- Email: [email protected]
Pour plate blood cultures to detect bacteraemias related to indwelling central venous catheters
Journal of Hospital Infection (1986) 8, 203-206
Letters
to the Editor
Sir,
Pour
plate
blood cultures to detect bacteraemias indwelling central venous catheters
related
to
Cross, Hayworth & Spencer (1986) h ave reported on the use of pour plate blood cultures and their value in immunocompromised patients. We use this quantitative blood culture method to diagnose bacteraemias related to the indwelling central venous catheters (Hickman catheters) placed in children with leukaemia and other oncological diseases. Although these infections can be diagnosed by culture of the catheter tip (Maki et al., 1977), removal and replacement of the catheter is expensive and distressing, and not without risk, particularly in this group of patients. At the time when conventional broth blood cultures are set up, 1 ml samples of blood obtained both through the catheter and from a peripheral vein, are added to 1 ml amounts of brain-heart infusion broth (Gibco) containing 1% sodium polyanethol sulphonate. Eighteen millilitres of molten blood agar base (Lab M) at 48°C are added and, after mixing, .pour plates are made and incubated aerobically with 7% added CO, for up to 72 h at 37°C. Of 12 bacteraemias since August 1985 nine have been diagnosed as catheter-related, with pour plates containing blood drawn through the catheter yielding > 1000 colonies and plates containing peripheral blood yielding < 60 colonies. Of the catheter-related bacteraemias, four were due to coagulase-negative staphylococci, one to a combined infection with both Enterobacter agglomerans and Acinetobacter calcoaceticus var. Iwo& and one to each of Streptococcus faecalis, Str. sanguis, Klebsiella oxytoca, and Ent. agglomerans. Bacteraemias arising from a source other than the catheter give approximately equal colony counts in pour plates containing peripheral and catheter samples. Over 50% of catheter related bacteraemias are due to coagulase-negative staphylococci (Press et al., 1984; Darbyshire, Weightman & Speller, 1985) and contamination of conventional broth blood cultures with these organisms can lead to delayed or incorrect interpretation of isolates, whereas the quantitative method clearly distinguishes significant catheter-associated isolates. The isolates are also available as colonies in a solid medium and this often allows better presumptive identification at this early stage. The pour plate blood culture technique is a simple and economical method of diagnosing bacteraemias associated with indwelling central 203
Letters
204
to the Editor
venous catheters. It is much cheaper than the use of the ‘Isolator’ (DuPont) blood culture system (Myint & Lowes, 1985) and gives equally good results.
N. C. Weightman D. C. E. Speller
Bristol
Royal Infirmary Bristol BS2 8HW
References Cross, A. J., Haworth, E. & Spencer, R. C. (1986). A re-evaluation of the pour plate blood culture method for the detection of candida and other septicaemias. Journal of Hospital
Infection 7, 96-101. Darbyshire, P. J., Weightman, N. C. & Speller, D. C. E. (1985). Problems associated with indwelling central venous catheters. Archiwes of Disease in Childhood 60, 129-l 34. Maki, D. G., Weise, C. E. & Sarafin, M. S. (1977). A semiquantitative method for identifying intravenous catheter-related infection. New England Journal of Medicine 296, 1305-l 309. Mvint. S. & Lowes. A. (1985). Bacterial endocarditis with Hickman catheters. Lancet i.
289-270. Press, 0. W., Ramsey, catheter infections
.
’
