Prevalence and Antimicrobial Susceptibility of Salmonellae Isolates from Reptiles in Taiwan

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Journal of Veterinary Diagnostic

http://vdi.sagepub.com/content/22/1/44The online version of this article can be found at:

DOI: 10.1177/104063871002200107

2010 22: 44J VET Diagn Investand Chao-Chin Chang

n-Yu Chen, Wan-Ching Chen, Shih-Chien Chin, Yen-Hsueh Lai, Kwong-Chung Tung, Chien-Shun Chiou, Yuan-MPrevalence and Antimicrobial Susceptibility of Salmonellae Isolates from Reptiles in Taiwan

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Prevalence and antimicrobial susceptibility of salmonellae isolates from

reptiles in Taiwan

Chun-Yu Chen, Wan-Ching Chen, Shih-Chien Chin, Yen-Hsueh Lai, Kwong-Chung Tung,Chien-Shun Chiou, Yuan-Man Hsu, Chao-Chin Chang1

Abstract. Pets, including reptiles, have been shown to be a source ofSalmonella infection in humans. Dueto increasing popularity and variety of exotic reptiles as pets in recent years, more human clinical cases ofreptile-associated Salmonella infection have been identified. However, limited information is available withregard to serotypes in different reptiles (turtles, snakes, and lizards) and antimicrobial resistance ofSalmonellain pet reptiles. The current study was thus conducted to determine the prevalence ofSalmonella colonization inpet reptiles. Salmonella organisms were isolated from 30.9% of 476 reptiles investigated. The isolationprevalences were 69.7% (23/33), 62.8% (27/43), and 24.3% (97/400) in snakes, lizards, and turtles, respectively.A total of 44 different Salmonella serovars were identified. Compared with S. Heron, Bredeney, Treforest, and4,[5],12:i:-, S. Typhimurium isolates were resistant to many antimicrobials tested, and notably 61.1% of theisolates were resistant to cephalothin. The results indicated that raising reptiles as pets could be a possible

source of Salmonella infection in humans, particularly zoonotic Salmonella serovars such as S. Typhimuriumthat may be resistant to antimicrobials.

Key words: Antimicrobial resistance; pet reptiles; prevalence; zoonotic Salmonella serovar.

Introduction

Salmonella are mainly considered to be food-borne

pathogens transmitted through consumption of con-taminated meat, eggs, vegetables, and fruits.2,19,26,35,37

Pets, including reptiles, have been shown to be a

source of infection in humans.31,33,36,39,41 The diseaseusually causes abdominal cramps and self-limiting

diarrhea. However, serious complications may occur,especially among children less than 10 years of age,

elderly people, and immunocompromised patients.30

In recent years, reports of salmonellosis fromreptile reservoirs have gained more attention, espe-

cially in the United States,1,6,7 where it has been

estimated that 1.4 million human cases with Salmo-nella infections and approximately 600 associated

deaths occur annually.21 Due to the increasing

popularity and variety of exotic reptiles as pets in

recent years, more human clinical cases with reptile-associated Salmonella infection have been identified.

The Centers for Disease Control and Prevention(CDC) estimated that over 50,000 cases of reptile-

associated salmonellosis occurred in 1996.22 Theresults from a previous study23 further suggested that

reptile and amphibian exposure is associated withabout 74,000 Salmonella infections in the United

States every year. According to results of Salmonella

surveillance in the United States during 19871997,25

7 out of the top 20 serovars were reptile-associatedSalmonella serovars, including S. IV 48:g,z51:-

(previously S. Marina), S. Flint (now known as S.

IV 50:z4,z23:-), S. Kintambo, S. Wassenaar (now

known as S. IV 50:g,z51:-), S. Ealing, S. Carrau, andS. Abaetetuba.

Recently, Salmonella infection in humans and

animals has become an important issue in Taiwan,

and antimicrobial-resistant Salmonella infections

have been identified.8,13,20 According to a previousreport,20 the leading 4 Salmonella serovars recovered

from human patients were S. Typhimurium, S.

