Routine disinfection of patients’ environmental surfaces.pdf

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Introduction

The routine use of disinfectants to clean hospi-

tal floors and other surfaces is controversial in

relation to nosocomial infections.1–7 The prac-

tice varies nationally. In England, detergent

alone is used widely, while in France, Switzer-

land and the USA, the use of a detergent/

disinfectant is more common. At the University

Hospitals of Geneva (HUG), Switzerland, we

routinely use a detergent/disinfectant to clean

floors and furniture. In a period of cost con-

tainment, care of the environment, and the pos-

sible selective pressure exerted on bacteria to

become resistant to antibiotics by exposing

0195–6701/99/060113 + 05 $12.00 © 1999 The Hospital Infection Society

Journal of Hospital Infection (1999) 42: 113–117

Routine disinfection of patients’

environmental surfaces. Myth or reality?

S. Dharan*, P. Mourouga*, P. Copin*, G. Bessmer†,B.Tschanz† and D. Pittet*

*Infection Control Programme, †Service Propreté-Hygiène, University Hospitals of Geneva,Switzerland

Summary: We have evaluated the need for daily disinfection of environmental surfaces not conta-minated by biological fluids, in patient areas of a medical unit with two wings [North (N) and

South (S)] at the University Hospitals of Geneva, Switzerland. Weekly bacteriological monitoring

of surfaces was carried out at random (N = 1356 samples). In the S wing (control), we used deter-

gent/disinfectant for daily cleaning of the floors and furniture. In the N wing we began by using a

detergent for floors and furniture; after four weeks the results suggested changing to a rotation of

detergent, dust attracting disposable dry mops and disinfectant. During this period the furniture

was cleaned with an active oxygen-based compound. The average differences in contamination

before and after cleaning floors were (mean reduction in bacterial counts and 95% confidence inter-

vals; CI95

): disposable mops: 92·7 cfu/24 cm2 (CI95

; 74–112), active oxygen based compound 111·1

(90–133), and quaternary ammonium compound –0·6 (–27–26). Use of detergent alone was associ-

ated with a significant increase in bacterial colony counts: on average by 103·6 cfu (CI 95 73–134).The quaternary ammonium compound was inadequate for disinfecting bathrooms and toilets but

the active oxygen based compound was satisfactory. For furniture, there was a significant reduction

in bacterial counts with both the methods using disinfectants. As the detergent was contaminated,

by using it alone for cleaning, we were actually seeding surfaces with bacteria.

A total of 1117 patients was studied and we observed no change in the incidence of nosocomial

infections during the four months of the trial. In conclusion, uncontrolled routine disinfection of

environmental surfaces does not necessarily make it safe for the patient and could seed the environ-

ment with potential pathogens.

Keywords: Surfaces; detergents; disinfectants; nosocomial infections.

Received 3 June 1998; revised manuscript accepted 16

December 1998

Address correspondence to: Didier Pittet, Associate

Professor of Medicine, Chair, Infection Control

Programme, Hôpitaux Universitaires de Genève, 24, rue

Micheli-du-Crest. 1211 Genève 14, Switzerland Tel:

41–22–3729828 Fax: 41–22–3723987


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them to disinfectants8,9 we prospectively evalu-

ated the necessity of daily disinfection of sur-

faces not contaminated by biological fluids and

of isolation rooms.

Materials and methods

Setting

HUG is a large healthcare centre providing pri-

mary and tertiary medical care for Geneva,

Switzerland, and the surrounding area serving

a population of about 800,000. Approximately

40,000 patients are admitted annually. This

study was carried out in a medical unit (106

beds), which has two wings. Wing North (N)has three wards, A, B, and C; wing South (S)

has two wards, D and E. Each ward has two

seven-patient rooms, two two-patient rooms

and two single-patient rooms. Ward E has six

additional beds. The ward floors are PVC lined

and those of the bathrooms and toilets are tiled.

The infection Control Team (ICT), estab-

lished in October 1992, consists of a hospital

epidemiologist, one associate and six full-time

infection control nurses (ICNs). Since January

1993, the ICT has conducted several hospital-wide period-prevalence studies to detect

nosocomial infections using total chart surveil-

lance.10 Collection of data was based on stan-

dard definitions.11 The ICT conducts on-going

surveillance for nosocomial infections, by

twice-weekly visits to general wards and daily

visits (weekends excepted) to critical care units.

