Carriage of methicillin-resistant Staphylococcus aureus in children <6 years old: a retrospective follow-up study of the natural course and effectiveness of decolonization treatment.

BACKGROUND: Decolonization treatment of MRSA carriers is recommended in Denmark, except in households with MRSA-positive children <2 years old (wait-and-see approach). OBJECTIVES: To investigate a wait-and-see approach in children 2-5 years old, and the effect of decolonization treatment of MRSA carriage in all children <6 years old. PATIENTS AND METHODS: In this retrospective follow-up study, we included MRSA carriers <6 years old in the Capital Region of Denmark from 2007 to 2021. Data were collected from laboratory information systems and electronic patient records. We divided children into age groups of <2 years or 2-5 years and decolonization treatment versus no treatment. Treatment was chlorhexidine body washes and nasal mupirocin, sometimes supplemented with systemic antibiotics. Children were followed until becoming MRSA free, or censoring. The probability of becoming MRSA free was investigated with Cox regression (higher HRs indicate faster decolonization). RESULTS: Of 348 included children, 226 were <2 years old [56/226 (25%) received treatment] and 122 were 2-5 years old [90/122 (74%) received treatment]. Multivariable analyses did not show a larger effect of decolonization treatment versus no treatment in <2-year-olds (HR 0.92, 95% CI 0.52-1.65) or 2-5-year-olds (HR 0.54, 95% CI 0.26-1.12). Without treatment, 2-5-year-olds tended to clear MRSA faster than <2-year-olds (HR 1.81, 95% CI 0.98-3.37). CONCLUSIONS: We did not find a larger effect of decolonization treatment versus no treatment in children <6 years old, and 2-5-year-olds tended to become MRSA free faster than <2-year-olds. These results support a wait-and-see approach for all children <6 years old, but further studies are needed.

Surveillance of vancomycin-resistant enterococci reveals shift in dominating clusters from vanA to vanB Enterococcus faecium clusters, Denmark, 2015 to 2022.

BackgroundVancomycin-resistant enterococci (VRE) are increasing in Denmark and Europe. Linezolid and vancomycin-resistant enterococci (LVRE) are of concern, as treatment options are limited. Vancomycin-variable enterococci (VVE) harbour the vanA gene complex but are phenotypically vancomycin-susceptible.AimThe aim was to describe clonal shifts for VRE and VVE in Denmark between 2015 and 2022 and to investigate genotypic linezolid resistance among the VRE and VVE.MethodsFrom 2015 to 2022, 4,090 Danish clinical VRE and VVE isolates were whole genome sequenced. We extracted vancomycin resistance genes and sequence types (STs) from the sequencing data and performed core genome multilocus sequence typing (cgMLST) analysis for Enterococcus faecium. All isolates were tested for the presence of mutations or genes encoding linezolid resistance.ResultsIn total 99% of the VRE and VVE isolates were E. faecium. From 2015 through 2019, 91.1% of the VRE and VVE were vanA E. faecium. During 2020, to the number of vanB E. faecium increased to 254 of 509 VRE and VVE isolates. Between 2015 and 2022, seven E. faecium clusters dominated: ST80-CT14 vanA, ST117-CT24 vanA, ST203-CT859 vanA, ST1421-CT1134 vanA (VVE cluster), ST80-CT1064 vanA/vanB, ST117-CT36 vanB and ST80-CT2406 vanB. We detected 35 linezolid vancomycin-resistant E. faecium and eight linezolid-resistant VVEfm.ConclusionFrom 2015 to 2022, the numbers of VRE and VVE increased. The spread of the VVE cluster ST1421-CT1134 vanA E. faecium in Denmark is a concern, especially since VVE diagnostics are challenging. The finding of LVRE, although in small numbers, ia also a concern, as treatment options are limited.

Contaminated dicloxacillin capsules as the source of an NDM-5/OXA-48-producing Enterobacter hormaechei ST79 outbreak, Denmark and Iceland, 2022 and 2023.

