Pre-Operative SARS-CoV-2 Testing in Asymptomatic Heart Transplantation Recipients.

INTRODUCTION: From the start of the coronavirus disease 2019 (COVID-19) pandemic, international guidelines have recommended pre-operative screening for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) before heart transplantation (HTx). Due to the changing prevalence of COVID-19, the chances of false positive results have increased. Because of increased immunity in the population and evolution of SARS-CoV-2 to current Omicron variants, associated mortality and morbidity have decreased. We set out to investigate the yield and side effects of SARS-CoV-2 screening in our center. METHODS: We performed a retrospective cohort study in the University Medical Center Utrecht. The study period was from March 2019 to January 2023. All data from patients who underwent HTx were collected, including all pre-operative and post-operative SARS-CoV-2 tests. Furthermore, all clinical SARS-CoV-2 tests for the indication of potential HTx were screened. RESULTS: In the period under study, 51 patients underwent HTx. None of the recipients reported any symptoms of a viral infection. Fifty HTx recipients were screened for SARS-CoV-2. Forty-nine out of fifty patients tested negative. One patient had a false positive result, potentially delaying the HTx procedure. There were no cancelled HTx procedures due to a true positive SARS-CoV-2 test result. CONCLUSION: Pre-operative SARS-CoV-2 screening in asymptomatic HTx recipients did not lead to any true positive cases. In 2% of the cases, screening resulted in a false positive test result. With the current Omicron variants, in combination with a low-prevalence situation, we propose to abandon pre-operative SARS-CoV-2 screening and initiate a symptom-driven approach for the general viral testing of patients who are called in for a potential HTx.

Enterococcus faecium genome dynamics during long-term asymptomatic patient gut colonization.

Enterococcus faecium is a gut commensal of humans and animals. In addition, it has recently emerged as an important nosocomial pathogen through the acquisition of genetic elements that confer resistance to antibiotics and virulence. We performed a whole-genome sequencing-based study on 96 multidrug-resistant E. faecium strains that asymptomatically colonized five patients with the aim of describing the genome dynamics of this species. The patients were hospitalized on multiple occasions and isolates were collected over periods ranging from 15 months to 6.5 years. Ninety-five of the sequenced isolates belonged to E. faecium clade A1, which was previously determined to be responsible for the vast majority of clinical infections. The clade A1 strains clustered into six clonal groups of highly similar isolates, three of which consisted entirely of isolates from a single patient. We also found evidence of concurrent colonization of patients by multiple distinct lineages and transfer of strains between patients during hospitalization. We estimated the evolutionary rate of two clonal groups that each colonized single patients at 12.6 and 25.2 single-nucleotide polymorphisms (SNPs)/genome/year. A detailed analysis of the accessory genome of one of the clonal groups revealed considerable variation due to gene gain and loss events, including the chromosomal acquisition of a 37 kbp prophage and the loss of an element containing carbohydrate metabolism-related genes. We determined the presence and location of 12 different insertion sequence (IS) elements, with ISEfa5 showing a unique pattern of location in 24 of the 25 isolates, suggesting widespread ISEfa5 excision and insertion into the genome during gut colonization. Our findings show that the E. faecium genome is highly dynamic during asymptomatic colonization of the human gut. We observed considerable genomic flexibility due to frequent horizontal gene transfer and recombination, which can contribute to the generation of genetic diversity within the species and, ultimately, can contribute to its success as a nosocomial pathogen.

Independent root-cause analysis of contributing factors, including dismantling of 2 duodenoscopes, to investigate an outbreak of multidrug-resistant Klebsiella pneumoniae.

