Things We Do for No Reason – The “48 Hour Rule-out” for Well-Appearing Febrile Infants

Journal of Hospital Medicine 13(5). 2018 May;343-346 | 10.12788/jhm.2960

May 1, 2018|Journal of Hospital Medicine

Carrie Herzke, MD;Weijen Chang, MD;Rianna Leazer, MD

Fever, defined as a rectal temperature of ≥38°C (100.4°F), is a common reason for hospital admission of infants aged ≤ 90 days. Febrile infants are often admitted to the hospital due to risk for serious bacterial infections, such as urinary tract infection, bacteremia, and meningitis. The traditional observation time is 48 hours following the collection of blood, urine, and cerebrospinal fluid cultures. In the majority of these infants, bacterial infection is not the source of fever. When a bacterial source is identified, less than 0.3% of the bacteria will be detected more than 24 hours after the cultures were obtained in low-risk infants.1 Recent studies show that the traditional 48 hour hospital observation period is unnecessary for infants aged ≤ 90 days who are at low risk for serious bacterial infection based on available scoring systems.

When a Longer Observation Period May Be Warranted

An observation time of >36 hours for febrile infants can be considered if the patient does not meet the generally accepted low-risk clinical and/or laboratory criteria (Table 2) or if the patient clinically deteriorates during hospitalization. Management of CSF pleocytosis both on its own²⁸ and in the setting of febrile urinary tract infection in infants remains controversial²⁹ and may be an indication for prolonged hospitalization. Incomplete laboratory evaluation (eg, lack of CSF due to unsuccessful lumbar puncture,³⁰ lack of CBC due to clotted samples) and pretreatment with antibiotics³¹ can also affect clinical decision making by introducing uncertainty in the patient’s pre-evaluation probability. Other factors that may require a longer period of hospitalization include lack of reliable follow-up, concerns about the ability of parent(s) or guardian(s) to appropriately detect clinical deterioration, lack of access to medical resources or a reliable telephone, an unstable home environment, or homelessness.

What You Should Do Instead: Limit Hospitalization to a Maximum of 36 Hours

For well-appearing febrile infants between 0–90 days of age hospitalized for observation and awaiting bacterial culture results, providers should consider discharge at 36 hours or less, rather than 48 hours, if blood, urine, and CSF cultures do not show bacterial growth. In a large health system, researchers implemented an evidence-based care process model for febrile infants to provide specific guidelines for laboratory testing, criteria for admission, and recommendation for discontinuation of empiric antibiotics and discharge after 36 hours in infants with negative bacterial cultures. These changes led to a 27% reduction in the length of hospital stay and 23% reduction in inpatient costs without any cases of missed bacteremia.²¹ The reduction in the in-hospital observation duration to 24 hours of culture incubation for well-appearing febrile infants has been advocated ³² and is a common practice for infants with appropriate follow up and parental assurance. This recommendation is supported by the following:

Recent data showing the overwhelming majority of pathogens will be identified by blood culture <24 hours in infants aged 0-90 days³² with blood culture TTP in infants aged 0-30 days being either no different²⁶ or potentially shorter³²
Studies showing that infants meeting low-risk clinical and laboratory profiles further reduce the likelihood of identifying serious bacterial infection after 24 hours to 0.3%.¹

RECOMMENDATIONS

Determine if febrile infants aged 0-90 days are at low risk for serious bacterial infection and obtain appropriate bacterial cultures.
If hospitalized for observation, discharge low-risk febrile infants aged 0–90 days after 36 hours or less if bacterial cultures remain negative.
If hospitalized for observation, consider reducing the length of inpatient observation for low-risk febrile infants aged 0–90 days with reliable follow-up to 24 hours or less when the culture results are negative.

CONCLUSION

Monitoring patients in the hospital for greater than 36 hours of bacterial culture incubation is unnecessary for patients similar to the 3 week-old full-term infant in the case presentation, who are at low risk for serious bacterial infection based on available scoring systems and have negative cultures. If patients are not deemed low risk, have an incomplete laboratory evaluation, or have had prior antibiotic treatment, longer observation in the hospital may be warranted. Close reassessment of the rare patients whose blood cultures return positive after 36 hours is necessary, but their outcomes are excellent, especially in well-appearing infants.^7,33

What do you do?

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Disclosures

There are no conflicts of interest relevant to this work reported by any of the authors.

References

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