104
Letters Table
I. MRSA
isolation
to the Editor
rates over a Z-year
periad
(1984-85)
MRSA Specialty
Total patient throughout
Intensive care General surgery and urology Trauma and orthopaedics Geriatrics and psychogeriatrics General medicine and radiotherapy
Microbiology specimens per patient
isolates
New cases
New cases per 1000 patients
Adjusted new cases per 1000 patients*
297 7000
3.06 0.14
15 49
50.5 7.0
2379
0.30
15
6.3
21
2305
0.21
9
3.9
19
8205
0.17
29
3.5
20
* New cases per 1000 patients + microbiology
specimens per patient
organism. From the beginning of 1989, we have limited our activities to the treatment of affected individuals and intervention in acute outbreaks; large-scale routine screening and isolation are no longer undertaken. Since adopting this more conservative approach we have not been aware of any increase in morbidity due to EMRSA-1. S. P. Barrett J. A. Mellor
Departments of Microbiology and Medicine for the Elderly, Southend Hospital, Westcliff-on-Sea, Essex, SSO OR Y, UK References
Barrett, S. P., Gill, 0. N., Mellor, J. A. & Bryant, J. C. (1988). A descriptive survey of uncontrolled methicillin-resistant Staphylococcus aureus in a twin-site general hospital. Postgraduate Medical Journal 64, 606-609. Cheng, A. F. & French, G. L. (1988). Methicillin-resistant Staphylococcus aureus bacteraemia in Hong Kong. Journal of Hospital Infection 12, 91-101. Thompson, R. L., Cabezudo, I. & Wenzel, R. P. (1982). Epidemiology of nosocomial infections caused by methicillin-resistant Staphylococcus aureus. Annals of Internal Medicine 97, 309-317.
Sir, Viability
of bacteria
in some
intravenous
fluids
There have been several reports of patients receiving intravenous (IV) fluids contaminated with various types of organisms (Michaels & Ruebner, 1953; Guynn, Poretz & Duma, 1973). Several routes by which micro-
Letters
105
to the Editor
organisms may accidentally be introduced into these fluids have been identified; preparative processes and the addition of drugs to the fluids are considered to be the common routes of contamination (Phillips, Eykyn & Laker, 1972; Holmes & Allwood, 1979). The viability with time of Lancefield group A haemolytic Streptococcus pyogenes and Pseudomonas aeruginosa in some hospital prepared IV fluids is reported. Five hundred ml volumes of 5% dextrose solution (DS), 0.9% sodium chloride solution (SC) and a solution of 0.45% sodium chloride with 2.7% dextrose (DSC) obtained from the Pharmacy Department of the University College Hospital, Ibadan, Nigeria were used. They were all freshly prepared and sterilized by autoclaving in glass bottles fitted with a rubber bung and metal seal. The strains were clinical isolates from the University College Hospital grown on nutrient agar slopes at 37°C for 16 h. Bacteria were washed from the slopes and resuspended in sterile distilled water to produce approximately 5 x lo5 cfu ml-‘. One ml of the suspension was introduced into each IV fluid (to obtain approximately lo3 cfu ml-‘) and kept at room temperature (24-26°C). The viability of the bacteria in the fluids was determined by pour plate method; one ml of a solution-bacteria mixture was removed and diluted further in 0.1% peptone water, after which one ml of the final dilution was inoculated into a petri dish. Molten nutrient agar (20 ml) at 48°C was mixed with the suspension in the plate. Plates were incubated at 37°C for 24 h and the colonies counted with a Gallenkamp colony counter. Experiments were made in duplicate. The viability experiments were repeated at 4 h and 3 days. The results of the changes in viable cell count with time are shown in Table I. There was no multiplication of the organisms in DS within 4 h, while there was loss of viability of the organisms in SC and DSC (about lo-30%) and as much as 50% loss of viability for Pseudomonas aeruginosa in DSC. After 3 days storage, the cfu ml-’ of the organisms in the fluids had increased by about 2-3 log cycles. These results indicate that IV fluids may Table
I. Viability
of Streptococcus
pyogenes and Pseudomonas fluids
aeruginosa
in intravenous
cfu ml-‘*
DSt SC2 §DSC
1.0 1.0 1.0
11.0 8.7 9.0
*To, zero time; T4, 4h; TD,, 3 days. 5% dextrose solution; $SC, 0.9% dextrose solution.