BACKGROUND AND AIMS: Worldwide, an increasing number of duodenoscope-associated outbreaks are reported. The high prevalence rate of contaminated duodenoscopes puts patients undergoing ERCP at risk of exogenous transmission of microorganisms. The contributing factors of the duodenoscope design to contamination are not well understood. This article reports on the investigation after the outbreak of a multidrug-resistant Klebsiella pneumoniae (MRKP) related to 2 Olympus TJF-Q180V duodenoscopes. METHODS: We conducted a contact patient screening and microbiologic laboratory database search. Reprocessing procedures were audited, and both duodenoscopes were fully dismantled to evaluate all potential contamination factors. Outcomes were reviewed by an experienced independent expert. RESULTS: In total, 102 patients who had undergone an ERCP procedure from January to August 2015 were invited for screening. Cultures were available of 81 patients, yielding 27 MRKP-infected or -colonized patients. Ten patients developed an MRKP-related active infection. The 2 duodenoscopes had attack rates (the number of infected or colonized cases/number of exposed persons) of 35% (17/49) and 29% (7/24), respectively. Identical MRKP isolates were cultured from channel flushes of both duodenoscopes. The review revealed 4 major abnormalities: miscommunication about reprocessing, undetected damaged parts, inadequate repair of duodenoscope damage, and duodenoscope design abnormalities, including the forceps elevator, elevator lever, and instrumentation port sealing. CONCLUSIONS: Outbreaks are associated with a combination of factors, including duodenoscope design issues, repair issues, improper cleaning, and systemic monitoring of contamination. To eliminate future duodenoscope-associated infections, a multipronged approach is required, including clear communication by all parties involved, a reliable servicing market, stringent surveillance measures, and eventually new duodenoscope designs and reprocessing procedures with a larger margin of safety.

Long-term Mortality After Rapid Screening and Decolonization of Staphylococcus Aureus Carriers: Observational Follow-up Study of a Randomized, Placebo-controlled Trial.

OBJECTIVE: To identify patients who benefit most from Staphylococcus aureus screening and decolonization treatment upon admission. BACKGROUND: S. aureus carriers are at increased risk of developing surgical-site infections with S. aureus. Previously, we demonstrated in a randomized, placebo-controlled trial (RCT) that these infections can largely be prevented by detection of carriage and decolonization treatment upon admission. In this study, we analyzed 1- and 3-year mortality rates in both treatment arms of the RCT to identify patient groups that should be targeted when implementing the screen-and-treat strategy. METHODS: Three years after enrolment in the RCT, mortality dates of all surgical patients were checked. One- and 3-year mortality rates were calculated for all patients and for various subgroups. RESULTS: After 3 years, 44 of 431 (10.2%) and 43 of 362 (11.9%) patients had died in the mupirocin/chlorhexidine and placebo groups, respectively. No significant differences in mortality rates were observed between the treatment groups or the subgroups according to type of surgery. In the subgroup of patients with clean procedures (382 cardiothoracic, 167 orthopedic, 61 vascular, and 56 other), mupirocin/chlorhexidine reduced 1-year mortality: 11 of 365 (3.0%) died in the mupirocin/chlorhexidine versus 21 of 301 (7.0%) in the placebo group [hazard ratio = 0.38 (95% CI: 0.18-0.81)]. CONCLUSIONS: Detection and decolonization of S. aureus carriage not only prevents S. aureus surgical-site infections but also reduces 1-year mortality in surgical patients undergoing clean procedures. Such patients with a high risk of developing S. aureus infections should therefore be the primary target when implementing the screen-and-treat strategy in clinical practice.

Within-Host and Population Transmission of blaOXA-48 in K. pneumoniae and E. coli.

During a large hospital outbreak of OXA-48 producing bacteria, most K. pneumoniaeOXA-48 isolates were phenotypically resistant to meropenem or imipenem, whereas most E. coliOXA-48 isolates were phenotypically susceptible to these antibiotics. In the absence of molecular gene-detection E. coliOXA-48 could remain undetected, facilitating cross-transmission and horizontal gene transfer of blaOXA-48. Based on 868 longitudinal molecular microbiological screening results from patients carrying K. pneumoniaeOXA-48 (n = 24), E. coliOXA-48 (n = 17), or both (n = 40) and mathematical modelling we determined mean durations of colonisation (278 and 225 days for K. pneumoniaeOXA-48 and E. coliOXA-48, respectively), and horizontal gene transfer rates (0.0091/day from K. pneumoniae to E. coli and 0.0015/day vice versa). Based on these findings the maximum effect of horizontal gene transfer of blaOXA-48 originating from E. coliOXA-48 on the basic reproduction number (R0) is 1.9%, and it is, therefore, unlikely that phenotypically susceptible E. coliOXA-48 will contribute significantly to the spread of blaOXA-48.

Validation of an automated surveillance approach for drain-related meningitis: a multicenter study.

