Contract grant sponsor: Deutsche Forschungsgemeinschaft; Contract grant numbers: EI 247/8–1, LE 1813/4–1; Contract grant sponsor: BMBF; Contract grant numbers: 01KI1009A, 0315832A.
Drug-Resistant Human Staphylococcus Aureus in Sanctuary Apes Pose a Threat to Endangered Wild Ape Populations
Article first published online: 21 AUG 2012
© 2012 Wiley Periodicals, Inc.
American Journal of Primatology
Volume 74, Issue 12, pages 1071–1075, December 2012
How to Cite
SCHAUMBURG, F., MUGISHA, L., PECK, B., BECKER, K., GILLESPIE, T. R., PETERS, G. and LEENDERTZ, F. H. (2012), Drug-Resistant Human Staphylococcus Aureus in Sanctuary Apes Pose a Threat to Endangered Wild Ape Populations. Am. J. Primatol., 74: 1071–1075. doi: 10.1002/ajp.22067
- Issue published online: 20 NOV 2012
- Article first published online: 21 AUG 2012
- Manuscript Accepted: 8 JUL 2012
- Manuscript Revised: 4 JUN 2012
- Manuscript Received: 22 APR 2012
- Deutsche Forschungsgemeinschaft. Grant Numbers: EI 247/8–1, LE 1813/4–1
- BMBF. Grant Numbers: 01KI1009A, 0315832A
- Staphylococcus aureus;
- great apes;
Reintroduction of sanctuary apes to natural habitat is considered an important tool for conservation; however, reintroduction has the potential to endanger resident wild apes through the introduction of human pathogens. We found a high prevalence of drug-resistant, human-associated lineages of Staphylococcus aureus in sanctuary chimpanzees (Pan troglodytes) from Zambia and Uganda. This pathogen is associated with skin and soft tissue diseases and severe invasive infections (i.e. pneumonia and septicemia). Colonization by this bacterium is difficult to clear due to frequent recolonization. In addition to its pathogenic potential, human-related S. aureus can serve as an indicator organism for the transmission of other potential pathogens like pneumococci or mycobacteria. Plans to reintroduce sanctuary apes should be reevaluated in light of the high risk of introducing human-adapted S. aureus into wild ape populations where treatment is impossible. Am. J. Primatol. 74:1071-1075, 2012. © 2012 Wiley Periodicals, Inc.
Animal sanctuaries care for and protect endangered animals confiscated by national authorities from animal dealers or private holders. Reintroduction of wildlife housed in sanctuaries to their natural habitat is considered an important conservation tool for endangered species; however, for sanctuaries to have a net positive effect for species conservation, it is critical that reintroduction efforts do not endanger resident wildlife populations [Beck et al., 2007]. The close phylogenetic relationship between humans and apes, coupled with the high rates of human–ape contact characteristic of sanctuaries (i.e., especially infant and juvenile apes receiving comfort and play from humans which is necessary to ensure their survival and development, Figure 1) results in an exceptionally high potential for pathogen exchange [Calvignac-Spencer et al., 2012; Gillespie et al., 2008; Leendertz et al., 2006]. In contrast to wild apes, sanctuary apes may acquire protective antibody levels against human pathogens since they receive medical treatment when severe symptoms are observed. Although no studies have been conducted to determine the relative risk of ape reintroductions exposing naïve wild conspecifics to human-adapted pathogens, several sanctuaries have reintroduced great apes in areas with existing communities of wild conspecifics and the majority of ape sanctuaries are planning and/or implementing reintroductions [Faust et al., 2011].
Staphylococcus aureus is a common bacterium that asymptomatically colonizes humans and animals but can also cause a wide range of mild-to-severe diseases including skin and soft tissue infection, endocarditis, pneumonia, and sepsis [Wertheim et al., 2005]. Colonized individuals have a markedly higher risk to develop an S. aureus infection [von Eiff et al., 2001]. Decolonization of S. aureus requires nasal application of mupirocin ointment and a strict hygiene regime or antibiotic treatments but recolonization is frequent [Lucet & Regnier, 2010].