tDS, 2.7%
8.0 5.2 20.0
1.0 0.98 1.0
sodium chloride solution; §DSC,
1.0 0.7 0.5
0.45%
3.0 1.0 4.0
sodium chloride with
Letters
106
to the Editor
not support the multiplication of contaminating bacteria within the first few hours, the time frame during which the solutions are administered. Hugbo & Imhanlahimi (1983) reported that under simulated actual-use conditions, bacteria introduced into IV fluids did not increase in numbers within the first 5 h. The results of the present study show that with longer time the organisms will begin to multiply rapidly. In 1981, the American National Co-ordinating Committee on Large Volume Parenterals recommended that bottles of IV fluids need to be changed every 24 h. Traditional glass bottles are used for packing IV fluids and a batch may not always be used on the same day. Bottle closures are known to be a route of entry by contaminating organisms during sterilization, and the risks increase on prolonged use of the containers. It is not always possible to detect contamination by visual inspection and conventional sterility testing is time consuming. Strict adherence to the recommendations for production, storage and use of these solutions is required. Department of Pharmaceutical Microbiology &3 Clinical Pharmacy, University of Ibadan, Nigeria.
Y. B. Acheampong*
References Guynn, J. B., Poretz, D. M. & Duma, R. J. (1973). Growth of bacteria in a variety of intravenous infusions. New England Journal of Medicine 284, 257-260. Holmes, C. J. & Allwood, M. C. (1979). The microbial contamination of intravenous infusions during clinical use. Journal of Applied Bacteriology 46, 246-267. Hugbo. P. G. & Imhanlahimi, W. A. A. (1983). Growth of bacteria in intravenous fluids -under simulated actual-use conditions. American Journal of Hospital Pharmacy 40, 998-1001. infusion fluids. Lancet Michaels, L. & Ruebner, E. (1953). G rowth of bacteria in intravenous
i, 772-774. National Co-ordinating Committee on Large Volume Parenterals (1981). Recommendations of the Committee for compounding and administration of intravenous solutions.Journal of the American Society of Hospital Pharmacy p. 45. Phillips, I., Eykyn, S. & Laker, M. (1972). Outbreak of hospital infection caused by contaminated autoclaved fluids. Lancet i, 1258-1260. *Present address: Bello University,
Department of Pharmaceutics Zaria, Nigeria.
& Pharmaceutical
Microbiology,
Ahmadu
Letters Table
I. MRSA
isolation
to the Editor
rates over a Z-year
periad
(1984-85)
MRSA Specialty
Total patient throughout
Intensive care General surgery and urology Trauma and orthopaedics Geriatrics and psychogeriatrics General medicine and radiotherapy
Microbiology specimens per patient
isolates
New cases
New cases per 1000 patients
Adjusted new cases per 1000 patients*
297 7000
3.06 0.14
15 49
50.5 7.0
2379
0.30
15
6.3
21
2305
0.21
9
3.9
19
8205
0.17
29
3.5
20
* New cases per 1000 patients + microbiology
specimens per patient
organism. From the beginning of 1989, we have limited our activities to the treatment of affected individuals and intervention in acute outbreaks; large-scale routine screening and isolation are no longer undertaken. Since adopting this more conservative approach we have not been aware of any increase in morbidity due to EMRSA-1. S. P. Barrett J. A. Mellor
Departments of Microbiology and Medicine for the Elderly, Southend Hospital, Westcliff-on-Sea, Essex, SSO OR Y, UK References
Barrett, S. P., Gill, 0. N., Mellor, J. A. & Bryant, J. C. (1988). A descriptive survey of uncontrolled methicillin-resistant Staphylococcus aureus in a twin-site general hospital. Postgraduate Medical Journal 64, 606-609. Cheng, A. F. & French, G. L. (1988). Methicillin-resistant Staphylococcus aureus bacteraemia in Hong Kong. Journal of Hospital Infection 12, 91-101. Thompson, R. L., Cabezudo, I. & Wenzel, R. P. (1982). Epidemiology of nosocomial infections caused by methicillin-resistant Staphylococcus aureus. Annals of Internal Medicine 97, 309-317.