OBJECTIVE Manual surveillance of healthcare-associated infections is cumbersome and vulnerable to subjective interpretation. Automated systems are under development to improve efficiency and reliability of surveillance, for example by selecting high-risk patients requiring manual chart review. In this study, we aimed to validate a previously developed multivariable prediction modeling approach for detecting drain-related meningitis (DRM) in neurosurgical patients and to assess its merits compared to conventional methods of automated surveillance. METHODS Prospective cohort study in 3 hospitals assessing the accuracy and efficiency of 2 automated surveillance methods for detecting DRM, the multivariable prediction model and a classification algorithm, using manual chart review as the reference standard. All 3 methods of surveillance were performed independently. Patients receiving cerebrospinal fluid drains were included (2012-2013), except children, and patients deceased within 24 hours or with pre-existing meningitis. Data required by automated surveillance methods were extracted from routine care clinical data warehouses. RESULTS In total, DRM occurred in 37 of 366 external cerebrospinal fluid drainage episodes (12.3/1000 drain days at risk). The multivariable prediction model had good discriminatory power (area under the ROC curve 0.91-1.00 by hospital), had adequate overall calibration, and could identify high-risk patients requiring manual confirmation with 97.3% sensitivity and 52.2% positive predictive value, decreasing the workload for manual surveillance by 81%. The multivariable approach was more efficient than classification algorithms in 2 of 3 hospitals. CONCLUSIONS Automated surveillance of DRM using a multivariable prediction model in multiple hospitals considerably reduced the burden for manual chart review at near-perfect sensitivity.

Acquisition of high-level mupirocin resistance in CoNS following nasal decolonization with mupirocin.

OBJECTIVES: The association between mupirocin use and plasmid-based high-level resistance development mediated through mupA in CoNS has not been quantified. We determined acquisition of mupirocin resistance in Staphylococcus aureus and CoNS in surgery patients treated peri-operatively with mupirocin. PATIENTS AND METHODS: Patients admitted for surgery were treated with nasal mupirocin ointment and chlorhexidine soap for 5 days, irrespective of S. aureus carrier status. Nasal swabs were obtained before decolonization (T1) and 4 days after surgery (T2) and were inoculated onto agars containing 8 mg/L mupirocin. Staphylococci were identified by MALDI-TOF MS and mupirocin resistance was confirmed by Etest. RESULTS: Among 1578 surgical patients, 936 (59%) had nasal swabs obtained at T1 and T2; 192 (21%) patients carried mupirocin-resistant CoNS at T1 and 406 (43%) at T2 (P<0.001). Of 744 patients not colonized at T1, 277 acquired resistance (37%), corresponding to an acquisition rate of 7.4/100 patient days at risk. In all, 588 (97%) of 607 mupirocin-resistant CoNS had an MIC >256 mg/L (high level) and 381 of 383 (99.5%) were mupA positive. No acquisition of mupirocin resistance was observed in S. aureus. CONCLUSIONS: Acquisition of mupirocin resistance following decolonization was widespread in CoNS and absent in S. aureus. As almost all isolates harboured the mupA gene, monitoring resistance development in S. aureus when decolonization strategies containing mupirocin are used is recommended.

Transmissibility of livestock-associated methicillin-resistant Staphylococcus aureus.

Previous findings have suggested that the nosocomial transmission capacity of livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) is lower than that of other MRSA genotypes. We therefore performed a 6-month (June 1-November 30, 2011) nationwide study to quantify the single-admission reproduction number, RA, for LA-MRSA in 62 hospitals in the Netherlands and to compare this transmission capacity to previous estimates. We used spa typing for genotyping. Quantification of RA was based on a mathematical model incorporating outbreak sizes, detection rates, and length of hospital stay. There were 141 index cases, 40 (28%) of which were LA-MRSA. Contact screening of 2,101 patients and 7,260 health care workers identified 18 outbreaks (2 LA-MRSA) and 47 secondary cases (3 LA-MRSA). RA values indicated that transmissibility of LA-MRSA is 4.4 times lower than that of other MRSA (not associated with livestock).

Automated surveillance for healthcare-associated infections: opportunities for improvement.