From October 2022 through January 2023, nine patients with NDM-5/OXA-48-carbapenemase-producing Enterobacter hormaechei ST79 were detected in Denmark and subsequently one patient in Iceland. There were no nosocomial links between patients, but they had all been treated with dicloxacillin capsules. An NDM-5/OXA-48-carbapenemase-producing E. hormaechei ST79, identical to patient isolates, was cultured from the surface of dicloxacillin capsules in Denmark, strongly implicating them as the source of the outbreak. Special attention is required to detect the outbreak strain in the microbiology laboratory.

Mesenteric Lymphadenitis and Terminal Ileitis is Associated With Yersinia Infection: A Meta-analysis.

BACKGROUND: Yersinia infection affects terminal ileum and lymph nodes and could therefore mimic the symptoms of appendicitis. We aimed to systematically characterise the suspected or confirmed abdominal diseases and/or surgeries associated with Yersinia infection. MATERIALS AND METHODS: This systematic review and meta-analysis was reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A protocol (CRD42016053252) was uploaded to PROSPERO. The searches were conducted in PubMed and EMBASE on October 2, 2020. Original reports on patients with abdominal surgical diseases were included. The primary outcome was to characterise suspected or confirmed abdominal surgical diseases and/or surgeries associated with Yersinia infection, while the secondary outcomes were the positive rate of Yersinia species for each disease and surgery, and to investigate the rate of Yersinia spp. in different geographic regions. We calculated the weighted mean prevalence of positive tests for Yersinia spp. for the different diseases and surgeries according to the detection method and for subgroups based on geographic region. RESULTS: From the search, 33 studies were included in the systematic review and 18 in the meta-analysis. Across geographic regions, the weighted mean prevalence for Yersinia spp. was 51% (95% CI 34%-69%) in mesenteric lymphadenitis, 65% (95% CI 45%-85%) in terminal ileitis, and 8% (95% CI 2%-15%) in normal appendices. CONCLUSIONS: Around half of the patients with mesenteric lymphadenitis and terminal ileitis were serologically positive for infections with Yersinia spp. Yersinia infection may cause unnecessary surgery for suspected appendicitis due to symptoms from mesenteric lymphadenitis or terminal ileitis.

Possible misinterpretation of penicillin susceptibility in Staphylococcus aureus blood isolate due to in vitro loss of the blaZ gene.

We describe a case of recurrent catheter-related blood stream infections (BSI) with Staphylococcus aureus, in which the first isolate tested susceptible to penicillin, while subsequent isolates were resistant. Phenotypic susceptibility correlated with the absence/presence of the blaZ gene. The in vitro stability of penicillin resistance was investigated by subculturing single colonies. In two out of five colonies, phenotypical resistance was lost after a single subculture, which correlated with loss of the blaZ gene. This in vitro phenomenon probably resulted in a very major error in the microbiology report of the first BSI, where penicillin had been recommended as treatment.

Intravenous mecillinam compared with other ß-lactams as targeted treatment for Escherichia coli or Klebsiella spp. bacteraemia with urinary tract focus.

BACKGROUND: Mecillinam (amdinocillin) is active against Gram-negative bacteria. Clinical data on the efficacy of IV mecillinam for severe urinary tract infections is sparse. OBJECTIVES: To assess the effectiveness of targeted IV mecillinam compared with other ß-lactams for bacteraemia with Escherichia coli and Klebsiella spp. and a urinary tract focus. PATIENTS AND METHODS: We performed a retrospective cohort study at five university hospitals in the Capital Region of Denmark from 1 January 2012 to 31 December 2017. We used Cox proportional hazard regression to compare the primary composite endpoint (all-cause mortality or bacteraemia recurrence within 30 days) between patients treated with mecillinam versus ampicillin, cefuroxime, piperacillin/tazobactam and meropenem. RESULTS: We included 1129 patients in the primary analysis, of which 146 were given IV mecillinam as targeted treatment. We found no significant difference in the primary endpoint between patients treated with mecillinam versus ampicillin and cefuroxime, but found a higher risk for the primary endpoint in the piperacillin/tazobactam and meropenem groups, with adjusted HRs of 2.22 (95% CI 1.24-3.97, P < 0.01) and 2.48 (95% CI 1.04-5.93, P = 0.04), respectively, compared with mecillinam. CONCLUSIONS: The results of this study suggest that IV mecillinam may be a suitable targeted treatment for bacteraemia with a urinary tract focus. However, these results need confirmation by randomized controlled studies.

