Slov Vet Res 2016; 53 (1): 43-8 UDC 615.33.015.8:579.842.14:598.1
Original Scientific Article
THE PREVALENCE AND ANTIMICROBIAL RESISTANCE OF Salmonella SPECIES ISOLATED FROM CAPTIVE REPTILES AT LJUBLJANA ZOO
Silvia Barazorda Romero1*, Pavel Kvapil3, Alois Čižek2, Zdenek Knotek1
1Avian and Exotic Animal Clinic; 2Department of Infectious Diseases and Microbiology, Faculty of Veterinary Medicine, University of Veterinary and Pharmaceutical Sciences Brno, Palackeho tr. 1946/1, 612 42 Brno, Czech Republic, 3Ljubljana Zoo, Večna pot 70, 1000 Ljubljana Slovenia.
Corresponding author, E-mail: silviabr@seznam.cz
Summary: Cloacal swabs from 74 healthy reptiles at Ljubljana Zoo were examined for the presence of salmonellae. Thirty nine reptiles underwent at least one antimicrobial treatment 24 - 48 months before sample collection. The identification of salmonellae was performed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry, and positive strains were serotyped. Salmonellae were found in 29.7% of all reptiles investigated, in 55.6% of reptiles kept with regularly direct contact with zoo visitors, and in 26.2% of reptiles kept strictly in terraria. The isolation prevalence was 38.6%, 18.2% and 12.5% in snakes, lizards and chelonians, respectively. Salmonella enterica subspecies entericawas the most common (63.6%) followed by subspecies diarizone (31.8%) and subspecies arizonae (4.5%). The Salmonella enterica subsp. enterica serotypes Infantis 6,7,14:r:1,5 and Uzaramo 1,6,14,25:z4,z24- were detected in 27.3% and 36.4% of Salmonella positive samples, respectively. Resistance to antimicrobial agents was found in 9% of strains. A high percentage (63.6%) of Salmonella positive reptiles at Ljubljana Zoo shed serotypes that are known to be causative agents of human salmonellosis. This is the first documented isolation of Salmonella enterica subsp. diarizonae, serotype Illb 57:k:e,n,x,z15 from captive reptiles.
Key words: captive reptiles; salmonellosis; antibiotic resistance; MALDI-TOF MS
Introduction
As a source of educational programs many zoos and rescue centres traditionally provide opportunities to visitors for direct contact and handling with certain captive reptiles. Reptiles are important reservoirs of salmonellae as they harbour these bacteria without showing any clinical signs (1, 2). Carriage rates of Salmonella spp. in captive reptiles vary between 50% and 86% (3, 4, 5). Factors associated with poor husbandry, systemic
Received: 3 March 2015 Accepted for publication: 13 July 2015
viral infections and intestinal parasitism in reptile collections may lead to reactivation of clinical salmonellosis and bacterial shedding (6, 7, 8). Cases of human salmonellosis associated with pet reptiles are known and have been well documented (9, 10, 11). The infection can be transmitted to humans by direct contact or through an environment contaminated with salmonellae (2, 12).
Salmonellae are often resistant to ampicillin, tetracycline, colistin sulphate, streptomycin, sulfamethoxazole/trimethoprim and nalidixic acid (5, 13, 14). For that reason care must be taken with the use of antibiotics as it may result in the development of antibiotic resistance (6).
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S. Barazorda Romero, P. Kvapil, A. Cizek, Z. Knotek
The purpose of this study was to investigate the prevalence and antimicrobial resistance of salmonellae isolated from captive reptiles at Ljubljana Zoo.
Materials and methods
Animals
Cloacal swabs from 74 clinically healthy reptiles at Ljubljana Zoo, Slovenia, were examined for the presence of salmonellae. Sixty-seven reptiles (19 lizards, 42 snakes, six chelonians) were captive bred, and seven reptiles (three lizards, two snakes, two chelonians) were rescued from the wild. In the period of sample collection all reptiles were kept at the Ljubljana Zoo for more than one year. From the 74 reptiles, 39 underwent at least one five-day fluoroquinolone treatment against salmonellae 24 - 48 months before the study. Nine reptiles have been used for teaching purposes and have had contact with visitors, whereas the remaining 65 reptiles did not have any contact with visitors.
