Pathogens on Hospital Surfaces

The everyday presence of pathogens on common hospital surfaces is well documented, and reducing the environmental reservoir is recognized as a positive step as part of an overall strategy to reduce health care infections nosocomial infections. Common pathogens can survive on surfaces for an extended time and can be transferred to patients. VRE has been cultured from monitor knobs, doorknobs, gowns, linens, bed rails, side tables, IV pumps, pressure cuffs, walls, floors, wall plates, and many other environmental surfaces. Dry cotton fabrics have been shown to support vancomycin resistant Enterococci (VRE) for up to 18 hrs and fungi for over five days. VRE has also been found to survive on surfaces and equipment for over three days. In one study of potential fomitic surfaces in a hospital, countertops inoculated with E faecalis and E faecium showed survival for five and seven days, respectively. In the same study bed rails supported both species for 24 hours, telephones and fingers (gloved or not) for 60 minutes, and stethoscope diaphragms for 30 minutes. Pseudorabies virus remains infectious on steel surface for 7 days.

Common coronaviruses, known to be transmissible by fomites, are able to survive on ordinary environmental surfaces for up to 3 hours. Chlamydia can survive on surfaces for a similar period. A wide variety of surfaces can become contaminated under ordinary clinical conditions. Within 7 days of the onset of a zoster eruption in a hospitalized patient, varicella virus was detected on all tested room surfaces, including the back of a chair, the door handle, the table and the air conditioner filter.

Parainfluenza and herpes simplex both survive on untreated toothbrushes for at least 24 hours. Herpes simplex remains infectious for at least 8 hours on a moist applanation tonometer. Recent evidence suggests that hospital environments are particularly likely to serve as a reservoir for Methicillin-resistant staphylococcus aureus (MRSA) and Vancomycin-resistant enterococcus (VRE) as compared with gram-negative bacteria.

A team from the Centers for Disease Control (CDC) investigated the role of environmental transmission of disease at two hospitals that had contained SARS patients and found a high proportion of surface swabs positive for SARS viral RNA. Contamination was found on many surfaces in patient rooms as well as in nearby nursing stations and other parts of the hospital. Contaminated surfaces included computer "mice" at the nursing station and the handrail of the public elevator.

In the 1980s a National Institutes of Health campaign to promote hand washing used a stuffed teddy bear (“T. Bear”) as a handwashing spokesperson and as a promotional item. Ironically, a prospective study of 39 sterilized T. Bears released into a pediatric ward found that 100% were colonized with bacteria, fungi, or both within 1 week. Nosocomial organisms cultured from the bears included Staphylococcus epidermidis, Staphylococcus aureus, Alpha Streptococci, Corynebacterium acnes, Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli, Micrococcus sp, Bacillus sp, and species of Candida, Cryptococcus, Trichosporon, Aspergillus and others.

Fomitic surfaces that are transported between hospital rooms are of particular concern, and have been implicated in nosocomial outbreaks. In one study, significant bacterial contamination was found on 92.9% of 42 writing tools taken from 42 doctors. Fifteen different genera and species were isolated including methicillin-resistant staphylococci. French 39 reports a similar experience in which 36 pens were tested from wards experiencing outbreaks of MRSA, VRE and Multiple drug resistant (MDR) Kelbsiella pneumoniae. From the wards affected by MRSA, 25% of the pens possessed the outbreak strain. From the wards affected by VRE, 17% of the pens were colonized with VRE. None of the pens from the MDR Klebsiella ward showed contamination by the MDR strain, which the authors attribute to a greater susceptibility of Klebsiella to drying than the gram-positive organisms. However, the authors also note from other references that in some cases “…klebsiellas can survive quite well on surfaces.” When 55 stethoscopes and 42 otoscopes used by physicians in community clinics were swabbed for culture, 100% of stethoscopes and 90% of otoscopes were colonized or contaminated by a variety of organisms, including several contaminated with methicillin-resistant staphylococcus aureus.

Source:
Novel Antimicrobial Surface Coatings And The Potential For Reduced
Fomite Transmission Of SARS And Other Pathogens
Craig Feied, MD © 2004