Literature Update - August 2010
Compiled by Dr Leon Worth, ID Physician
'Aiming for Zero'- Feasibility of Reducing CLABSI Rates using Revised NHSN Definition with Bundle Approach to Prevention
A number of centres have reported vast reductions in central line-associated bloodstream infections (CLABSIs) with application of the revised
National Healthcare Safety Network (NHSN) case definition. The use of multimodal prevention bundles for further reduction in CLABSI rates has
also been successful at many sites. Shuman EK et al. (Infect Control Hosp Epidemiol 2010; 31:551-553) retrospectively
report the impact of these two measures in 2 adult ICUs at a single US centre.
A bundle of prevention measures was implemented in March 2004 in a Critical Care Medicine Unit and in June 2005 in a Surgical ICU. This bundle included: education of medical and nursing staff, use of line insertion carts, use of checklists, stopping of procedures if guidelines were violated, and daily assessment of the need for venous catheters. Added interventions included the use of 2% chlorhexidine and 70% isopropyl alcohol solution for skin preparation and the use of chlorhexidine/silver sulfadiazine impregnated catheters. For the period 2004 to 2007, primary bloodstream infections were classified as CLABSI by the NHSN surveillance definition, then blinded review by 2 physicians was performed to determine if a catheter source for infection was evident for the identified cases.
During the study period, the number of CLABSIs decreased in both ICUs – from 5.3 to 2.2 per 1000 CVC days in the medical ICU, and from 1.6 to 0.9 per 1000 CVC days in the surgical ICU. Following physician review of the 20 cases of CLABSI identified in the medical ICU, 9 were considered to be due to a central venous catheter, 9 were the result of a contaminated blood sample (6 due to vancomycin-resistant enterococci, VRE), and 2 were considered to be ‘transient postoperative BSIs’. Of the 8 cases of CLABSI identified in the surgical ICU, physician review suggested 5 to be secondary to an intra-abdominal source, 2 to be due a central venous catheter, and 1 from an unknown, non-venous catheter related source. Overall, 17/28 (61%) of CLABSI cases had sources of infection from other than central venous catheters.
The NHSN definition is a surveillance definition, and is therefore intentionally sensitive at the expense of specificity. The authors of this study suggest that a bundle approach was able to effectively reduce CLABSI rates over the study period, but that the goal of ‘zero infections’ is not achievable. They suggest that given a very high rate of discordance with physician review, the NHSN definition is too sensitive, and will not allow ‘zero tolerance’ for CLABSI to be achieved. In addition, interventions to enhance aseptic blood sample collection (for example, chlorhexidine bathing and environmental cleaning) may be justified, especially if high rates of contamination are thought to contribute to events.
Examining the Effectiveness of Alcohol-based Hand Rubs for Removal of Clostridium difficile Spores from
Hands
The 2002 World Health Organization Guideline for Hand Hygiene in healthcare settings recommends routine use of alcohol-based hand rubs (ABHRs)
before and after patient contact when hands are not visibly soiled with proteinaceous material or bodily fluids. However, with a large burden of
healthcare-associated illness now arising from infection with Clostridium difficile, and in vitro studies suggesting
these agents to be non-sporicidal, there is a need for the activity of these agents to be re-examined. Jabbar U et al.
(Infect Control Hosp Epidemiol 2010; 31:565-570) observed the retention of C. difficile spores on the hands of
volunteers after using ABHR and the subsequent transfer of these spores through physical contact.
Standardised inoculates of non-toxigenic C. difficile spores were seeded onto the palms of 10 volunteers. Three ABHRs
and chlorhexidine soap-and-water washing were compared with plain water rubbing alone for removal of spores. Transferability of
C. difficile after the application of ABHR was tested by having each volunteer shake hands with an uninoculated
volunteer.
Plain water rubbing lead to a reduction in palmar counts by a mean of 1.57 log10 CFU per cm2, and this was used as the zero
point for comparison of all other products. Compared with this baseline, chlorhexidine soap washing reduced spore counts by a mean of 0.89 CFU per
cm2. For the tested ABHRs, Isagel, Endure and Purrell, reductions of 0.11, 0.37 and 0.14 CFU per cm2, were observed,
respectively. Of these 3 ABHR products, only Endure had a reduction statistically different from that for water control rubbing (p = 0.040).
Following ABHR use, handshaking transferred a mean of 30% of the residual C. difficile spores to the hands of recipients.
Unfortunately, the clinical significance of these findings is not known. If hand hygiene with soap and water is recommended for healthcare workers
caring for patients colonised or infected with C. difficile, while hand hygiene with ABHR continues to be recommended
in other settings, a number issues must also be addressed. Ellingson and McDonald, in an accompanying commentary (Infect Control Hosp
Epidemiol 2010; 31:571-573) raise important questions, including the fact that if policies contain different hand hygiene recommendations for
C. difficile, then these patients must be reliably identified within healthcare facilities, and that measures must be
instituted to ensure that discouraging ABHR use for specific situations will not discourage use for patients colonised with other important
hospital-acquired pathogens. Complexity in hand hygiene recommendations is likely to impact negatively upon compliance rates, and communication
of situation-specific guidelines must be done carefully.