Outbreak of staphylococcal bullous impetigo in a maternity ward linked to an asymptomatic healthcare worker

Therapeutic Potential of an Endolysin Derived from Kayvirus S25-3 for Staphylococcal Impetigo

Impetigo is a contagious skin infection predominantly caused by Staphylococcus aureus. Decontamination of S. aureus from the skin is becoming more difficult because of the emergence of antibiotic-resistant strains. Bacteriophage endolysins are less likely to invoke resistance and can eliminate the target bacteria without disturbance of the normal microflora. In this study, we investigated the therapeutic potential of a recombinant endolysin derived from kayvirus S25-3 against staphylococcal impetigo in an experimental setting. First, the recombinant S25-3 endolysin required an incubation period of over 15 minutes to exhibit efficient bactericidal effects against S. aureus. Second, topical application of the recombinant S25-3 endolysin decreased the number of intraepidermal staphylococci and the size of pustules in an experimental mouse model of impetigo. Third, treatment with the recombinant S25-3 endolysin increased the diversity of the skin microbiota in the same mice. Finally, we revealed the genus-specific bacteriolytic effect of recombinant S25-3 endolysin against staphylococci, particularly S. aureus, among human skin commensal bacteria. Therefore, topical treatment with recombinant S25-3 endolysin can be a promising disease management procedure for staphylococcal impetigo by efficient bacteriolysis of S. aureus while improving the cutaneous bacterial microflora.

Rapid containment of nosocomial transmission of a rare community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) clone, responsible for the Staphylococcal Scalded Skin Syndrome (SSSS)

Background

The aims of this study were to identify the source and the transmission pathway for a Staphylococcal Scalded Skin Syndrome (SSSS) outbreak in a maternity setting in Italy over 2 months, during 2014; to implement appropriate control measures in order to prevent the epidemic spread within the maternity ward; and to identify the Methicillin-Resistant Staphylococcus aureus (MRSA) epidemic clone.

Methods

Epidemiological and microbiological investigations, based on phenotyping and genotyping methods, were performed. All neonates involved in the outbreak underwent clinical and microbiological investigations to detect the cause of illness. Parents and healthcare workers were screened for Staphylococcus aureus to identify asymptomatic carriers.

Results

The SSSS outbreak was due to the cross-transmission of a rare clone of ST5-CA-MRSA-SCCmecV-spa type t311, exfoliative toxin A-producer, isolated from three neonates, one mother (from her nose and from dermatological lesions due to pre-existing hand eczema) and from a nurse (colonized in her nose by this microorganism). The epidemiological and microbiological investigation confirmed these as two potential carriers.

Conclusions

A rapid containment of these infections was obtained only after implementation of robust swabbing of mothers and healthcare workers. The use of molecular methodologies for typing was able to identify all carriers and to trace the transmission.

Nosocomial outbreak of staphyloccocal scalded skin syndrome in neonates in England, December 2012 to March 2013

Staphylococcal scalded skin syndrome (SSSS) is a blistering skin condition caused by exfoliative toxin-producing strains of Staphylococcus aureus. Outbreaks of SSSS in maternity settings are rarely reported. We describe an outbreak of SSSS that occurred among neonates born at a maternity unit in England during December 2012 to March 2013. Detailed epidemiological and microbiological investigations were undertaken. Eight neonates were found to be infected with the outbreak strain of S. aureus, of spa type t346, representing a single pulsotype. All eight isolates contained genes encoding exfoliative toxin A (eta) and six of them contained genes encoding toxin B (etb). Nasal swabs taken during targeted staff screening yielded a staphylococcal carriage rate of 21% (17/80), but none contained the outbreak strain. Mass screening involving multi-site swabbing and pooled, enrichment culture identified a healthcare worker (HCW) with the outbreak strain. This HCW was known to have a chronic skin condition and their initial nasal screen was negative. The outbreak ended when they were excluded from work. This outbreak highlights the need for implementing robust swabbing and culture methodswhen conventional techniques are unsuccessful in identifying staff carrier(s). This study adds to the growing body of evidence on the role of HCWs in nosocomial transmission of S. aureus.

Health care workers causing large nosocomial outbreaks: a systematic review

Backgrounds

Staff in the hospital itself may be the source of a nosocomial outbreak (NO). But the role of undetected carriers as an outbreak source is yet unknown.

Methods

A systematic review was conducted to evaluate outbreaks caused by health care workers (HCW). The Worldwide Outbreak Database and PubMed served as primary sources of data. Articles in English, German or French were included. Other reviews were excluded. There were no restrictions with respect to the date of publication.

Data on setting, pathogens, route of transmission, and characteristics of the HCW was retrieved. Data from large outbreaks were compared to smaller outbreaks.

Results

152 outbreaks were included, mainly from surgery, neonatology, and gynecology departments. Most frequent corresponding infections were surgical site infections, infection by hepatitis B virus, and septicemia. Hepatitis B virus (27 NO), S. aureus (49 NO) and S. pyogenes (19 NO) were the predominant pathogens involved. 59 outbreaks (41.5%) derived from physicians and 56 outbreaks (39.4%) derived from nurses. Transmission mainly occurred via direct contact. Surgical and pediatric departments were significantly associated with smaller outbreaks, and gynecology with larger outbreaks. Awareness of carrier status significantly decreased the risk of causing large outbreaks.

Conclusions

As NO caused by HCW represent a rare event, screening of personnel should not be performed regularly. However, if certain species of microorganisms are involved, the possibility of a carrier should be taken into account.

Epidemiological data of staphylococcal scalded skin syndrome in France from 1997 to 2007 and microbiological characteristics of Staphylococcus aureus associated strains

Epidemiological data on staphylococcal scalded skin syndromes (SSSS), including bullous impetigo (BI) and generalized exfoliative syndrome (GES), are scarce. To better characterize SSSS and associated Staphylococcus aureus strains, we conducted a retrospective study of 349 cases collected in France between 1997 and 2007 by the National Reference Centre of Staphylococci. Our results showed a stationary evolution of SSSS cases, with a heterogeneous distribution of cases in France. Although notification was not exhaustive, we estimated an incidence of 0.56 cases/year/million inhabitants, in accordance with previous studies conducted in France and Europe, with a median age of 2 years old and sex ratios of 1. A seasonal effect was observed, with a higher GES/BI ratio in autumn compared with other seasons, which could be explained by the impact of viral co-infection. Genetic analysis of S. aureus strains showed that accessory gene regulator (agr) 4, exfoliative toxin A (eta) and B (etb) genes, staphylococcal and enterotoxin-like O (selo) gene and agr4 etb selo profiles were predominantly associated with GES, whereas agr2 eta and agr4 eta selo were more frequently observed with BI. Only one methicillin-resistant strain was found. Protein A (spa) typing identified two main genotypes: spa clonal complex (CC) 159/sequence-type (ST) 121 (75%) and spaCC346/ST15 (18%). spaCC159 was mainly associated with agr4 eta etb selo, agr4 eta selo and agr4 etb selo, and spaCC346 was mainly associated with agr2 eta, suggesting that French SSSS cases are caused by these two main lineages. However, in a multivariate analysis, only etb was independently associated with GES.