Observations on the distribution of Staphylococcus aureus in the atmosphere of a surgical ward

Hospital cleaning: past, present, and future

INTRODUCTION

The importance of hospital cleaning for controlling healthcare-associated infection (HAI) has taken years to acknowledge. This is mainly because the removal of dirt is inextricably entwined with gender and social status, along with lack of evidence and confusion over HAI definitions. Reducing so-called endogenous infection due to human carriage entails patient screening, decolonisation and/or prophylaxis, whereas adequate ventilation, plumbing and cleaning are needed to reduce exogenous infection. These infection types remain difficult to separate and quantitate. Patients themselves demonstrate wide-ranging vulnerability to infection, which further complicates attempted ranking of control interventions, including cleaning. There has been disproportionate attention towards endogenous infection with less interest in managing environmental reservoirs.

QUANTIFYING CLEANING AND CLEANLINESS

Finding evidence for cleaning is compromised by the fact that modelling HAI rates against arbitrary measurements of cleaning/cleanliness requires universal standards and these are not yet established. Furthermore, the distinction between cleaning (soil removal) and cleanliness (soil remaining) is usually overlooked. Tangible bench marking for both cleaning methods and all surface types within different units, with modification according to patient status, would be invaluable for domestic planning, monitoring and specification.

AIMS AND OBJECTIVES

This narrative review will focus on recent history and current status of cleaning in hospitals. While its importance is now generally accepted, cleaning practices still need attention in order to determine how, when and where to clean. Renewed interest in removal and monitoring of surface bioburden would help to embed risk-based practice in hospitals across the world.

A study of post-operative wound infection in a provincial general hospital

1. A survey of post-operative wound infection was done in 1959–60 on 559 surgical patients admitted to a provincial general hospital.

2. Clinical evidence of post-operative wound sepsis was observed in 71(12·7 %), suppuration in 51(9·1 %) and staphyloccocal wound sepsis in 48 (8·6 %).

3. Seventeen of the patients died in hospital. Although 5 of these had septic wounds, the sepsis did not appear to have been the cause of death.

4. Contrary to some reported findings, the post-operative wound sepsis rate was considerably lower in patients who were staphylococcal nasal carriers on admission to hospital than in non-carriers. Nine out of 153 carriers (5·9 %) developed wound sepsis and 36 out of 385 non-carriers (9·4 %). When allowance is made for 3 highly probable self-infections, the incidence of wound cross-infection was 3 % in carriers and 9 % in non-carriers.

5. The excess of sepsis in non-carriers could not be explained in terms of different age or sex distribution in carrier and non-carrier groups, nor by differences in the types of operation undergone or in degree of exposure to staphylococcal contamination.

6. The excess of sepsis in non-carriers was accounted for by the patients whose wounds had drains rather than by clean-stitched wounds.

7. Those carriers who harboured a staphylococcus of the 80/81 group in the nose on admission to hospital had a higher incidence of wound sepsis than carriers of other phage types or staphylococcus.

8. Three probable instances of wound self-infection occurred, and in the early stages of the survey at least 5 wound infections were probably directly caused by two members of the theatre staff carrying staphylococci of the 80/81 group in the nose and with existing skin sepsis or a recent history.

9. The survey findings and a study of the literature suggested: (a) that the acquisition of a nasal staphylococcus in hospital was probably, as a rule, evidence of exposure to staphylococeal contamination and not a determinant of wound sepsis, unless the patient also became a skin carrier; (b) that a small proportion of patients are self-infected, some are directly infected by theatre personnel, and the wounds of other patients are directly or indirectly contaminated by staphylococci from the ward environment; (c) that wool or cotton fluff contaminated with staphyloccoci may cause wound sepsis by falling into open wounds and as foreign bodies induce a significant reduction in the minimum pus-forming dose of staphylococci; (d) that before ascribing high or low sepsis rates to factors such as the nasal carrier state, the relevant groups should be shown not to differ materially in respect of other factors known to influence the incidence of wound sepsis.

We gratefully acknowledge the help and encouragement of our surgical colleagues Mr H. P. Guerrier, Mr P. J. W. Monks, Mr J. Macpherson and Mr C. C. Jeffery; and of Dr C. P. Warren, consultant pathologist to the Torbay Hospital, Mrs M. Stamp, Matron, Sister E. M. Cottrell, first Infection Control Sister at the Torbay Hospital, and her successor Mr H. Street.

Acknowledgement is also due to the South Western Regional Hospital Board for its encouragement and for a research grant for technical aid, without which the surveys described would not have been possible.

