The transmission of MRSA via orthopaedic marking pens--fact or fiction

A Study of the Relationship Between Environmental Contamination with Methicillin-ResistantStaphylococcus aureus(MRSA) and Patients' Acquisition of MRSA

Objective.

The study aimed to examine the presence of methicillin-resistantStaphylococcus aureus(MRSA) in the environment and its relationship to patients' acquisition of MRSA.

Design.

A prospective study was conducted in a 9-bed intensive care unit for 14 months. At every environmental screening, samples were obtained from the same 4 sites in each bed space. Patients were screened at admission and then 3 times weekly. All environmental and patient strains were typed using pulsed-field gel electrophoresis.

Results.

MRSA was isolated from the environment at every environmental screening, when both small and large numbers of patients were colonized. Detailed epidemiological typing of 250 environmental and 139 patient isolates revealed 14 different pulsed-field gel electrophoresis profiles, with variants of EMRSA-15 being the predominant type. On only 20 (35.7%) of 56 occasions were the strains isolated from the patients and the strains isolated from their immediate environment indistinguishable. There was strong evidence to suggest that 3 of 26 patients who acquired MRSA while in the intensive care unit acquired MRSA from the environment.

Conclusions.

This study reveals widespread contamination of the hospital environment with MRSA, highlights the complexities of the problem of contamination, and confirms the need for more-effective cleaning of the hospital environment to eliminate MRSA.

Comparison of three different sterilization and disinfection methods on orthodontic markers

Background:

Marking pencils which are frequently used in orthodontics may cause microbial contamination. The purpose of this study was to evaluate and compare the effectiveness of three disinfection and sterilization methods (autoclave, glutaraldehyde solution, and Deconex spray) on orthodontic markers.

Materials and Methods:

One hundred and twenty orthodontic markers were divided into four groups each 30 pencils: One control group and three groups for three different disinfection/sterilization methods. To evaluate the effectiveness of these methods, pencils were initially contaminated by common pathogen by immersing the pencils in a suspension containing 1.5 × 10⁸ CFU/ml organisms. Then, the pencils were subjected to corresponding disinfection/sterilization methods, and the number of remaining microorganisms was calculated and compared with control group.

Results:

In the control group, the mean number of Escherichia coli was significantly higher than the other two microorganisms (P = 0.01, P = 0.031). However, the mean numbers of Staphylococcus aureus and Candida albicans were not significantly different (P = 0.1). After sterilization with autoclave and glutaraldehyde, no microbial growth was observed, whereas after disinfection with Deconx spray some colonies of microorganisms still could be observed.

Conclusion:

Autoclaving and glutaraldehyde solution are the best methods for disinfecting orthodontic markers.

Cross-infection risk of felt-tipped marker pens in cataract surgery

PURPOSE

To assess the potential of bacterial transmission using felt-tipped marker pens on forehead skin before cataract surgery.

METHODS

A total of 64 marker pens taken from clinical stock were tested. Forty-eight new pens were cultured in the laboratory. They were first left to desiccate for 0, 4, and 16 h, then dipped into solutions of 0.5 Macfarlane's concentration of coagulase negative staphylococci (CNS), methicillin-resistant Staphylococcus aureus (MRSA) and coliforms, and transferred onto the culture medium after 5, 10, 30, and 120 min intervals of exposure to air. A further 16 pens were collected after routine clinical use for 5 working days and cultured.

RESULTS

Positive cultures were observed in 100% of pens at 0 min, and 44.4% at 5 min after the organism was exposed to air. Escherichia coli showed least transmissibility with no growth in all plates after 5 min of exposure. Only MRSA showed heavy growth after 10 min of exposure. No pattern emerged with reference to the length of time; each pen was left to desiccate. No growth was observed in the cultures of all 16 marking pens after clinical use.

