Micro News

Review 2008

1. VRE environmental contamination: be careful what you touch!

A recent US study investigated VRE environmental and hand contamination on an ICU (Hayden et al. 2008). A stunning 21% of the 131 HCW hands sampled before touching either the patient or the surfaces in the room already had VRE on their hands. 52% of 23 healthcare workers who touched environmental surfaces in the rooms of VRE-positive patients but did not touch the patients themselves picked up VRE on their hands. Each contact with patient or environmental surface represented a 10% risk of picking up VRE so it seems that touching a surface in the room of a VRE-positive patient is just about as risky as touching the VRE-colonised patient in terms of picking up VRE on your hands!

2. Prior room occupants and the risk of VRE acquisition

A study on two ICUs in the USA investigated the risk factors for VRE acquisition (Drees et al. 2008). Weekly environmental cultures and routine surveillance cultures for VRE were conducted over the 14 months study period and a VRE colonised patient as a prior room occupant, a VRE colonised prior room occupant in the prior 2 weeks or a previous positive VRE environmental culture were all independent predictors for VRE acquisition in a multivariate analysis adjusted for colonisation pressure and antimicrobial exposure. These data suggest that residual VRE room contamination is increasing the likelihood of VRE acquisition for subsequent room occupants and that improved room disinfection should be implemented.

3. CA-MRSA and CDI continue to increase nationally in the USA

Using national databases, a US team investigated visits to emergency departments and outpatient units to treat various skin and soft tissue infections (SSTIs), which are characteristic of CA-MRSA (Hersh et al. 2008). Significant increases were observed for all SSTIs and abscesses/cellulites in particular, which increased 88% from 17.3 to 32.5 visits per 1000 individuals from 1997 to 2005. Increases were notably larger among black and among young patients visiting emergency departments, suggesting that CA-MRSA disproportionately affects certain populations.

Analysis of ICD-9 codes by a team in the US has identified a doubling of the rate of C. difficile hospitalisations from 5.5 cases per 10,000 population in 2000 to 11.2 in 2005 (Zilberberg et al. 2008). The increase was sharpest in the >85 age group, followed by the 65-84 age group. Furthermore, CDI-related age-adjusted case-fatality rate rose from 1.2% in 2000 to 2.2% in 2004. Therefore, it seems that the prevalence and severity of CDI in the US continues to increase probably due to the emergence of the NAP1/027 strain.

4. Routine HPV decontamination reduces rates of CDI in a US hospital

A collaborative study between the Hospital of St. Raphael (a Yale University-affiliated hospital), the CDC and BIOQUELL investigated the impact of routine hospital-wide hydrogen peroxide vapour (HPV) decontamination on the incidence of C. difficile infection (CDI) (Boyce et al. 2008). The results of the prospective intervention study indicate a significant reduction in environmental contamination (25.6% of 43 cultures positive for C. difficile before HPV compared with 0 of 37 cultures HPV, P < .001) and in the incidence of CDI (1.28 vs 2.28 cases per 1,000 patient-days; P = .047 on five high incidence wards and 0.88 vs 1.89 cases per 1,000 patient-days; P = .047, hospital wide, when the analysis limited to months in which the epidemic strain was present during both the preintervention and the intervention periods). Despite some potentially important cofounders and the lack of an extant control unit, these data suggest that routine use of HPV may reduce rates of CDI.   

5. C. difficile skin contamination?

A team from Cleveland, Ohio, investigated skin contamination on patients with C. difficile-associated disease (CDAD), which is not often investigated (Bobulsky et al. 2008). The study found that 93% of the 27 patients tested had C. difficile spores on their skin at one or more of the five sites tested, that the spores were readily transferred to the hands of healthcare workers on contact and that the spores on the skin persisted for a median 7 days after the resolution of symptoms. This study raises important questions about when to take patients with CDAD off contact precautions.

6. Community-associated C. difficile – an emerging problem?

C. difficle infection (CDI) is classically associated with older patients who are hospitalised and have had recent antibiotic usage. However, a recent retrospective case-control study from Leeds suggests that the traditional risk factors for CDI do not hold true for community-associated CDI (Wilcox et al. 2008). In this study, community-acquired CDI did not exclude patients with recent healthcare contact and CDI was associated with antibiotic use, older patients and hospitalisation. Surprisingly, cases were more likely to be associated with infants ≤2 years, almost half of the cases had not received antibiotic therapy in the month before CDI, and approximately one-third did not have exposure to antibiotics or recent hospitalization. It remains to be seen whether there has always been a low undetected background of CA-CDI or whether CA-CDI is a new phenomenon associated with 027 or other strains.