Investigation of the introduction and dissemination of vanB Enterococcus faecium in the Capital Region of Denmark and development of a rapid and accurate clone-specific vanB E. faecium PCR.

BACKGROUND: During 2018-19, an increase of vanB vancomycin-resistant Enterococcus faecium (VREfm) was observed in the Capital Region of Denmark. vanA/vanB PCR performed directly on rectal swabs is accurate in detection of vanA; however, the positive predictive value for vanB-positive samples is low because of the presence of vanB in non-enterococcal gut commensals. OBJECTIVES: We investigated the epidemiology and clonal relatedness of vanB VREfm from the period 2015-19 and describe the application of a clone-specific vanB VREfm PCR assay for rapid and accurate detection of vanB VREfm in rectal screening samples. METHODS: vanB VREfm were investigated using epidemiological data and WGS data. The SeqSphere+ software was used to analyse MLST and cgMLST, and de novo assemblies were annotated to determine insertion sites for the vanB transposon (Tn1549). A clone-specific vanB VREfm PCR assay was designed to detect the sequence bridging Tn1549 and the E. faecium chromosome (araA2) in the dominant cluster. RESULTS: Two hundred and seventy-five vanB VREfm isolates were identified, of which 76% were identified in 2019. A dominant cluster (Cluster 1, n = 204, 74%), six minor clusters and 15 singletons were identified. All Cluster 1 isolates and six non-Cluster 1 isolates had Tn1549 integrated into araA2. In 2019, the PCR assay would have detected 92% of all rectal screening samples containing vanB VREfm. CONCLUSIONS: vanB VREfm increased due to the introduction and nosocomial transmission of the successful Cluster 1. The clone-specific PCR assay detected vanB VREfm outbreak isolates in rectal screening samples rapidly and accurately.

Antibiotic prescribing in Danish general practice in the elderly population from 2010 to 2017.

OBJECTIVE: This study aimed to describe prescription of antibiotics to the elderly population in general practice in Denmark from 2010-2017. DESIGN: This is a national register-based observational study. SETTING: General practice, Denmark. MAIN OUTCOME MEASURE: The main outcome measure was prescriptions/1,000 inhabitants/day (PrID) in relation to year, age and sex, indication, and antibiotic agent. SUBJECTS: In this study, we included inhabitants of Denmark, ≥65 years of age between 01st July 2010-30th June 2017. RESULTS: A total of 5,168,878 prescriptions were included in the study. Antibiotic prescriptions decreased from 2.2 PrID to 1.7 (-26.9%, CI95% [-31.1;-22.4]) PrID during the study. The decrease in PrID was most noticeable among 65-74-year-olds (-25%). The ≥85-year-olds were exposed to twice as many PrID than the 65-74-year-olds, but only accounted for 20% of the total use. Urinary tract infection (UTI) was the most common indication for antibiotic prescription and increased with advancing age. The most commonly prescribed antibiotics were pivmecillinam and phenoxymethylpenicillin. Prescribing with no informative indication was present in one third of all cases. CONCLUSION: The prescription of antibiotics in the elderly population in general practice decreased from 2010 to 2017. The oldest age group was exposed twice as frequently to antibiotic prescriptions as the 65-74-year-olds. The smallest reduction was observed for the ≥85-year-olds, suggesting targeting interventions at this group.Key PointsHigh antibiotic use among elderly is well known and studies indicate mis- and overuse within this population. Our study shows.The prescription rate is decreasing within all age groups of the elderly population.The ≥85-year-olds receive twice as many prescriptions/1000/day as the 65-74-years-olds.

Surveillance of OXA-244-producing Escherichia coli and epidemiologic investigation of cases, Denmark, January 2016 to August 2019.

