Active follow-up of patients identified with multidrug-resistant Gram-negative bacteria to discontinue contact precautions and isolation measures.

BACKGROUND: It is essential to refrain from unnecessary isolation measures indicated for patients identified with multidrug-resistant Gram-negative bacteria (MDR-GNB). AIM: To evaluate whether a pro-active follow-up strategy to discontinue isolation measures of patients identified with MDR-GNB (without carbapenemase production) resulted in reduced isolation days during hospitalization, compared to passive follow-up. METHODS: A comparison was made between active and passive follow-up strategies over a two-year period after first MDR-GNB identification. Patients could be declared negative after two consecutive negative screening cultures. Active follow-up patients received a questionnaire for screening cultures within six months of MDR-GNB identification. Of the 2208 patients included, 1424 patients (64.5%) underwent passive follow-up and 784 patients (35.5%) underwent active follow-up. FINDINGS: A significantly higher proportion of active follow-up patients who had sufficient (at least two) screening cultures were declared MDR-GNB negative compared to those with passive follow-up; 66.9% vs 20.6% (P < 0.001) for adult patients and 76.0% vs 17.1% (P < 0.001) for paediatric patients. A comparison between active follow-up patients with sufficient versus those with active follow-up but insufficient cultures revealed a reduction of isolation days for paediatric patients (median 10.6 vs 1.6 days; P = 0.031). Though this difference was not statistically significant for adults (median 5.3 vs 4.2 isolation days), there was a valuable decrease in the number of isolation days for both adult and paediatric patients under active follow-up with sufficient (≥2) cultures, indicating clinical relevance. CONCLUSION: We recommend an active follow-up strategy for patients identified with an MDR-GNB, to prevent further unneeded infection prevention measures.

Antimicrobial susceptibility profile of clinically relevant Bacteroides, Phocaeicola, Parabacteroides and Prevotella species, isolated by eight laboratories in the Netherlands.

OBJECTIVES: Recently, reports on antimicrobial-resistant Bacteroides and Prevotella isolates have increased in the Netherlands. This urged the need for a surveillance study on the antimicrobial susceptibility profile of Bacteroides, Phocaeicola, Parabacteroides and Prevotella isolates consecutively isolated from human clinical specimens at eight different Dutch laboratories. METHODS: Each laboratory collected 20-25 Bacteroides (including Phocaeicola and Parabacteroides) and 10-15 Prevotella isolates for 3 months. At the national reference laboratory, the MICs of amoxicillin, amoxicillin/clavulanic acid, piperacillin/tazobactam, meropenem, imipenem, metronidazole, clindamycin, tetracycline and moxifloxacin were determined using agar dilution. Isolates with a high MIC of metronidazole or a carbapenem, or harbouring cfiA, were subjected to WGS. RESULTS: Bacteroides thetaiotaomicron/faecis isolates had the highest MIC90 values, whereas Bacteroides fragilis had the lowest MIC90 values for amoxicillin/clavulanic acid, piperacillin/tazobactam, meropenem, imipenem and moxifloxacin. The antimicrobial profiles of the different Prevotella species were similar, except for amoxicillin, for which the MIC50 ranged from 0.125 to 16 mg/L for Prevotella bivia and Prevotella buccae, respectively. Three isolates with high metronidazole MICs were sequenced, of which one Bacteroides thetaiotaomicron isolate harboured a plasmid-located nimE gene and a Prevotella melaninogenica isolate harboured a nimA gene chromosomally.Five Bacteroides isolates harboured a cfiA gene and three had an IS element upstream, resulting in high MICs of carbapenems. The other two isolates harboured no IS element upstream of the cfiA gene and had low MICs of carbapenems. CONCLUSIONS: Variations in resistance between species were observed. To combat emerging resistance in anaerobes, monitoring resistance and conducting surveillance are essential.

Proposal for a screening protocol for Candida auris colonization.

BACKGROUND: Candida auris is an emerging multidrug-resistant yeast which can cause severe infection in hospitalized patients. Since its first detection in 2009, C. auris has spread globally. The control and elimination of this pathogen in a hospital setting is particularly challenging because of its ability to form biofilms, allowing for long-term patient colonization and persistence in the environment. Identification of C. auris from cultures is difficult due to the morphologic similarities to other yeasts, its slow growth, and the low culture sensitivity when using standard agars and temperatures. AIM: We have developed a screening protocol for C. auris colonization using an in-house-developed polymerase chain reaction (PCR), combined with confirmatory culture in optimized conditions. METHODS: C. auris-specific primers and probe were developed, targeting the internal transcribed spacer (ITS) region, and specificity was confirmed in silico using the BLAST tool. The PCR was validated using a panel of 12 C. auris isolates and 103 isolates from 22 other Candida species and was shown to be 100% accurate. The limit of detection of the assay was determined at approximately four cells per PCR. FINDINGS: C. auris screening was introduced on February 15th, 2023, and was used for patients who had been admitted to a healthcare facility abroad in the two months prior to admission to our hospital. The screening protocol included swabs from nose, throat, rectum, axilla, and groin. In the first eight months, 199 patients were screened and seven were found positive (4%). CONCLUSION: Our proposed screening protocol may contribute to control C. auris in hospitals.