7. MRSA carriage in various populations

A plethora of articles have been published over the last few months on MRSA carriage by various population subsets. The prevalence of MRSA colonisation varied from:

• 30% of 50 pig farmers in Holland (VAN, IV et al. 2008).
• 16% of 602 individuals arrested in Baltimore, Maryland, USA (Farley et al. 2008).
• 15% of 105 healthcare workers in an emergency department in Las Vegas (Bisaga et al. 2008), 4% of 225 healthcare workers in an emergency department in Pittsburg (Suffoletto et al. 2008), 2% of 1721 healthcare workers in contact with veal calves in Holland (Wulf et al. 2008) and 4-6% of healthcare workers in general (Albrich and Harbarth 2008).
• 3% of 123 uninfected children in Greece (Sdougkos et al. 2008). In the same study, 56% of 170 S. aureus infections in Greek children were methicillin-resistant.
• 1% of 959 healthy members of the Greek air force (Karapsias et al. 2008).

The finding of MRSA colonisation in 30% of pig farmers in Holland and 15% of healthcare workers in one US emergency department is of great concern, indicating that community associated strains are becoming increasingly established.

8. CA-MRSA rears its ugly head in London

Despite CA-MRSA being reported with increasing frequency from the USA, relatively little CA-MRSA has been reported from the UK. A study from King’s College London used ciprofloxacin-susceptibility as a phenotypic marker and found that the number of ciprofloxacin-susceptible CA-MRSA is on the increase at St. Thomas’ Hospital from 2000-2006 and that the strains show considerable clonal diversity, with most internationally recognised CA-MRSA clones represented (Otter and French 2008b). The most common clone identified was a previously reported CA-MRSA clone associated with the homeless and injecting drug users in the community served by the hospital (Otter and French 2008a). This is one of the first systematic reports on CA-MRSA in the UK and further work is required to assess the true prevalence of CA-MRSA in the UK.  

9. Norovirus outbreak traced to a contaminated keyboard

An outbreak of Norovirus occurred in a US elementary school affecting 103 (39%) of 266 staff members and children at the school (CDC 2008). One classroom in particular was associated with transmission, and this was the only classroom in which staff and students shared computers. Norovirus DNA matching the outbreak strain was detected on one such shared computer keyboard in this classroom. Fomites that are shared but not commonly cleaned, such as computer keyboards, should be decontaminated during outbreaks of Norovirus.

10. And finally…

Legionella from a garden hose (Piso et al. 2007), alcohol supping Acinetobacter (Dixon 2008), computers telling us to wash our hands (Venkatesh et al. 2008) and doctors not washing theirs (Duggan et al. 2008), the dangers of bedside Bibles (Lloyd-Hughes et al. 2008) and really scary acupuncture needles (Murray et al. 2008). What does 2009 have in store…?

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References

Albrich WC & Harbarth S (2008) Health-care workers: source, vector, or victim of MRSA? Lancet Infect Dis. 8, 289-301.

Bisaga A, Paquette K, Sabatini L & Lovell EO (2008) A prevalence study of methicillin-resistant Staphylococcus aureus colonization in emergency department health care workers. Ann Emerg.Med. 52, 525-528.

Bobulsky GS, Al-Nassir WN, Riggs MM, Sethi AK & Donskey CJ (2008) Clostridium difficile skin contamination in patients with C. difficile-associated disease. Clin.Infect Dis. 46, 447-450.

Boyce JM, Havill NL, Otter JA, McDonald LC, Adams NM, Cooper T, Thompson A, Wiggs L, Killgore G, Tauman A & Noble-Wang J (2008) Impact of Hydrogen Peroxide Vapor Room Decontamination on Clostridium difficile Environmental Contamination and Transmission in a Healthcare Setting. Infect Control Hosp Epidemiol. 29, 723-729.

Dixon B (2008) There's the rub: infection control that spreads infection. Lancet Infect Dis. 8, 91.

Drees M, Snydman D, Schmid C, Barefoot L, Hansjosten K, Vue P, Cronin M, Nasraway S & Golan Y (2008) Prior Environmental Contamination Increases the Risk of Acquisition of Vancomycin-Resistant Enterococci. Clin Infect Dis. 46, 678-685.

