High Prevalence of CC92 OXA-23-Producing Acinetobacter Baumannii in Community Hospitals in South Korea.

Clinical isolates of Acinetobacter species in South Korea are continuously exhibiting high rates of antimicrobial resistance to carbapenems, indicating that there are public health concerns among both healthcare-associated infections and community-associated infections. The aim of this study was to describe the prevalence and characteristics of carbapenem-resistant Acinetobacter isolates originating from community hospitals. A total of 817 non-duplicated Acinetobacter species were isolated from December 2022 to July 2023 at long-term care facilities and general hospitals in 16 regions geographically distributed throughout South Korea. Bacterial identification and antimicrobial susceptibility testing were performed using the VITEK-2 system. The bacteria were identified as Acinetobacter baumannii by blaOXA-51 PCR and as non-baumannii Acinetobacter species by rpoB sequence analysis. The carbapenem resistance genes (OXA-23, OXA-48, OXA-58, IMP, VIM, NDM, GES, and KPC) were identified via PCR and sequencing. The genetic relatedness of carbapenem-resistant A. baumannii (CRAB) isolates was assessed by multilocus sequence typing. A total of 659 A. baumannii and 158 non-baumannii Acinetobacter isolates, comprising 19 different species, were identified in all 16 regions. The carbapenem resistance rate was 87.4% (n=576) for the A. baumannii isolates, and all the strains produced blaOXA-23. For non-baumannii Acinetobacter, the rate of carbapenem resistance was 8.9% (n=14); this resistance was primarily caused by blaOXA-23 (n=9), followed by blaNDM-1 (n=3) and blaVIM-2 (n=2). Of the 576 CRAB isolates, clonal complex 92 (CC92) was the predominant genotypes, followed by sequence type 229 (ST229), ST373, ST397, ST447, and ST620. Our results showed the distribution of Acinetobacter species and showed that CC92 CRAB clinical isolates with widespread production of blaOXA-23 were predominant in community hospitals. Our findings suggest that there is a need for urgent and effective methods to reduce carbapenem resistance in A. baumannii in South Korea.

A neoteric antibacterial ceria-silver nanozyme for abiotic surfaces

Community-associated and hospital-acquired infections caused by bacteria continue to yield major global challenges to human health. Bacterial contamination on abiotic surfaces is largely spread via high-touch surfaces and contemporary standard disinfection practices show limited efficacy, resulting in unsatisfactory therapeutic outcomes. New strategies that offer non-specific and broad protection are urgently needed. Herein, we report our novel ceria-silver nanozyme engineered at a molar ratio of 5:1 and with a higher trivalent (Ce3+) surface fraction. Our results reveal potent levels of surface catalytic activity on both wet and dry surfaces, with rapid, and complete eradication of Pseudomonas aeruginosa, Staphylococcus aureus, and methicillin resistant S. aureus, in both planktonic and biofilm form. Preferential electrostatic adherence of anionic bacteria to the cationic nanozyme surface leads to a catastrophic loss in both aerobic and anaerobic respiration, DNA damage, osmodysregulation, and finally, programmed bacterial lysis. Our data reveal several unique mechanistic avenues of synergistic ceria-Ag efficacy. Ag potentially increases the presence of Ce3+ sites at the ceria-Ag interface, thereby facilitating the formation of harmful H2O2, followed by likely permeation across the cell wall. Further, a weakened Ag-induced Ce–O bond may drive electron transfer from the Ec band to O2, thereby further facilitating the selective reduction of O2 toward H2O2 formation. Ag destabilizes the surface adsorption of molecular H2O2, potentially leading to higher concentrations of free H2O2 adjacent to bacteria. To this end, our results show that H2O2 and/or NO/NO2−/NO3− are the key liberators of antibacterial activity, with a limited immediate role being offered by nanozyme-induced ROS including O2•- and OH•, and likely other light-activated radicals. A mini-pilot proof-of-concept study performed in a pediatric dental clinic setting confirms residual, and continual nanozyme antibacterial efficacy over a 28-day period. These findings open a new approach to alleviate infections caused by bacteria for use on high-touch hard surfaces.

Changes in antimicrobial resistance of Escherichia coli isolated from community-associated urinary tract infection before and during the COVID-19 pandemic in India