P. G., Larson, E. B., Fefer, A. & Hickman, R. 0. (1984). in patients with malignancies. Medicine 63, 189-200.
Hickman
Sir,
Group B streptococcal
bacteraemia intravenous
associated catheter
with
a triple
lumen
Group B streptococcal infections have classically been associated with infections in the neonate, and have recently become recognized as important pathogens in the elderly adult population. The majority of patients have serious underlying diseases including maligancy, peripheral vascular disease, liver disease, or diabetes mellitus. Mortality ranged from 31-70% in three large series, and probably reflects the underlying diseases of the patients. (Baber, Chow & Guze, 1976; Lerner et al., 1977; Gallagher & Watanakunakorn, 1985). Group B streptococcal bacteraemia may originate from a variety of infected foci, i.e., meningitis, arthritis, cellulitis, pneumonia, or endocarditis. Recently, the organism has been reported in association with villous adenomas of the colon. (Wiseman, Rene & Crelinsten, 1985). Group B streptococcal urinary tract infections have long been recognized in women, elderly males, and in diabetics. Bacteraemia due to group B streptococci is infrequently polymicrobial, but one case has been reported of bacteraemia involving group B streptococci and polymicrobial aweus that resulted from an infected intravenous Staphylococcus haemoperfusion catheter. (Gallagher & Watanakunakorn, 1985). Case history The patient was a 42-year-old dependent diabetes mellitus,
white chronic
female with obstructive
a history of insulin pulmonary disease,
Letters
to the Editor
Sir,
Pour
plate
blood cultures to detect bacteraemias indwelling central venous catheters
related
to
Cross, Hayworth & Spencer (1986) h ave reported on the use of pour plate blood cultures and their value in immunocompromised patients. We use this quantitative blood culture method to diagnose bacteraemias related to the indwelling central venous catheters (Hickman catheters) placed in children with leukaemia and other oncological diseases. Although these infections can be diagnosed by culture of the catheter tip (Maki et al., 1977), removal and replacement of the catheter is expensive and distressing, and not without risk, particularly in this group of patients. At the time when conventional broth blood cultures are set up, 1 ml samples of blood obtained both through the catheter and from a peripheral vein, are added to 1 ml amounts of brain-heart infusion broth (Gibco) containing 1% sodium polyanethol sulphonate. Eighteen millilitres of molten blood agar base (Lab M) at 48°C are added and, after mixing, .pour plates are made and incubated aerobically with 7% added CO, for up to 72 h at 37°C. Of 12 bacteraemias since August 1985 nine have been diagnosed as catheter-related, with pour plates containing blood drawn through the catheter yielding > 1000 colonies and plates containing peripheral blood yielding < 60 colonies. Of the catheter-related bacteraemias, four were due to coagulase-negative staphylococci, one to a combined infection with both Enterobacter agglomerans and Acinetobacter calcoaceticus var. Iwo& and one to each of Streptococcus faecalis, Str. sanguis, Klebsiella oxytoca, and Ent. agglomerans. Bacteraemias arising from a source other than the catheter give approximately equal colony counts in pour plates containing peripheral and catheter samples. Over 50% of catheter related bacteraemias are due to coagulase-negative staphylococci (Press et al., 1984; Darbyshire, Weightman & Speller, 1985) and contamination of conventional broth blood cultures with these organisms can lead to delayed or incorrect interpretation of isolates, whereas the quantitative method clearly distinguishes significant catheter-associated isolates. The isolates are also available as colonies in a solid medium and this often allows better presumptive identification at this early stage. The pour plate blood culture technique is a simple and economical method of diagnosing bacteraemias associated with indwelling central 203
Letters
204
to the Editor
venous catheters. It is much cheaper than the use of the ‘Isolator’ (DuPont) blood culture system (Myint & Lowes, 1985) and gives equally good results.
N. C. Weightman D. C. E. Speller
Bristol
Royal Infirmary Bristol BS2 8HW
References Cross, A. J., Haworth, E. & Spencer, R. C. (1986). A re-evaluation of the pour plate blood culture method for the detection of candida and other septicaemias. Journal of Hospital
Infection 7, 96-101. Darbyshire, P. J., Weightman, N. C. & Speller, D. C. E. (1985). Problems associated with indwelling central venous catheters. Archiwes of Disease in Childhood 60, 129-l 34. Maki, D. G., Weise, C. E. & Sarafin, M. S. (1977). A semiquantitative method for identifying intravenous catheter-related infection. New England Journal of Medicine 296, 1305-l 309. Mvint. S. & Lowes. A. (1985). Bacterial endocarditis with Hickman catheters. Lancet i.
289-270. Press, 0. W., Ramsey, catheter infections
.
’
P. G., Larson, E. B., Fefer, A. & Hickman, R. 0. (1984). in patients with malignancies. Medicine 63, 189-200.
Hickman
Sir,
Group B streptococcal
bacteraemia intravenous
associated catheter
with
a triple
lumen
Group B streptococcal infections have classically been associated with infections in the neonate, and have recently become recognized as important pathogens in the elderly adult population. The majority of patients have serious underlying diseases including maligancy, peripheral vascular disease, liver disease, or diabetes mellitus. Mortality ranged from 31-70% in three large series, and probably reflects the underlying diseases of the patients. (Baber, Chow & Guze, 1976; Lerner et al., 1977; Gallagher & Watanakunakorn, 1985). Group B streptococcal bacteraemia may originate from a variety of infected foci, i.e., meningitis, arthritis, cellulitis, pneumonia, or endocarditis. Recently, the organism has been reported in association with villous adenomas of the colon. (Wiseman, Rene & Crelinsten, 1985). Group B streptococcal urinary tract infections have long been recognized in women, elderly males, and in diabetics. Bacteraemia due to group B streptococci is infrequently polymicrobial, but one case has been reported of bacteraemia involving group B streptococci and polymicrobial aweus that resulted from an infected intravenous Staphylococcus haemoperfusion catheter. (Gallagher & Watanakunakorn, 1985). Case history The patient was a 42-year-old dependent diabetes mellitus,
white chronic
female with obstructive
a history of insulin pulmonary disease,