Research Article: A Cross-Sectional Study of Colonization Rates with Methicillin-Resistant Staphylococcus aureus (MRSA) and Extended-Spectrum Beta-Lactamase (ESBL) and Carbapenemase-Producing Enterobacteriaceae in Four Swiss Refugee Centres

Date Published: January 13, 2017

Publisher: Public Library of Science

Author(s): Rein Jan Piso, Roman Käch, Roxana Pop, Daniela Zillig, Urs Schibli, Stefano Bassetti, Dominik Meinel, Adrian Egli, Yhu-Chering Huang.


The recent crisis of refugees seeking asylum in European countries challenges public health on many levels. Most refugees currently arrive from Syria, Afghanistan, or Eritrea. Data about multidrug resistant bacteria (MDR) prevalence are not present for these countries. However, when entering the European heath care systems, data about colonisation rates regarding highly resistant bacterial pathogens are important.

We performed a cross-sectional screening in four Swiss refugee centres to determine the colonization rates for MRSA and ESBL- and carbapenemase-producing Enterobacteriaceae. We used pharyngeal, nasal, and inguinal swabs for MRSA and rectal swabs and urine for ESBL and carbapenemase screening using standard microbiological procedures. Whole genome sequencing (WGS) was used to determine the relatedness of MRSA isolates with high resolution due to a suspected outbreak.

41/261(15.7%) refugees were colonized with MRSA. No differences regarding the country of origin were observed. However, in a single centre significantly more were colonized, which was confirmed to be a recent local outbreak. 57/241 (23.7%) refugees were colonized with ESBL with significantly higher colonisation in persons originating from the Middle East (35.1%, p<0.001). No carbapenemase producers were detected. The colonisation rate of the refugees was about 10 times higher for MRSA and 2–5 times higher for ESBL compared to the Swiss population. Contact precaution is warranted for these persons if they enter medical care. In cases of infections, MRSA and ESBL-producing Enterobacteriaceae should be considered regarding antibiotic treatment choices.

Partial Text

As poverty, violent conflicts, or persecution of minorities remain important problems throughout the world, migration to countries with stable political situation or higher income will hardly diminish. According to the United Nations Refugee Agency (UNHCR), about 42’500 persons are forced to leave their homes every day due to conflict and persecutions [1]. While the majority of the worldwide 60 million refugees are displaced within the country of origin or distributed in neighbouring countries, developed countries provide asylum to 25% of the global total [1].

The colonisation rates of MDR bacteria is influenced by the regions and populations studied. Our study showed a MRSA carriage rate of 15.7%, which seems to be much higher compared to most European countries with rates of around 0.5–2% [10–12]. However, outside of Europe higher rates have been described. The nasal MRSA carriage rate range from 3.6%[13] (Taiwan janitors workers) to 32% and 25% in outpatients from Egypt and Saudi Arabia, respectively[14]. In our study, no statistically different MRSA carriage rates between different geographical regions were detected. We identified a larger outbreak in one of the Swiss refugees camps and a series of smaller transmission events. As a consequence, the “true” prevalence rate in the country of origin is not reliably assessable in such a cross-sectional study design. WGS analysis provided a high resolution to address this important caveat. When we accounted each outbreak for one (initial) carrier, the estimated prevalence rate of MRSA was 7.7%. We however think that the situation of refugees in the centres facilitates transmission, and outbreaks could also occur in other centres. The reason why the MRSA rate is much higher in the developing rather than in the western world is poorly understood, and data from origin countries of the refugees are scarce. However, our findings confirm some more recent work. In Ethiopia, the overall MRSA colonisation in health care workers was 12.7%[15]. In Eritrea, 9% of all S. aureus from healthy hospital staff was found to be resistant to methicillin[16]. For Syria and Afghanistan, no clear data about prevalence of MRSA exists, but case series with MRSA infections have been described [17,18]. However, the “true” prevalence rate might be over-estimated due to local outbreaks. For physicians treating patients from a refugee centre, local surveillance of refugee centres in regards of MDR bacteria might be very important. In our cross-sectional study, the MRSA colonization rate between refugee centres ranged from 2.4% to 25.4%. The high rate of PVL positive MRSA strains is interesting, and a recent comparison between Eritrean and Non-Eritrean patients with common skin infections found a higher percentage of PVL in MSSA of Eritrean patients as well [19].




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