CONCLUSIONS

The potential for transmission of bacteria through felt-tipped marker pens has not been explored in cataract surgery. This study demonstrated that a theoretical risk of transmission exists in a laboratory setting, and survival times of the bacteria decreased with time. This suggests that the interval in which patients are marked with the same pen may play a role in bacterial transmission.

MRSA and the environment: implications for comprehensive control measures

Environmental contamination with methicillin-resistant Staphylococcus aureus (MRSA) is established soon after colonized or infected patients become resident. There are many studies that detail the mechanisms of spread and environmental survival of methicillin-susceptible Staphylococcus aureus (MSSA); this knowledge translates directly into the same findings for MRSA. The potential ubiquity of MRSA in a health-care setting poses challenges for decontamination. Whereas patients and medical staff are important sources for MRSA spread, the environmental burden may contribute significantly in various contexts. Effective control measures must therefore include consideration for MRSA in the environment.

Using marker pens on patients: a potential source of cross infection with MRSA

INTRODUCTION

Marker pens are widely used in surgery but pre-operative marking of patients may be a cause of bacterial cross-infection.

PATIENTS AND METHODS

Two experiments were performed to assess whether marking pens can be cause of cross-infection: (i) 26 indelible marker pens were collected from surgical wards for analysis; and (ii) 'fresh' as well as 'dry' (artificially dried by removing cap and exposing tip for 2 h) new permanent marker pens, and whiteboard marker pens were inoculated by dipping the tips into various concentrations of methicillin-resistant Staphylococcus aureus (MRSA). Each pen was inoculated onto 2 blood agar plates at 0 (immediately after inoculation) to 30 min at various intervals, 4 h and 24 h. The plates were incubated for 18 h at 35 degrees C in an incubator.

RESULTS

Of 26 pens collected from the wards, 2 cultured Micrococci spp. (skin commensals). The constituents of new 'fresh' pen tips rapidly kill MRSA - in all cases by 4 h, but usually within minutes. At high inoculum concentrations, MRSA is not killed immediately. Dry marker pens harbour MRSA for at least 30 min and probably longer.

CONCLUSIONS

Marker pens can act as fomites for nosocomial infection. The ethanol-based ink in permanent marker pens has a bactericidal action against MRSA that starts within seconds, and they are likely to be safe to use with a gap of at least 2 min between patients. Usually, harmless skin commensals are not pathogenic except in immunocompromised patients. Old or dried-out marker pens can harbour pathogens and should be discarded before attempted use on patients. We recommend disposable markers for the immunocompromised and patients with a known positive MRSA status.

Rhys-davies exsanguinator: a haven for bacteria

Serial swabs were taken from the inner and outer surfaces of a new Rhys-Davies exsanguinator before and after use on the limbs of patients to exsanguinate limbs prior to tourniquet inflation and surgery. Both surfaces of the exsanguinator showed increasing levels of contamination with bacterial colonisation with use starting from the first use. The organisms grown included potentially harmful bacteria such as Pseudomonas sp. The Rhys-Davies exsanguinator can harbour potentially harmful organisms and, thus, may raise the risk of infection transmission between patients when used without cleaning between uses. Methods of effective cleaning of the exsanguinator between uses are discussed.

The risk of cross-infection when marking surgical patients prior to surgery - review of two types of marking pens

INTRODUCTION

Two types of marker pens were compared to find whether they produced different risks of infection transmission over different time intervals.

PATIENTS AND METHODS

Twenty-four patients were marked according to the type of surgery: each had a set of new dry white-board marker (DWM) and a permanent marker (PM) pen. Once used, their tips were used to inoculate blood agar plates at different time intervals.

RESULTS

At 0 min, 96% of the DWM pens and 29% of the PM pens were positive of growth. At 3 and 10 min, all of the DWM pens remained positive. The rate dropped to 16.67% in 3 min down to none at 10 min for the PM pens.

CONCLUSIONS

DWM pens carry a significant risk of transmitting infection between patients. It is recommended that they are not used in marking. PM pens should not be used between patients in less than a 10-min interval.