Rami Sommerstein

Prolonged Outbreak of Mycobacterium chimaera Infection After Open-Chest Heart Surgery

BACKGROUND Invasive Mycobacterium chimaera infections were diagnosed in 2012 in 2 heart surgery patients on extracorporeal circulation. We launched an outbreak investigation to identify the source and extent of the potential outbreak and to implement preventive measures. METHODS We collected water samples from operating theaters, intensive care units, and wards, including air samples from operating theaters. Mycobacterium chimaera strains were characterized by randomly amplified polymorphic DNA polymerase chain reaction (RAPD-PCR). Case detection was performed based on archived histopathology samples and M. chimaera isolates since 2006, and the patient population at risk was prospectively surveyed. RESULTS We identified 6 male patients aged between 49 and 64 years with prosthetic valve endocarditis or vascular graft infection due to M. chimaera, which became clinically manifest with a latency of between 1.5 and 3.6 years after surgery. Mycobacterium chimaera was isolated from cardiac tissue specimens, blood cultures, or other biopsy specimens. We were able also to culture M. chimaera from water circuits of heater-cooler units connected to the cardiopulmonary bypass, and air samples collected when the units were in use. RAPD-PCR demonstrated identical patterns among M. chimaera strains from heater-cooler unit water circuits and air samples, and strains in 2 patient clusters. CONCLUSIONS The epidemiological and microbiological features of this prolonged outbreak provided evidence for the airborne transmission of M. chimaera from contaminated heater-cooler unit water tanks to patients during open-heart surgery.

Transmission of Mycobacterium chimaera from Heater-Cooler Units during Cardiac Surgery despite an Ultraclean Air Ventilation System.

All such units should be separated from air that can gain access to sterile areas.

Reemergence of Mycobacterium chimaera in Heater–Cooler Units despite Intensified Cleaning and Disinfection Protocol

Invasive Mycobacterium chimaera infections after open-heart surgery have been reported internationally. These devastating infections result from aerosols generated by contaminated heater–cooler units used with extracorporeal circulation during surgery. Despite intensified cleaning and disinfection, surveillance samples from factory-new units acquired during 2014 grew nontuberculous mycobacteria after a median of 174 days.

Cerebrospinal fluid findings in an adult with human metapneumovirus–associated encephalitis

markdownabstract__To the Editor:__ Acute encephalitis/encephalopathy associated with human metapneumovirus (HMPV) has been documented in children. Recently, Fok et al. described an encephalitis case in an adult but were unable to test cerebrospinal fluid (CSF) for HMPV. Following authors’ recommendations, we performed diagnostic testing on the CSF of an adult with HMPV-associated encephalitis. A previously healthy 61-year-old man came to our institution with headache and seizures 5 days after onset of an influenza-like illness. A lumbar puncture on admission revealed pleocytosis (36 cells/μL) and a mononuclear predominance of 98%. Results of magnetic resonance imaging and computed tomography of the head and chest radiography on admission were inconclusive. The patient was treated in the intensive care unit for possible viral and bacterial meningoencephalitis. Although results of routine CSF-workup for infectious causes were unremarkable, total CSF protein level was elevated at 1.39 g/L (reference range 0.2–0.4 g/L). A nasopharyngeal swab specimen was positive for HMPV (cycle threshold 28.6) using duplex reverse transcription PCR (r-gene; Biomerieux, Marcy l’Etoile, France). However, HMPV reverse transcription PCR results were negative in the concurrent CSF sample. Immunofluorescence assays demonstrated HMPV IgG (serum titer 1:8,192; CSF titers 1:64 and 1:32). Indices calculated using the formula (IgGCSF HMPV/IgGSerum HMPV)/(IgGCSF total/IgGSerum total) were lower than the cut-off value of 4, indicating absence of intrathecal IgG against HMPV (Table). As in the study by Fok et al., our case supports consideration of HMPV as a causative agent of acute encephalitis after respiratory tract infection in adults. We could not demonstrate direct or indirect evidence of HMPV CSF invasion as the cause for HMPV-associated encephalitis in an adult, in contrast to a case in a child in which detection of HMPV in CSF suggested a causative role in acute encephalitis. Our data may point toward the role of nonspecific inflammatory response as the main pathogenic factor in HMPV-related encephalitis in adults.

Point prevalence of healthcare-associated infections and antibiotic use in three large Swiss acute-care hospitals

BACKGROUND The overall burden of healthcare-associated infections (HAIs) remains high, even in high-income countries. However, the current burden of HAI in Switzerland is unknown. Prevalence surveys have a long tradition in the field of infection prevention and control for measuring both HAI and antimicrobial use. The objective of this survey was to test the point prevalence survey (PPS) methodology of the European Centre for Disease Prevention and Control (ECDC) in acute-care hospitals in Switzerland. METHODS Two tertiary care hospitals and one secondary care hospital in central and western Switzerland participated in the survey. Patients from all wards except for emergency departments and psychiatric wards were included. Data were collected on a single day for every ward with a maximum time frame of 2 weeks for completing data collection. Methodology and definitions were based on the most recent ECDC PPS protocol. RESULTS Data on a total of 2421 patients were analysed. One hundred thirty-six patients had 153 HAIs, corresponding to a prevalence of 5.6% (95% confidence interval [CI] 4.7-6.5%). Rapidly fatal McCabe score, hospitalisation in the intensive care unit (ICU), and having a medical device in place were independent risk factors for HAI. Lower respiratory tract infection was the most frequent HAI type (24.8%), followed by surgical site infection (22.2%), bloodstream infection (17.0%) and urinary tract infection (13.7%). The highest HAI prevalence (26.2%) was observed in the ICU. In total, 60.8% of all HAIs were microbiologically confirmed. The most common microorganism was Escherichia coli (21.1%). Six hundred sixty-nine patients (27.6%, 95% CI 25.9-29.4%) received 893 antimicrobials for 705 indications. Community-acquired infections (39.0%) were the most common indication for antimicrobial use and amoxicillin-clavulanate was the most commonly prescribed antimicrobial (18.4%). CONCLUSIONS HAI prevalence and antimicrobial use in this survey were similar to findings of the past ECDC PPS. The ECDC methodology proved applicable to Swiss acute-care hospitals.

Epidemiology of subsequent bloodstream infections in the ICU

Subsequent bloodstream infections (sBSI) occur with a delay after removal of the intravascular catheter (IVC) whose tip revealed microbial growth. Here we describe the epidemiology of sBSI in the intensive care setting. Serratia marcescens, Staphylococcus aureus, Pseudomonas aeruginosa, and yeast were the pathogens most frequently associated with sBSI. In contrast, Enterococci were rarely found in sBSI.