To evaluate the risk of S. aureus transmission from humans to animals, we compared resistance pattern, genotypes, and the possession of Panton-Valentine leukocidin of S. aureus isolates from chimpanzees (Pan troglodytes) of two characteristic ape sanctuaries in Uganda and Zambia with isolates from sanctuary veterinarians and data published on classic human S. aureus isolates. We found a high proportion of typically human-related S. aureus in sanctuary apes and conclude that reintroduction of sanctuary apes poses a risk to naïve wild populations through the introduction of human-adapted pathogens.
In a cross-sectional study, we collected nasal swabs from 23 chimpanzees housed in Chimfunshi Wildlife Orphanage, Chingola, Zambia in 2011. These swabs were stored in Amies medium until culture. In addition, oral swabs were obtained from 39 chimpanzees from Ngamba Island Chimpanzee Sanctuary, Entebbe, Uganda in 2007. These swabs were stored in RNAlater (Qiagen) in liquid nitrogen until culture. Swabs from animals were taken as part of routine health checks at participating sanctuaries and analyzed on request. The research complied with protocols approved by the Institutional Animal Care Committees of each sanctuary and country.
We also collected nasal samples from veterinarians working in various African great ape sanctuaries (N = 30) during a conference in Johannesburg, South Africa in 2010. Nasal swabs were stored in Amies medium until culture within 5 days.
Ethical clearance for human participation was obtained from the independent ethics committee of the medical faculty, University of Münster (2009–227-b-S). Informed consent was obtained from all participants.
The noninvasive samples from animals were collected in accordance with the international guidelines and under the permission of the national authorities. This research adhered to the American Society of Primatologists principles for the ethical treatment of primates. The results of this study have been shared with the authorities of the sanctuaries, which exchange information with the respective governmental bodies.
Samples were cultured on Columbia blood agar and SAID agar (bioMérieux, Marcy l'Etoile, France). We used Vitek2 automated systems (bioMérieux) for species identification and susceptibility tests. Species of S. aureus was confirmed by 16s rRNA gene sequencing [Becker et al., 2004]. Resistance against penicillin and methicillin was confirmed by detection of BlaZ and mecA, respectively [Becker et al., 2006; Kaase et al., 2008]. Genes encoding Panton-Valentine leukocidin (lukF-PV and lukS-PV) were detected as published [Lina et al., 1999]. Sequence-based typing of the hypervariable region of S. aureus protein A (spa typing) and multilocus sequence typing (MLST) was performed for each isolate [Enright et al., 2000; Mellmann et al., 2006]. In general, spa typing is considered to be more discriminatory than MLST [Strommenger et al., 2006]. To assign the MLST ST to a known clonal complex, we compared the ST of our study with the STs of the whole MLST database of S. aureus using the stringent group definition of six shared identical alleles (http://saureus.mlst.net). Different spa types were clustered in spa clonal complexes (spa CC) using the BURP algorithm implemented in Ridom StaphType software (Version 2.2.1) with preset parameters as published [Mellmann et al., 2007].
S. aureus was found in 36 chimpanzees (58%) and 10 humans (33%). Resistance rates were slightly higher in isolates from humans compared to chimpanzees for penicillin (100% vs. 75%), oxacillin (20% vs. 0%), trimethoprim/sulfamethoxazol (SXT; 40% vs. 3%), erythromycin (10% vs. 3%), and clindamycin (10 vs. 3%). Higher resistance rates in animals compared to humans were found for tetracyclin (36% vs. 20%). No resistance was detected to glycopeptides, fluorquinolones nitrofurantoin, fosfomycin, rifampicin, and aminoglycosides (Table I). The resistance to antibiotic agents was not restricted to specific clonal lineages but was present in all clonal complexes (Table I).
|S. aureus from humans (n = 10)||S. aureus from chimpanzees (n = 36)|
|Antibiotic resistance||Antibiotic resistance|
|MLST-CC||ST||Spa-CC||Spa type||Isolates (n)||pattern||Isolates (n)||pattern|
Genotypes and Panton-Valentine Leukocidin
Genotypes of S. aureus isolates were compared using multilocus sequence typing (MLST) and typing of the hypervariable region of protein A (spa typing). In total, eight different spa types (t012, t021, t122, t186, t279, t701, t1855, t1877) were found in humans compared to nine different types in animals (t084, t224, t279, t304, t934, t1247, t2864, t7722, t7723). Noteworthy, a veterinarian and chimpanzee from the same sanctuary shared the same spa type (t279, Table I).