Sir, Viability
of bacteria
in some
intravenous
fluids
There have been several reports of patients receiving intravenous (IV) fluids contaminated with various types of organisms (Michaels & Ruebner, 1953; Guynn, Poretz & Duma, 1973). Several routes by which micro-
Letters
105
to the Editor
organisms may accidentally be introduced into these fluids have been identified; preparative processes and the addition of drugs to the fluids are considered to be the common routes of contamination (Phillips, Eykyn & Laker, 1972; Holmes & Allwood, 1979). The viability with time of Lancefield group A haemolytic Streptococcus pyogenes and Pseudomonas aeruginosa in some hospital prepared IV fluids is reported. Five hundred ml volumes of 5% dextrose solution (DS), 0.9% sodium chloride solution (SC) and a solution of 0.45% sodium chloride with 2.7% dextrose (DSC) obtained from the Pharmacy Department of the University College Hospital, Ibadan, Nigeria were used. They were all freshly prepared and sterilized by autoclaving in glass bottles fitted with a rubber bung and metal seal. The strains were clinical isolates from the University College Hospital grown on nutrient agar slopes at 37°C for 16 h. Bacteria were washed from the slopes and resuspended in sterile distilled water to produce approximately 5 x lo5 cfu ml-‘. One ml of the suspension was introduced into each IV fluid (to obtain approximately lo3 cfu ml-‘) and kept at room temperature (24-26°C). The viability of the bacteria in the fluids was determined by pour plate method; one ml of a solution-bacteria mixture was removed and diluted further in 0.1% peptone water, after which one ml of the final dilution was inoculated into a petri dish. Molten nutrient agar (20 ml) at 48°C was mixed with the suspension in the plate. Plates were incubated at 37°C for 24 h and the colonies counted with a Gallenkamp colony counter. Experiments were made in duplicate. The viability experiments were repeated at 4 h and 3 days. The results of the changes in viable cell count with time are shown in Table I. There was no multiplication of the organisms in DS within 4 h, while there was loss of viability of the organisms in SC and DSC (about lo-30%) and as much as 50% loss of viability for Pseudomonas aeruginosa in DSC. After 3 days storage, the cfu ml-’ of the organisms in the fluids had increased by about 2-3 log cycles. These results indicate that IV fluids may Table
I. Viability
of Streptococcus
pyogenes and Pseudomonas fluids
aeruginosa
in intravenous
cfu ml-‘*
DSt SC2 §DSC
1.0 1.0 1.0
11.0 8.7 9.0
*To, zero time; T4, 4h; TD,, 3 days. 5% dextrose solution; $SC, 0.9% dextrose solution.
tDS, 2.7%
8.0 5.2 20.0
1.0 0.98 1.0
sodium chloride solution; §DSC,
1.0 0.7 0.5
0.45%
3.0 1.0 4.0
sodium chloride with
Letters
106
to the Editor
not support the multiplication of contaminating bacteria within the first few hours, the time frame during which the solutions are administered. Hugbo & Imhanlahimi (1983) reported that under simulated actual-use conditions, bacteria introduced into IV fluids did not increase in numbers within the first 5 h. The results of the present study show that with longer time the organisms will begin to multiply rapidly. In 1981, the American National Co-ordinating Committee on Large Volume Parenterals recommended that bottles of IV fluids need to be changed every 24 h. Traditional glass bottles are used for packing IV fluids and a batch may not always be used on the same day. Bottle closures are known to be a route of entry by contaminating organisms during sterilization, and the risks increase on prolonged use of the containers. It is not always possible to detect contamination by visual inspection and conventional sterility testing is time consuming. Strict adherence to the recommendations for production, storage and use of these solutions is required. Department of Pharmaceutical Microbiology &3 Clinical Pharmacy, University of Ibadan, Nigeria.
Y. B. Acheampong*
References Guynn, J. B., Poretz, D. M. & Duma, R. J. (1973). Growth of bacteria in a variety of intravenous infusions. New England Journal of Medicine 284, 257-260. Holmes, C. J. & Allwood, M. C. (1979). The microbial contamination of intravenous infusions during clinical use. Journal of Applied Bacteriology 46, 246-267. Hugbo. P. G. & Imhanlahimi, W. A. A. (1983). Growth of bacteria in intravenous fluids -under simulated actual-use conditions. American Journal of Hospital Pharmacy 40, 998-1001. infusion fluids. Lancet Michaels, L. & Ruebner, E. (1953). G rowth of bacteria in intravenous
i, 772-774. National Co-ordinating Committee on Large Volume Parenterals (1981). Recommendations of the Committee for compounding and administration of intravenous solutions.Journal of the American Society of Hospital Pharmacy p. 45. Phillips, I., Eykyn, S. & Laker, M. (1972). Outbreak of hospital infection caused by contaminated autoclaved fluids. Lancet i, 1258-1260. *Present address: Bello University,
Department of Pharmaceutics Zaria, Nigeria.
& Pharmaceutical
Microbiology,
Ahmadu
