APIC 2026: How Active Surveillance and Genomic Sequencing Helped Control a NICU CLABSI Outbreak

A neonatal intensive care unit (NICU) outbreak investigation presented at the Association for Professionals in Infection Prevention and Epidemiology Annual Conference and Exposition held from June 15 to 17, 2026, in Nashville, Tennessee, highlighted the importance of combining genomic sequencing, active surveillance, and infection prevention fundamentals to identify transmission patterns and halt the spread of Staphylococcus aureus bloodstream infections.

In the poster, "What's Sticky in the NICU? Managing a Staphylococcus aureus NICU CLABSI Outbreak: Transmission Factors and Control Measures," Darien Woods, MPH, CIC, infection preventionist, and Michael TeKippe, MD, PhD, at Advocate Health's Advocate Children's Hospital, described a cluster of central line-associated bloodstream infections (CLABSIs) that prompted an extensive outbreak response in a Level IV NICU.

CLABSIs remain among the most serious health care-associated infections, particularly in neonatal populations. Premature and critically ill infants often require prolonged central venous access and face additional risks because of immature skin barriers and decreased intestinal integrity.

"Patients in a neonatal intensive care unit are particularly at risk for CLABSI due to increased need for central access, underdeveloped skin protection, and decreased intestinal integrity," Woods and TeKippe wrote.

The investigation began after five infants developed CLABSIs over a 3-week period. Four of the cases were attributed to methicillin-susceptible Staphylococcus aureus (MSSA), and a sixth MSSA case was identified less than a month later.

The unusual clustering of cases triggered a formal outbreak investigation that included establishing a case definition, identifying possible transmission factors, implementing enhanced infection prevention measures, and performing genomic analysis of clinical isolates.

To address the outbreak, the hospital implemented a comprehensive response strategy. Interventions included enhanced S aureus screening for all NICU admissions, biweekly surveillance testing, a targeted infection prevention campaign focused on CLABSI prevention practices, and an MSSA decolonization protocol. Investigators also conducted detailed reviews of each infection event to identify opportunities for improvement.

A key component of the investigation involved whole genome sequencing of bloodstream isolates to determine whether the infections were linked to a single outbreak strain.

The results revealed a more nuanced picture.

Seven MSSA blood isolates from 5 patients underwent genomic sequencing. Investigators found that only 2 isolates—those from Case 1 and Case 6—were genetically identical. "Two isolates (from Case #1 and Case #6) were identical, indicating limited direct transmission," the authors noted.

Importantly, the genomic data demonstrated that the cluster was not caused by a single hypervirulent MSSA strain circulating throughout the unit. "Genome sequencing showed no common isolate among all cases, ruling out a hypervirulent MSSA strain as the outbreak source," the authors wrote.

However, the investigation did identify evidence that transmission was occurring within the NICU. During 2 months of biweekly surveillance, researchers found that approximately 19% of NICU patients tested positive for S aureus. Ongoing screening also detected newly positive patients who had previously tested negative.

The findings suggested that lapses in routine infection prevention practices may have contributed more to the outbreak than a single infectious source. According to Woods and TeKippe, the investigation indicated the outbreak was "likely due to lapses in best practices, such as hand hygiene and line maintenance."

The surveillance program also highlighted the potential for continued horizontal transmission among patients if interventions were not maintained.

Ultimately, the combination of enhanced surveillance, decolonization efforts, infection prevention education, and genomic epidemiology helped investigators better understand transmission dynamics and interrupt ongoing spread.

"The outbreak response measures implemented ultimately interrupted transmission, identified sources and patterns, and reinforced best practices within the NICU," the authors wrote.

The study demonstrates how modern genomic tools can complement traditional infection prevention strategies, helping health care organizations distinguish between a true outbreak caused by a single organism and broader systems issues involving transmission opportunities and adherence with best practices. For NICUs caring for highly vulnerable patients, the findings reinforce the continued importance of hand hygiene, central line maintenance, active surveillance, and rapid outbreak investigation.