Robert Koch-Institut; Epidemiologisches Bulletin Nr. 50; 19. 

Dezember 2011

In 2006, the World Health Organization (WHO) called for investigating the effectiveness of non-pharmacological interventions (NPI) such as facemasks and hand hygiene measures for preventing influenza transmission in households. As NPI are easy to apply and quickly accessible, they can be used at an early stage of an influenza pandemic. However, the results of the studies on this topic since then have not been consistent. To obtain more data, the Robert Koch-Institute (RKI), between November 2009 and January 2010 as well as between January 2011 and April 2011, carried out a cluster-randomised intervention trial on the effectiveness, adherence and tolerability of facemasks and hand hygiene measures in households with influenza index patients.
The authors recruited households with index patients and randomised them into one of the three study arms: a) Mask/Hygiene(MH) group, which used both facemasks and hand disinfectants for the duration of the study. b) Mask(M) group, which used facemasks for the duration of the study. c) Control group that did not carry out any intervention measures. The observation period per household was 8 days, starting on the day of symptom onset of the index patient. During this period, all household members self-recorded occurring symptoms and their own behaviour, i.e. their adherence to the intervention measures. Additionally, all households were visited four to five times to obtain nasal wash specimens. Data of 84 index patients and 218 household contacts from 84 households were included in the analysis. 96 % of the index patients and around 20 % of the household contacts were children under 14 years of age.

Results
Effectiveness of NPI: The rate of secondary infection (number of household contacts that acquired an influenza infection during the observation period) was 9 % in the M group and 15 % in the MH group. Both rates were not significantly lower than in the control group (23 %). However, when NPI were implemented at an early stage (within 36 hours after symptom onset), the secondary infection rate for both the M group (7 %) and the MH group (4 %) was significantly lower than for the control group (23 %).
Adherence: Overall, the observed adherence to NPI was good. From the 3rd day on, around 50 % of all participants in the M and MH groups wore the facemasks “always” or “mostly” in situations relevant to transmission. The majority of all participants (62 %) in the M and MH groups did not report any problems when wearing facemasks. The majority of those recording problems reported “heat and moisture” as the main problem (53 % of children; 35 % of adults). In terms of hand hygiene measures, the adherence among index patients was 47 % (season 2009/10) and 9 % (season 2010/11). For household contacts, it was 38 % and 46 % respectively. Participants of the MH group reported to have disinfected their hands around 7 to 8 times per day. In the 2010/11 season, this value was considerably lower among index patients (4 times per day).

According to the authors, the results of the study indicate that NPI can be effective in preventing influenza transmission in households, provided they are implemented at an early stage and used for several days. In addition, the authors recommend focusing future studies on the relevance of the facemask user (index patient or household contact) and on the independent importance of hand hygiene measures.

The study has been published on 19th December 2011 in Robert Koch-Institute’s Epidemiological Bulletin. Please click here to download it (in German language only).

An article describing the results of the first study: Facemasks and intensified hand hygiene in a German household trial during the 2009/2010 influenza A(H1N1) pandemic: adherence and tolerability in children and adults von T. Suess et al. is available in English language. Please click here to download it. 

Infection Control and Hospital Epidemiology; December 2010, Vol. 31 (12): 1273-1278.

There are only a few surveillance systems that also survey hospital-acquired gastrointestinal infections. Between 2002 and 2008, Michaela Spackova and her team have investigated the share of nosocomial gastroenteritis occurring in Germany among hospitalised patients triggered by noroviruses, rotaviruses, salmonella species and campylobacter species. The study’s aim was to determine the frequency of nosocomial gastroenteritis caused by the four most important pathogens as well as to monitor the development within the study period and, if applicable, identify risk groups to draw conclusions to advance the prevention of hospital-acquired infections.

All laboratory-confirmed notifications and gastrointestinal infections with epidemiological link triggered by norovirus, rotavirus, salmonella and campylobacter and reported to the Robert Koch-Institute served as data base. In line with the CDC* and RKI** definitions, infections were considered nosocomial if disease onset was more than 2 days after hospitalisation (norovirus, rotavirus, and Salmonella infection) and more than 5 days after hospitalisation (Campylobacter infection) respectively.

Results: During the study period from 2002 to 2008, 49 per cent of all norovirus-associated infections, 14 per cent of all rotavirus-associated infections, 3 per cent of all salmonella-associated infections and 2 per cent of all campylobacter-associated infections were identified as nosocomial cases. 

The study confirmed a higher risk for gastrointestinal nosocomial infections in patients aged more than 70 years, particularly when triggered by noroviruses and rotaviruses. The risk for norovirus-, rotavirus- and salmonella-associated infections was higher for patients in the former West German States, but not for infections caused by campylobacter. The risk of developing nosocomial gastroenteritis was lower for women. Patients < 1 year revealed the highest rate of rotavirus infection (39 per cent).