The impact of the COVID-19 pandemic on antimicrobial resistance (AMR) is largely studied in healthcare settings. There is a need to understand the fluctuations in AMR during pandemic at the community level. With urinary tract infection (UTI) being one of the most common infections in the community, the AMR profile of community-acquired UTI (CA-UTI) is considered representative AMR at the community level. The study was taken in a cohort of patients with a clinical diagnosis of CA-UTI. The four study sites represented different community health centres in India. Escherichia coli isolates were analysed phenotypically and genotypically for AMR pre-COVID (October 2019-February 2020) and in the first (March 2020-February 2021) and second waves of COVID-19 (March 2021-December 2021). E. coli was the predominant uropathogen (229, 82%). Increased susceptibility to nitrofurantoin was observed during the pandemic. Reduced susceptibility to first-line oral antibiotics and carbapenems was seen during the second wave, and an increased minimum inhibitory concentration (MIC50) to beta-lactams and fluoroquinolones was seen during the pandemic. Genomic analysis of E. coli isolates showed some AMR genes (aacC1, aacC4, SHV, QepA) only during the second wave. One good outcome of the pandemic was increased susceptibility to nitrofurantoin, while drawback was a significant decrease in susceptibility to oral antibiotics during the second wave and increased MIC50 of some antibiotics. Decreased susceptibility to last-resort carbapenems and the occurrence of various AMR genes during the second wave of the pandemic are of great concern.

860. Molecular Characterization of Isolated Staphylococcus aureus Specimens Using Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS)

Abstract Background Staphylococcus aureus (S. aureus) is a common cause of skin and soft tissue infections (SSTIs). Both the β-lactam resistant form, methicillin resistant S. aureus (MRSA), and non-resistant form, methicillin susceptible S. aureus (MSSA) are associated with disparate infections across age and race; community-associated infections are often due to S. aureus US300. Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) is a used in clinical microbiology laboratories to identify bacterial species, but limited data is available on if this tool can identify different strains of S. aureus. We hypothesize that MALDI-TOF MS can be used to identify strain-specific peaks of S. aureus USA300. Methods Children were enrolled from emergency departments and swabbed for S. aureus (anterior nares, axilla, perirectal, oropharyngeal, and wounds) during two time periods (2006-2008 and 2015-2016). MALDI-TOF MS was performed on S. aureus cultured from study participants. Default parameters used for variance stability, smoothing, baseline subtraction, and normalization in R 4.4.3. and MALDIquant v1.22 were applied to raw data. Peak detection and alignment were performed with a signal-to-noise ratio of three and tolerance of 300 ppm. Binning and machine learning algorithms were used to identify intensity differences of each peak identified; significance of peaks was determined using Chi Square statistical analyses, comparing MRSA and MSSA, and then between all S. aureus isolates compared to USA300. Statistical significance was considered with p-value < 0.05 using R and SAS 9.4. Results From 57 MRSA and 53 MSSA isolates, 320 peaks were identified. 31 significant peaks were identified, with 14 unique peaks for MRSA and 17 for MSSA. With S. aureus USA300, eight of the 31 peaks remained statistically significant. Conclusion MALDI-TOF MS can identify unique peak differences between MRSA and MSSA. This tool can be potentially used to distinguish S. aureus at the strain level in a clinical setting. MALDI-TOF MS can be an impactful and rapid diagnostic tool to detect antibiotic resistance in S. aureus in a clinical setting. Disclosures Lilly Immergluck, MD,MS, Melinta: Grant/Research Support|Melinta: Grant/Research Support

481. Trends in SARS-CoV-2-related Pediatric Hospitalizations in the Canadian Nosocomial Infection Surveillance Program, March 2020 to December 2022

Abstract Background National surveillance can provide insights into trends in pediatric SARS-CoV-2-related hospitalizations during the pandemic and healthcare-associated infections.Figure:Proportion of all pediatric hospitalizations by age group and wave Methods From March 1, 2020, to December 31, 2022, the Canadian Nosocomial Infection Surveillance Program collected patient-level data on pediatric patients (under age 18 years) hospitalized with laboratory-confirmed SARS-CoV-2 from 9 pediatric and 25 mixed adult-pediatric hospitals. Pediatric COVID-19 vaccines became available for 12-17 years in May 2021 and for 5-11 years in November 2021. Results Of 4,878 pediatric patients, most (80.3%) were hospitalized with SARS-CoV-2 infection during the Omicron-dominant period (since Jan 2022); a higher proportion involved patients under five years of age (58.5% vs 46.9%, p < 0.001). Most hospitalizations pre-Omicron involved children not vaccinated against COVID-19 (92%) versus 70% during Omicron (p < 0.001). However, a lower proportion required intensive care during Omicron (15% vs 20%, p < 0.001). There was no difference in pre-existing comorbidities or mortality between periods. Overall, there were 257 healthcare-associated COVID-19 infections (HA-COVID) reported (5.4%); 89% occurred during Omicron. While there was no difference in median ages of patients with HA-COVID and community-associated COVID-19 infections (CA-COVID), 62% of patients with HA-COVID had a pre-existing comorbidity compared to 44% with CA-COVID (p < 0.001), and 24% remained in hospital at 30 days after HA-COVID, compared to 2.2% with CA-COVID (p < 0.001). Nearly 50% of patients with HA-COVID had received at least one vaccine dose, compared to 25% with CA-COVID. Conclusion During the Omicron-dominant period, a higher proportion of admitted patients with SARS-CoV-2 infection were under five years, but a lower proportion were unvaccinated and a lower proportion required intensive care and mortality was comparable between both periods. Only 5.4% of pediatric COVID-related hospitalizations were HAI, with most during Omicron. Patients with HAI were more likely to have a pre-existing comorbidity and increased hospital stay, potentially related to their underlying conditions. Disclosures All Authors: No reported disclosures