Surveillance and measures to control methi-

cillin-resistant S. aureus (MRSA) transmission

have already been described.12,13

Study design

The study was conducted from 1 February to

31 May, 1997. In the S wing, the routine prac-

tice was continued, i.e., use of a quaternary

ammonium compound (QA) 0·5% ISEQUAT®

(ISE S.A. Locarno, Switzerland) daily for

cleaning and disinfecting all floors. It was

diluted according to manufacturer’s instruc-

tions. Furniture was cleaned with the detergent

1% TASKI® R50 (T) (Diversey and Lever SA,

Geneva, Switzerland), then disinfected with an

alcoholic solution (DOSPRAY®; D) containing

0·028% aldehydes (local preparation).

In the N wing, we started off by using deter-gent T for floors and furniture, except in bath-

rooms, toilets and isolation rooms, where we

used an active oxygen based compound (AOB),

1% PERFORM® (Schulke & Mayer, Ger-

many). Floors were cleaned with TASKI mops

(Diversey & Lever SA, Geneva, Switzerland).

The mops have a reservoir for cleaning or dis-

infecting solution and a detachable head so that

the cleaning tissue can be changed when neces-

sary. After four weeks trial of detergent, the

protocol was modified in wing N due to theobserved results. On Mondays, the floors were

cleaned and disinfected with AOB, followed by

three days cleaning with disposable dust-

attracting floor mops (DM). On Fridays, the

floors were cleaned with the detergent only and

at the weekends with DM. The furniture was

cleaned and disinfected with AOB.

Bacteriological sampling

Bacteriological sampling was carried out weekly.For all surfaces we used the Count-Tact® plates

and applicator (bioMérieux, Marcy l’Etoile,

France). By using the applicator, a uniform

pressure of 500 g can be applied to the plate for

ten seconds. Ten surface samples of floors and

ten of furniture in patients’ rooms were taken

before cleaning and disinfecting. The surfaces

were cleaned and/or disinfected and the same

number of samples taken when the surfaces

were dry (10–15 minutes later). There was very

little patient movement during sampling as thefloors were wet. The same procedure was car-

ried out in bathrooms and toilets. Surface sam-

pling was done randomly over the entire floor

and furniture. Rooms sampled varied weekly,

alternating between a seven-patient room and a

two-patient room. The occupancy of the seven

patient-rooms varied between three and five

patients at time of sampling. The bed occu-

pancy rate of the wards averaged 78% (62–100)

during the study.

114 S. Dharan et al.


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Samples were incubated at 35°C for 48 h

with observation of plates at 24 h. Colony

counts were made at 48 h; the plates were fur-

ther left at room temperature for 72 h for fungal

growth. Identification of bacteria was by colo-nial morphology, Gram stain, coagulase test for

staphylococci and APl 20E (bioMérieux, Marcy

l’Etoile, France) for Enterobacteriaceae.

Statistical analysis

ANOVA was used to compare the average differ-

ences. For each surface, a specific analysis was

carried out; a priori comparisons between meth-

ods were then calculated. No Bonferroni correc-

tion or other correction approaches were used.

All tests were two tailed; P -values less than 0·05

were considered statistically significant.

Results

In all 1356 bacteriological samples were pro-

cessed. Results obtained according to the differ-

ent detergent/disinfectant techniques used for

regular room floors, bathroom and toilet floors

and patient room furniture are shown in Figure1. For the regular room floors, the average

colony counts of 80 samples over eight weeks

shows that QA did not reduce the total bacterial

count (average reduction = –0·6 cfu/24 cm2; CI95

–27–26) and at times they were higher than

before disinfecting (Figure 1a). With the deter-

gent T, we were introducing bacteria into the

patients’ environment (average increase = 103·6

cfu/24 cm2, CI95

73–134). With DM we obtained

an average reduction in bacterial counts of 92·7

CFU/24 cm2

, (CI95 74–111) and with AOB alarger reduction of 111·1 cfu/24 cm2, (CI95

87–133). Differences observed between the

effects of DM vs. QA (F(1,314)

) =28·02, P < 0·001)

and AOB vs. QA (F(1,314)

) =40·17, P < 0·001)

were statistically significant; there was no statis-

tically significant difference (F(1,314)

= 1·08, P =

0·30) between the effects of DM and AOB.

