From Nares to Wound: Exploring the mechanisms for Staphylococcal surgical site infections, implications for infection prevention

Surgical site infections (SSIs) are important healthcare-associated infections, leading to increased morbidity and mortality, healthcare costs, and prolonged hospital stays. Staphylococcus aureus is an important and common microbial cause of SSI. Nasal carriage of S. aureus has been shown to be an important determinant for the development of SSI, and interventions aimed at eradicating preoperative nasal carriage are associated with a reduced risk of infection. Yet, it is not entirely clear how the nasally residing S. aureus causes SSI at distant body sites. In this commentary, we describe our view on how S. aureus can be transported from the nares to the incision site during surgery. In addition, we shed light on the implications of our view for infection prevention research

Methicillin-Resistant Staphylococcus aureus in Meat Products, the Netherlands

A new methicillin-resistant Staphylococcus aureus (MRSA) clone related to pig and cattle farming was detected in the Netherlands. We investigated the extent of S. aureus presence in meat and found 36 S. aureus strains in 79 samples. Two strains were MRSA; 1 was multilocus sequence type 398, the clone related to farming

Gut microbiome dynamics in index patients colonized with extended-spectrum beta-lactamase (ESBL)-producing Enterobacterales after hospital discharge and their household contacts

This study investigated the gut microbiome dynamics of index patients colonized with extended-spectrum beta-lactamase-producing Escherichia coli (ESBL-Ec) (n = 5) or extended-spectrum beta-lactamase-producing Klebsiella pneumoniae (ESBL-Kp) (n = 3) and their household contacts (n = 9) up to 4 months after hospital discharge of the index patient using 16S rRNA amplicon gene sequencing. Samples were collected at the day of hospital discharge of the index patient, 1 week and 2 and 4 months after discharge. Compared to household contacts, we observed a significant lower alpha diversity (P < 0.001) among index patients and significant (P < 0.05) separation between the two groups for beta diversity. Principal component analysis of the samples from each household (i.e., index patient and respective household contact) showed a clear shift in microbiome composition, in 4/8 index patients, from dissimilar to more similar to the household contact group. This suggests recovery of the microbiome to a healthier status, which was also reflected by de novo colonization of (health-associated) taxa. In contrast, the four time-point samples of the household contacts clustered together indicating a stable microbiome composition over time irrespective of low-level ESBL-Ec (n = 3) or ESBL-Kp (n = 2) colonization. In conclusion, here we show that, at the day of hospital discharge, the microbiome composition of index patients is dissimilar from that of household contacts. Over time, signals of microbiome recovery were observed in half of the index patients. The stable microbiome composition in household contacts irrespective of low-level ESBL-Ec or ESBL-Kp colonization suggests that the gut microbiome in these healthy people provided colonization resistance against ESBL-PE outgrowth

Livestock density as risk factor for livestock-associated methicillin-resistant Staphylococcus aureus, the Netherlands

To determine whether persons living in areas of high animal density are at increased risk for carrying livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA), we used an existing dataset of persons in the Netherlands with LA-MRSA carriage and controls who carried other types of MRSA. Results of running univariate and multivariate logistic regression models indicated that living in livestock-dense areas increases the odds of nasal carriage of LA-MRSA. We found that doubling pig, cattle, and veal calf densities per municipality increased the odds of LA-MRSA carriage over carriage of other types of MRSA by 24.7% (95% CI 0.9%–54.2%), 76.9% (95% CI 11.3%–81.3%), and 24.1% (95% CI 5.5%–45.9%), respectively, after adjusting for direct animal contact, living in a rural area, and the probable source of MRSA carriage. Controlling the spread of LA-MRSA thus requires giving attention to community members in animal-dense regions who are unaffiliated with livestock farming

Genome-wide analysis in Escherichia coli unravels a high level of genetic homoplasy associated with cefotaxime resistance