The predominant MLST sequence type (ST) was ST15 (30%, N = 3) in humans and ST2168 (44%, N = 16) in chimpanzees, both belonged to MLST clonal complex (CC) 15 but were clustered in different subgroups (Table I). Isolates belonging to the classical human ST15, the most prevalent ST in sub-Saharan Africa, were also found in chimpanzees (13.9%, N = 5). Other human-related STs from chimpanzees included ST80 (25%, N = 9) and ST101 (5.7%, N = 2).
The Panton-Valentine leukocidin (PVL) was markedly more frequent in isolates from chimpanzees than from humans (28% vs. 10%). In chimpanzees, PVL positive isolates were always associated with ST80 (90%, N = 9) and ST2178 (10%, N = 1). The human PVL-positive S. aureus isolate belonged to ST30.
We compared characteristics of S. aureus from sanctuary chimpanzees to strains isolated from sanctuary veterinarians and published data on the basis of resistance pattern to antibiotic agents, genotypes, and the presence of Panton-Valentine leukocidin. We found higher resistance rates for penicillin, oxacillin, trimethoprim/sulfamethoxazol, erythromycin, and clindamycin in the veterinarians (Table I). This is not surprising as these resistance rates are consistent with other reports of human S. aureus in Africa [Okon et al., 2009; Schaumburg et al., 2011]. In contrast, it was surprising that resistance rates were high in isolates from animals, as wild great apes and monkeys very rarely display appreciable antibiotic resistance [Schaumburg et al., 2012]. In a study of S. aureus in wild apes and monkeys in Côte d'Ivoire and Gabon, penicillin resistance was only found in one isolate derived from a habituated chimpanzee that had received antibiotic treatment before (Côte d'Ivoire) and all isolates were susceptible to aminoglycosides, lincosamides, fluorquinolones glycopeptides, nitrofurantoin, fosfomycin, rifampicin, tetracycline, trimethoprim/sulfamethoxazol [Schaumburg et al., 2012]. The high rates of antibiotic resistance observed in our data set may be due to frequent treatment of sanctuary animals with antibiotics or transmission of resistant isolates from humans to animals during close contact associated with care-giving or a combination of both. Infant and juvenile sanctuary apes require extensive care and contact from human care-givers to provide the body warmth, socialization, and play a mother would provide in the wild (Fig. 1). In support of such linkages for transmission, we found that 45% of all S. aureus from sanctuary chimpanzees in both study sites (Uganda and Zambia) were colonized with isolates belonging to known human-related STs (ST15, ST80, ST101). These STs have never been detected in wild apes [Schaumburg et al., 2012]. In further support of transmission of S. aureus from humans to apes, direct transmission was evident in one case as a veterinarian and a chimpanzee from the same sanctuary shared the same spa-type t279 (Table I). Considering that sanctuary veterinarians represent a small proportion of all personnel caring for sanctuary apes, frequent exchange of S. aureus between humans and great apes is likely the norm.
The high proportion of PVL positive isolates from chimpanzees further supports human-to-animal transmission of human-adapted S. aureus, as PVL is frequent in S. aureus from humans but uncommon in wildlife in sub-Saharan Africa [Breurec et al., 2011; Schaumburg et al., 2012]. Here, we used PVL as a marker for human S. aureus of African origin. To the best of our knowledge, no data are available on the pathogenic potential of PVL in great apes; however, in humans, PVL is associated with severe skin and soft-tissue infection and necrotizing disease such as necrotizing pneumonia [Lina et al., 1999]. In addition, it is a string cytotoxic factor for human neutrophils [Löffler et al., 2010].
