Observations on the role of hospital blankets as reservoirs of infection

Abstract

A planned experiment to gauge the effect of regular blanket disinfection on bacterial, especially staphylococcal, contamination and infection in an acute geriatric unit is described.With formalinization of blankets, the total colony counts of sweep-plates of blankets in use fell to 43 and 34% of the control period counts on two test wards respectively. The staphylococcal counts fell to 20 and 25% of their previous levels on the two test wards. Ordinary laundering with soap and water did not significantly alter the degree of bacterial contamination of the blankets.Colony counts of slit-sampler plates taken during bed-making fell, with formalinization, to about one-third and one-half of the control period counts on the two test wards respectively. Staphylococcal colony counts fell to about one-fifth and one-third of their previous levels.Staphylococcal contamination of patients was measured by the nasal carrier rate, there being very little sepsis on the unit. The gross figures for nasal carriage of Staph. aureus showed little variation attributable to blanket disinfection. The number of patients acquiring a new strain of staphylococcus after admission tended to increase as the investigation continued. This trend was reversed on both test wards coincident with the introduction of blanket disinfection, and it would seem that this measure may have the effect of lessening the chances of the hospitalized patient becoming a nasal carrier of Staph. aureus, but the results are not formally statistically significant.There appears to be a lack of parallelism between the degree of environmental contamination and cross-infection rates. It is considered unlikely that contaminated blankets may cause infection except in two special circumstances: (a) in the wards, by direct contact with the patient's skin or in-dwelling catheter, and (b) in the operating theatre suite, either directly by contact with the patient's skin, or indirectly via the air.I am grateful to Professor R. E. O. Williams for the loan of a slit-sampler; to Dr Martin Hynes for advice and encouragement; to Mr M. P. Curwen for the analysis of statistical significance; to Mr F. Seage for much technical help; to Dr J. Sharkey, geriatrician; to Sister J. Cleary and the nurses of the geriatric unit; and to Mrs H. M. Page and Miss M. Hanworth for secretarial assistance.The work was supported by a grant from the free funds of the Northern Group Hospital Management Committee.