Publikationsdatenbank

Emergence of antimicrobial resistant bacteria in and beyond companion animal medicine (2021)

Art

Hochschulschrift

Autor

Walther, Birgit

Quelle

Berlin, 2021 — 103 Seiten

Sprache

Englisch

Verweise

URL (Volltext): https://refubium.fu-berlin.de/handle/fub188/34231

Kontakt

Institut für Mikrobiologie und Tierseuchen

Robert-von-Ostertag-Str. 7-13
14163 Berlin
+49 30 838 51843 / 66949
mikrobiologie@vetmed.fu-berlin.de

Abstract / Zusammenfassung

This habilitation thesis summarizes the results of 10 scientific publications (references: paper1-10) addressing the topic "Emergence of antimicrobial resistant bacteria in and beyond companion animal medicine”. The first chapter’s intention is to introduce my research area to the reader by providing basic information on the occurrence of antimicrobial resistance (AMR) in bacteria, including general resistance mechanisms, distribution and spread in different ecological environments and the commonly applied clinical classifications relevant for the veterinary medicine field. The following section characterizes the nature of health care associated infections (HAIs) in human and veterinary medicine, including baseline similarities and differences. Subsequently, bacterial pathogens exhibiting particular antibiotic resistances are introduced. Here, a strong focus is set on AMR bacteria frequently associated with HAIs in human and veterinary medicine, which are therefore also considered as “indicator pathogens”. Since β-lactams such as penicillins and cephalosporins are known for their excellent pharmacokinetic properties which is commonly accompanied by a low toxicity for mammals, this group of active substances is of particular importance for antimicrobial treatment of bacterial infectious diseases in both humans and animals. Infections with indicator pathogens harboring resistance towards β-lactams such as Staphylococcus aureus [methicillin resistant S. aureus, (MRSA)] and Escherichia coli [Extended-Spectrum β-Lactamase (ESBL)-producing E. coli (ESBL-E. coli)] are therefore often accompanied by treatment failure. Since antibiotics belonging to this group are among the “first choices” for empirical treatment of infectious diseases, including life-threatening scenarios such as septicemia, collaborative efforts to limit spread of β-lactam resistance are currently an important goal in human- and veterinary medicine. Additional resistances towards further classes of antibiotic substances are frequently associated with MRSA and ESBL-E. coli, leading to a further reduction of therapeutic possibilities in case of infection. In the second chapter, the publications’ results are summarized into four distinct sections. First, the importance of HAI in small animal and equine medicine is illustrated by a literature review considering outbreak events reported so far. A brief historical sketch reveals that problems due to HAI in animal clinics, including cases of zoonotic transmission, have been known since at least 1961. While there have been numerous reports in the past highlighting the technical and scientific developments during the last decades in companion-animal medicine, other important fields such as hygiene management, infection control and occupational safety of employees still lack comparable achievements. The current challenges faced by companion animal clinics are described by studies evaluating the introduction rates for multi drug resistant (MDR) indicator pathogens via colonized horses in a large German university clinic. Overall, n = 341 horses representing distinct medical indications (i.e. 233 horses with "colic symptoms" and 108 with "open wounds") were sampled immediately upon hospital admission. The overall screening results showed that MRSA was detected in 3.5% of the nasal swabs and ESBL-Enterobacteriaceae in 10.3% (mainly ESBL-E. coli) of the fecal samples. Subsequent molecular typing of the isolates showed that all MRSA belonged to sequence type (ST) 398, the currently predominating MRSA lineage identified in clinical samples of horse origin in Europe. In contrast, ESBL-E. coli showed a broad heterogeneity in genomic backgrounds associated with the β-lactam resistance. However, isolates belonging to ST complexes (STC) 1250 (31.7%) and STC10 (19.5%) clearly dominated the collection. Notably, all MRSA and ESBL- E. coli isolates isolated in these studies showed additional antimicrobial resistances to a minimum of three further classes of antibiotics. For assessment of a particular AMR situation in certain bacterial pathogens and/or environments, e.g. if surveillance of AMR in a pathogen causing HAI is needed, an unambiguous species identification is mandatory. Species identification is essential for sound interpretation of antimicrobial sensitivity testing (AST) results and therefore a prerequisite to classify the resistance phenotype of the pathogen correctly. Moreover, species identification is also needed for precise interpretation of additional results gained by other molecular biological methods. A combination of bacterial genome analysis with matrix-assisted laser desorption ionization - time of flight mass spectrometry (MALDI-TOF MS) allowed us to differentiate between the species Staphylococcus intermedius, S. delphini and S. pseudintermedius, which was previously a