Background objective:
On rthe 17/10/22, the Neonatology Service alerted the Preventive Medicine Service of a subjective increase in cases of omphalitis in new-borns since the beginning of September. An epidemiological investigation was carried out to confirm the existence of an epidemic outbreak, determining the risk factors and indicating control measures.

Methods:
The cumulative incidence of omphalitis during the epidemic period (September-October 2022) was compared with that of the same period in 2021 (control period). A descriptive study of the cases, a hygienic review and an environmental microbiological study (equipment, antiseptics, surfaces, water) including hand-prints were carried out.

Results:
The incidence of omphalitis in the epidemic period (5.6% IC: 2.28%-11.2% ,7 cases) was higher than the incidence in developed countries (0.7%), detecting a statistically significant difference (p-value 0.004) with that observed during the control period (0.45% IC: 0.01%-2.5% , 1 case). All cases occurred in new-borns without perinatal risk factors for omphalitis and during the first 6 days from birth. The most frequently isolated microorganisms were faecal and urinary flora. During the epidemic period there were no changes in techniques, antiseptics, procedures, equipment, materials, personnel, infrastructure and organization of the Obstetrics Service except for the use of a new model of diaper. Incorrect hand-prints sample amounted to 19 (95% IC: 75.1%-99.9%) while there were 76 correct environmental samples (88.6% IC: 79.7%-94.3%.) No new cases were registered since the hygienic education carried out to correct the detected deficits.

Conclusion:
Our research suggests that poor adherence to hand hygiene protocols and inappropriate use of the new diaper may have contributed to an increased incidence of nosocomial omphalitis.