Enteritidis, S. Stanley, and S. Schwarzengrund.Furthermore, multi-antimicrobialresistant S. Cho-leraesuis has gained much attention in Taiwan.8,10,12,13

Although these serovars are mainly food-borne

pathogens, pet exposure could be also considered asanother way of transmission. Pet reptiles are increas-ingly popular in Taiwan. However, there have been

From the Graduate Institute of Microbiology and Public

Health, National Chung Hsing University, Taichung, Taiwan(C-Y Chen, Chang), the Department of Safety Health andEnvironmental Engineering, Central Taiwan University of Science

and Technology, Taichung, Taiwan (W-C Chen), Taipei Zoo,

Taipei, Taiwan (Chin, Lai), the Department of VeterinaryMedicine, College of Veterinary Medicine, National Chung HsingUniversity, Taichung, Taiwan (Tung), The Third Branch Office,

Centers for Disease Control, Taichung, Taiwan (Chiou), and theDepartment of Biological Science and Technology, College of LifeSciences, China Medical University, Taichung, Taiwan (Hsu).

1 Corresponding Author: Chao-Chin Chang, 250 Kuo-KuangRoad, Graduate Institute of Microbiology and Public Health,

National Chung Hsing University, Taichung 402, [email protected]

J Vet Diagn Invest 22:4450 (2010)

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no epidemiological studies conducted in these animalsconcerning their colonization and excretion of zoo-notic pathogens. In pet reptiles, limited informationhas been reported with regard to antimicrobialresistance of Salmonella worldwide. A previousstudy32 in Trinidad indicated that 100%, 66.7%,

66.7%

, and 33.3%

of the Salmonella isolates fromreptiles were resistant to streptomycin, cephalothin,neomycin, and gentamycin, respectively. The currentstudy was thus conducted to determine the epidemi-ological patterns of Salmonella colonization inreptiles collected from various sources in Taiwan.

Materials and methods

Sample collection

From September 2005 through April 2006, a total of 476samples were collected by convenience sampling, including418 cloacal swabs obtained from smuggled pet reptiles keptin Taipei Zoo (Taipei, Taiwan), 20 fecal samples of pet

reptiles from pet shops, and 38 fecal samples of reptilespresented to the Veterinary Teaching Hospital, NationalChung Hsing University (Taichung, Taiwan). At the timeof the sampling, information with regard to health status,whether the animals showed signs of diarrhea, wasobtained through the records offered by the Zoo, byveterinarians in the hospital, or by direct inspection in petshops. Clinical manifestations reported for ill animalsincluded nasal discharge, ocular discharge, anorexia,hepatitis, or parasite infection. According to diet patterns,the animals were categorized as carnivorous, omnivorous,and herbivorous. In the study area, not all pet shops couldbe investigated, and only pet reptiles from pet shops whereowners provided permission were sampled and further

investigated.

Cultivation, identification, and serotyping of

Salmonella isolates

Cultivation of bacteria from the cloacal swabs or fecalsamples was performed according to procedures byInternational Organization for Standardization 6579(http://www.iso.org/iso/catalogue_detail.htm?csnumber540377) with minor modifications. Each cloacal swab wasfirst soaked in 4.5 ml of buffered peptone watera fortransportation. The swabs were then incubated at 37uC for1824 hr with 3.5 relative centrifugal force (rcf) mildshaking. Five hundred microliters of the incubated productwere transferred from each tube into 4.5 ml of Rappaport

Vassiliadis R10 (RV) brotha and incubated for 1824 hr at42uC. One loopful of the incubated broth was streaked ontoduplicate plates of xyloselysinedeoxycholate (XLD) agara

and SalmonellaShigella (SS) agar.a The plates wereincubated at 37uC for 1824 hr. Simultaneously, 30 ml ofincubated RV broth were inoculated onto the surface of themodified semi-solid RV (MSRV) medium.a The plates wereincubated at 42uC for 1824 hr and examined for growthand development of a migration zone. When a migrationzone was observed, specimens sampled from the rim of themigration zone in the MSRV plates were subcultured onto