More than hand hygiene is needed to affect methicillin-resistant Staphylococcus aureus clinical indicator rates: clean hands save lives, part IV

OBJECTIVE

To examine whether improved hand hygiene compliance in health care workers after a statewide hand hygiene campaign in New South Wales hospitals was associated with a fall in rates of infection with multiresistant organisms.

DESIGN AND SETTING

Data on rates of new methicillin-resistant Staphylococcus aureus (MRSA) infections (expressed as four clinical indicators) are reported by some Australian hospitals to the Australian Council on Healthcare Standards (ACHS) for accreditation purposes and are mandatorily reported by all NSW hospitals to the NSW Department of Health. Infections are classified according to whether they are acquired in the intensive care unit (ICU) or other wards and whether they are from sterile sites (blood cultures) or non-sterile sites. The clinical indicators reflect four different site categories (ICU sterile site, ICU non-sterile site, non-ICU sterile site and non-ICU non-sterile site) and are expressed as the number of new health care-associated infections per 10,000 acute care bed-days. Clinical indicator rates were examined for any decline between the pre-campaign period (July-December 2005) and post-campaign period (January-July 2007), and were compared with trends over a similar period in states without a hand hygiene campaign.

MAIN OUTCOME MEASURES

Pre-campaign and post-campaign rates for four MRSA clinical indicators.

RESULTS

Between the pre- and post-campaign periods, there was a 25% fall in MRSA non-ICU sterile site infections, from 0.60/10,000 bed-days to 0.45/10,000 bed-days (P = 0.027), and a 16% fall in ICU non-sterile site infections, from 36.36/10,000 bed-days to 30.43/10,000 bed-days (P = 0.037). The pre- and post-campaign rates of MRSA infection from ICU sterile sites (5.28/10,000 bed-days v 4.80/10,000 bed-days; P = 0.664) and non-ICU non-sterile sites (5.92/10,000 bed-days v 5.66/10,000 bed-days; P = 0.207) remained stable. Australia-wide MRSA data reported to the ACHS showed a 45% decline in infections from ICU non-sterile sites, from 25.89/10,000 bed-days to 14.30/10,000 bed-days (P < 0.001), and a 46% decline in infections from non-ICU non-sterile sites, from 3.70/10,000 bed-days to 1.99/10,000 bed-days (P < 0.001) over the period 2005-2006.

CONCLUSION

Two out of four clinical indicators of MRSA infection remained unchanged despite significant improvements in hand hygiene compliance in NSW hospitals. The reduction in MRSA infections from ICU non-sterile sites in NSW hospitals was mirrored in ACHS data for other Australian states and cannot be assumed to be the result of improved hand hygiene compliance. Concurrent clinical and infection control practices possibly influence MRSA infection rates and may modify the effects of hand hygiene compliance. More sensitive measurements of hand hygiene compliance are needed.

Staphylococcus aureus in Antarctica: carriage and attempted eradication

The carriage of Staphylococcus aureus was studied in a group of 28 men living in a totally isolated environment for a year. Initially, nasal, axillary and perineal swabs were taken at weekly intervals, but from week 24 throat swabs were taken from known nasal carriers. Several attempts were made during the study to eradicate S. aureus. Eight subjects consistently carried their own phage type throughout the study, despite the application of antibacterial agents. In three subjects strains were isolated late in the study of a phage type which had either not been isolated before in this study, or had not been found for a prolonged period. Nine of the 12 nasal carriers also yielded S. aureus from the throat. It is apparent that following attempted eradication, S. aureus may seem to disappear, only to reappear some time later; 'eradication' in this case would be an erroneous appellation.

Staphylococcal epidemiology in Antarctica

An investigation of staphylococcal epidemiology was undertaken at an Australian National Antarctic Research Expedition station during 1965-1966. It concerned the carriage of staphylococci by the men and their dogs, and the occurrence of staphylococci in the station environment. The year-long study indicated that coagulase-negative strains survived better in the Antarctic environment than coagulase-positive strains. It was demonstrated that naturally acquired coagulase-positive strains could not maintain colonization on forearm skin under the usual cold exposure experienced at Mawson station, though coagulase-negative skin strains appeared to thrive during the winter. Staphylococcus albus and S. aureus were able to persist in the anterior nares, despite the sometimes lower temperatures recorded in this micro-climate, probably because of the greater humidity and denser populations found there. The majority of the nasal carriers of S. aureus were persistent carriers, only two men in 27 being found to be occasional carriers of nasal strains, which was consistent with the observation that transfer of this pathogen from man to man is not common under Antarctic conditions. Half of the 27 sledge dogs at the station were found to carry coagulase-positive staphylococci but this did not appear to be of pathological significance to their human handlers. The local inanimate environment, including mess hut, sleeping huts and sleeping bags used on expeditions, was searched for contamination by S. aureus but none was detected.