Sample collection
Each animal was manually restrained and a sterile cotton swab (Copan Italia S.p.A, Italy) was gently inserted and turned inside the reptile's cloaca. Samples were transported in Amies transport medium (Copan Italia S.p.A, Italy) and kept in 5 °C until processed, 48-120 hours after collection.
Cultivation, identification and serotyping of
salmonellae strains
Cloacal swabs were placed into 5 ml of buffered peptone water (BPW) (Oxoid Ltd., UK) and incubated overnight at 37 °C. Upon incubation, 0.1ml of BPW was dropped onto modified semisolid Rappaport-Vassiliadis agar (Oxoid Ltd., UK), incubated at 41.5 °C and inspected for typical growth (halo zone around the inoculated drop) at 24 and 48hrs. In parallel, Xylose lysine deoxycholate agar (Oxoid Ltd., UK) was inoculated with the positive samples and incubated at 37 °C overnight to select Salmonella isolates. Suspect Salmonella colonies were cultured on blood agar, incubated at 37 °C for 24 hours, and then confirmed by matrixassisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS, Microflex LT,
Bruker Daltonics, Germany). Salmonella isolates were serotyped by slide agglutination assay using commercial O and H antisera (BioRad, France; Denka Seiken, Japan). The identification of serotypes was carried out according to Kauffmann-White-Le Minor scheme (15).
Antimicrobial susceptibility test
Salmonella isolates were tested for susceptibilities to amoxicillin/clavulanic acid (30 ^g), ampi-cillin (10 ^g), ceftazidime (30 ^g), chloramphenicol (30 ^g), tetracycline (30 ^g), colistin sulphate (10 pg), streptomycin (10 ^g), neomycin (30 pg), gen-tamicin (10 ^g), sulfonamide compounds (300 ^g), sulfamethoxazole/trimethoprim (25 ^g), ciprofloxacin (5 ^g), enrofloxacin (5 pg) and marbofloxacin (5 pg) (Oxoid Ltd., UK), using antibiotic disk diffusion method (16).
Results
Salmonellae were found in 29.7% of all reptiles investigated (Table 1), in 55.6% of reptiles kept with regularly direct contact with zoo visitors, and in 26.2% of reptiles kept without direct contact with visitors. The prevalence of salmonellae in reptiles with previous antimicrobial treatment and without antimicrobial treatment was 35.9% and 62.9% respectively. Snakes had the highest prevalence (38.6%) of salmonellae. Salmonella enterica subspecies enterica was the most common (63.6%), followed by the subspecies diarizone (31.8%) and subspecies arizonae (4.5%). In each positive individual one serotype was isolated. The Salmonella enterica subsp. enterica serotypes Infantis 6,7,14:r:1,5 and Uzaramo 1,6,14,25:z4,z24-were detected in 27.3% and 36.4% of Salmonella positive samples, respectively.
