Mycobacterium chimaera infections following open-heart surgery associated with contaminated heater-cooler units
Mycobacterium chimaera is a nontuberculous mycobacteria species responsible for human infections, primarily pulmonary infections in patients with existing chronic respiratory disease (e.g. cystic fibrosis). Identification of this organism requires molecular diagnosis using 16S ribosomal RNA gene sequencing. Sax H et al. (Clin Infect Dis 2015; 61:67-75) identified 6 patients with M. chimaera infection who underwent open-chest heart surgery at a Swiss healthcare facility between 2008 and 2012. Environmental sampling was performed to investigate potential sources of infection.
A case was defined as a patient with proven invasive M. chimaera infection following open-chest heart surgery. The definition of infection included cultures or confirmation by molecular diagnostics in heart valves with histopathological signs of infection. Cases were identified retrospectively, after the infection control team at the studied institution were notified initially of 2 cases of infection. Water and air samples were collected from operating rooms, ICUs, and wards.
For the 6 cases of infection, latency between surgery and infection ranged between 1.5 and 3.6 years. Five cases had echocardiographic findings of endocarditis. Diversity of prosthetic valves and aortic valves was noted, suggesting that production-related contamination was unlikely. M. chimaera was cultured from 5 heater-cooler units and an air sample associated with one of the affected units. Different PCR patterns were observed for isolates sampled from different units, indicating a diversity of infecting strains.
During open-chest heart surgery, heater-cooler units are used for the purposes of warming patients and cooling of cargioplegia solution. These units are placed inside operating rooms and utilise non-sterilised tap water. While outbreaks of non-tuberculous mycobacteria infections in cardiac surgery have previously been reported, these have mostly been without source identification. This outbreak investigation confirmed an airborne transmission pathway associated with contaminated heater-cooler units. Given the long latency period for the reported cluster of infections, it is conceivable that similar problems may have not been identified in other institutions. Effective measures for prevention, including surveillance and sterilisation processes for units, are required.
Achieving high influenza vaccine uptake among healthcare workers without use of mandatory programs
Despite international guidelines recommending healthcare worker (HCW) influenza vaccination, uptake among HCWs frequently remains low. While some institutions have implemented mandatory programs, this practice remains controversial and Australian healthcare facilities do not routinely adopt mandatory strategies. Drees M et al. (Infect Control Hosp Epidemiol 2015; 36:717-724) reported experience of a dedicated (but non-mandatory) program used to successfully increase uptake of HCW influenza vaccination across a 2-hospital 1100 bed academic healthcare system in the U.S.
In the 3 years prior to the 2011-2012 influenza season, HCW vaccine uptake was 57-72%. A multidisciplinary team was convened to improve vaccination uptake to at least 90%. A multimodal campaign was implemented in the 2011-2012 influenza season and continued through 2014-2015 seasons. After implementation, influenza vaccination uptake increased to 92%, followed by 93% for 3 consecutive seasons.
Key components of the intervention included: strengthening tracking and enforcement of policies, increasing availability and promotion of vaccination, disciplinary process for noncompliance, and financial incentive. A mandatory declination policy was introduced, mask-wearing was employed for non-vaccinated staff, ‘I’m vaccinated’ badges were worn by vaccinated staff and weekly compliance reports were issued to managers. A minimum 75% vaccination uptake was set, with payment of a financial bonus to all full-time employees compliant with the program.
Findings indicate the sustainability of the program without resorting to a mandate, and are consistent with previous reports of successful programs based on psychology theory and behavioural change interventions. Notably, the campaign did build upon an existing bonus program, and it is likely that this component would not be feasible for other healthcare systems planning to implement similar interventions.