BackgroundCarbapenemase-producing Escherichia coli are increasing worldwide. In recent years, an increase in OXA-244-producing E. coli isolates has been seen in the national surveillance of carbapenemase-producing organisms in Denmark.AimMolecular characterisation and epidemiological investigation of OXA-244-producing E. coli isolates from January 2016 to August 2019.MethodsFor the epidemiological investigation, data from the Danish National Patient Registry and the Danish register of civil registration were used together with data from phone interviews with patients. Isolates were characterised by analysing whole genome sequences for resistance genes, MLST and core genome MLST (cgMLST).ResultsIn total, 24 OXA-244-producing E. coli isolates were obtained from 23 patients. Among the 23 patients, 13 reported travelling before detection of the E. coli isolates, with seven having visited countries in Northern Africa. Fifteen isolates also carried an extended-spectrum beta-lactamase gene and one had a plasmid-encoded AmpC gene. The most common detected sequence type (ST) was ST38, followed by ST69, ST167, ST10, ST361 and ST3268. Three clonal clusters were detected by cgMLST, but none of these clusters seemed to reflect nosocomial transmission in Denmark.ConclusionImport of OXA-244 E. coli isolates from travelling abroad seems likely for the majority of cases. Community sources were also possible, as many of the patients had no history of hospitalisation and many of the E. coli isolates belonged to STs that are present in the community. It was not possible to point at a single country or a community source as risk factor for acquiring OXA-244-producing E. coli.

LRE-Finder, a Web tool for detection of the 23S rRNA mutations and the optrA, cfr, cfr(B) and poxtA genes encoding linezolid resistance in enterococci from whole-genome sequences.

OBJECTIVES: In enterococci, resistance to linezolid is often mediated by mutations in the V domain of the 23S rRNA gene (G2576T or G2505A). Furthermore, four genes [optrA, cfr, cfr(B) and poxtA] encode linezolid resistance in enterococci. We aimed to develop a Web tool for detection of the two mutations and the four genes encoding linezolid resistance in enterococci from whole-genome sequence data. METHODS: LRE-Finder (where LRE stands for linezolid-resistant enterococci) detected the fraction of Ts in position 2576 and the fraction of As in position 2505 of the 23S rRNA and the cfr, cfr(B), optrA and poxtA genes by aligning raw sequencing reads (fastq format) with k-mer alignment. For evaluation, fastq files from 21 LRE isolates were submitted to LRE-Finder. As negative controls, fastq files from 1473 non-LRE isolates were submitted to LRE-Finder. The MICs of linezolid were determined for the 21 LRE isolates. As LRE-negative controls, 26 VRE isolates were additionally selected for linezolid MIC determination. RESULTS: LRE-Finder was validated and showed 100% concordance with phenotypic susceptibility testing. A cut-off of 10% mutations in position 2576 and/or position 2505 was set in LRE-Finder for predicting a linezolid resistance phenotype. This cut-off allows for detection of a single mutated 23S allele in both Enterococcus faecalis and Enterococcus faecium, while ignoring low-level sequencing noise. CONCLUSIONS: A Web tool for detection of the 23S rRNA mutations (G2576T and G2505A) and the optrA, cfr, cfr(B) and poxtA genes from whole-genome sequences from enterococci is now available online.

Surveillance of vancomycin-resistant enterococci reveals shift in dominating clones and national spread of a vancomycin-variable vanA Enterococcus faecium ST1421-CT1134 clone, Denmark, 2015 to March 2019.

We describe clonal shifts in vanA Enterococcus faecium isolates from clinical samples obtained from patients in Denmark from 2015 to the first quarter (Q1) of 2019. During Q1 2019, the vancomycin-variable enterococci (VVE) ST1421-CT1134 vanA E. faecium became the most dominant vanA E. faecium clone and has spread to all five regions in Denmark. Among 174 E. faecium isolates with vanA, vanB or vanA/vanB genes in Q1 2019, 44% belonged to this type.

Norovirus Genotypes in Hospital Settings: Differences Between Nosocomial and Community-Acquired Infections.