Surveillance of healthcare-associated infections is a cornerstone of infection prevention programs, and reporting of infection rates is increasingly required. Traditionally, surveillance is based on manual medical records review; however, this is very labor intensive and vulnerable to misclassification. Existing electronic surveillance systems based on classification algorithms using microbiology results, antibiotic use data, and/or discharge codes have increased the efficiency and completeness of surveillance by preselecting high-risk patients for manual review. However, shifting to electronic surveillance using multivariable prediction models based on available clinical patient data will allow for even more efficient detection of infection. With ongoing developments in healthcare information technology, implementation of the latter surveillance systems will become increasingly feasible. As with current predominantly manual methods, several challenges remain, such as completeness of postdischarge surveillance and adequate adjustment for underlying patient characteristics, especially for comparison of healthcare-associated infection rates across institutions.

Accuracy of hospital discharge coding data for the surveillance of drain-related meningitis.

Surveillance of healthcare-associated infections is labor intensive and complex. Discharge coding is an accessible source of information that may support detection of cases. For drain-related meningitis, however, discharge coding data had low sensitivity (32%) and positive predictive value (35%) and could neither replace nor improve existing complex surveillance systems.

Automated detection of healthcare associated infections: external validation and updating of a model for surveillance of drain-related meningitis.

OBJECTIVE: Automated surveillance of healthcare-associated infections can improve efficiency and reliability of surveillance. The aim was to validate and update a previously developed multivariable prediction model for the detection of drain-related meningitis (DRM). DESIGN: Retrospective cohort study using traditional surveillance by infection control professionals as reference standard. PATIENTS: Patients receiving an external cerebrospinal fluid drain, either ventricular (EVD) or lumbar (ELD) in a tertiary medical care center. Children, patients with simultaneous drains, <1 day of follow-up or pre-existing meningitis were excluded leaving 105 patients in validation set (2010-2011) and 653 in updating set (2004-2011). METHODS: For validation, the original model was applied. Discrimination, classification and calibration were assessed. For updating, data from all available years was used to optimally re-estimate coefficients and determine whether extension with new predictors is necessary. The updated model was validated and adjusted for optimism (overfitting) using bootstrapping techniques. RESULTS: In model validation, the rate of DRM was 17.4/1000 days at risk. All cases were detected by the model. The area under the ROC curve was 0.951. The positive predictive value was 58.8% (95% CI 40.7-75.4) and calibration was good. The revised model also includes Gram stain results. Area under the ROC curve after correction for optimism was 0.963 (95% CI 0.953- 0.974). Group-level prediction was adequate. CONCLUSIONS: The previously developed multivariable prediction model maintains discriminatory power and calibration in an independent patient population. The updated model incorporates all available data and performs well, also after elaborate adjustment for optimism.

Costs and benefits of rapid screening of methicillin-resistant Staphylococcus aureus carriage in intensive care units: a prospective multicenter study.

INTRODUCTION: Pre-emptive isolation of suspected methicillin-resistant Staphylococcus aureus (MRSA) carriers is a cornerstone of successful MRSA control policies. Implementation of such strategies is hampered when using conventional cultures with diagnostic delays of three to five days, as many non-carriers remain unnecessarily isolated. Rapid diagnostic testing (RDT) reduces the amount of unnecessary isolation days, but costs and benefits have not been accurately determined in intensive care units (ICUs). METHODS: Embedded in a multi-center hospital-wide study in 12 Dutch hospitals we quantified cost per isolation day avoided using RDT for MRSA, added to conventional cultures, in ICUs. BD GeneOhm™ MRSA PCR (IDI) and Xpert MRSA (GeneXpert) were subsequently used during 17 and 14 months, and their test characteristics were calculated with conventional culture results as reference. We calculated the number of pre-emptive isolation days avoided and incremental costs of adding RDT. RESULTS: A total of 163 patients at risk for MRSA carriage were screened and MRSA prevalence was 3.1% (n=5). Duration of isolation was 27.6 and 21.4 hours with IDI and GeneXpert, respectively, and would have been 96.0 hours when based on conventional cultures. The negative predictive value was 100% for both tests. Numbers of isolation days were reduced by 44.3% with PCR-based screening at the additional costs of €327.84 (IDI) and €252.14 (GeneXpert) per patient screened. Costs per isolation day avoided were €136.04 (IDI) and €121.76 (GeneXpert). CONCLUSIONS: In a low endemic setting for MRSA, RDT safely reduced the number of unnecessary isolation days on ICUs by 44%, at the costs of €121.76 to €136.04 per isolation day avoided.

