Author: Dr. Philipp Zanger

USA300 MRSA infections has been sporadically detected in Europe. Genetic analysis revealed that the most probable source of infections with USA300 clones were multiple introductions due to importation (1, 2).  In line with these findings, our network found that USA300 MRSA clones were indeed the most commonly imported MRSA to the European Continent (3).

Even though the wide-spread of these particularly virulent MRSA clones was deemed unlikely, we recently detected the first in-hospital transmission of the pandemic MRSA clone, USA300 Latin-American variant in a neonatal ward at a German hospital (4). The index case had no travel history to either North America or South America, where the USA300 / USA300-LV MRSA clones are endemic.

Although nosocomial transmission of pandemic MRSA clones rarely occurs, these clones might already circulate in our community and are waiting for the right time to strike and invade European hospitals. The spread and introduction of USA300 and USA300-LV should be closely monitored to prevent outbreak situations similar to those observed in North and South America. Presented by Dennis Nurjadi

References:

(1) Von Dach E, Diene SM, Fankhauser C, Schrenzel J, Harbarth S, Francois P (2016)
Comparative Genomics of Community-Associated Methicillin-Resistant Staphylococcus aureus shows the Emergence of Clone ST8-USA300 in Geneva, Switzerland.
Journal of Infectious Diseases 213:1370-9

(2) Toleman MS, Reuter S, Coll F, Harrison EM, Blane B, Brown NM, et al. (2016)
Systematic Surveillance Detects Multiple Silent Introductions and Household Transmission of Methicillin-Resistant Staphylococcus aureus USA300 in the East of England.
Journal of Infectious Diseases 214:447-53.

(3) Nurjadi D, Zanger P for the StaphTrav Network (2017)
USA300 and its variants are the most commonly imported methicillin-resistant Staphylococcus aureus to Europe.
Poster presentation, ECCMID, Vienna 2017

 

(4) Nurjadi D, Klein S, Zimmermann S, Heeg K, Zanger P (2017)
Transmission of ST8-USA300 Latin American Variant Methicillin-Resistant Staphylococcus aureus on a Neonatal Intensive Care Unit: Recurrent Skin and Soft- Tissue Infections as a Marker for Epidemic Community-Associated-MRSA Colonization.
Infection Control and Hospital Epidemiology (epub ahead of print)

 

Using confocal laser-scanning microscopy, Hanssen and colleagues from Tromsø in Norway (1) could identify S. aureus intracellularly in keratinocytes of deeper epidermal layers. For their experiments, they biopsied the vestibula nasi of healthy nasal carriers. Their findings corroborate earlier observations in patients with recurrent sinusitis made by Clement et al. (2) and confirm that intracellular S. aureus localization is an important concept for our improved understanding of nasal carriage in the general population. This hideaway may protect staphylococci thus explaining both, commonly observed re-colonization after topical decolonization therapy as well as improved eradication success after systemic application of intracellularly accumulating antibiotics with activity against S. aureus such as rifampicin. Presented by Philipp Zanger

(1) Hanssen AM, Kindlund B, Stenklev NC, Furberg AS, Fismen S, Olsen RS, Johannessen M, Sollid JU (2017)
Localization of Staphylococcus aureus in tissue from the nasal vestibule in healthy carriers
BMC Microbiology 17:89. doi: 10.1186/s12866-017-0997-3.

(2) Clement S, Vaudaux P, Francois P, Schrenzel J, Huggler E, Kampf S, Chaponnier C, Lew D, Lacroix JS (2005)
Evidence of an intracellular reservoir in the nasal mucosa of patients with recurrent Staphylococcus aureus rhinosinusitis
Journal of Infectious Diseases 192:1023-8.