BACKGROUND: Norovirus (NoV) is a major cause of gastroenteritis and hospital outbreaks, leading to substantial morbidity and direct healthcare expenses as well as indirect societal costs. The aim of the study was to estimate the proportion of nosocomial NoV infections among inpatients testing positive for NoV in Denmark, 2002-2010, and to study the distribution of NoV genotypes among inpatients with nosocomial and community-acquired NoV infections, respectively. METHODS: Admission and stool sampling dates from 3656 NoV-infected patients were used to estimate the proportion of nosocomial infections. The associations between nosocomial infection and patient age, sex, and NoV genotype GII.4 were examined. RESULTS: Of the 3656 inpatients, 63% were classified as having nosocomial infections. Among these, 9 capsid and 8 polymerase NoV genotypes were detected, whereas in the smaller group of inpatients with community-acquired infections, 12 capsid and 9 polymerase genotypes were detected. Nosocomial NoV infections were associated with age ≥60 years and infections with genotype GII.4. CONCLUSIONS: The majority of NoV infections in hospitalized patients were nosocomial. Nosocomial infection was mainly associated with older age but also with the specific genotype GII.4. The genotypes in community-acquired NoV infections were more heterogeneous than in nosocomial infections.

Parenteral Fosfomycin in Gastrointestinal Surgery: A Systematic Review.

BACKGROUND: To investigate if perioperative parenteral administration of fosfomycin given before or during gastrointestinal surgery could protect against postoperative infectious complications and characterise the administration of fosfomycin and its harms. METHODS: This systematic review included original studies on gastrointestinal surgery where parental administration of fosfomycin was given before or during surgery to≥5 patients. We searched three databases on March 24 2023 and registered the protocol before data extraction (CRD42020201268). Risk of bias was assessed with Cochrane Handbook risk of bias assessment tool or the Newcastle-Ottawa Scale. A narrative description was undertaken. For infectious complications, results from emergency and elective surgery were presented separately. RESULTS: We included 15 unique studies, reporting on 1,029 patients that received fosfomycin before or during gastrointestinal surgery. Almost half of the studies were conducted in the 1980s to early 1990s, and typically a dose of 4 g fosfomycin was given before surgery co-administered with metronidazole and often repeated postoperatively. The risk of bias across studies was moderate to high. The rates of infectious complications were low after fosfomycin; the surgical site infection rate was 0-1% in emergency surgery and 0-10% in elective surgery. If reported, harms were few and mild and typically related to the gastrointestinal system. CONCLUSION: There were few postoperative infectious complications after perioperative parenteral administration of one or more doses of 4 g fosfomycin supplemented with metronidazole in various gastrointestinal procedures. Fosfomycin was associated with few and mild harms.

The microbiome of the appendix differs in patients with and without appendicitis: A prospective cohort study.

BACKGROUND: Appendicitis seems to be a disease of infectious origin, but the detailed pathogenesis is unknown. We aimed to investigate the microbiome of the appendix lumen in patients with and without appendicitis, including a comparison of the subgroups of complicated versus uncomplicated appendicitis. METHODS: This prospective observational cohort study included adult patients undergoing laparoscopic appendectomy for suspected appendicitis. According to histopathologic findings, the investigated groups consisted of patients with and without appendicitis, including subgroups of complicated versus uncomplicated appendicitis based on the surgical report. A swab of the appendix lumen was analyzed for genetic material from bacteria with shotgun metagenomics, and outcomes included analyses of microbiome diversity and differential abundance of bacteria. RESULTS: A total of 53 swabs from patients with suspected appendicitis were analyzed: 42 with appendicitis (16 complicated) and 11 without appendicitis. When comparing patients with and without appendicitis, they were equally rich in bacteria (alpha diversity), but the microbiome composition was dissimilar between these groups (beta diversity) (P < .01). No consistent bacterial species were detected in all patients with appendicitis, but a least 3 genera (Blautia, Faecalibacterium, and Fusicatenibacter) and 2 species, Blautia faecis and Blautia wexlerae, were more abundant in patients without appendicitis. For the subgroups complicated versus uncomplicated appendicitis, both measures for microbiome diversity were similar. CONCLUSION: The appendix microbiome composition of genetic material from bacteria in adult patients with and without appendicitis differed, but the microbiome was similar for patients with complicated versus uncomplicated appendicitis. Trial registration NCT03349814.