1933. Characteristics of Community-Associated Extended-Spectrum β-Lactamase Producing Enterobacterales Infections in Monroe County, NY, 2020-2021

Abstract Background Extended-spectrum β-lactamase–producing Enterobacterales (ESBL) have emerged as a serious multidrug resistant threat to the community. Epidemiologic data for community-associated (CA) ESBL infections are limited compared to that for healthcare-associated (HA) infections. We examined characteristics of CA ESBL cases over a two-year period and compared them to those of HA cases to guide prevention. Methods CA ESBL cases from 1/2020-12/2021 were identified via laboratory and population-based surveillance in Monroe County as part of the CDC Emerging Infections Program. Cases were defined as the first instance of positive culture in a county resident from a normally sterile site or urine of Escherichia coli, Klebsiella pneumoniae, or K. oxytoca resistant to ≥ 1 3rd-generation cephalosporin and nonresistant to carbapenems. Epidemiologic data were collected through medical record abstraction. Cases were classified as HA if they had prior healthcare exposures (e.g. hospitalization, surgery, chronic dialysis, indwelling devices, or external catheters) and CA if they did not. Case addresses were geocoded to the census tract level to obtain Social Vulnerability Index (SVI) percentiles. Chi-square analyses were conducted to quantify the difference in distribution of these characteristics between CA and HA cases. Results From 2020-2021, 1729 incident cases were identified; 854 (49%) were classified as CA. Compared to HA cases, CA cases were younger (median 59 vs. 70 years), more likely to be female (89.8% vs 65.3%), less likely to have a urinary tract abnormality (27.0% vs 56.8%) or underlying comorbidities (73.2 % vs 95.8%), and less likely to have received prior antibiotics (24.0% vs 55.1%). Interestingly, CA cases were more widely spread across SVI quartiles compared to HA cases; a higher proportion of HA cases resided in census tracts in the 3rd or 4th SVI quartiles (Table 1). Conclusion Patient-specific risk factors classically associated with HA ESBL are less commonly associated with CA ESBL in Monroe County. Community-based preventions may need to target different populations than hospital-based strategies. As ESBL incidence increases, continued surveillance to identify at-risk groups and explore the association of specific social determinants of health is necessary. Disclosures Rebecca Tsay, MPH, CDC: Grant/Research Support Ghinwa Dumyati, MD, Pfizer: Grant/Research Support

705. Burden of Medically-Attended Diarrhea and Clostridioides difficile Infection (CDI) Among Persons in the Community in an Integrated Healthcare Setting, 2016-2021

Abstract Background Population-based surveillance by the Centers for Disease Control and Prevention (CDC) indicates that the incidence of community-associated Clostridioides difficile infection (CDI) is increasing. However, CDI testing practices and incidence among patients seeking care for diarrhea in the outpatient setting have not been well described. Further, little is known about healthcare utilization and outcomes of patients with medically-attended CDI who are not subsequently hospitalized. Methods We conducted a retrospective cohort study of Kaiser Permanente Southern California (KPSC) and Northwest (KPNW) adult (≥ 18 years of age) members from January 1, 2016 to December 31, 2021. We identified medically-attended diarrhea (MAD) in the outpatient setting through ICD-10 diagnosis codes. Among those with MAD, we identified C. difficile testing and outpatient CDI (oCDI), defined as a positive CDI test without hospitalization in the following 0-7 days. We described the demographic and clinical characteristics of patients with MAD and oCDI and calculated incidence rates (IR) of oCDI. We also described the occurrence of oCDI-associated healthcare visits, CDI testing, and oCDI treatment in the 12 months following oCDI diagnosis. Results We identified 777,533 outpatient MAD episodes of which 93,964 (12.1%; 93,964/777,533) were tested for CDI. Among tested episodes, 10,110 (10.8%; 10,110/93,964)), involving 9,517 patients, had a positive CDI laboratory test. IR of outpatient oCDI decreased from 58.2 (95%CI: 55.7-60.7) per 100,000 person-years (PY) in 2016 to 45.7 (43.7-47.8) per 100,000 PY in 2021. Among 9,517 oCDI patients, 84.1% (n=8,006) CDI were ‘community-associated’ (without hospitalizations in the 84 days prior to index date) and only 44.1% (n=4,200) received an antibiotic in the previous 30 days. Only 6.7% (n=526) of oCDI patients had a CDI-associated hospitalization in the 12 months after diagnosis. Conclusion There was a high incidence of MAD and CDI in among outpatients. The majority of our outpatient CDI population had no recent hospitalization and no recent antibiotic exposure. Further studies are needed to understand the factors associated with CDI diagnosed and managed in the outpatient setting. Disclosures Sara Y. Tartof, PhD MPH, Genentech: Grant/Research Support|GSK: Grant/Research Support|Pfizer: Grant/Research Support|SPERO: Grant/Research Support Mark A. Schmidt, PhD, MPH, Intercept Pharmaceuticals: Grant/Research Support|Pfizer: Grant/Research Support|Vir Biotechnology: Grant/Research Support Fredrick J. Angulo, DVM, PhD, Pfizer Vaccines: Employee|Pfizer Vaccines: Employee|Pfizer Vaccines: Stocks/Bonds|Pfizer Vaccines: Stocks/Bonds Ana Florea, PhD MPH, Gilead: Grant/Research Support|GlaxoSmithKline: Grant/Research Support|Moderna: Grant/Research Support|Pfizer: Grant/Research Support Joann M. Zamparo, MPH, Pfizer Inc.: Full Time Employee|Pfizer Inc.: Stocks/Bonds Deborah S. Ling Grant, PhD, MPH, MBA, Pfizer: Grant/Research Support Elisa Gonzalez, MPH, Pfizer: Stocks/Bonds Jennifer L. Kuntz, MS, PhD, Pfizer: Grant/Research Support