At the concentration used, QA was inade-

quate for disinfecting bathrooms and toilets.

AOB worked significantly better: bacterial

colony counts decreased by an average of 186·5cfu/24 cm2 (CI95

155–218) with AOB, while

they increased by 50 (CI95

10–90) with QA

(F(1.157)

) = 84·77, P < 0·001, Figure 1 b).

For furniture, there was a reduction in bacte-

rial counts with both disinfectants (AOB, aver-

age decrease = 57·6 cfu/24 cm2, CI95

36–79;

T+D, average decrease = 44·6 cfu/24 cm2, CI95

10–79, Figure 1c), but an increase in bacterial

counts after cleaning with detergent only (aver-

age increase = 114·9 cfu/24 cm2, CI95

64–166).

Disinfection of hospital surfaces 115

200

150

100

50

0–50

–100

–150

–200

–250200

150

100

50

0

–50

–100

–150

–200

–250200

150

100

50

0

–50

–100

–150

–200

–250

B a c t e r i a l s u r f a c e

c o n t a m i n a t i o n ( c f u / 2 4 c m

2 )

A) Ward floors

B) Bathroom and toilet floors

C) Furniture

QA

DM AOB

QA

AOB

TT

AOBT+D

Figure 1 Bacterial contamination of patients environmental surfaces

after cleaning with different procedures/disinfectants – Average differ-

ences () in total bacterial colony counts before/after cleaning are

expressed as cfu/24 cm2 with 95% confidence intervals (bars).

AOB refers to active oxygen-based compound; DM, dust-attracting

floor mops; QA, quaternary ammonium compound;T, detergent;T+D,

combined use of detergent and dust-attracting mops.

See text for statistical comparisons


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A total of 1117 patients were admitted during

the study period, accounting for 8214 patient-

days of care. Prospective surveillance for noso-

comial bloodstream infection showed stable

rates; in particular, the incidence of infectionwas similar to that of the preceding twelve

months: 1·22 versus 1·36 episodes per 1000

patient-days, respectively; and did not differ

between the N and the S wings during the study.

Furthermore, the incidence of patients colo-

nized or infected with MRSA remained stable

during the study period compared with that

observed during the 12 preceding months (2·19

versus 1·93 case patients per 1000 patient-days,

respectively). Prospective surveillance for noso-

comial infections (all sites) was performed dur-ing the first half of the study period over the two

wings of the medical unit; infection rates were

similar, and environmental culture results were

not associated with concomitant identification of

pathogens responsible for nosocomial infections.

Discussion

This study was undertaken with the intention

of reducing routine disinfection of the patients’environmental surfaces, and evaluating our dis-

infection policy. It is rather difficult to convince

nursing and housekeeping staff to discard rou-

tine disinfection of all surfaces and that floor

contamination has very little to do with nosoco-

mial infections.

Despite following the manufacturer’s

instructions the in-use concentration of QA

was inadequate. Mops often contributed to the

mechanical spread of bacteria from contami-

nated spots over entire surfaces; especially inbathrooms. Enterobacteriaceae, P. aeruginosa

and other Gram-negative non-fermentative

bacilli were the most frequent contaminants

found on bathroom floors after disinfection

with QA. The T solution was often contami-

nated and resulted in seeding the patients’ envi-

ronment with bacteria, so that we could not

really evaluate its capacity to reduce microbial

load on surfaces. When uncontaminated T

solution was used there was very little change in

the microbial load after cleaning (sample size

too small for statistical analysis).

Contamination of detergent solutions used

for cleaning of surfaces was also reported by

Werry et al.14

Detergent T had been preparedin tap water and stored before use. The contam-

inants were mainly Gram-negative non-

fermentative bacilli, including Acinetobacter

spp. and P. aeruginosa. Although we attempted

to remedy this situation by preparation of fresh

solutions daily, the problem persisted. Then we

discovered that although the reservoirs on

mops were emptied and left to dry after use, the

tubing leading from the reservoir to the mop

head was never thoroughly emptied. Cultures

showed that the residues were always contami-nated; this sometimes happened when using the

mops with QA, but never with the disinfectant

AOB. This could have been due to the fresh

preparation of the use AOB solution from

granules. The predominant organisms found

after disinfecting with AOB were Bacillus spp.

and fungi. Presumably vegetative forms of bac-

teria were killed within the drying time and the

spores survived. Housekeeping staff could

never understand why when using a disinfec-

tant they have to take extra care in maintainingthe mops in clean dry conditions. For them dis-

infectants are supposed to kill all bacteria!