XLD and SS agars and then incubated at 37uC for 1824 hr.For the identification of suspected Salmonella isolates,subculture from a single colony pick was used for theagglutination reaction using polyvalent somatic (O) antiserab

for Salmonella.32 Only isolates with a positive result byagglutination test were tentatively confirmed to be Salmo-nella. The Salmonella isolates were stored at 280uC after

subculture on XLD agar for further serotyping and testingof antimicrobial resistance. Salmonella isolates were sero-typed with specific O- and H-antisera,b,c and serovaridentification was carried out according to the principles ofthe KauffmannWhite scheme.4,29

Antimicrobial susceptibility test

All the Salmonella isolates were tested for antimicrobialsusceptibility to a panel of 12 antimicrobials by agar discdiffusion test on MuellerHinton II agar,d following theClinical and Laboratory Standards Institute (CLSI) guide-lines. The following antibiotic discse were used in this study:ampicillin (AMP), 10 mg; cephalothin (KF), 30 mg; chlor-amphenicol (C), 30 mg; ciprofloxacin (CIP), 5 mg; enro-

floxacin (ENR), 5 mg; gentamicin (CN), 10 mg; nalidixic acid(NA), 30 mg; nitrofurantoin (F), 300 mg; norfloxacin (NOR),10 mg; streptomycin (S), 10 mg; trimethoprimsulfamethox-azole (SXT), 25 mg; and tetracycline (TE), 30 mg. Theisolates were classified as susceptible (S), intermediate (I),or resistant (R) following the zone diameter standards by theNational Committee for Clinical Laboratory Standards.38

Escherichia coliATCC15922 was utilized for internal qualitycontrol.

Statistical analysis

For each categorical group, percentage of Salmonellaisolation or antimicrobial resistance was calculated. To testif percentages among different categorical groups were

statistically different, chi-square (x2) test or Fishers exact test(when the expected number of observations was less than 5)wasperformed using SASversion 9.1for Windows.fA P-valueless than 0.05 was considered to be statistically significant.

Results

Isolation

Overall, Salmonella organisms were isolated from147 (30.9%) of 476 reptiles investigated, and a total of358 isolates were obtained. The use of both XLD agarand SS agar plates for Salmonella isolation resulted inthe recovery of more than 1 isolate from some reptilesamples. The isolation rates were 69.7% (23/33),62.8% (27/43), and 24.3% (97/400) in snakes, lizards,and turtles, respectively. The prevalence in turtles wassignificantly lower than that of snakes (odds ratio:0.14, 95% confidence interval [CI]: 0.060.32) orlizards (odds ratio: 0.19, 95% CI: 0.090.38).

Serotyping

The most frequently isolated Salmonella wasserogroup B (24.0%). Other serogroups ofSalmonellaincluded serogroup I (11.5%), C2 (8.1%), and C1

Salmonella serovars in reptiles in Taiwan 45



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(5.9%). Although serovars could not be determined

for 87 isolates due to the limited spectrum of specificO- and H-antisera, a total of 44 different Salmonella

serovars were identified in reptiles (Table 1). More-over, 15.0% (22/147) of reptiles were co-colonized

with different Salmonella serovars. Overall, the most

common Salmonella serovars were S. Heron (8.9%),S. Bredeney (7.8%), S. Typhimurium (5.0%), and S.

Treforest (5.0%). It was further observed that the

distribution of various Salmonella serovars was

different in snakes, lizards, and turtles (Table 1).

Analysis of factors associated with Salmonella infection

The results are listed in Table 2. The isolationprevalences were 66.0% (31/47), 42.9% (42/98), and21.7% (68/313) in the carnivorous, omnivorous, andherbivorous reptiles, respectively. Such a differencewas statistically significant (P, 0.05). In carnivorousanimals, the most common serovars were S. Newport(8.9%) and S. Othmarschen (8.9%), followed by S.Muenchen (7.6%), S. Aqua (7.6%), S. Stanley (5.1%),S. Java (now known as S. Paratyphi B var. L(+)tartrate+; 5.1%), S. Poona (5.1%), and S. Ago (5.1%).