Screening Dolosigranulum pigrum Strains for Secreted Factors that InhibitStaphylococcus aureus

Abstract Background Staphylococcus aureus is a leading cause of community-associated and hospital-acquired infections, and methicillin-resistant S. aureus (MRSA) is a significant global health concern. Approximately 30% of the human population is asymptomatically colonized by S. aureus in the upper respiratory tract, with this colonization typically preceding respiratory infections caused by S. aureus. Dolosigranulum pigrum is a putatively beneficial bacterium that is a frequent colonizer of the human upper respiratory tract. The presence and abundance of D. pigrum in the upper respiratory tract has been negatively associated with S. aureus colonization among infants and young children. Additionally, in cocultivation experiments, D. pigrum has been shown to inhibit S. aureus growth, although the mechanisms for this antistaphylococcal activity have not been identified. Methods We hypothesized that D. pigrum strains secrete a protein factor that inhibits growth of S. aureus. To evaluate this hypothesis, we screened D. pigrum strains for antistaphylococcal activity using a plate-based cocultivation assay. Briefly, 5 µL aliquots of D. pigrum strains in liquid brain heart infusion (BHI) medium (OD600=0.3) were spotted onto a BHI agar plate and incubated at 37°C and 5% CO2 for 48 hours. Next, 5 µL aliquots of S. aureus strain Newman in liquid BHI medium (OD600=0.1) were spotted onto this plate at varying distances from the D. pigrum inocula and incubated at 37°C and 5% CO2 for an additional 24 hours. Secretion of an anti-staphylococcal factor was assessed based on the presence of a visible zone of inhibition between the D. pigrum and S. aureus inocula. We excised agar fragments adjacent to 4 inhibitory and 4 non-inhibitory D. pigrum strains and submitted these samples for liquid chromatography with tandem mass spectrometry (LC-MS/MS)-based proteomics. The proteomic data were searched against the TrEMBL D. pigrum database and a common contaminant/spiked protein database, and signal intensity values for identified peptides were quantified. Results Four of 43 (9%) D. pigrum strains screened in cocultivation assays consistently produced a zone of inhibition against S. aureus. We identified 531 unique proteins from proteomic analysis of agar fragments, including 28 D. pigrum proteins that were significantly more abundant in zones adjacent to inhibitory vs. non-inhibitory strains. The most differentially abundant protein was an S8 family serine protease (112 times more abundant in fragments adjacent to inhibitory strains). Using previously generated whole-genome sequencing data from these 43 D. pigrum strains, we found that the gene encoding this serine protease was present in 41 of 43 (95%) D. pigrum strains, including all 4 strains that were inhibitory in the cocultivation assay. The predicted active domain for the final protein was highly conserved across strains. Other secreted D. pigrum proteins that were more abundant in gel fragments adjacent to inhibitory strains included a peptidoglycan hydrolase and 7 uncharacterized D. pigrum proteins. Conclusion D. pigrum inhibits S. aureus growth in vitro through secretion of inhibitory factors in a strain-dependent manner. We identified an S8 family serine protease as a possible candidate mechanism for the anti-staphylococcal activity of D. pigrum. Future experiments will screen cell-free supernatants from inhibitory D. pigrum strains for S. aureus inhibition and evaluate the effect of protease inhibitor treatment on the antistaphylococcal activity of these supernatants.

