Is a positive urine culture for Streptococcus A (Strep A) in a child likely to represent a urinary tract infection (UTI) or contamination from infected skin?

From the Guidelines

A positive urine culture for Streptococcus A (Group A Streptococcus or GAS) in a child is most likely to represent contamination from infected skin rather than a true urinary tract infection. Group A Streptococcus is not a typical urinary pathogen and rarely causes UTIs in children with normal urinary tracts. When GAS appears in urine cultures, it usually indicates sample contamination from the perineal area, especially if the child has concurrent streptococcal pharyngitis, impetigo, or other skin infections 1. True UTIs are typically caused by Enterobacteriaceae like Escherichia coli (accounting for 80-90% of pediatric UTIs), Klebsiella, Proteus, or Enterococcus species.

Some key points to consider in the diagnosis and management of UTIs in children include:

• The method of urine collection is crucial in determining the likelihood of contamination versus true infection. Urine obtained by catheterization or suprapubic aspiration is considered more reliable than a clean catch urine specimen 1.
• The presence of pyuria (white blood cells in the urine) and symptoms consistent with a UTI (such as dysuria, frequency, or abdominal pain) can support the diagnosis of a true UTI.
• If GAS is isolated from a properly collected urine specimen in a symptomatic child with pyuria, further evaluation would be warranted, but this scenario is extremely uncommon.

Given the information provided, it is likely that the positive urine culture for Streptococcus A in the 6-year-old child represents contamination from infected skin rather than a true urinary tract infection. Clinicians should look for alternative sources of streptococcal infection and consider repeating the urine culture with proper collection technique if UTI symptoms persist. The guidelines for the diagnosis and management of UTIs in febrile infants and young children, as outlined in the studies 1, can inform the approach to this child's care.

From the Research

Understanding the Results of a Clean Catch Urine Test

• A positive urine culture for Streptococcus A (Strep A) in a child can be due to a urinary tract infection (UTI) or contamination from infected skin 2.
• The decision to test for UTI is based on risk factors and the child's age, and urine culture is needed for definitive diagnosis 3.
• Urine specimens collected via perineal bagging should not be used for culture because of high false-positive rates, but a clean catch urine test is a more reliable method 3.

Contamination vs. Infection

• The presence of Strep A in the urine does not necessarily mean that the urine itself is infected, as the bacteria could have come from contaminated skin 2.
• However, a positive culture result should be taken seriously and further evaluated to determine the cause of the infection 4.
• It is essential to consider the child's symptoms, medical history, and physical examination results when interpreting the urine culture results 5.

Diagnosis and Treatment

• Diagnosis of UTI requires pyuria and bacterial growth in the urine culture, and prompt treatment of UTIs reduces renal scarring 3.
• Antibiotic selection should be based on local sensitivity patterns and adjusted once culture results are available 3.
• Treatment approaches have been changed by simplification of drug administration, and oral treatment is recommended especially in older infants and children instead of strict intravenous treatment and patient admission 6.