Fræðigrein

Objective: Positive blood cultures from children suggest serious bloodstream infections. Quick medical response with targeted therapy is important, taking the child's age and medical history into account. Antibiotic therapy and vaccination programs must be based on accurate knowledge of the prevalence and antibiotic susceptibility of the bacteria. The aim of this study was to investigate epidemiological parameters associated with positive blood cultures in children in Iceland from September 20th 1994 to March 16th 2005.

Materials and methods: All positive bacterial blood cultures from children 0-18 years of age identified at the Department of Clinical Microbiology of the Landspitali University Hospital during the study period. Age and sex of the children, bacterial aetiology, date of collection and results of antimicrobial susceptibility tests were registered. The children were divided into four age groups: neonates (<=30 days of age), infants (30 days to one year), preschool age (1-6y) and school age (6-18y). The blood cultures were classified as definite contamination, probable contamination, probable infection and definite infection.

Results: During the study period 1253 positive blood cultures were obtained from 974 children; 647 from boys and 606 from girls. Most of the blood cultures were from children less than one year old (594; 47.4%) of which 252 were neonates (42.4% of all children <1y of age). Coagulase negative staphylococci were the most commonly isolated organisms (37%). Of positive blood cultures considered definite infections Streptococcus pneumoniae was the most common (21.7%) followed by Staphylococcus aureus (19.8%) and Neisseria meningitidis (15.2%). N. meningitidis C was not isolated in children after a meningococcal C vaccination was launched in 2002. The most common pneumococcal serotypes/serogroups were 23, 6B, 7, 19 and 14. Macrolide resistance was common in pneumococci (19%) and group A haemolytic streptococci (33%).

Conclusion: The results provide important information for empirical antibiotical therapy and prophylactic measures such as vaccination. Increasing macrolide resistance limits their usefulness as empiric antibiotics in septic children. The results demonstrate the excellent efficacy of meningococcal C vaccination. Furthermore the results help in predicting the efficacy of pneumococcal vaccination of Icelandic children.

Correspondence: Ásgeir Haraldsson, asgeir@landspitali.is

Table I.  Assessment of the results of  positive blood cultures from children (0-18y) in Iceland 1994-2005.

Group I: Definite contamination*	Group IV: Infection
Bacillus sp.	Acinetobacter
Micrococcus sp.	Bacillus sp.
Propionibacterium	Bacteroides fragilis
Group II: Probable contamination*	Brevibacterium sp.
Acidominimus	Brevundimonas vesicularis
Corynebacterium sp.	Burkholderia cepacia
Corynebacterium striatum	Campylobacter jejuni
Gram positive bacteria	Clostridium perfringens
Gram positive cocci	Clostridium sp.
Gram positive bacilli	Enterobacter
Coagulase negative staphylococci	Enterococcus
Lactococcus	Escherichia coli
Leukonostoc	Fusobacterium sp.
Staphylococcus sp.	Haemophilus (non-influenzae)
Streptococcus sp.	Haemophilus influenzae
Streptococcus (non-hemolytic)	Kingella kingae
Viridans streptococci	Klebsiella
Veillonella sp.	Listeria monocytogenes
Group III: Probable infection	Moraxella
Gram positive anaerobic cocci	Neiss. meningitidis
Gram positive anaerobic bacilli	Nocardia sp.
Gram negative bacteria	Non-fermenting Gram negative bacilli
Gram negative anaerobic bacilli	Pseudomonas
Gram negative rods	Salmonella
Neisseria sp.	Serratia
	Staph. aureus Hemolytic streptococci gr. A, B, D, G Streptococcus pneumoniae Xanthomonas maltophilia
*If two or more identical cultures were obtained within a 30 day period the result ascended one group.

 

Table II.  The most prevalent bacteria in bloodstream infections in children in Iceland 1994-2005.

Organism	Gram	Incidence	Ratio
Coagulase negative staphylococci	Positive	465	37,1%
Streptococcus Pneumoniae	Positive	103	8,2%
Streptococcus Viridans	Positive	95	7,6%
Staphylococcus aureus	Positive	94	7,5%
Micrococcus sp.	Positive	76	6,1%
Neisseria meningitidis	Negative	72	5,7%
Corynebacterium sp.	Positive	63	5,0%
Escherichia coli	Negative	47	3,8%
Hemolytic streptococci group B	Positive	42	3,4%
Enterococcus sp.	Positive	26	2,1%
Propionibacterium	Positive	26	2,1%
Hemolytic streptococci group A	Positive	15	1,2%

 

Table III. Probable and definite infections: The most prevalent bacteria in bloodstream infections in Icelandic children 1994-2005.

Organism	Number of PBCs	Ratio (of probable and definite infections)
Streptococcus pneumoniae	103	19,3%
Staphylococcus aureus	94	17,6%
Neisseria meningitidis	72	13,5%
Escherichia coli	47	8,8%
Group B streptococci	42	7,9%
Coagulase negative staphylococci	38	7,1%
Enterococcus sp.	26	4,9%
Group A streptococci	15	2,8%
Klebsiella sp.	11	2,1%
Haemophilus influenzae	8	1,5%
Total:	456	85,5%

PBC: Positive blood culture.

 

Figure 1. The five most prevalent bacteria in bloodstream infections in children of different age groups  in Iceland 1994-2005.

CNS: Coagulase negative staphylococci; GBS: Group B streptococci.

 

Figure 2. Relative ratio of the most prevalent bacteria in bloodstream infections in children in Iceland 1994-2005.

GBS: Group B streptocooci.

 

Figure 3. Incidence of capsular types of Streptococcus pneumoniae in bloodstream infections in children in Iceland 1994-2005.

PBC: Positive blood culture; NOS: Streptococcus pneumoniae not otherwise specified.

 

Figure 4. Meningococcal bloodstream infections in children (0-18y) in Iceland 1994-2005.  PBC: Positive blood culture.