Mortality, hospital length of stay, and recurrent bloodstream infections associated with extended-spectrum beta-lactamase-producing Escherichia coli in a low prevalence region: A 20-year population-based large cohort study

ObjectivesThis population-based study aimed to investigate the risk factors and effect of extended-spectrum beta-lactamase (ESBL) production on clinical outcomes in Escherichia coli bloodstream infection (BSI) patients. MethodsThe study population was defined as patients aged ≥15 years with E. coli BSI in Queensland, Australia, from 2000 to 2019. Outcomes were defined as 30-day case fatality, hospital length of stay (LOS), and recurrent E. coli BSI. ResultsA total of 27,796 E. coli BSIs were identified, of which 1112 (4.0%) were ESBL-producers. Patients with ESBL-Ec BSI were more frequently older, male, with comorbidity, recurrent E. coli BSI, and less likely with community-associated community-onset infections as compared to non-ESBL-Ec BSI patients. The standardized mortality rate of ESBL-Ec BSI increased 8-fold from 2000 to 2019 (1 to 8 per million residents) and case fatality was 12.8% (n = 142) at 30 days from positive blood culture. Patients with ESBL-Ec BSI were not at higher risk of 30-day case fatality (adjusted hazard ratio [HR] = 0.98, 95% CI: 0.83-1.17), but had higher risk of recurring episodes (adjusted subdistribution HR = 1.58, 95% CI: 1.29-1.92) and observed 14% longer LOS (adjusted incidence rate ratio = 1.14, 95% CI: 1.10-1.18) than non-ESBL-Ec BSI patients. ConclusionIn this large patient cohort, ESBL-Ec BSI did not increase case fatality risk but observed higher hospital LOS and recurrent E. coli BSI than non-ESBL-Ec BSI. Clinical resources are warranted to account for the higher morbidity risk associated with ESBL production and incidence.

The population-level impact of Enterococcus faecalis genetics on intestinal colonization and extraintestinal infection.

Enterococcus faecalis is a commensal bacterium of the human gastrointestinal tract that causes opportunistic infections. The E. faecalis genetic changes associated with pathogenicity, particularly gut-to-bloodstream translocation, remain poorly understood. Here, we performed a genome-wide association study (GWAS) of 736 whole-genome sequences of fecal and bloodstream E. faecalis isolates from hospitalized and nonhospitalized individuals, respectively, to identify E. faecalis genetic signatures associated with the patient's hospitalization status and body isolation source. We found that infection by hospitalization status and extraintestinal infection are heritable traits, with ~40% and ~30% of their variation explained by E. faecalis genetics, respectively. Furthermore, a GWAS using linear mixed models did not pinpoint any clear overrepresentation of individual genetic changes by hospitalization status or body isolation source after controlling for the population structure. However, we observed elevated signals in a genomic region containing a prophage element. However, the lineages themselves and their associated virulence factors and antibiotic resistance genes showed variable frequency among blood and fecal isolates and in hospitalized and nonhospitalized individuals. Altogether, our findings indicate that E. faecalis infection by hospitalization status and body sites is partially influenced by the overall genetic background of the isolates and antibiotic resistance patterns rather than genetic variation at individual loci, which suggests a greater role of other host and environmental factors and ultimately the opportunistic pathogenic lifestyle of this versatile host generalist bacterium.IMPORTANCEEnterococcus faecalis causes life-threatening invasive hospital- and community-associated infections that are usually associated with multidrug resistance globally. Although E. faecalis infections cause opportunistic infections typically associated with antibiotic use, immunocompromised immune status, and other factors, they also possess an arsenal of virulence factors crucial for their pathogenicity. Despite this, the relative contribution of these virulence factors and other genetic changes to the pathogenicity of E. faecalis strains remain poorly understood. Here, we investigated whether specific genomic changes in the genome of E. faecalis isolates influence its pathogenicity-infection of hospitalized and nonhospitalized individuals and the propensity to cause extraintestinal infection and intestinal colonization. Our findings indicate that E. faecalis genetics partially influence the infection of hospitalized and nonhospitalized individuals and the propensity to cause extraintestinal infection, possibly due to gut-to-bloodstream translocation, highlighting the potential substantial role of host and environmental factors, including gut microbiota, on the opportunistic pathogenic lifestyle of this bacterium.

