Written by Gabby Leonard
There is no definitive low temperature threshold that predicts severe bacterial infections in hypothermic infants. Clinical judgment and adjunct diagnostics are important considerations.
Why does this matter?
Serious bacterial infections (SBI – UTI, bacteremia, or meningitis) and invasive bacterial infections (IBI – bacteremia or meningitis) should be considered in infants <90 days presenting with hypothermia. The WHO defines hypothermia in newborns as severe (<32ºC), moderate (32-35.9ºC) and mild (36-36.4ºC). Typically, the lower the temperature, the higher the likelihood of bacterial infection.
Baby, it’s cold outside….
Hypothermia is considered a sign of SBI or IBI in infants due to altered regulatory responses, increased catabolism, and endothelial dysfunction. This cross-sectional study evaluated over 3,000 infants and aimed to statistically derive a clear temperature threshold that would indicate SBI or IBI in hypothermic infants, defined as <90 days old and <36.4ºC.
1.8% of hypothermic infants had SBI and 0.5% had IBI, with the most common infection being E. coli UTI. The minimum median temperature was 36.2ºC. Those with SBI or IBI had a lower median temperature of 35.8ºC (IQR 35.8-36.3ºC) and 35.4ºC (IQR 35.7-36.3ºC), respectively, compared to those without infection (p < 0.05). Unfortunately, the sensitivity curves were unable to identify a temperature threshold that would have strong sensitivity or specificity for SBI or IBI.
Instead of relying solely on temperature to guide workup for SBI in infants <90 days, additional data should be considered, including the clinical picture and diagnostics such as lab parameters.
Editor’s note: Speaking of clinical picture, we will cover a new study tomorrow that found sepsis very unlikely (zero cases) when hypothermia was incidentally discovered, such as on a well-child visit to the PCP, in the absence of other clinical signs of illness. ~Clay Smith
Temperature threshold in the screening of bacterial infections in young infants with hypothermia. Emerg Med J. 2022 Nov 17;emermed-2022-212575. doi: 10.1136/emermed-2022-212575. Online ahead of print.