Rapid detection of vanB vancomycin-resistant enterococci by laboratory-developed PCR on enrichment broth.

Diagnostic accuracy of laboratory-developed PCR after overnight enrichment for the detection of vanB vancomycin-resistant enterococci was evaluated on 537 rectal swabs. Defining Ct-values of 27-34 (40 samples, 7 % inconclusive), we found an excellent sensitivity of 98,3 % and specificity of 99,7 % for the remaining 497 samples.

Long-term carriage and evolution of VREfmLong-term carriage and evolution of vancomycin-resistant Enterococcus faecium: a genomic study on consecutive isolates.

Objectives: To determine if vancomycin-resistant Enterococcus faecium (VREfm) carriers carry the same VREfm clone after a minimum follow-up of 365 days. For those carrying the same clone, we investigated the genomic evolution per year per genome. Methods: We used WGS results to assign VREfm clones to each isolate and determine clone shifts. Finally, we calculated distance in core-genome MLST alleles, and the number of SNPs between consecutive VREfm isolates from patients carrying the same VREfm clone. Results: In total, 44.2% of patients carried the same VREfm clone, and the genomic evolution was 1.8 alleles and 2.6 SNPs per genome per year. Conclusions: In our population of long-term carriers, we calculated a molecular clock of 2.6 SNPs.

Comparison of morbidity and mortality after bloodstream infection with vancomycin-resistant versus -susceptible Enterococcus faecium: a nationwide cohort study in Denmark, 2010-2019.

The emergence of bloodstream infections (BSI) caused by vancomycin-resistant Enterococci (VRE) has caused concern. Nonetheless, it remains unclear whether these types are associated with an excess risk of severe outcomes when compared with infections caused by vancomycin-susceptible Enterococci (VSE). This cohort study included hospitalized patients in Denmark with Enterococcus faecium-positive blood cultures collected between 2010 and 2019 identified in the Danish Microbiology Database. We estimated 30-day hazard ratio (HR) of death or discharge among VRE compared to VSE patients adjusted for age, sex, and comorbidity. The cohort included 6071 patients with E. faecium BSI (335 VRE, 5736 VSE) among whom VRE increased (2010-13, 2.6%; 2014-16, 6.3%; 2017-19; 9.4%). Mortality (HR 1.08, 95%CI 0.90-1.29; 126 VRE, 37.6%; 2223 VSE, 37.0%) or discharge (HR 0.89, 95%CI 0.75-1.06; 126 VRE, 37.6%; 2386 VSE, 41.6%) was not different between VRE and VSE except in 2014 (HR 1.87, 95% CI 1.18-2.96). There was no interaction between time from admission to BSI (1-2, 3-14, and >14 days) and HR of death (P = 0.14) or discharge (P = 0.45) after VRE compared to VSE, despite longer time for VRE patients (17 vs. 10 days for VSE, P < 0.0001). In conclusion, VRE BSI was not associated with excess morbidity and mortality. The excess mortality in 2014 only may be attributed to improved diagnostic- and patient-management practices after 2014, reducing time to appropriate antibiotic therapy. The high level of mortality after E. faecium BSI warrants further study.

Oral chlorhexidine and microbial contamination during endoscopy: possible implications for transgastric surgery. A randomized, clinical trial.