Distribution and antibiogram of Staphylococci from pigs and contact humans in Abia State

Staphylococcus species are among the dominant groups of saprophytic bacteria; however, lately, they are globally known for being opportunistic pathogens and prime cause of community-associated and hospital-acquired infections in humans and animals. This study was conducted to determine the phenotypic characteristics of Staphylococcus isolated from pigs and in-contact humans in Abia Central Senatorial Zone, Nigeria. Using standard microbiological methods 1084 nasal swab samples were collected from 968 pigs and 116 in-contact humans. Kirby-Bauer's disc diffusion method was used to determine the antibiogram of the isolates, and the findings were interpreted using CLSI interpretive values. Staphylococcus species were recovered from 38 (3.9%) of the 968 pigs screened and 2 (1.7%) of the 116 humans. The recovered species distributions were S. aureus (1), S. intermedius (10), S. hyicus (21), S. chromogens (1), S. haemolyticus (5), S. warneri (1) and S. xylosus (1). Most of the isolates were resistant to at least one antimicrobial agent. Resistance to ampicillin in 33(86.8%) of the isolates while 31(81.6%), 30(78.9%), 24(63.2%) and 23(60.5%) were resistant to vancomycin, oxacillin, penicillin and tetracycline, respectively. Thirty one unique resistance patterns were identified among the staphylococci isolates. The multiple antibiotics resistance index (MARI) for all the isolates was greater than 0.2 indicating that the isolates may have originated from an environment where antibiotics were frequently used. All the staphylococcal isolates that were resistant to vancomycin by disc

Community-associated Clostridioides difficile infection in a general hospital from Argentina

Toxin-producing Clostridioides difficile infection (CDI) is the leading cause of hospital-acquired diarrhea. However, it is now recognized as a cause of diarrhea in the community. This single-center study aimed to determine the epidemiological origin of CDI cases between January 2014 and December 2019 and to compare demographic characteristics, comorbidities, risk factors, severity, and mortality of community CDI with healthcare facility-associated CDI. There were 52 CDI cases from the community (34.4%). Community patients were significantly younger (53 yo vs. 65 yo), less comorbid (Charlson Index 1.65 vs. 3.98), and less severe (only one case). The main risk factor was the use of antibiotics in the previous 90 days (65%). However, we did not find any known risk factor in 7 patients.

An ultra-small fluorescence zero-valent iron nanoclusters selectively kill gram-positive bacteria by promoting reactive oxygen species generation

A list of the most dangerous bacteria that are multiple-drug resistance has been published by WHO, among which are various Gram-positive bacteria related with serious healthcare and community-associated infection. An effort is called for developing new strategies to combat the resistance, and nanomaterial-based approaches provide an ideal potential to mitigate the antimicrobial resistance as an alternative to antibiotics. Nanoscale zero-valent iron particles exhibited a good antimicrobial activity by triggering Fenton reaction, however, no zero-valent iron nanoclusters are developed as antimicrobial medical materials. In this work, a novel ultra-small zero-valent iron nanoclusters (usZVIN) was synthesized by one-step reduction in aqueous solutions, which exhibited bright red fluorescence at 616 nm. Interestingly, the usZVIN displayed an excellent selectively antibacterial activity against Gram-positive bacteria, and little effects on Gram-negative bacteria. The killing efficiency of usZVIN against S. aureus can reach 100 % with a concentration of 40 μg mL−1 after 1 h incubation, whereas there is no killing effect of usZVIN against E.coli even with a concentration of 900 μg mL−1 for 4 h. The antimicrobial mechanism of usZVIN was demonstrated to be the intracellular reactive oxygen species (ROS) production triggered by usZVIN due to its excellent peroxidase-like activity. Collectively, our findings suggested that usZVIN is a good medical-material candidate for fighting against Gram-positive bacterial infections, especially when we need leave beneficial Gram-negative bacteria intact.

Comprehensive Analysis of Bacteriocins Produced by the Hypermucoviscous Klebsiella pneumoniae Species Complex.

Klebsiella pneumoniae produces several kinds of bacteriocins that have antimicrobial effects against closely related species, but few studies have comprehensively reported bacteriocin distribution among the Klebsiella population. In this study, we identified bacteriocin genes in 180 K. pneumoniae species complex genomes, including 170 hypermucoviscous isolates, and investigated the antibacterial activity against 50 strains, including antimicrobial-resistant organisms, belonging to multiple species, namely, Klebsiella spp., Escherichia coli, Pseudomonas spp., Acinetobacter spp., Enterobacter cloacae, Stenotrophomonas maltophilia, Chryseobacterium indologenes, Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus mutans. Our study determined that 32.8% (59/180) of isolates carried at least one bacteriocin type. Different types of bacteriocin were usually present in different specific sequence types (STs); meanwhile, bacteriocins were not detected in certain STs. Microcin E492 was the most prevalent bacteriocin (14.4%), mostly in ST23 isolates, and displayed a wide spectrum of activity, including against Klebsiella spp., E. coli, Pseudomonas spp., and Acinetobacter spp. Cloacin-like bacteriocin was detected in 7.2% of strains, all of which were non-ST23 isolates, and exhibited inhibitory activity against closely related species, mainly Klebsiella spp. Klebicin B-like bacteriocin was detected at a rate of 9.4%, although 82.4% of these strains carried a disrupted bacteriocin gene, and an inhibitory effect could not be observed from the intact-gene-carrying isolates. Other bacteriocins, such as microcin S-like, microcin B17, and klebicin C-like, were detected at lower rates and had limited inhibitory activity. Our findings suggested that Klebsiella strains that carry different bacteriocin types may affect the composition of the surrounding bacterial community. IMPORTANCE Klebsiella pneumoniae is a Gram-negative commensal bacterium that asymptomatically colonizes human mucosal membranes, such as the intestinal tract, but it is also a leading cause of health care- and community-associated infections. Additionally, multidrug-resistant K. pneumoniae has been continuously evolving, which significantly challenges the available chemotherapeutic treatment for its infections. K. pneumoniae produces several kinds of antimicrobial peptides known as bacteriocins, which have antibacterial activity against closely related species. This work was the first comprehensive report of bacteriocin distribution among the hypermucoviscous K. pneumoniae species complex population and the inhibitory activity of each bacteriocin type against various species, including multidrug-resistant strains. Our findings provide a foundation for future studies on the K. pneumoniae species complex, including studies on the competition within the microflora and the potential applications of bacteriocins in treating multidrug-resistant bacteria.