Cefotaxime (CTX) is a third-generation cephalosporin (3GC) commonly used to treat infections caused by Escherichia coli. Two genetic mechanisms have been associated with 3GC resistance in E. coli. The first is the conjugative transfer of a plasmid harbouring antibiotic-resistance genes. The second is the introduction of mutations in the promoter region of the ampC β-lactamase gene that cause chromosome-encoded β-lactamase hyperproduction. A wide variety of promoter mutations related to AmpC hyperproduction have been described. However, their link to CTX resistance has not been reported. We recultured 172 cefoxitin-resistant E. coli isolates with known CTX minimum inhibitory concentrations and performed genome-wide analysis of homoplastic mutations associated with CTX resistance by comparing Illumina whole-genome sequencing data of all isolates to a PacBio sequenced reference chromosome. We mapped the mutations on the reference chromosome and determined their occurrence in the phylogeny, revealing extreme homoplasy at the -42 position of the ampC promoter. The 24 occurrences of a T at the -42 position rather than the wild-type C, resulted from 18 independent C>T mutations in five phylogroups. The -42 C>T mutation was only observed in E. coli lacking a plasmid-encoded ampC gene. The association of the -42 C>T mutation with CTX resistance was confirmed to be significant (false discovery rate T mutation of the ampC promotor as significantly associated with CTX resistance and underlines the role of recurrent mutations in the spread of antibiotic resistance

Household acquisition and transmission of extended-spectrum β-lactamase (ESBL) -producing Enterobacteriaceae after hospital discharge of ESBL-positive index patients

MODERN WP2 study group: Caroline Brossier, Elodie von Dach, Gesuele Renzi, Jacques Schrenzel, Stefanie Bunk, Siri Goepel, Florian Hölzl, Michael Eib, Ingo B.Autenrieth, Álvaro Pascual, Xavier Bertrand, Jelle Scharringa, Patrick Musicha.[Objectives] This study aimed to determine rates and risk factors of extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-PE) acquisition and transmission within households after hospital discharge of an ESBL-PE-positive index patient.[Methods] Two-year prospective cohort study in five European cities. Patients colonized with ESBL-producing Escherichia coli (ESBL-Ec) or Klebsiella pneumoniae (ESBL-Kp), and their household contacts were followed up for 4 months after hospital discharge of the index case. At each follow up, participants provided a faecal sample and personal information. ESBL-PE whole-genome sequences were compared using pairwise single nucleotide polymorphism-based analysis.[Results] We enrolled 71 index patients carrying ESBL-Ec (n = 45), ESBL-Kp (n = 20) or both (n = 6), and 102 household contacts. The incidence of any ESBL-PE acquisition among household members initially free of ESBL-PE was 1.9/100 participant-weeks at risk. Nineteen clonally related household transmissions occurred (case to contact: 13; contact to case: 6), with an overall rate of 1.18 transmissions/100 participant-weeks at risk. Most of the acquisition and transmission events occurred within the first 2 months after discharge. The rate of ESBL-Kp household transmission (1.16/100 participant-weeks) was higher than of ESBL-Ec (0.93/100 participant-weeks), whereas more acquisitions were noted for ESBL-Ec (1.06/100 participant-weeks) compared with ESBL-Kp (0.65/100 participant-weeks). Providing assistance for urinary and faecal excretion to the index case by household members increased the risk of ESBL-PE transmission (adjusted prevalence ratio 4.3; 95% CI 1.3–14.1).[Conclusions] ESBL-PE cases discharged from the hospital are an important source of ESBL-PE transmission within households. Most acquisition and transmission events occurred during the first 2 months after hospital discharge and were causally related to care activities at home, highlighting the importance of hygiene measures in community settings.[Clinical study registration] German Clinical Trials Register, DRKS-ID: DRKS00013250.This study was part of a Joint Programming Initiative on Antimicrobial Resistance collaborative research project, under the 2016 Joint Call framework (Transnational Research Projects on the Transmission Dynamics of Antibacterial Resistance). It received funding from the following national research agencies: Instituto de Salud Carlos III (grant no. AC16/00076), Netherlands Organization for Health Research and Development (grant no. AC681055), Swiss National Science Foundation (grant no. 40AR40-173608), German Federal Ministry of Education and Research (grant no. 01KI1830) and Agence Nationale de la Recherche (grant no. ANR-16-JPEC-0007-03). As part of a separate research project, Marlieke de Kraker has received support from the Innovative Medicines Initiative Joint Undertaking under grant agreement nos 115523, 115620 and 115737 (Combatting Bacterial Resistance in Europe projects (COMBACTE)), resources of which are composed of financial contribution from the European Union's 7th Framework Programme (FP7/2007±2013) and the European Federation of Pharmaceutical Industries and associations companies' in-kind contribution. Also, Elena Salamanca, Mercedes Delgado and Jesús Rodríguez-Baño received support for research from by the Plan Nacional de I+D+i 2013-2016 and Instituto de Salud Carlos III, Subdirección General de Redes y Centros de Investigación Cooperativa, Ministerio de Ciencia, Innovación y Universidades, Spanish Network for Research in Infectious Diseases (REIPI RD16/0016/0001), co-financed by the European Development Regional Fund ‘A way to achieve Europe’, Operative Programme Intelligence Growth 2014-2020.Peer reviewe