Automated detection of external ventricular and lumbar drain-related meningitis using laboratory and microbiology results and medication data.

OBJECTIVE: Monitoring of healthcare-associated infection rates is important for infection control and hospital benchmarking. However, manual surveillance is time-consuming and susceptible to error. The aim was, therefore, to develop a prediction model to retrospectively detect drain-related meningitis (DRM), a frequently occurring nosocomial infection, using routinely collected data from a clinical data warehouse. METHODS: As part of the hospital infection control program, all patients receiving an external ventricular (EVD) or lumbar drain (ELD) (2004 to 2009; n = 742) had been evaluated for the development of DRM through chart review and standardized diagnostic criteria by infection control staff; this was the reference standard. Children, patients dying <24 hours after drain insertion or with <1 day follow-up and patients with infection at the time of insertion or multiple simultaneous drains were excluded. Logistic regression was used to develop a model predicting the occurrence of DRM. Missing data were imputed using multiple imputation. Bootstrapping was applied to increase generalizability. RESULTS: 537 patients remained after application of exclusion criteria, of which 82 developed DRM (13.5/1000 days at risk). The automated model to detect DRM included the number of drains placed, drain type, blood leukocyte count, C-reactive protein, cerebrospinal fluid leukocyte count and culture result, number of antibiotics started during admission, and empiric antibiotic therapy. Discriminatory power of this model was excellent (area under the ROC curve 0.97). The model achieved 98.8% sensitivity (95% CI 88.0% to 99.9%) and specificity of 87.9% (84.6% to 90.8%). Positive and negative predictive values were 56.9% (50.8% to 67.9%) and 99.9% (98.6% to 99.9%), respectively. Predicted yearly infection rates concurred with observed infection rates. CONCLUSION: A prediction model based on multi-source data stored in a clinical data warehouse could accurately quantify rates of DRM. Automated detection using this statistical approach is feasible and could be applied to other nosocomial infections.

Eradication of carriage with methicillin-resistant Staphylococcus aureus: determinants of treatment failure.

BACKGROUND: Using data from an observational study in which the effectiveness of a guideline for eradication of methicillin-resistant Staphylococcus aureus (MRSA) carriage was evaluated, we identified variables that were associated with treatment failure. METHODS: A multivariate logistic regression model was performed with subgroup analyses for uncomplicated and complicated MRSA carriage (the latter including MRSA infection, skin lesions, foreign-body material, mupirocin resistance and/or exclusive extranasal carriage) and for those treated according to the guideline (i.e. mupirocin nasal ointment and chlorhexidine soap solution for uncomplicated carriage, in combination with two oral antibiotics for complicated carriage). RESULTS: Six hundred and thirteen MRSA carriers were included, of whom 333 (54%) had complicated carriage; 327 of 530 patients (62%) with known complexity of carriage were treated according to the guideline with an absolute increase in treatment success of 20% (95% confidence interval 12%-28%). Among those with uncomplicated carriage, guideline adherence [adjusted odds ratio (OR(a)) 7.4 (1.7-31.7)], chronic pulmonary disease [OR(a) 44 (2.9-668)], throat carriage [OR(a) 2.9 (1.4-6.1)], perineal carriage [OR(a) 2.2 (1.1-4.4)] and carriage among household contacts [OR(a) 5.6 (1.2-26)] were associated with treatment failure. Among those with complicated carriage, guideline adherence was associated with treatment success [OR(a) 0.2 (0.1-0.3)], whereas throat carriage [OR(a) 4.4 (2.3-8.3)] and dependence in activities of daily living [OR(a) 3.6 (1.4-8.9)] were associated with failure. CONCLUSIONS: Guideline adherence, especially among those with complicated MRSA carriage, was associated with treatment success. Adding patients with extranasal carriage or dependence in daily self-care activities to the definition of complicated carriage, and treating them likewise, may further increase treatment success.

Eradication of carriage with methicillin-resistant Staphylococcus aureus: effectiveness of a national guideline.

