MRSA colonization rates of readmitted patients previously colonized or infected with MRSA

Letters

161

to the Editor

Department of Microbiology, City Hospital NHS Trust, Birmingham, West Midlands, B18 7QH, UK

C. Catchpole R. Wise A. Fraise

References 1. Cox RA, Conquest C, Mallaghan C, Marples RR. A major outbreak of methicillinresistant Staphylococcus aweus caused by a new phage-type (EMRSA 16). J Hosp Infect 199.5; 29: 87-106. 2. Sheppard MJ. Control of methicillin-resistant Staphylococcus aweus (letter). J Hosp Infect 1996; 32: 73-75. 3. Romero-Vivas J, Rubio M, Fernandez C, Picazo JJ. Mortality associated with nosocomial bacteraemia due to methicillin resistant Staphylococcus auyeus. C/in Infect Dis 1995; 21: 1417-1423. 4. Lacey RW. Multiresistant Staphylococcus aureus-a suitable case for inactivity? J Hosp Infect 1987; 9: 103-105. 5. Bradley SF, Terpenning MS, Ramsay MA, Zarius CT, Jorgensen KA, Sottile WS, Shaberg DR, Kaufmann CA. Methicillin-resistant Staphylococcus aureus: colonisation and infection in a long-term care facility. Ann Intern Med 1989; 115: 417-422. 6. Cafferkey MT, Hove R, Keane CT. Sources and outcome for methicillin-resistant Staphylococcus aweus bacteraemia. J Hosp Infect 1988; 11: 136-143. 7. Cheng AF, French GL. Methicillin-resistant Staphylococcus aureus bacteraemia in Hong Kong. J Hasp Infect 1988; 12: 91-101. 8. French GL, Cheng AF, Ling JM, MO P, Donnan S. Hong Kong strains of mcthicillinresistant and methicillin-sensitive Staphylococcus aureus have similar virulence. J Hosp Znfect 1990; 15: 117-125.

Sir, MRSA

colonization

rates

of readmitted infected with

patients MRSA

previously

colonized

or

It is now a well-accepted practice that patients who are colonized and/or infected with methicillin-resistant Staphylococcus aweus (MRSA) should be placed in isolation rooms.1-3 Most guidelines also state that patients with a high probability of MRSA colonization should be isolated and screened prior to admission to a multibedded ward. Such high MRSA probability groups include patients transferred from large teaching hospitals and nursing homes, and those previously known to have MRSA. With regard to the latter group, we know that MRSA colonization can persist for prolonged periodsG6 but we have very little information on what proportion of returning patients remain colonized, and therefore, how actively we should target this group. The Central Coast Area Health Service comprises 750 beds spread over Correspondence Gosford, NSW

to: Dr D de 2250, Australia.

Wit,

Department

of

Microbiology,

Gosford

Hospital,

PO

Box

361,

Letters

162

to the Editor

four sites with one main referral hospital. Our MRSA rate is approximately 20% of all S. UUY~USisolates. We performed a retrospective study from June 1994 to December 1995 in which we identified all previous MRSA patients and determined their MRSA status on each readmission. Patients were negative if MRSA was not grown from three sets of screening swabs (nose, axilla, groin). Patients were deemed positive if any routine or screening swab showed MRSA. Patients were indeterminate if they had two or less sets of negative screening swabs. Although attempts to eradicate colonization were made in some cases, most patients were discharged before successful eradication, and hence, the effect of this practice could not be ascertained but requires further evaluation. Because many of these patients had chronic illnesses and returned on a number of occasions, the results were analysed as a rate according to readmission episodes (Table). Table.