Resistance to antimicrobial agents was found in 9% of Salmonella strains. Resistance to ampicillin and amoxicillin/clavulanic acid was detected in one strain of Salmonella enterica subsp. enterica serotype Infantis 6,7,14:r:1,5 isolated from a Zamenis longissimus, and resistance to streptomycin was detected in one strain of Salmonella enterica subsp. diarizonae serotype Illb 57:k:e,n,x,z15 isolated from a Vipera ammodytes. Both snakes were previously treated with fluoroquinolones. Strains of Salmonella enterica subsp. enterica serotype Infantis 6,7,14:r:1,5,
Table 1: The prevalence of Salmonella species and serotypes isolated from reptiles at Ljubljana Zoo
_	.	Number of samples	Samples positive	_ , „
Reptile species	^ ,	_ _ ,r „	,„,,	Salmonella serotypes
v *	collected	for Salmonella spp. (%
Lizards	22	4 (18.2%)	
Pogona vitticeps	5	0	
Chlamydosaurus kingii	2	0	
Lacerta viridis	1	0	
Lacerta agilis	7	2	Infantis 6,7,14:r:l,5
Furcifer pardalis	2	0	
Iguana iguana	1	1	Illb 65:z10:e,n,x,z15
Ophisaurus apodus	4	1	Illb 57:k:e,n,x,z15
Snakes	44	17 (38.6%)	
Python regius	2	0	
Python bivtitatus	2	0	
Pantherophis guttatus Elaphe quatuorlineata	10 3	4 1	Infantis 6,7,14:r:l,5*, Illb 53:z10:z35, Ilia 53:z4,z23:- Illb 53:z10:z35
Zamenis longissimus	3	2	Infantis 6,7,14:r:l,5, Uzaramo l,6,14,25:z4,zQ4-
Pantherophis emoryi	6	3	Uzaramo l,6,14,25:z4,zQ4-*, Illb 53:z1Q:z35
Lampropeltis triangulum	1	0	
Thamnophis sirtalis	6	3	Uzaramo l,6,14,25:z4,zQ4-
Nat rix tessellata	2	0	
Nat rix not rix	4	1	Infantis 6,7,14:r:l,5
Vipera berus bosniensis	2	1	Illb 53:z10:z35
Vipera ammodytes	2	2	Illb 57:k:e,n,x,z15, Uzaramo l,6,14,25:z4,zQ4-
Vipera aspis francisciredi	1	0	
Chelonians	8	1 (12.5%)	
Geochelone sulcata	2	0	
Emys orbicularis hellenica	1	0	
Emys orbicularis orbicularis	4	0	
Trachemys scripta scripta	1	1	Uzaramo l,6,14,25:z4,zQ4-*
Total	74	22 (29.7%)	
* Serotypes isolated from reptiles with direct contact with zoo visitors
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S. Barazorda Romero, P. Kvapil, A. Cizek, Z. Knotek
Salmonella enterica subsp. enterica serotype Uzaramo 1,6,14,25:z4,z24-, Salmonella enterica subsp. diarizonae serotype Illb 53:z10:z35 and Salmonella enterica subsp. diarizonae serotype Illb 57:k:e,n,x,z15 isolated from a Pantherophis guttatus, Zamenis longissimus, Pantherophis emoryi and Ophisaurus apodus respectively, were intermediate susceptible to streptomycin.
Discussion
Despite modern zoos make efforts to provide suitable conditions for captive reptiles, the enclosure design would hardly replicate the reptile's natural habitat. Keeping reptiles in groups leads to intense competition for basking spots and food items, sexual frustration and increased exposure to faeces (17). In comparison with the results of Martínez Barreda et al. (3), Geue and Loschner (4) and Corrente et al. (5) who assumed shedding rates up to 50% in captive reptiles, a relatively low prevalence of Salmonella spp. (29.7%) was found in our study. This difference may be due to the fact that the animals in the present study were only sampled once, and the excretion of Salmonella spp. is intermittent (18, 19). The higher frequency of salmonellae isolation in snakes than in lizards and chelonians is in agreement with previously published data (4, 14, 20).
In the present study Salmonella subspecies enterica was the most common (63.6%) followed by the subspecies diarizone (31.8%) that was isolated mainly in snakes with a history of previous antimicrobial treatment.
Mitchell and Shane (6) and Johnson-Delaney (8) remarked that antimicrobials may merely suppress the excretion of salmonellae without their complete elimination, and antimicrobial treatment in reptiles without any clinical symptoms of salmonellosis can promote the emergence of antimicrobial resistant strains. This statement is accordance with our finding because more than one third of reptiles treated with fluoroquinolones were found positive for salmonellae. Generalized use of antimicrobial agents in reptiles or in their environment is not recommended (21).
A high percentage (63.6%) of Salmonella spp. positive reptiles at Ljubljana Zoo shed serotypes that are known to be causative agents of clinical salmonellosis. Salmonella enterica subsp. enterica serotype Infantis 6,7,14:r:1,5 belongs to the top ten
Salmonella serotypes that may cause gastroenteritis in humans (22), and multidrug-resistant clones of this serotype have been already detected (23). Salmonella enterica subsp. enterica serotype Uzaramo 1,6,14,25:z4,z24- has been related to a case of reptile-associated human salmonellosis (24). To our knowledge this study is the first to document isolation of Salmonella enterica subsp. diarizonae serotype IIIb 57:k:e,n,x,z15 from captive reptiles.