BACKGROUND: We evaluated the effectiveness of eradication of methicillin-resistant Staphylococcus aureus (MRSA) carriage in the Netherlands after the introduction of a guideline in 2006. The guideline distinguishes complicated (defined as the presence of MRSA infection, skin lesions, foreign-body material, mupirocin resistance and/or exclusive extranasal carriage) and uncomplicated carriage (not meeting criteria for complicated carriage). Mupirocin nasal ointment and chlorhexidine soap solution are recommended for uncomplicated carriers and the same treatment in combination with two oral antibiotics for complicated carriage. METHODS: A prospective cohort study was performed in 18 Dutch centres from 1 October 2006 until 1 October 2008. RESULTS: Six hundred and thirteen MRSA carriers underwent one or more decolonization treatments during the study period, mostly after hospital discharge. Decolonization was achieved in 367 (60%) patients with one eradication attempt and ultimately 493 (80%) patients were decolonized, with a median time until decolonization of 10 days (interquartile range 7-43 days). Three hundred and twenty-seven (62%) carriers were treated according to the guideline, which was associated with an absolute increase in treatment success of 20% [from 45% (91/203) to 65% (214/327)]. CONCLUSIONS: Sixty percent of MRSA carriers were successfully decolonized after the first eradication attempt and 62% were treated according to the guideline, which was associated with an increased treatment success.

Neutralization of Neisseria meningitidis outer membrane vesicles.

INTRODUCTION: We aimed to determine the neutralization of Neisseria meningitidis outer membrane vesicles (blebs) by humoral and cellular elements of whole blood. METHODS: The interaction of FITC-labeled blebs with monocytes was studied by spectrofluorometry. Blebs are able to induce an oxidative burst in neutrophils, and we evaluated the inhibitory effect of plasma on this process. RESULTS: Human plasma reduced the priming activity of blebs containing 1-3 ng/ml lipopolysaccharide (LPS) by 50-60% and bactericidal permeability increasing protein (BPI) reduced priming to background levels. A complete neutralization of LPS and blebs by plasma and BPI was measured using the limulus amebocyte lysate (LAL) assay. Furthermore, only 3% of blebs were cell-associated, while the remainder were in the supernatant. CONCLUSIONS: Plasma and BPI are able to neutralize blebs, with phagocytosis playing only a minor role. As such, we conclude that blebs do not behave like particles but more like free LPS.

Impact of different empirical antibiotic treatment regimens for community-acquired pneumonia on the emergence of Clostridium difficile.

BACKGROUND: Treatment of community-acquired pneumonia (CAP) with newer fluoroquinolones may contribute to selection for Clostridium difficile. We studied the prevalence of C. difficile carriage and C. difficile infection (CDI) on admission, and nosocomial acquisition rates in patients hospitalized for CAP and compared different empirical treatment strategies. METHODS: In a prospective study among patients admitted for antibiotic treatment of CAP, consecutive stool and skin samples were collected and cultured for C. difficile. Cultured isolates were typed by PCR ribotyping and characterized for toxinogenicity. RESULTS: In total, 20 of 107 (18.7%) patients included carried C. difficile. Various ribotypes were found and 14 (70%) isolates were toxinogenic. On admission, prevalence of C. difficile carriage was 9.4% (n=9), of which 22% also carried C. difficile on the skin and one patient had mild CDI with persistent positive cultures. The overall nosocomial acquisition rate of C. difficile carriage was 11.2%. No nosocomially acquired CDI occurred. Acquisition rates of C. difficile were 11.9% (5/45) in moxifloxacin-, 11.1% (5/47) in ß-lactam- and 9.0% (1/14) in ß-lactam plus macrolide- or fluoroquinolone-treated patients (P=0.84). Risk factors for C. difficile carriage were intravenous antibiotic treatment >7 days [odds ratio (OR) 3.89; 95% confidence interval (CI) 1.30 to 11.79] and hospitalization during the past 3 months (OR 4.08; 95% CI 1.40 to 11.90). CONCLUSIONS: In a non-outbreak setting with a low endemic rate, the prevalence of C. difficile carriage in patients admitted because of CAP is high and nosocomial acquisition rates for C. difficile colonization are 11%. Fluoroquinolones were not associated with increased acquisition rates for C. difficile as compared with other empirical regimens for CAP.

Preventing surgical-site infections in nasal carriers of Staphylococcus aureus.