Targeted Killing of Staphylococcus aureus Using Specific Peptides Displayed on Yeast Vacuoles.

Staphylococcus aureus is a common pathogen that causes health care-related and community-associated infections. In this study, we provide a novel system that can recognize and kill S. aureus bacteria. The system is specifically based on a combination of the phage display library technique and yeast vacuoles. A phage clone displaying a peptide capable of specific binding to a whole S. aureus cell was selected from a 12-mer phage peptide library. The peptide sequence was SVPLNSWSIFPR. The selected phage's ability to bind specifically with S. aureus was confirmed using an enzyme-linked immunosorbent assay, and the chosen peptide was then synthesized. The results showed that the synthesized peptides displayed high affinity with S. aureus but low binding ability with other strains, including Gram-negative and Gram-positive bacteria such as Salmonella sp., Shigella spp., Escherichia coli, and Corynebacterium glutamicum. In addition, yeast vacuoles were used as a drug carrier by encapsulating daptomycin, a lipopeptide antibiotic used to treat Gram-positive bacterial infections. The expression of specific peptides at the encapsulated vacuole membrane created an efficient system that can specifically recognize and kill S. aureus bacteria. IMPORTANCE The phage display method was used to select peptides with high affinity and specificity for S. aureus, and these peptides were then induced to be expressed on the surface of yeast vacuoles. These surface-modified vacuoles can act as drug carriers, with drugs such as the lipopeptide antibiotic daptomycin loaded inside. An advantage of using yeast vacuoles as a drug carrier is that they can be easily produced through yeast culture, making the approach cost-effective and suitable for large-scale production and potential implementation in clinical settings. This novel approach offers a promising way to specifically target and eliminate S. aureus that could ultimately lead to improved treatment of bacterial infections and reduced risk of antibiotic resistance.

Epidemiology and Risk Factors of Community-Associated Bloodstream Infections in Zhejiang Province, China, 2017-2020.

Community-associated bloodstream infection (CA-BSI) is increasing in many community settings. However, the clinical significance and epidemiology of CA-BSI present in hospital admissions in China are not well established. In this work, we identified the risk factors in outpatients presenting with CA-BSI, and investigate the role of procalcitonin (PCT) and hypersensitive C-reactive protein (CRP) in diagnosing different types of the pathogen in patients with acute CA-BSI. A retrospective study enrolling 219 outpatients with CA-BSI from The Zhejiang People's Hospital from January 2017 to December 2020 was performed. Susceptibility of the isolates obtained from these patients was examined. Subjecting receiver operating characteristic curves (ROC) were constructed to analyze the specificity and sensitivity of PCT, CRP, and WBC in determining infections caused by different bacterial genera. Risk factors for CA-BSI in the emergency setting were analyzed using essential information and simple identification of other pathogenic bacterial species through rapidly tested biomarkers. A total of 219 patients were included in the selection criteria, of which 103 were infected with Gram-positive bacteria (G+) and 116 with Gram-negative bacteria (G-). The PCT was significantly higher in the GN-BSI group than in the GP-BSI group, while no significant difference was observed between the two groups for CRP. Subjecting ROC curves were constructed to analyze WBC, CRP, and PCT, and the area under the curve (AUC) of the PCT in this model was 0.6661, with sensitivity = 0.798 and specificity = 0.489. The PCT between the GP-BSI group and the GN-BSI group was significantly different. By combining the knowledge of clinicians and the clinical signs of patients, PCT should be utilized as a supplementary approach to initially determine pathogens and direct medication in the early stages of clinical practice.