Duggan JM, Hensley S, Khuder S, Papadimos TJ & Jacobs L (2008) Inverse correlation between level of professional education and rate of handwashing compliance in a teaching hospital. Infect Control Hosp Epidemiol. 29, 534-538.

Farley JE, Ross T, Stamper P, Baucom S, Larson E & Carroll KC (2008) Prevalence, risk factors, and molecular epidemiology of methicillin-resistant Staphylococcus aureus among newly arrested men in Baltimore, Maryland. Am.J Infect Control 36, 644-650.

Hayden MK, Blom DW, Lyle EA, Moore CG & Weinstein RA (2008) Risk of hand or glove contamination after contact with patients colonized with vancomycin-resistant enterococcus or the colonized patients' environment *. Infect Control Hosp Epidemiol. 29, 149-154.

Hersh AL, Chambers HF, Maselli JH & Gonzales R (2008) National trends in ambulatory visits and antibiotic prescribing for skin and soft-tissue infections. Arch.Intern.Med. 168, 1585-1591.

Karapsias S, Piperaki ET, Spiliopoulou I, Katsanis G & Tseleni-Kotsovili A (2008) Methicillin-resistant Staphylococcus aureus nasal carriage among healthy employees of the Hellenic Air Force. Euro.Surveill 13.

Lloyd-Hughes R, Talbot S & Jumaa P (2008) Bedside Bibles, notes trolleys and other forgotten sites for cleaning. J Hosp Infect. 69, 200-201.

Murray RJ, Pearson JC, Coombs GW, Flexman JP, Golledge CL, Speers DJ, Dyer JR, McLellan DG, Reilly M, Bell JM, Bowen SF & Christiansen KJ (2008) Outbreak of invasive methicillin-resistant Staphylococcus aureus infection associated with acupuncture and joint injection. Infect Control Hosp Epidemiol. 29, 859-865.

Otter JA & French GL (2008a) Community-associated meticillin-resistant Staphylococcus aureus in injecting drug users and the homeless in south London. J Hosp Infect 69, 198-200.

Otter JA & French GL (2008b) The emergence of community-associated methicillin-resistant Staphylococcus aureus at a London teaching hospital, 2000-2006. Clin.Microbiol.Infect 14, 670-676.

Piso RJ, Caruso A & Nebiker M (2007) Hose as a source of Legionella pneumonia. A new risk factor for gardeners? J Hosp Infect 67, 396-397.

Sdougkos G, Chini V, Papanastasiou DA, Christodoulou G, Stamatakis E, Vris A, Christodoulidi I, Protopapadakis G & Spiliopoulou I (2008) Community-associated Staphylococcus aureus infections and nasal carriage among children: molecular microbial data and clinical characteristics. Clin.Microbiol.Infect 14, 995-1001.

Suffoletto BP, Cannon EH, Ilkhanipour K & Yealy DM (2008) Prevalence of Staphylococcus aureus nasal colonization in emergency department personnel. Ann Emerg.Med. 52, 529-533.

van den Broek IV, van Cleef BA, Haenen A, Broens EM, van der Wolf PJ, van den Broek MJ, Huijsdens XW, Kluytmans JA, van de Giessen AW, Tiemersma EW (2008) Methicillin-resistant Staphylococcus aureus in people living and working in pig farms. Epidemiol Infect. 24, 1-9

Venkatesh AK, Lankford MG, Rooney DM, Blachford T, Watts CM & Noskin GA (2008) Use of electronic alerts to enhance hand hygiene compliance and decrease transmission of vancomycin-resistant Enterococcus in a hematology unit. Am.J Infect Control 36, 199-205.

Wilcox MH, Mooney L, Bendall R, Settle CD & Fawley WN (2008) A case-control study of community-associated Clostridium difficile infection. J Antimicrob.Chemother. 62, 388-396.

Wulf MW, Tiemersma E, Kluytmans J, Bogaers D, Leenders AC, Jansen MW, Berkhout J, Ruijters E, Haverkate D, Isken M & Voss A (2008) MRSA carriage in healthcare personnel in contact with farm animals. J Hosp Infect 70, 186-190.

Zilberberg MD, Shorr AF & Kollef MH (2008) Increase in adult Clostridium difficile-related hospitalizations and case-fatality rate, United States, 2000-2005. Emerg.Infect Dis. 14, 929-931.