Compliance with cleaning protocols consti-

tutes the major problem highlighted by the

bacteriological results observed. However,

whatever the degree of contamination found

after cleaning and/or disinfecting the floors, the

bacterial counts evened out with time as shown

by the samples taken just before cleaning. The

recontamination rates have been shown in stud-

ies by Ayliffe and colleagues,

1

and Palmer andYeoman.3 Only on four occasions did we find

Gram-negative bacilli on samples taken before

cleaning of patient room floors; Acinetobacter

spp. twice, Enterobacter cloacae and E. coli each

on a single occasion. Once we found heavy con-

tamination with S. aureus on a toilet floor, but

after disinfection with QA we recovered only

one colony on culture. On two occasions we

recovered Acinetobacter spp. and Enterobacter

cloacae from furniture before cleaning.

116 S. Dharan et al.


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Even though we did not have good bacterio-

logical results with T, we have decided to do away

with routine disinfection of ward floors. We have

introduced the use of dust attracting disposable

mops, alternating with a detergent solution everyother day. This is because disposable mops do

not remove spill marks and a wetting agent is

necessary. We have also instituted better mainte-

nance of cleaning equipment and daily prepara-

tion of in-use dilutions of detergent. For the time

being we will continue disinfecting furniture in

patient rooms because compliance with hand-

washing practices by healthcare personal at our

institution only averaged 40–50%15 and we hope

to limit cross transmission from the environment

to the patient via indirect contamination.Over the evaluation period we did not

observe any significant change in nosocomial

bloodstream infection rates or in colonisation

due to MRSA compared with the twelve pre-

ceding months; similarly there was no differ-

ence in the observed infection rates between the

two wings. We concluded that there is no direct

link between nosocomial infection rate and use

of disinfectants to clean ward floors. Such a

finding deserves further testing in larger trials.

We are convinced that reduction of bacterialcontamination of the patient’s environment can

be achieved only with frequent cleaning i.e.,

more than once daily, rather than using disin-

fectants once a day. However to introduce more

cleaning is almost impossible due to the organi-

zation of work schedule in the wards and the

economic climate of downsizing.

References

1. Ayliffe GAJ, Collins BJ, Lowbury EJL.

Cleaning and disinfection of hospital floors. Br

Med J 1966; 2: 442–445.

2. Ayliffe GAJ, Collins BJ, Lowbury EJL. Ward

floors and other surfaces as reservoirs of hospi-

tal infection. J Hyg 1967; 65: 515–536.

3. Palmer PH, Yeoman DM. A study to asses the

value of disinfectants when washing ward

floors. Med J Aust 1972; 2: 1237–1239.

4. Daschner J, Rabbenstein G, Lanhmaack H.

Flächendekontamination zur Verhütung und

Bekämpfung von Krankenhaus-Infektionen.

Dtsch Med Wochenschr 1980; 10: 325–329.

5. Maki DG, Alvarado CJ, Hassemer CA, Zilz

MA. Relation of the inanimate hospital envi-

ronment to endemic nosocomial infection. N

Engl J Med 1982; 307: 1562–1566.

6. Danforth D, Nicolle LE, Hume K, Alfieri N,

Sims H. Nosocomial infections on nursing units

with floors cleaned with a disinfectant compared

with detergent. J Hosp Infect 1987; 10: 229–235.

7. Boyce JM, Potter-Bynoe G, Chenevert C, King

T. Environmental contamination due to methi-

cillin-resistant Staphylococcus aureus: possible

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8. Sivaji Y, Mandal A, Agarwal DS. Disinfectant

induced changes in the antibiotic sensitivity and

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9. Moken MC, McMurry LM, Levy SB. Selection

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11. Garner JS, Jarvis WR, Emori TG, Horan TC,

Hughes JM. CDC definitions for nosocomial

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12. Pittet D, Safran E, Harbarth S, et al . Automatic

alerts for methicillin-resistant Staphylococcus

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tion system. Infect Control Hosp Epidemiol 1996;

17: 496–502.

13. Harbarth S, Pittet D. Controlling a long-term,

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Disinfection of hospital surfaces 117

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