Apart from norovirus, yearly rates of hospital-acquired gastroenteritis remained stable. From 2002 to 2004, the rate of norovirus-associated nosocomial infections declined, but increased again in 2007. The authors conclude that this development is due to the improvements in infection control since 2002. And they attribute the sudden rise to the spread of a new norovirus strain, which caused epidemics in the winter months of 2006-2007, 2007-2008 and 2008-2009 and exceeded the capacities of the hospitals.

Conclusion: According to the authors, the high rates of hospital-acquired gastroenteritis in Germany require better prevention. In this context, they emphasise the importance of hand disinfection to break the chain of infection and of hand hygiene compliance, which needs to be improved.

The original study in English language can be purchased here.

* Centers for Disease Control and Prevention (CDC), Atlanta, USA.
** Robert Koch-Institute (RKI), Berlin, Germany.

CDC/NHSN Surveillance Definition of Healthcare-Associated Infection and Criteria for Specific Types of Infections in the Acute Care Setting

Clinical Microbiology and Infection (CMI), Article first published online: 27 JUL 2011; DOI: 10.1111/j.1469-0691.2011.03570.x

Many different definitions for multidrug-resistant (MDR), extensively drug-resistant (XDR) and pandrug-resistant (PDR) bacteria are being used in the medical literature to characterize the different patterns of resistance found in healthcare-associated, antimicrobial-resistant bacteria. A group of international experts came together through a joint initiative by the European Centre for Disease Prevention and Control (ECDC) and the Centers for Disease Control and Prevention (CDC), to create a standardized international terminology with which to describe acquired resistance profiles in Staphylococcus aureus, Enterococcus spp., Enterobacteriaceae (other than Salmonella and Shigella), Pseudomonas aeruginosa and Acinetobacter spp., all bacteria often responsible for healthcare-associated infections and prone to multidrug resistance.

Full version of the overview.
 

A team of scientists from Cambridge University detected a new MRSA strain in milk from cows suffering from mastitis, a bacterial infection in the cows' udders. Additionally, the strain has been proven in humans.

In the study “Methicillin-resistant Staphylococcus aureus with a novel mecA homologue in human and bovine populations in the UK and Denmark: a descriptive study”, L. Garcia-Álvarez et al. present their findings.

Laboratory tests showed that the pathogen is able to grow despite the addition of antibiotics (e.g. oxacillin). Subsequent PCR tests, however, turned up negative for the mecA gene, which encodes methicillin resistance in staphylococci. But the researchers discovered a mecA gene that was only 60 % similar to the typical resistance gene – this divergence sufficed for the gene not to be identified when tested under normal PCR test conditions.

By using a newly developed PCR test, the scientists then found this MRSA pathogen in humans as well, for example in UK, Denmark and Germany.

Despite the genetic change, the novel pathogen can be detected with common MRSA screening procedures, e.g. nasal swabs in hospitals. However, simple and quick PCR testing shows negative results for this strain, thus not being reliable.

The scientists therefore call for additional research on further and improved PCR test methods in order to be able to reliably identify this new strain.

Click the following link to read the study’s abstract: www.thelancet.com

Screening at hospital admission for carriage of methicillin-resistant Staphylococcus aureus (MRSA) has been proposed as a strategy to reduce nosocomial infections. The objective of this study was to determine the long-term costs and health benefits of selective and universal screening for MRSA at hospital admission, using both PCR-based and chromogenic media-based tests in various settings.

A simulation model of MRSA transmission was used to determine costs and effects over 15 years from a US healthcare perspective. We compared admission screening together with isolation of identified carriers against a baseline policy without screening or isolation. Strategies included selective screening of high risk patients or universal admission screening, with PCR-based or chromogenic media-based tests, in medium (5%) or high nosocomial prevalence (15%) settings.

The costs of screening and isolation per averted MRSA infection were lowest using selective chromogenic-based screening in high and medium prevalence settings, at $4,100 and $10,300, respectively. Replacing the chromogenic-based test with a PCR-based test costs $13,000 and $36,200 per additional infection averted, and subsequent extension to universal screening with PCR would cost $131,000 and $232,700 per additional infection averted, in high and medium prevalence settings respectively. Assuming $17,645 benefit per infection averted, the most cost-saving strategies in high and medium prevalence settings were selective screening with PCR and selective screening with chromogenic, respectively. Admission screening costs $4,100–$21,200 per infection averted, depending on strategy and setting. Including financial benefits from averted infections, screening could well be cost saving.

Source:
PLoS ONE; 2011, e14783 3 (6): 1-11.

Full version of the overview:
www.egms.de