The use of typing methods and infection prevention measures to control a bullous impetigo outbreak on a neonatal ward

Neonatal Staphylococcus aureus acquisition at a tertiary intensive care unit

BACKGROUND

In this study, we explored the role of colonization in health care workers (HCWs) in transmission of methicillin-susceptible Staphylococcus aureus (MSSA) to neonates at a level IV neonatal intensive care unit (NICU).

METHODS

All available screening and clinical MSSA isolates, from the period March 2015 through April 2016, isolated from HCWs and neonates at the level IV NICU, were included. MSSA isolates were initially genotyped using spa typing, and for the most prevalent spa types, whole-genome sequencing (WGS) was performed.

RESULTS

From March 2015 through April 2016, 159 neonates and 115 HCWs were found positive for MSSA, and all isolates were typed by means of spa typing. Twenty-three spa types were found in both HCWs and neonates. Within the most prevalent spa types (t002, t015 and t2787), 4 WGS clusters of genetically indistinguishable MSSA isolates were found in which 4 HCWs and 35 neonates were involved. A total of 10 neonates included in the 4 WGS clusters suffered from bacteremia.

CONCLUSIONS

We showed that HCWs carried the same MSSA isolates as those found in neonates, and that HCWs might serve as a reservoir for transmission of MSSA to neonates. Ten neonates suffered from a bacteremia caused by a MSSA previously detected in a HCW.

Whole-genome sequencing to explore nosocomial transmission and virulence in neonatal methicillin-susceptible Staphylococcus aureus bacteremia

BACKGROUND

Neonatal Staphylococcus aureus (S. aureus) bacteremia is an important cause of morbidity and mortality. In this study, we examined whether methicillin-susceptible S. aureus (MSSA) transmission and genetic makeup contribute to the occurrence of neonatal S. aureus bacteremia.

METHODS

A retrospective, single-centre study was performed. All patients were included who suffered from S. aureus bacteremia in the neonatal intensive care unit (NICU), Erasmus MC-Sophia, Rotterdam, the Netherlands, between January 2011 and November 2017. Whole-genome sequencing (WGS) was used to characterize the S. aureus isolates, as was also done in comparison to reference genomes. Transmission was considered likely in case of genetically indistinguishable S. aureus isolates.

RESULTS

Excluding coagulase-negative staphylococci (CoNS), S. aureus was the most common cause of neonatal bacteremia. Twelve percent (n = 112) of all 926 positive blood cultures from neonates grew S. aureus. Based on core genome multilocus sequence typing (cgMLST), 12 clusters of genetically indistinguishable MSSA isolates were found, containing 33 isolates in total (2-4 isolates per cluster). In seven of these clusters, at least two of the identified MSSA isolates were collected within a time period of one month. Six virulence genes were present in 98-100% of all MSSA isolates. In comparison to S. aureus reference genomes, toxin genes encoding staphylococcal enterotoxin A (sea) and toxic shock syndrome toxin 1 (tsst-1) were present more often in the genomes of bacteremia isolates.

CONCLUSION

Transmission of MSSA is a contributing factor to the occurrence of S. aureus bacteremia in neonates. Sea and tsst-1 might play a role in neonatal S. aureus bacteremia.

An outbreak of skin infections in neonates due to a Staphylococcus aureus strain producing the exfoliative toxin A

PURPOSE

Staphylococcus aureus is an important cause of infections in hospitalized neonates. Preterm or low birthweight infants are especially at risk to develop a S. aureus infection due to the immaturity of the immune system, length of hospital stay and invasive procedures. Exfoliative toxin (ET)-producing S. aureus is often responsible for neonatal infections, causing clinical manifestations such as staphylococcal scalded skin syndrome, characterized by both localized blisters or generalized exfoliation of the skin.

METHODS

We describe an outbreak due to an S. aureus strain producing ETA occurring in a local hospital in Northern Italy. Molecular typing of the isolates included spa typing and multilocus sequence typing. DNA microarray hybridization was also performed on one representative strain.

RESULTS

In the period from July 2013 to February 2014, 12 neonates presented with skin infections, mainly bullae or pustules. Cultures of skin swabs yielded methicillin-susceptible S. aureus (MSSA). By molecular typing, an epidemic strain (t1393/ST5) was identified in nine neonates; microarray analysis and PCR revealed that it contained the ETA encoding gene. Screening of staff, mothers and healthy neonates and environmental cultures did not reveal the presence of the epidemic strain. However, the father of an infected neonate was found to be a carrier of MSSA t1393 five months after the outbreak started.

CONCLUSION

Implementation of hygiene procedures and sanitization of the ward twice terminated the outbreak. Timely surveillance of infections, supported by molecular typing, is fundamental to prevent similar episodes among neonates.