BACKGROUND: Nasal carriers of Staphylococcus aureus are at increased risk for health care-associated infections with this organism. Decolonization of nasal and extranasal sites on hospital admission may reduce this risk. METHODS: In a randomized, double-blind, placebo-controlled, multicenter trial, we assessed whether rapid identification of S. aureus nasal carriers by means of a real-time polymerase-chain-reaction (PCR) assay, followed by treatment with mupirocin nasal ointment and chlorhexidine soap, reduces the risk of hospital-associated S. aureus infection. RESULTS: From October 2005 through June 2007, a total of 6771 patients were screened on admission. A total of 1270 nasal swabs from 1251 patients were positive for S. aureus. We enrolled 917 of these patients in the intention-to-treat analysis, of whom 808 (88.1%) underwent a surgical procedure. All the S. aureus strains identified on PCR assay were susceptible to methicillin and mupirocin. The rate of S. aureus infection was 3.4% (17 of 504 patients) in the mupirocin-chlorhexidine group, as compared with 7.7% (32 of 413 patients) in the placebo group (relative risk of infection, 0.42; 95% confidence interval [CI], 0.23 to 0.75). The effect of mupirocin-chlorhexidine treatment was most pronounced for deep surgical-site infections (relative risk, 0.21; 95% CI, 0.07 to 0.62). There was no significant difference in all-cause in-hospital mortality between the two groups. The time to the onset of nosocomial infection was shorter in the placebo group than in the mupirocin-chlorhexidine group (P=0.005). CONCLUSIONS: The number of surgical-site S. aureus infections acquired in the hospital can be reduced by rapid screening and decolonizing of nasal carriers of S. aureus on admission. (Current Controlled Trials number, ISRCTN56186788.)

Bacterial colonisation of collagen-coated polypropylene vaginal mesh: are additional intraoperative sterility procedures useful?

INTRODUCTION AND HYPOTHESIS: The use of vaginally implanted polypropylene meshes in the treatment of prolapse is becoming increasingly popular. We set out to detect how often bacterial colonisation of the mesh occurs and if the intraoperative sterility procedures that are applied matter. METHODS: In 64 consecutive women, bacterial colonisation was compared between two intraoperative sterility procedures. Culture swabs of the core mesh were taken during surgery, and the mesh arms removed at the end of surgery were cultured separately. RESULTS: Sixty-seven implants were cultured. In 56 (83.6%) implants, a positive culture with vaginal bacteria was found with very low bacterial density (<10(3 )colony-forming units). No significant differences in bacterial species, density, clinical infection and erosion (two anterior and one posterior) were found between the two intraoperative sterility methods. CONCLUSIONS: Colonisation of vaginally implanted mesh occurs frequently but in low bacterial densities, irrespective of the intraoperative sterility procedure used.

Quantifying changes in incidences of nosocomial bacteraemia caused by antibiotic-susceptible and antibiotic-resistant pathogens.

OBJECTIVES: The aim of this study was to determine, over time, changes in annual trends of nosocomial bacteraemia (NB) and to quantify pathogen-specific changes and emergence of antibiotic resistance. METHODS: A retrospective cohort study in a 997 bed tertiary care centre in the Netherlands was performed. All adult patients (> or =18 years old) admitted for >48 h between 1 January 1996 and 31 December 2005 were included. RESULTS: A total of 163 525 patients, comprising 1 826 852 patient-days and 1785 episodes of NB, were analysed. The number of admissions per year and length of hospital stay decreased over time. Crude incidence of NB per year remained unchanged, but cumulative incidence (cases/10 000 admissions) and incidence densities (cases/100 000 patient-days at risk) increased, on average, by 2.0% and 4.0% per year, respectively, primarily because of infections caused by Enterococcus spp. and Pseudomonas aeruginosa. The incidence density of NB caused by highly resistant microorganisms increased, on average, by 26.1% [95% confidence interval (CI): 17-37] per year, when compared with an annual increase of 3% (95% CI: 1-5) for NB caused by susceptible pathogens. Ratios of increased incidence densities of resistant and susceptible bacteria were 8.7, 3.5, 2.6 and >37.9 for all pathogens, Enterococcus spp., P. aeruginosa and Enterobacteriaceae, respectively. CONCLUSIONS: Due to changes in the patient population, increased incidences of NB over time are only evident when expressed as cumulative incidence or incidence densities. Despite overall low levels of antibiotic resistance, the incidence of NB caused by multiresistant pathogens rapidly increased, adding to the total burden of NB.