time-consuming and uncertain approach. Since methicillin resistant S. pseudintermedius (MRSP) are often associated with resistances towards several other antimicrobials, a rapid and reliable species identification using MALDI-TOF MS promotes early and targeted antimicrobial therapy in cases of infection and, if necessary, the initiation of additional hygiene measures to prevent its spread. The following results demonstrate the overwhelming importance of constant adjustments of microbiological diagnostic screening methods for identification of MDR: In 2011, a novel variant of the methicillin resistance gene (later: mecC) was described for MRSA of cattle and human origin. A study we immediately initiated identified mecC-MRSA in clinical samples from horses, dogs, cats, wild animals and rodents. Here, the “weak” expression of the resistance phenotype, now known to be a common feature of mecC-MRSA, was a challenge to classify an isolate as MRS, which was achieved after diagnostic adjustments. As described above, methicillin resistance is often associated with other resistances, e.g. towards tetracyclines, zinc and arsenic compounds. Our detailed analysis of the integration site for the methicillin resistance-mediating mobile genetic element in staphylococci was identified as a "hot spot" for recombination events: We discovered a mosaic-like genomic structure which is prone to integration of mobile resistance-mediating elements of different types. The combination of up-to-date microbiological diagnostics with classical principles of infection epidemiology allowed us to answer important questions concerning possible transmission scenarios for MDR pathogens in companion animal clinics and identify risk factors for MRSA infections in these animals. In 2012, the ability of MRSA to cause HAI in companion animals and its importance as an indicator pathogen for veterinary medicine was already known. At that time however, similar information was not available for ESBL- E. coli. To address this deficit, we retrospectively investigated several cases of serious infections caused by ESBL-E. coli in hospitalized horses in a veterinary clinic. Comparative analysis of molecular typing results obtained for 13 ESBL-E. coli together with the horses’ clinical data revealed a putative spatio-temporal relationship of the isolates, which probably reflected several transmission events between these patients. In another case-control study, we have examined the possible risk factors for wound infections caused by MRSA in horses, dogs and cats. Multivariable logistic regression identified the following variables as risk factors for MRSA infection compared to methicillin susceptible infection: (i) the number of employees working at the veterinary setting (n>10; p<0.001), (ii) antibiotic treatment prior to sampling (systemic: p=0.002; local: p=0.049, both: p=0.011) and (iii), surgical site infection (p<0.001). Spa typing revealed clonal complexes (CC) previously known for hospital-associated lineages spreading in human health-care settings in Germany (i.e. CC5 and CC22) as the dominating lineages among isolates of dog and cat origin. Equine MRSA belonged nearly exclusively to CC398, a CC previously described as a nosocomial pathogen in equine clinical settings. While performing the studies mentioned above, we considered whether transmission of relevant AMR bacteria between pets and their owners (e.g. MRS) occur outside the typical hospital environment, and further, which circumstances and human behavioral patterns might influence such events. Therefore, we investigated different aspects of the human-to-dog relationship together with MRS carriage at a dog show in 2009. We introduced a questionnaire accompanied by a screening program of the nasal swabs of dog owners (108) and their dogs (108) with respect to staphylococci. S. aureus was identified in swabs obtained from 20 (18.5%) humans and two dogs (1.8%), respectively. 15 dogs (13.9%) and six owners (5.6%) harbored S. pseudintermedius, including one MRSP. Interestingly, 68.5% of the dog owners allowed their dog(s) to rest on the sofa, 39.8% allowed their dog(s) to lay on their bed, 93.5% let them lick their hands, and 52.8% let them lick their face. A bivariate analysis of putative risk factors showed that dog owners who kept more than two dogs were significantly more likely to become colonized with S. pseudintermedius than those who kept only one or two dogs (p<0.05). The results section closes with the most recent results, which demonstrated the continuing adaptation of MDR bacteria to the companion animal hospital environment. We showed that equine MRSA-ST398 have acquired different mobile genetic elements (i.e. pathogenicity islands, phages) harboring immune-modulating factors which impede the activation of the complement system, which is among the most important defense measures of the innate immune system towards invasive S. aureus infections. The equine MRSA harbored genes encoding variants of the staphylococcal complement inhibitor protein (SKIN), known for its function in subverting the complement system in plasma of humans, cattle, pigs and horses. These results clearly demonstrated the existence of extended host (EHSG) lineages and their characteristic flexibility with respect to niche- and host-adaptation. Chapter 3’s