BACKGROUND: One of the biggest concerns associated with transgastric surgery is contamination and risk of intra-abdominal infection with microbes introduced from the access route. The purpose of this study was to evaluate the effect of oral decontamination with chlorhexidine on microbial contamination of the endoscope. METHODS: In a prospective, randomized, single-blinded, clinical trial the effect of chlorhexidine mouth rinse was evaluated. As a surrogate for the risk of intra-abdominal contamination during transgastric surgery, microbial contamination of the endoscope during upper endoscopy was examined. Patients referred to upper endoscopy were assessed for eligibility and randomized to either chlorhexidine or no mouth rinse. Culture samples were collected from gastric aspirates and endoscopes. The primary outcome measure was colony forming units (CFU) in the endoscope samples. Secondary outcome measures were species specific effect of chlorhexidine on micro-organisms with abscess forming capabilities and the effect of proton pump inhibitor (PPI) treatment on CFU. RESULTS: Chlorhexidine mouth rinse resulted in a significant reduction of CFU in the endoscope samples (p = 0.001). There was no species specific effect and micro-organisms with abscess forming capabilities were equally present. PPI treatment was associated with significantly higher CFU counts in both the gastric (p = 0.004) and endoscope samples (p = 0.049). CONCLUSIONS: Chlorhexidine mouth rinse was effective in reducing microbial contamination of the endoscope, but micro-organisms with abscess forming capabilities were still present. PPI treatment significantly increased CFU and should be discontinued before transgastric surgery.

Diarrhoea-causing microorganisms are rare in adult patients undergoing diagnostic laparoscopy for suspected appendicitis: a prospective observational cohort study.

We investigated if diarrhoea-causing bacteria, including Yersinia species, could mimic the symptoms of appendicitis and lead to surgery. This prospective observational cohort study (NCT03349814) included adult patients undergoing surgery for suspected appendicitis. Rectal swabs were analysed with polymerase chain reaction (PCR) for Yersinia, Campylobacter, Salmonella, Shigella and Aeromonas spp. Blood samples were analysed routinely and with an in-house ELISA serological test for Yersinia enterocolitica antibodies. We compared patients without appendicitis and patients with appendicitis confirmed by histopathology. The outcomes included PCR-confirmed infection with Yersinia spp., serologic-confirmed infection with Y. enterocolitica, PCR-confirmed infection with other diarrhoea-causing bacteria and Enterobius vermicularis confirmed by histopathology. A total of 224 patients were included, 51 without and 173 with appendicitis, and followed for 10 days. PCR-confirmed infection with Yersinia spp. was found in one patient (2%) without appendicitis and no patients (0%) with appendicitis (p = 0.23). Serology was positive for Y. enterocolitica for the same patient without appendicitis and two patients with appendicitis (p = 0.54). Campylobacter spp. were detected in 4% vs 1% (p = 0.13) of patients without and with appendicitis, respectively. Infection with Yersinia spp. and other diarrhoea-causing microorganisms in adult patients undergoing surgery for suspected appendicitis was rare.

Risk factors for methicillin-resistant Staphylococcus aureus colonization in a level-IV neonatal intensive care unit: a retrospective study.

Objective: To identify risk factors associated with methicillin-resistant Staphylococcus aureus (MRSA) colonization in neonatal patients during an MRSA outbreak to minimize future outbreaks. Design: Retrospective case-control study. Setting: Level-IV neonatal intensive care unit (NICU) at Copenhagen University Hospital, Rigshospitalet, Denmark. Patients: Neonates with either MRSA or methicillin-susceptible Staphylococcus aureus (MSSA). Methods: Methicillin-resistant Staphylococcus aureus-positive neonates were matched with those colonized or infected with MSSA in a 1:1 ratio. The control group was selected from clinical samples, whereas MRSA-positive neonates were identified from clinical samples or from screening. A total of 140 characteristics were investigated to identify risk factors associated with MRSA acquisition. The characteristics were categorized into three categories: patient, unit, and microbiological characteristics. Results: Out of 1,102 neonates screened for MRSA, between December 2019 and January 2022, 33 were MRSA positive. They were all colonized with an MRSA outbreak clone (spa type t127) and were included in this study. Four patients (12%) had severe infection. Admission due to respiratory diseases, need for intubation, need for peripheral venous catheters, admission to shared rooms with shared toilets and bath facilities in the aisles, and need for readmission were all correlated with later MRSA colonization (P < 0.05). Conclusion: We identified clinically relevant diseases, procedures, and facilities that predispose patients to potentially life-threatening MRSA infections. A specific MRSA reservoir remains unidentified; however, these findings have contributed to crucial changes in our NICU to reduce the number of MRSA infections and future outbreaks.