Given the high percentage of chimpanzees with classical human STs, which all have been associated with disease development, reintroductions of chimpanzees carrying human S. aureus into areas inhabited by conspecifics have a high probability of exposing naïve wild great apes to pathogenic strains of S. aureus. Transmission is theoretically also possible through human–ape overlap associated with activities such as tourism and research; however, S. aureus transmission requires direct contact or contact with contaminated items. Although such conditions historically occurred at research and tourist sites, they have become rare as increased awareness of disease risks has led to policy changes at all sites reducing human–ape interaction.
Once established in a population, S. aureus would be impossible to monitor and control since symptoms cannot be observed in unhabituated individuals and daily nasal application of mupirocin ointment and antibiotic treatment over several days is not feasible at the population level. Further, clearing infected groups of apes prior to reintroduction is unrealistic since apes cannot adhere to the required hygiene regime for S. aureus decolonization. Strict health management would be required to ensure “human-pathogen-free” great ape groups designated for reintroduction. In such a scenario, candidate reintroduction apes could be screened for human S. aureus strains as well as other human-related pathogens. A prerelease quarantine could then be established and individuals who repeatedly test negative over several months could be considered at a lower risk for reintroduction. Apes colonized with human pathogens could be isolated and treated repeatedly, e.g. with antibiotics (tetracycline, rifampicin, cotrimoxazol, vancomycin) and only returned to the general sanctuary population once the infection has cleared. Such individuals could later be reconsidered to join the prerelease quarantine to advance toward reintroduction. A spontaneous decolonization without medical intervention might also occur in animals that are only intermittently colonized. Such individuals could also join the prerelease quarantine group. Such protocols are needed to assure that reintroductions adhere to the primary mandate of the IUCN reintroduction guidelines: it is critical that reintroduction efforts do not endanger resident wildlife populations [Beck et al., 2007].
Implementing such a process would be challenging since great ape social structure is complex and isolating individuals and changing group composition may result in aggression, anxiety, depression, and stress, which in return may alter temporarily an individual's immune function
Further data are needed to understand carriage and disease development in sanctuary great apes to pinpoint the effective risk for wild populations. Also, guidelines for the management of sanctuary great apes carrying human S. aureus strains will need to be developed. However, S. aureus is just one out of many human pathogens that may be carried chronically by sanctuary apes. Data on the range of human pathogens carried by sanctuary great apes, an assessment of their impact on ape health, and an assessment of their potential to spread into wild populations are needed.
To pinpoint the spread of human S. aureus into wild populations through re-introduction, it will be important to track re-introduced great apes, wild individuals of groups joined by re-introduced apes, and neighboring great ape communities since pathogens may spread through immigrating individuals for all great ape species. Noninvasive tools for such studies are available [Schaumburg et al., 2012].
This is an empirical demonstration that ape reintroduction programs may pose a risk to wild populations. In addition to its pathogenic potential, S. aureus serves as an indicator of transmission potential for other human-adapted pathogens. In light of these findings, preparatory measures for ape reintroductions must be enforced and a cost benefit analysis should be made for each project before initiating reintroduction programs. In a world of ever-growing human-wildlife overlap, it is critical that pathogen-related risks for endangered wildlife populations are better understood and that innovative approaches are adopted to avoid introduction of such pathogens into wild populations.
For samples, we thank the participants of the PASA veterinary workshop. We thank the sanctuaries from Uganda and Zambia for support during sample collection and shipment. We also thank the authorities from the respective countries for permission for exporting and importing samples. For comments and Figure 1, we thank S.A. Leendertz. The study was funded in parts to G.P. and F.H.L by the Deutsche Forschungsgemeinschaft (DFG, EI 247/8–1, LE 1813/4–1) and to K.B. by the BMBF (01KI1009A and 0315832A).
The authors declare that they have no competing interests.
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