discussion section presents the general concepts of surveillance of antibiotic consumption, HAI and antibiotic resistance in human medicine, and expands the context with respect to the results of this habilitation thesis. The importance of HAI and MDR pathogens in companion animals for human health is pointed out and current developments in this area are discussed. With regard to integrated surveillance for antibiotic resistance, antibiotic consumption and HAI, a "best practice" model featuring the One Health concept is outlined. This is followed by a discussion of prospects for small animal and horse medicine, taking into account realistic human and financial resources to establish fundamental surveillance structures. The following section summarizes the key factors for HAI prevention in veterinary clinics. In particular, technical progress (i.e. genomics/bioinformatics) in the field of molecular epidemiology has contributed to these findings, a development which is reflected in the publications presented. Finally, possible reasons for the occurrence of MDR pathogens in animal clinics are given, using horse clinics as an example. The occurrence of ESBL-E. coli and MRSA belonging to EHSG-lineages explain why further research on these MDR pathogens is necessary, especially with respect to further host- and niche-adaptation. In summary, the publications presented make it clear that research on EHSG pathogens and their importance has only just begun. New methods of molecular epidemiology currently (2020) offer completely new opportunities to study adaptive changes in bacterial genomes in large, representative studies. However, care is needed with respect to establishment of a suitable, representative isolate collection, which is of crucial importance for the validity of the studies. Integrated One Health surveillance, as outlined in this document, could reflect the current importance of MDR EHSG pathogens for human and veterinary medicine. An integrated approach would lead to a better understanding of the bacterial adaptation processes to ecological niches as a whole and reveal new, epidemiologically significant developments in a timely manner, whereas currently we can often only trace these types of developments in retrospect. References paper1 Walther, B., K. Tedin, and A. Lübke-Becker, Multidrug-resistant opportunistic pathogens challenging veterinary infection control. Vet Microbiol, 2017. 200: p. 71-78. paper2 Walther, B., Klein, K.S., Barton, A.K., Semmler, T., Huber, C., Wolf, S.A., Tedin, K., Merle, R., Mitrach, F., Guenther, S., Lübke-Becker, A., Gehlen, H., 2018. Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli and Acinetobacter baumannii among horses entering a veterinary teaching hospital: The contemporary "Trojan Horse". PLoS One 13, e0191873. paper3 Murugaiyan, J., Walther, B., Stamm, I., Abou-Elnaga, Y., Brüggemann-Schwarze, S., Vincze, S., Wieler, L.H., Lübke-Becker, A., Semmler, T., Roesler, U., 2014. Species differentiation within the Staphylococcus intermedius group (SIG) using a refined MALDI-TOF MS database. Species differentiation within the Staphylococcus intermedius group using a refined MALDI-TOF MS database. Clin Microbiol Infect 20(10): 1007-1015. paper4 Walther, B., Wieler, L.H., Vincze, Sz., Antão, E.-M., Brandenburg, A., Stamm, I., Kopp, P.A., Kohn, B., Semmler, T., Lübke-Becker, A., 2012b. MRSA variant in companion animals. Emerg Infect Dis 18, 2017-2020. paper5 Semmler, T., Harrison, E.M., Lübke-Becker, A., Ulrich, R. G., Wieler, L. H., Guenther, S., Stamm, I., Hanssen, A. M., Holmes, M. A., Vincze, Sz., Walther, B. 2016. A Look into the Melting Pot: The mecC-Harboring Region Is a Recombination Hot Spot in Staphylococcus stepanovicii." PLoS One 11(1): e0147150. paper6 Walther B, Lübke-Becker A, Stamm I, Gehlen H, Barton AK, Janssen T, Wieler LH, Guenther S. Suspected nosocomial infections with multidrug resistant E. coli, including extended-spectrum beta-lactamase (ESBL)-producing strains, in an equine clinic. Berl Muench Tieraerztl Wochenschr. 2014, 127(11-12):421-427. paper7 Vincze S., Brandenburg, A.G., Espelage W., Stamm I., Wieler L. H., Kopp P. A., Lübke-Becker A., Walther B., 2014. Risk factors for MRSA infection in companion animals: Results from a case-control study within Germany. Intl J Medical Microbiol 10/2014; DOI: 10.1016/j.ijmm.2014.07.007 paper8 Walther, B., Hermes, J., Cuny, C., Wieler, L.H., Vincze, S., Abou Elnaga, Y., Stamm, I., Kopp, P.A., Kohn, B., Witte, W., Jansen, A., Conraths, F.J., Semmler, T., Eckmanns, T., Lübke-Becker, A., 2012a. Sharing more than friendship--nasal colonization with coagulase-positive staphylococci (CPS) and co-habitation aspects of dogs and their owners. PLoS One 7, e35197 paper9 Walther, B., Monecke, S., Ruscher, C., Friedrich, A.W., Ehricht, R., Slickers, P., Soba, A., Wleklinski, C.G., Wieler, L.H., Lübke-Becker, A., 2009a. Comparative molecular analysis substantiates a zoonotic potential of equine Methicillin- resistant Staphylococcus aureus (MRSA). J Clin Microbiol. 47, 704-710. paper10 Walther B., Klein K.S., Barton A.K., Semmler T., Huber C., Merle R., Tedin K., Mitrach F., Lübke-Becker A., Gehlen H. Equine Methicillin-Resistant Sequence Type 398 Staphylococcus aureus (MRSA) Harbor Mobile Genetic Elements Promoting Host Adaptation. Front Microbiol 2018, 9:2516.