Risk factors for strains causing outbreaks
- Antibiotics and other medications
- Alcohol-based hand rubs (ABHRs)
- Hand hygiene
- Gloves and risk reduction
- Take home message
Are strains causing outbreaks of more severe CDAD really new? Comparison between strains causing outbreaks in healthcare facilities to archived isolates reveal these historic strains from 1983-92 also contained the genes to produce a binary toxin but the expression of the binary toxin is much more prevalent in those causing outbreaks. (13) So what are the reasons for this changing epidemiologic profile? CDAD requires at least three "hits."
- The first is receipt of an antibiotic which disrupts the normal microbial flora of the GI tract .
- Next step is acquisition of a toxin-producing strain of C. difficile – which because it is a spore-forming microbe – allows it to survive in the environment for some time.
- Third, the spore converts to a vegetative state and produces toxin in the GI tract resulting in disease. There are other factors involved in the third step that are as yet unidentified.
Paradoxically, asymptomatic colonization with C. difficile is protective. (14) This suggests that colonization with a non-toxigenic strain is an intervention worth more investigation.
Antibiotics and other medications – the good and the bad.
Antibiotics are life-saving medications, however, over-use and misuse of these have resulted in dramatic increases in multidrug resistant organisms.(15) Increased usage of one class of antibiotics, fluoroquinolones, has been identified as a significant risk factor in a number of outbreaks of the new strain.(5,8,10,16-19). A recent systematic review demonstrated that of all the pathogens implicated in HAIs, C. difficile does respond to changes in utilization of antibiotics – specifically minimizing use of certain classes of antibiotics can effectively lower frequency of CDAD.(20) Proton pump inhibitors (PPIs) and other gastric acid suppression medications also have been implicated as a risk for CDAD.(21-24)
Are alcohol-based hand rubs (ABHRs) a risk factor?
Not likely. The use of ABHR for hand hygiene by healthcare personnel is the centerpiece of guidelines from the Centers for Disease Control & Prevention (CDC) and in a recent 2005-06 draft by the World Health Organization.(25-26) This guideline is based on a broad body of evidence demonstrating efficacy of ABHR against a variety of pathogens that cause healthcare associated infections (HAIs). As a result, ABHR is in use at 98 percent of a nationwide survey of 800 hospitals in the U.S.(27) At hospitals that have experienced an outbreak, changes in technique in hygiene for both hands and the environment were implemented simultaneously. It is important to note, these changes that emphasized handwashing by personnel after caring for a patient with CDAD and disinfection of the patient's room and equipment were implemented in response to a possible cluster of CDAD. Hospitals that are not experiencing a cluster or outbreak of the new strain of C. difficile do not have to alter standard hygiene practices for hands or the environment. The CDC Hand Hygiene Guidelines state:
"None of the agents (including alcohols, chlorhexidine, hexachlorophene, iodophors, PCMX, and triclosan) used in antiseptic handwash or antiseptic hand-rub preparations are reliably sporicidal against Clostridium spp. or Bacillus spp. Washing hands with non-antimicrobial or antimicrobial soap and water may help to physically remove spores from the surface of contaminated hands. HCWs should be encouraged to wear gloves when caring for patients with C. difficile-associated diarrhea. After gloves are removed, hands should be washed with a non-antimicrobial or an antimicrobial soap and water or disinfected with an alcohol-based hand rub. During outbreaks of C. difficile-related infections, washing hands with a non-antimicrobial or antimicrobial soap and water after removing gloves is prudent." (3, 25, 28)
The underlined text is highlighted for emphasis. There are no published studies to date demonstrating a clear association between use of ABHR and outbreaks or increased frequency of CDAD – instead this remains a theoretical concern. To counter this "apprehension" over use of ABHR as a piece of the CDAD problem, Gordin and colleagues reported no change in frequency of CDAD but significant decreases in HA-MRSA and HA-VRE following use of ABHR.(29) Interestingly, there was a reduction in frequency of HA-CDAD after one hospital-wide hand hygiene campaign that featured ABHR.(30) There is one additional published study to date that examined a correlation between CDAD and ABHR. King reported a non-significant increase in CDAD following implementation of ABHR at the patient's bedside, however King acknowledges there were other factors that may have explained his observation such as more specimens sent for toxin detection or a change in antibiotic prescribing.(31)
Is pathogen-specific hand hygiene the answer?
No. For routine patient care, a pathogen-specific hand hygiene technique is problematic. It forces the care providers to remember which technique, wash versus rub, is needed for which patients and the complexity is likely to result in diminished sustainability. A recent review by Safdar offers a useful recommendation that we can apply to CDAD:
..."More restricted use of antibiotics, especially cephalosporins, and strategies to prevent medical device-related infection and cross-infection in the hospital would yield benefit with all types of resistant organisms...Conversely, programs that focus on only one organism or one antimicrobial drug are unlikely to succeed..."(32)
Do gloves play an important role in reducing risk of transmission?
Yes. The importance of personal protective equipment is also a key aspect to remember. A recent abstract on a small number of subject noted that alcohol gels were less effective at removing CD spores from the hands of volunteers when compared to hand washing but there was a higher than expected reduction of spore counts following use of alcohol gels.(33) This study reinforces the importance of protecting the hands with gloves. These same investigators had observed a decrease in the incidence of C. difficile diarrhea from 7.7 cases/1,000 patient discharges during the six months before to 1.5/1,000 during the six months after an intervention that consisted of consistent use of vinyl gloves by providers caring for those with CDAD.(34) This study clearly demonstrates that a very effective intervention to preventing cross transmission of C. difficile spores is to minimize contamination of hands of personnel through use of gloves. Additional reinforcement of this comes from another cluster of CDAD. Samore and others observed that lack of use of gloves was prevalent during a cluster in the study hospital and that contamination of hands of personnel was correlated with heavy contamination of the environment.(35) Last, an in-vivo study of hands of healthcare personnel contaminated with C. difficile also confirmed that gloves can significantly reduce the level of contamination.(36)
The 'take home message'
If hands are soiled wash them, but if not –e.g., gloves are worn and hands are clean – ABHR is effective after glove removal. The current outbreaks of CDAD in some hospitals should not undermine confidence in ABHR that is being used in U.S. hospitals with increased frequency.