Table 1. The comparison of percentages (number of isolates) of Salmonella serovars in turtles, lizards, and snakes in Taiwan (%).*

Salmonella serovar Turtle (225 isolates) Lizard (74 isolates) Snake (59 isolates)

S. Abaetetuba 1.8 (4) S. Abony 1.8 (4) S. Adelaide 4.0 (9) S. Adeoyo 2.7 (2)

S. Agbeni 0.9 (2) S. Ago 0.9 (2) 5.4 (4) S. Aqua 10.2 (6)S. Bareilly 2.7 (2) S. Bredeney 12.4 (28) S. Canastel 0.9 (2) S. Cerro 4.4 (10) S. Cotham 13.5 (10) S. Cubana 2.7 (2) S. Fayed 8.1 (6) S. Gatow 0.4 (1) 1.7 (1)S. Harburg 2.7 (2) S. Heron 13.3 (30) 2.7 (2) S. Herzliya 1.4 (1) S. Hull 1.8 (4)

S. Hvittingfoss 3.4 (2)S. Infantis 2.7 (2) S. Java (now known as S. Paratyphi B var. L(+) tartrate+) 6.8 (4)S. Kisarawe 1.4 (1) S. Kokomlemle 1.4 (1) S. Litchfield 5.4 (4) S. Muenchen 10.2 (6)S. Newport 11.9 (7)S. Othmarschen 11.9 (7)S. Panama 1.8 (4) 3.4 (2)S. Parera 1.4 (1) S. Pomona 0.9 (2) S. Poona 8.1 (6) S. Reading 1.8 (4) S. Rubislaw 2.7 (6) S. Saintpaul 1.3 (3) S. Stanley 4.0 (9) S. Treforest 8.0 (18) S. Typhimurium 6.2 (14) 6.8 (4)S. Typhimurium var. Copenhagen 3.4 (2)S. Urbana 3.4 (2)S. Uzaramo 3.1 (7) S. 4,[5],12:i:- 6.2 (14) S. 9+,12+:-:1,5 0.4 (1) S. II 50:b:z6 5.4 (4) Untypable 20.9 (47) 32.4 (24) 27.1 (16)

* 5 no isolate.

46 Chen et al.



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In omnivorous animals, the most frequent serovarwas Salmonella 4,[5],12:i:- (15.6%), and other com-

mon serovars included S. Typhimurium (13.3%) andS. Cotham (11.1%). In herbivorous animals, the mostfrequent serovar was S. Heron (17.5%), followed byS. Bredeney (14.0%) and S. Treforest (10.5%). Theprevalence in turtles was significantly higher than thatin tortoises (40.3% vs. 20.8%, odds ratio 5 2.57, P,0.05). There was no significant difference of preva-lence of Salmonella colonization between animalswith and without obvious clinical manifestations.Among sick animals, individuals with diarrhea weremore likely to excrete Salmonella organisms in fecesthan animals without diarrhea (55.6% vs. 31.9%,odds ratio: 2.67, 95% CI: 0.5712.96, P. 0.05).

Antimicrobial susceptibility testing

Except for 11 Salmonella isolates that containedmajor contamination problems, antimicrobial suscep-tibility testing by disk diffusion test was conducted on347 isolates. As shown in Table 3, although theoverall resistance percentages were not very high, it

was found that 24 (6.9%) isolates were resistant to 4

or more different antimicrobial agents tested in thecurrent study. The highest resistance percentages

were related to streptomycin (14.7%, 51/347) andtetracycline (9.2%, 32/347). After comparing the

antimicrobial resistance percentages in different

animal orders, the percentage of streptomycinresistance remained the highest in turtles, lizards,and snakes (Table 3). More kinds of antimicrobial

resistance were observed in isolates from turtles, as

compared with those from lizards and snakes(Table 3). Furthermore, 7.3% of the Salmonella

isolates from turtles were resistant to cephalothin.Nalidixic acid resistance was present only in isolates

from turtles (9.2%). Among the Salmonella serovarsrecovered from reptiles that are related to human

infections in Taiwan, it was observed that S.