Results of this study could help to improve knowledge about the prevalence of Salmonella spp. in zoo reptilian collections. It is clear that proper hygiene practices are needed in order to minimize the infectious risk for zoo personnel and visitors. Recommendations for reducing the risk of transmission of Salmonella to humans from reptiles include the following: (i) Veterinarians and pet store owners should provide information to clients about the risk of acquiring salmonellosis from reptiles. (ii) People with immature or weakened immune system, including children, pregnant women, elderly people and immunocompromised persons should avoid contact with reptiles. (iii) People should wash their hands after handling these animals or their environments. (iv) Kitchen sinks should not be used to bath reptiles or to wash their dishes, cages or aquariums. (v) Reptiles should not be allowed to roam freely throughout a home. (vi) Other household pets, such as dogs and cats, should not be in contact with reptiles, their cages, faeces or feed to reduce spread of transmission of salmonellae. (vii) Zoos and exhibits should be equipped with adequate hand-washing facilities, and food and drinking should not be allowed in animal-contact areas. (viii) Good care of household reptiles should be given to reduce stress, which may cause the excretion of salmonellae (25).
Future studies will be extended to identify sources of infection and transmission routes of salmonellae in reptiles at Ljubljana Zoo.
Acknowledgments
The authors thank to Zdenka Ban Fischinger and Dr. Marjan Kastelic from the Ljubljana Zoo, and Dr. Ludmila Kohoutova from the VFU Brno for their help. The study was partially supported by IMA (IMA 2014 - FVL - 05, University of Veterinary and Pharmaceutical Sciences Brno) and CEITEC (CZ.1.05/1.1.00/02.0068, European Regional Development Fund).
The prevalence and antimicrobial resistance of Salmonella species isolated from captive reptiles at Ljubljana Zoo
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POJAVLJANJE VRST Salmonella IN NJIHOVA ODPORNOST PROTI PROTIMIKROBNIM SREDSTVOM V IZOLATIH PLAZILCEV V ZOO LJUBLJANA
S. Barazorda Romero, P. Kvapil, A. Čfžek, Z. Knotek
Povzetek: Kloakalni brisi 74 zdravih plazilcev so bili v ljubljanskem živalskem vrtu pregledani na prisotnost salmonel. Devetintrideset plazilcev je bilo zdravljenih z vsaj enim protimikrobnim zdravilom 24 - 48 mesecev pred zbiranjem vzorcev. Določanje salmonel je bilo opravljeno s pomočjo masne spektrometrije MALDI (ionizacija v matriksu z lasersko desorpcijo) ter s pomočjo serotipizacije pozitivnih sevov. Salmonele so bile ugotovljene v 29,7 % vseh preiskanih plazilcev, in sicer pri 55,6 % plazilcev, ki so v rednem neposrednem stiku z obiskovalci živalskega vrta, in pri 26,2 % plazilcev, ki so nastanjeni izključno v terarijih. Okuženih je bilo 38,6 % kač, 18,2 % kuščarjev in 12,5 % želv. Najpogosteje je bila izolirana Salmonella enterica, podvrsta enterica (63,6 %), sledita pa podvrsti diarizone (31,8 %) in arizonae (4,5 %). Salmonella enterica, subsp. enterica serotipa Infantis 6,7,14: r: 1,5 je bila odkrita pri 27,3 %, seroptipa Uzaramo 1,6,14,25: z4, z24- pa v 36,4 %. Odpornost proti protimikrobnim sredstvom je bila ugotovljena pri 9 % sevov. Visok odstotek (63,6 %) na salmonelo pozitivnih plazilcev v ljubljanskem živalskem vrtu je bil okužen z enim izmed serotipov, ki so znani povzročitelji salmoneloze pri ljudeh. To je prva dokumentirana izolacija Salmonella enterica subsp. diarizonae, serotip IIIb 57: K: E, n, x, Z15 pri plazilcih v ujetništvu.
Ključne beside: plazilci v ujetništvu; salmoneloza; odpornost proti antibiotikom; MALDI-TOF MS