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Invasive Escherichia coli infections in children: bacterial characteristics in different age groups and clinical
A Siitonen1, A Takala, Y A Ratiner
1National Public Health Institute, Helsinki, Finland.
Insights
Escherichia coli strains causing neonatal infections and meningitis often possess K1 capsular type and O18 serogroup. Pyelonephritis in infants is linked to P-fimbriation and hemolysin production.
Area of Science:
- Microbiology
- Pediatric Infectious Diseases
- Bacterial Pathogenesis
Background:
- Escherichia coli (E. coli) is a common cause of pediatric infections, ranging from urinary tract infections to invasive diseases like meningitis and sepsis.
- Understanding the virulence factors and serotypes of E. coli associated with different clinical presentations in children is crucial for diagnosis and treatment.
Purpose of the Study:
- To characterize E. coli isolates from children with various infections and compare them with fecal isolates from healthy children.
- To identify specific E. coli serotypes, adhesins, and hemolysin production associated with different pediatric infections.
Main Methods:
- Characterization of 135 E. coli isolates from blood or cerebrospinal fluid of infected children.
- Comparison with 94 fecal E. coli isolates from healthy children.
- Analysis of capsular type (K), serogroup (O), lipopolysaccharide type, fimbriation (adhesins), and hemolysin production.
Main Results:
- Neonatal infections and meningitis/septicemia in infants were predominantly associated with capsular type K1, serogroup O18, and rough-type lipopolysaccharide.
- S-fimbriated strains were common in neonatal infections but rare in other groups.
- Pyelonephritis in infants was linked to P-fimbriation, specific O serogroups (O1, O2, O4, O6, O7), and hemolysin production.
- Invasive infections in older children were linked to hemolysin production, unlike fecal isolates.
Conclusions:
- Specific E. coli virulence factors and serotypes are associated with distinct pediatric infection types.
- K1 and O18 are significant in neonatal and invasive infections, while P-fimbriation and hemolysin are key in pyelonephritis.
- Hemolysin production is a potential marker for invasive E. coli infections in older children.
Abstract:
Escherichia coli isolates from blood or cerebrospinal fluid of 135 children were characterized for serotype, adhesin and hemolysin production and compared with 94 fecal isolates from healthy children. Capsular type K1, sero-group O18 and rough-type lipopolysaccharide were predominant in neonatal infections (49, 16 and 16%, respectively) and also in meningitis and septicemia of infants from 7 days to 23 months of age (39, 17 and 13%). S-fimbriated strains were common in neonatal infections (23%) but rare (< or = 5%) in all other clinical groups. Pyelonephritis was the most common diagnosis in infants (49 of 72); it was associated with P-fimbriation (63%); serogroups O1, O2, O4, O6 or O7 (41%), and hemolysin production (37%). Invasive infections in older children (age > or = 2 years) were associated with predisposing factors and were caused by strains resembling fecal isolates; the only exception was hemolysin production which was detected in 40% of the disease but only 9% of the fecal isolates. Eight O:K:H serotypes were associated with invasive infections; they usually had K1 or K5 capsule and either P, S or type 1C fimbriae.