Results

of MRSA

colonization episodes

as a function

Total readmission episodes (number of patients) Total readmission episodes where screens were performed Number of positive screens Number of indeterminate results Number of negative results

of readmission

301 (129) 106 66 (62%) 32 (30%) 8 (5.6%)

Of the 301 readmission episodes (from 129 patients) only 106 were evaluable (i.e., screens performed) and of these 66 (62%) remained colonized. The time between admissions ranged from one to 12 months and the mean readmission interval was 2.9 months. The low yield of screens performed (106 from 301) is of concern and is due to the failure to fully identify this group of patients; we have recently introduced measures which will hopefully resolve this problem. We can conclude that in our hospital, patients with previous MRSA have at least a 62% chance of being colonized on readmission. These patients form our single largest group of high MRSA probability patients, and hence, in order to control MRSA they need to be actively identified, isolated and screened before placement in a multibedded ward. L. Rodier* D. de Wit+

*Department

of Infection Control and j-Microbiology Central Coast Area Health Service, Gosford Hospital, NS W, Australia

References

1. Duckworth

G and combined working party of the Hospital Infection Society and British Society of Antimicrobial Chemotherapy. Revised guidelines for the control of epidemic methicillin-resistant Staphylococcus aureus. J Hosp Infect 1990; 16: 351-377.

Letters

163

to the Editor

2. Duckworth 3.

4. 5. 6.

GJ. Diagnosis and management of methicillin resistant Staphylococcus uuwus infection. SlllJ 1993; 307: 1049-1052. Mulligan ME, Murray-Leisure KA, Ribner BS, Standiford HC, John JF, Korvick JA, Kauffman CA, Yu VL. Methicillin-resistant Staphylococcus aureus: a consensus review of the microbiology, pathogenesis and epidemiology with implications for prevention and management. AmJ Med 1993; 94: 313-328. McNeil JJ, Proudfoot AD, Tosolini FA, Morris P, Booth JM, Doyle AE, Louis V\‘J. Methicillin-resistant Staphylococcus ~UWUS in an Australian teaching hospital. J Nosp Znfect 1984; 5: 18-28. Frenay HME, Vandenbroucke-Gauls CMJE, Molkenboer MJCH, Verhoef J. Long-term carriage and transmission of methicillin-resistant Staphylococcus aureus after discharge from hospital. J Hasp Infect 1992; 22: 207-215. Hicks NR, Moore EP, Williams EW. Carriage and community treatment of methicillinresistant Staphylococcus au7eus. What happens to colonized patients after discharge. 3’ Hosp Infect 1991; 19: 17-24.

Sir, Potted

plants

as a potential

reservoir

of Fusarium

species

Many studies have suggested that cut flowers and potted plants could be a way of introducing potential pathogens into hospital, and might also induce a reservoir of hospital strains. Such papers have usually focused on Gram-negative bacilli, however, compost is an excellent growth medium providing a substrate for fungal growth.lF3 During two months (November and December 1993), we observed three patients in whom Fusarium spp. was isolated from bile samples during the first month after liver transplantation. These patients had no clinical signs of infection. They received immunosuppressive drugs, particularly steroids but they were not granulocytopenic. All the intensive care unit rooms are private and equipped with high efficiency particulate air (HEPA) filters and positive air pressure. Air environmental survey was performed to determine the environmental fungal reservoir. Swabs were taken from various surfaces of the intensive care unit and from the secretary’s office where patients’ case notes were filed immediately adjacent to ornamental plants. Samples were inoculated onto Sabouraud-chloramphenicol plates and incubated for seven days at 20°C. Fusarium spp. was isolated from the soil of two of the potted plants. No further fungal investigations were performed. We postulate but cannot prove that Fusarium was transmitted between patients via the hands of healthcare personnel transiently contamined by contact with plants and case-books. However, no further cases with this fungus have been seen since the removal of the ornamental plants and their containers from the secretary’s office. Fusarium spp. are one of the fungi that are emerging as significant human pathogens causing disease in compromised patients.’ Although Address Amt-lie

correspondence Raba, L&XI,

to: Dr A. Xl. Rogues, 33 Bordeaux, France

Service

d’Hygi&e

Hospitalike,

H6pital

Pellegrin,

Place