Characterization of mobile genetic elements in multidrug-resistant Bacteroides fragilis isolates from different hospitals in the Netherlands.

OBJECTIVES: Five human clinical multidrug-resistant (MDR) Bacteroides fragilis isolates, including resistance to meropenem and metronidazole, were recovered at different hospitals in the Netherlands between 2014 and 2020 and sent to the anaerobic reference laboratory for full characterization. METHODS: Isolates were recovered from a variety of clinical specimens from patients with unrelated backgrounds. Long- and short-read sequencing was performed, followed by a hybrid assembly to study the presence of mobile genetic elements (MGEs) and antimicrobial resistance genes (ARGs). RESULTS: A cfxA gene was present on a transposon (Tn) similar to Tn4555 in two isolates. In two isolates a novel Tn was present with the cfxA gene. Four isolates harbored a nimE gene, located on a pBFS01_2 plasmid. One isolate contained a novel plasmid carrying a nimA gene with IS1168. The tetQ gene was present on novel conjugative transposons (CTns) belonging to the CTnDOT family. Two isolates harbored a novel plasmid with tetQ. Other ARGs in these isolates, but not on an MGE, were: cfiA, ermF, mef(EN2), and sul2. ARGs harboured differed between isolates and corresponded with the observed phenotypic resistance. CONCLUSIONS: Novel CTns, Tns, and plasmids were encountered in the five MDR B. fragilis isolates, complementing our knowledge on MDR and horizontal gene transfer in anaerobic bacteria.

The effect of an intervention bundle to prevent central venous catheter-related bloodstream infection in a national programme in the Netherlands.

INTRODUCTION: Central venous catheters (CVCs) can lead to central line-related bloodstream infections (CRBSIs). A six-item bundle was introduced in 2009 to prevent CRBSI in Dutch hospitals. AIM: This study aimed to determine the impact of an intervention bundle on CRBSI risk. METHODS: Data were obtained from hospitals participating in the national CRBSI surveillance between 2009 and 2019. Bundle compliance was evaluated as a total ('overall') bundle (all six items) and as an insertion bundle (four items) and a maintenance bundle (two daily checks). We estimated the impact of the overall and partial bundles, using multi-level Cox regression. FINDINGS: Of the 66 hospitals in the CRBSI surveillance 56 (84.8%) recorded annual bundle (non)compliance for >80% of the CVCs, for one to nine years. In these 56 hospitals CRBSI incidence decreased from 4.0 to 1.6/1000 CVC days. In the intensive care units (ICUs), compliance was not associated with CRBSI risk (hazard ratio (HR) for the overall, insertion and maintenance bundle were 1.14 (95% confidence interval 0.80-1.64), 1.05 (0.56-1.95) and 1.13 (0.79-1.62)), respectively. Outside the ICU the non-significant association of compliance with the overall bundle (HR 1.36 (0.96-1.93)) resulted from opposite effects of the insertion bundle, associated with decreased risk (HR 0.50 (0.30-0.85)) and the maintenance bundle, associated with increased risk (HR 1.68 (1.19-2.36)). CONCLUSION: Following a national programme to introduce an intervention bundle, CRBSI incidence decreased significantly. In the ICU, bundle compliance was not associated with CRBSI risk, but outside the ICU improved compliance with the insertion bundle resulted in a decreased CRBSI risk.

Systematic review found that there was moderate evidence that vaccinating healthcare workers prevented pertussis in infants.

This systematic review investigated the effectiveness of vaccinating healthcare workers against pertussis on the occurrence of nosocomial pertussis outbreaks or infections among unprotected infants. We focused on eight studies, with five different study designs, that involved 39,129 healthy adolescents and adults, 115 healthcare workers, 2000 simulated healthcare workers and a simulated population of 200,000 people. CONCLUSION: There was moderate evidence that tetanus-diphtheria acellular pertussis vaccinations for healthcare workers were effective in preventing pertussis in all age groups and specifically in infants. The results must be interpreted with caution due to the low quality and heterogeneity of the studies.

Staphylococcus aureus colonization at ICU admission as a risk factor for developing S. aureus ICU pneumonia.

