Correspondence

Volume 16-5, September/October 2003

‘Bugged’ phones:

Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a major clinical and epidemiological problem in hospitals in India.1 Despite the fact that recommendations for the management and control of the spread of MRSA are available,2 it continues to remain a major nosocomial pathogen. Nasal carriage of S. aureus or MRSA has been suggested as a risk factor for the development of nosocomial infections.3 In healthcare settings, telephones may get contaminated with MRSA from the anterior nares and act as fomites for transmission. We aimed to define the extent of contamination of telephone sets with MRSA in the wards and healthcare areas of our hospital, and thus ascertain the potential of these telephones to transmit MRSA.
Sterile cotton wool swabs moistened with sterile distilled water were wiped over the entire surface of 100 telephone handsets and bases to collect 200 samples. The swabs were broken into test-tubes containing 5 ml of nutrient broth and incubated aerobically for 48 hours at 37 °C. The broth was subcultured on blood and MacConkey agar plates and incubated aerobically at 37 °C for 48 hours. Colonies were identified by colonial morphology, Gram stain, catalase test, coagulase test, oxidase test, oxacillin susceptibility and fermentation of sugars.

The commonest isolate was S. aureus (37.9%). MRSA constituted 11.6% of the isolates. The other organisms isolated were Bacillus spp., coagulase-negative Staphylococcus and coliforms. Sixty-eight samples yielded multiple organisms as shown below.

Both S. aureus and MRSA were isolated in large numbers mainly from the handsets of telephones. This may be due to repeated contamination of the mouthpiece by aerosols from the nose and mouth while using the phone. MRSA screening had been carried out 6 months earlier on the staff of operation theatres, some surgical wards and the intensive care unit. S. aureus, both methicillin-sensitive and -resistant, was isolated from the nasal swabs of nearly 30% of them. MRSA was isolated from 10% of nasal swabs.

Contamination of telephones with S. aureus may indicate a considerable level of nasal carriage among persons using the phone. They may be staff, patients or relatives of patients. S. aureus has been shown to survive in an inanimate environment.4,5 Their isolation from telephone sets indicates that telephones may act as fomites in the spread of nosocomial S. aureus and MRSA infection.

The sources of coagulase-negative staphylococci may be the hands, hair or ears. The presence of coliforms on the handset may indicate poor compliance with handwashing guidelines. Bacillus spp. are ubiquitous in the environment. They usually do not have a human source. Not surprisingly, they were isolated in greater numbers from the instrument base, which is handled much less frequently than the handset.

As a part of the daily cleaning routine, telephones are swabbed and cleaned once a day. Obviously, this is not enough, or is not done well enough, which may be due to lack of awareness of the instrument’s potential to act as a fomite. Infection control measures would therefore need to include creation of awareness among personnel regarding the possible role of telephone instruments as fomites in the transmission of nosocomial infections. The instruments need to be disinfected more frequently and thoroughly, with special attention to the mouthpiece. It is possible that the holes in the mouthpiece may harbour organisms that are inaccessible to disinfection. Perhaps narrow swab sticks soaked in a suitable disinfectant could be used to clean them. In addition, handwashing guidelines need to be followed stringently to prevent the transmission of nosocomial infections through this route.
12 October 2003