O168
2-hour Oral Session
One health: resistant Gram-negative bacteria in animals and the environment
House flies and the spread of antimicrobial resistant bacteria: a geospatial analysis
from Münsterland, Germany, 2015
Francis Chinedum Onwugamba1, Ruslan Akulenko2, Robin Köck3, Georg Peters4, Karsten
Becker4, Frieder Schaumburg*5
1Institute
2Center
of Medical Microbiology , University Hospital Münster, Münster, Germany
for Bioinformatics, University of Saarland, Saarbrücken, Germany
3Institute
of Medical Microbiology, University Hospital Münster, University Hospital Münster,
Münster, Germany
4Institute
5Institut
of Medical Microbiology, University Hospital Münster, Münster, Germany
Für Medizinische Mikrobiologie, University Hospital Münster, Münster, Germany
Background: Livestock is considered as one reservoir of extended-spectrum betalactamase
producing Enterobacteriaceae (ESBL-E) and methicillin-resistant Staphylococcus aureus (MRSA).
These pathogens are excreted in the environment where they can be ingested by flies. Since some
flies might cover flight distances of more than 10 kilometres, they could facilitate the dispersal of these
multiresistant bacteria. The aim of this study was to assess the geographical distribution of flies
colonized ESBL-E and MRSA in a livestock-dense region in Germany.
Material/methods: Flies were collected at 80 randomly selected sites in the greater region of Münster
including rural areas (high density of pig production) and urban sites (no pig production) in 2015. Flies
were collected in gaze traps and killed with 70% ethanol. Each fly was mechanically homogenized in
BHI broth. After 18-24h at 35°C, the broths were cultured on Columbia blood agar and selective media
for the detection of S. aureus and ESBL-E.
Phenotypic susceptibility testing was done for each isolate. ESBL-Es were confirmed by double disc
diffusion test and were screened for the presence of blaTEM, blaSHV, blaCTX-M and blaCMY-2. The
phylogroups of E. coli were analysed by PCR. S. aureus were further screened for the presence of
mecA and genotyped (spa typing).
A map was created with “R” using the GPS-data of sampling sites and the respective colonization
rates of flies with ESBL-E.
Results: In total, 1364 flies were analysed. Overall, 13.3% were colonized with ESBL-E (9.0%
(Serratia fonticola, 3.4% Escherichia coli, 0.5% Klebsiella pneumoniae and 0.4% Rhanella aquatilis).
While the overall distribution of ESBL-E was equal in the study region, we found an increased
proportion of ESBL-producing E. coli in the North-Western rural part of the study region (Figure 1). The
predominant phylogroup was A (78.3%) followed by D (15.2%), B1 (4.4%) and B2 (2.2%).
Among all ESBL-producers, blaCTX-M was most abundant (49.7%) followed by blaTEM (7.8%). No isolate
harboured blaSHV or blaCMY-2.
In total, five flies carried S. aureus (0.4%); the only MRSA was found in the city centre of Münster and
had characteristics of livestock-associated MRSA (spa type t011, tetracycline and cotrimoxazole
resistant).
Conclusions: The colonization of house flies with ESBL-E, particularly with E. coli and S. fonticola, is
of importance and more pronounced in certain rural areas with high density of pig production. The
detection of LA-MRSA in an urban area (centre of the major city Münster) raises the question, if flies
contribute to the spread of resistant bacteria from livestock to urban areas.
Figure 1: Mapping of house flies colonized with ESBL-producing E. coli. Each circle represents one
sampling site. The colonization rates are indicated by the colour of circles.