OBJECTIVE: To quantify the incidence of intensive care unit (ICU)-acquired pneumonia caused by Staphylococcus aureus (S. aureus) and its association with S. aureus colonization at ICU admission. METHODS: This was a post-hoc analysis of two cohort studies in critically ill patients. The primary outcome was the incidence of microbiologically confirmed S. aureus ICU-acquired pneumonia. Incidences of S. aureus ICU pneumonia and associations with S. aureus colonization at ICU admission were determined using competing risks analyses. In all ICUs, patients were screened for respiratory tract S. aureus carriage on admission as part of infection control policies. Pooling of data was not deemed possible because of heterogeneity in baseline differences in patient population. RESULTS: The two cohort studies contained data of 9156 ICU patients. The average carriage rate of S. aureus among screened patients was 12.7%. In total, 1185 (12.9%) patients developed ICU pneumonia. Incidences of S. aureus ICU pneumonia were 1.33% and 1.08% in cohorts 1 and 2, respectively. After accounting for competing events, the adjusted subdistribution hazard ratio (SHR) of S. aureus colonization at admission for developing S. aureus ICU pneumonia was 9.55 (95% CI 5.31-17.18) in cohort 1 and 14.54 (95% CI 7.24-29.21) in cohort 2. CONCLUSION: The overall cumulative incidence of S. aureus ICU pneumonia in these ICUs was low. Patients colonized with S. aureus at ICU admission had an up to 15 times increased risk for developing this outcome compared with non-colonized patients.

A systematic review and meta-analysis on Staphylococcus aureus carriage in psoriasis, acne and rosacea.

Staphylococcus aureus might amplify symptoms in chronic inflammatory skin diseases. This study evaluates skin and mucosal colonization with S. aureus in patients with psoriasis, acne and rosacea. A systematic literature search was conducted. Both odds ratios (OR) for colonization in patients versus controls and the prevalence of colonization in patients are reported. Fifteen articles about psoriasis and 13 about acne (12 having a control group) were included. No study in rosacea met our inclusion criteria. For psoriasis, one study out of three controlled studies showed increased skin colonization (OR 18.86; 95 % confidence interval [CI] 2.20-161.99). Three out of the five studies that reported on nasal colonization showed significant ORs varying from 1.73 (95 % CI 1.16-2.58) to 14.64 (95 % CI 2.82-75.95). For acne one of the three studies that evaluated skin colonization reported a significant OR of 4.16 (95 % CI 1.74-9.94). A relation between nasal colonization and acne was not found. Limitations in study design and low sample sizes should be taken into consideration when interpreting the results. Colonisation with S. aureus seems to be increased in patients with psoriasis. This bacterial species, known for its potential to induce long-lasting inflammation, might be involved in psoriasis pathogenesis. Information on acne is limited. Prospective controlled studies should further investigate the role of S. aureus in chronic inflammatory skin diseases.

Sustained low prevalence of meticillin-resistant Staphylococcus aureus upon admission to hospital in The Netherlands.

The prevalence of meticillin-resistant Staphylococcus aureus (MRSA) carriage at hospital admission in The Netherlands was 0.03% in 1999-2000. The aim of the present study was to assess whether the prevalence of MRSA carriage in The Netherlands has changed over the last few years. In five Dutch hospitals, 6496 unique patients were screened for nasal S. aureus carriage at hospital admission by microbiological culture between 1 October 2005 and 7 June 2007. In total, 2036 of 6496 (31.3%) patients carried S. aureus in their nose, and seven of 6496 (0.11%) patients were nasal carriers of MRSA. Compared with 1999-2000, the prevalence of MRSA carriage in the Dutch population at hospital admission has increased more than three fold; however, this increase was not significant (P=0.06, Fisher's exact test). This prevalence is still among the lowest in the world, probably as a result of the stringent Dutch infection control policy, and the restrictive use of antibiotics in The Netherlands.

Heterogeneity of the humoral immune response following Staphylococcus aureus bacteremia.

Expanding knowledge on the humoral immune response in Staphylococcus aureus-infected patients is a mandatory step in the development of vaccines and immunotherapies. Here, we present novel insights into the antibody responses following S. aureus bacteremia. Fifteen bacteremic patients were followed extensively from diagnosis onwards (median 29 days, range 9-74). S. aureus strains (median 3, range 1-6) and serial serum samples (median 16, range 6-27) were collected. Strains were genotyped by pulsed-field gel electrophoresis (PFGE) and genes encoding 19 staphylococcal proteins were detected by polymerase chain reaction (PCR). The levels of IgG, IgA, and IgM directed to these proteins were determined using bead-based flow cytometry. All strains isolated from individual patients were PFGE-identical. The genes encoding clumping factor (Clf) A, ClfB, and iron-responsive surface-determinant (Isd) A were detected in all isolates. Antigen-specific IgG levels increased more frequently than IgA or IgM levels. In individual patients, different proteins induced an immune response and the dynamics clearly differed. Anti-ClfB, anti-IsdH, and anti-fibronectin-binding protein A IgG levels increased in 7 of 13 adult patients (p < 0.05). The anti-IsdA IgG level increased in 12 patients (initial to peak level: 1.13-10.72 fold; p < 0.01). Peak level was reached 7-37 days after diagnosis. In a bacteremic 5-day-old newborn, antistaphylococcal IgG levels declined from diagnosis onwards. In conclusion, each bacteremic patient develops a unique immune response directed to different staphylococcal proteins. Therefore, vaccines should be based on multiple components. IsdA is immunogenic and, therefore, produced in nearly all bacteremic patients. This suggests that IsdA might be a useful component of a multivalent staphylococcal vaccine.