Prevalence of Methicillin-Resistant and Methicillin Sensitive Staphylococcus aureus Nasal Carriage and their Antibiotic Resistant Patterns in Kirkuk City, Iraq

The carriage of community-acquired methicillin-resistant S. aureus (CA-MRSA) has become a source of community-associated infections, particularly in the anterior nares of people worldwide. This study was aimed at determining the prevalence of community-acquired S. aureus (CA-SA) and CA-MRSA nasal carriage among healthy individuals of various ages in Kirkuk City and evaluating the susceptibility of isolates to various antibiotics. A total of 597 healthy individuals were recruited in the community between December 1, 2021, and December 30, 2022. Nasal swabs obtained from participants were taken to the laboratory, where bacteria were isolated and identified using phenotypic characteristics. The MRSA isolates were identified by applying the modified Kirby Bauer disc diffusion technique. The results showed that the prevalence of CA-SA and CA-MRSA nasal carriers was 16.6 and 4.5%, respectively. The average age of the participants was 33.2 years, with a male-to-female ratio of 1.1: 1. The highest resistance of the isolates was observed against oxacillin (27.3%), followed by penicillin G (24.3%), amoxicillin (15.2%), erythromycin (12.1%), and tetracycline (6.1%). There was a 9.1% resistance rate to clindamycin, rifampin, gentamycin, and ciprofloxacin. However, all CA-MRSA isolates were multi-drug resistant. However, all the isolates were sensitive (100 %) to vancomycin, linezolid, and mupirocin. The findings of the present study highlight the potential for CA-SA and CA-MRSA acquisition in this population, which may be related to antibiotic abuse or overuse as well as poor hygiene. To lessen the impact of community-associated strains of MRSA nasal carriage, this necessitates the probable need for infection prevention measures and adequate antibiotic therapy.

Prevalence and Antimicrobial Susceptibility Pattern of Methicillin Resistant Staphylococcus aureus From Healthcare And Community Associated Sources

Introduction: Staphylococci are Gram-positive bacteria with diameter of 1 μm. Staphylococcus aureus is a versatile human pathogen responsible for nosocomial and community-associated infections which is associated with high morbidity and mortality. MRSA (also known as Mercer) is a bacterium responsible for several infections in humans that are difficult to treat. The study aimed at screening of microbial flora on mobile phones to find out the prevalence and antimicrobial susceptibility pattern of methicillin resistant Staphylococcus aureus. Materials and Methods: The present study was carried out in the Department of Medical Microbiology, NIMS Medical College and Hospital, NIMS University, Jaipur during the period of January 2014-June 2014. Results: The present study showed males prevalence of MRSA than Females. MRSA was seen among the age group 21-40 years. Maximum MRSA were obtained from pus/wound samples 12 (66.6%). The present study showed higher prevalence rate of MRSA from Doctors mobile phones. Higher prevalence rate of MRSA 58.8% in Hospital associated as compared to community associated sources 40%. HA(MRSA) showed highest resistance to penicillin 100%. The present study showed 35% MDR MRSA in HA. CA(MRSA) showed higher resistance to penicillin and ciprofloxacin 100%. HA and CAMRSA showed vancomycin and Linezolid 0% resistance. Conclusion: The study showed a higher prevalence of MRSA in HA as compared to CA sources and indicated high risk of infection in individual exposed to hospital environment. Thus, there is a need to screen individuals in hospitals for risk exposure and infection, to avoid outbreak and cross infection. There is a need of taking good Infection control measures and suggested that microbiological surveillance and monitoring of susceptibility patterns of MRSA may also help in arresting the spread of infections.

Characterization of extended-spectrum β-lactamase-producing Escherichia coli isolated from municipal and hospital wastewater in Japan

The purpose of this study was to characterize the strains of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli (ESBL-EC) isolated from municipal and hospital wastewater by detecting antibiotic resistance genes (ARGs) as well as antibiotic susceptibility. To identify the source of ESBL-EC, multi-locus sequence typing and typing plasmids that may carry ESBL-producing genes were conducted. Wastewater was sampled twice a month from February 2019 to February 2020 from a municipal wastewater treatment plant and hospital located in a city in northeastern Japan. Throughout the study period, 279 and 37 strains of ESBL-EC were isolated from municipal and hospital wastewater, respectively. All 316 isolates were resistant to ampicillin and cefotaxime and susceptible to imipenem and tigecycline. Almost all (98.1%) of the ESBL-EC isolates possessed blaCTX-M, and the blaCTX-M-9 group was detected most frequently (62.3%). Multi-locus sequence typing revealed a higher diversity of sequence types (STs) in the isolates from municipal wastewater than in those from hospital wastewater; although ST131, which recently caused nosocomial- and community-associated infections worldwide, was dominant in both types of wastewater. All ST131 isolates possessed the IncFII plasmid, which is often reported to carry blaCTX-M. These results demonstrated that healthy people carry clinically important antibiotic-resistant bacteria and ARGs, motivating routine monitoring of municipal wastewater to detect such antibiotic-resistant bacteria and ARGs from a variety of sources supported by the high diversity of STs in the present study.