COVID-19 in health-care workers in three hospitals in the south of the Netherlands:A cross-sectional study

Background: 10 days after the first reported case of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in the Netherlands (on Feb 27, 2020), 55 (4%) of 1497 health-care workers in nine hospitals located in the south of the Netherlands had tested positive for SARS-CoV-2 RNA. We aimed to gain insight in possible sources of infection in health-care workers. Methods: We did a cross-sectional study at three of the nine hospitals located in the south of the Netherlands. We screened health-care workers at the participating hospitals for SARS-CoV-2 infection, based on clinical symptoms (fever or mild respiratory symptoms) in the 10 days before screening. We obtained epidemiological data through structured interviews with health-care workers and combined this information with data from whole-genome sequencing of SARS-CoV-2 in clinical samples taken from health-care workers and patients. We did an in-depth analysis of sources and modes of transmission of SARS-CoV-2 in health-care workers and patients. Findings: Between March 2 and March 12, 2020, 1796 (15%) of 12 022 health-care workers were screened, of whom 96 (5%) tested positive for SARS-CoV-2. We obtained complete and near-complete genome sequences from 50 health-care workers and ten patients. Most sequences were grouped in three clusters, with two clusters showing local circulation within the region. The noted patterns were consistent with multiple introductions into the hospitals through community-acquired infections and local amplification in the community. Interpretation: Although direct transmission in the hospitals cannot be ruled out, our data do not support widespread nosocomial transmission as the source of infection in patients or health-care workers. Funding: EU Horizon 2020 (RECoVer, VEO, and the European Joint Programme One Health METASTAVA), and the National Institute of Allergy and Infectious Diseases, National Institutes of Health

Evaluation of yield of currently available diagnostics by sample type to optimize detection of respiratory pathogens in patients with a community-acquired pneumonia

Background: For the detection of respiratory pathogens, the sampling strategy may influence the diagnostic yield. Ideally, samples from the lower respiratory tract are collected, but they are difficult to obtain. Objectives: In this study, we compared the diagnostic yield in sputum and oropharyngeal samples (OPS) for the detection of respiratory pathogens in patients with community-acquired pneumonia (CAP), with the objective to optimize our diagnostic testing algorithm. Methods: Matched sputum samples, OPS, blood cultures, serum, and urine samples were taken from patients (>18 years) with CAP and tested for the presence of possible respiratory pathogens using bacterial cultures, PCR for 17 viruses and five bacteria and urinary antigen testing. Results: When using only conventional methods, that is, blood cultures, sputum culture, urinary antigen tests, a pathogen was detected in 49·6% of patients (n = 57). Adding molecular detection assays increased the yield to 80%. A pathogen was detected in 77 of the 115 patients in OPS or sputum samples by PCR. The sensitivity of the OPS was lower than that of the sputum samples (57% versus 74%). In particular, bacterial pathogens were more often detected in sputum samples. The sensitivity of OPS for the detection of most viruses was higher than in sputum samples (72% versus 66%), except for human rhinovirus and respiratory syncytial virus. Conclusion: Addition of PCR on both OPS and sputum samples significantly increased the diagnostic yield. For molecular detection of bacterial pathogens, a sputum sample is imperative, but for detection of most viral pathogens, an OPS is sufficient