Typhimurium isolates were resistant to a wide rangeof antimicrobials tested, as compared with resistance

exhibited by S. Heron, S. Bredeney, S. Treforest, andS. 4,[5],12:i:- isolates (Table 4). The percentage of

streptomycin resistance present in S. Typhimuriumisolates reached 83%, and 61% of S. Typhimurium

isolates were resistant to cephalothin.

Discussion

To the authors knowledge, this is the first

investigation of prevalence ofSalmonella colonizationin pet reptiles in Taiwan. The results indicated high

prevalence (30.9%) of Salmonella colonization inthese animals, especially in snakes (69.7%) and lizards

(62.8%). This observation was in accordance withprevious findings.1416,18,24,34 The prevalence of Sal-

monella infection in turtles varies in different studies,

ranging from 2.6% to 72.2%.18,24,27 In the currentstudy, Salmonella was recovered from 24.3% of the

turtles tested. Seasonal behaviors, such as hiberna-tion, have been speculated to result in a low isolation

Table 2. Risk factors associated with Salmonella infection.

Risk factor{ Isolation prevalence P-value{

Diet pattern

Carnivorous 66.0% (31/47) ,0.05Omnivorous 42.9% (42/98)Herbivorous 21.7% (68/313)

Living environment

Aqua turtle 40.3% (29/72) ,0.05

Tortoise 20.8% (68/327)

Health status

Healthy 30.0% (112/373) NS*Ill 34.0% (35/103)

* NS 5 not significant.{ Not all animals investigated have information of listed risk

factors.{ P-value was calculated by chi-square test.

Table 3. Antimicrobial resistance prevalence of 347 Salmonella isolates obtained from 476 animals.

Antimicrobial agent

Resistant (%)/intermediate (%)

Overall (N 5 347) Turtle ( N5 218) Lizard (N 5 73) Snake (N 5 56)

Ampicillin 6.9/0.0 7.3/0.0 2.7/0.0 10.7/0.0Cephalothin 4.6/0.0 7.3/0.0 0.0/0.0 0.0/0.0Chloramphenicol 6.3/0.3 7.3/0.5 0.0/0.0 10.7/0.0

Ciprofloxacin 0.0/0.0 0.0/0.0 0.0/0.0 0.0/0.0Enrofloxacin 0.3/0.3 0.5/0.5 0.0/0.0 0.0/0.0

Gentamicin 3.2/0.0 5.0/0.0 0.0/0.0 0.0/0.0Nalidixic acid 5.8/0.9 9.2/1.4 0.0/0.0 0.0/0.0

Nitrofurantoin 4.6/2.6 5.5/3.2 2.7/0.0 3.6/3.6Norfloxacin 0.0/0.3 0.0/0.5 0.0/0.0 0.0/0.0Streptomycin 14.7/23.1 11.5/20.6 16.4/41.1 25.0/8.9

Trimethoprimsulfamethoxazole 4.6/0.0 6.4/0.0 2.7/0.0 0.0/0.0Tetracycline 9.2/0.3 8.7/0.5 5.5/0.0 16.1/0.0




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rate of Salmonella in turtles.18 Nevertheless, aprevious study14 observed that low isolation rate of

Salmonella in turtles (10.3%) could also be obtainedin summer. It was considered that season of samplingcould be one of the factors associated with theprevalence of Salmonella colonization in turtles.

The majority of the study subjects were conve-nience samples collected from the smuggled petreptiles housed in the Taipei Zoo. Therefore, infor-mation with regard to imported countries wasunavailable. As different prevalence of Salmonellacolonization can be seen in animals across differentgeographical locations, serovars identified in thepresent study could not be reasonably compared withdata from other countries. For example, a U.S.

study25 identified that the top 7 reptile-associatedSalmonella serovars in the United States wereSalmonella IV 48:g,z51:-, S. Flint (now known as S.IV 50:z4,z23:-), S. Kintambo, S. Wassenaar (nowknown as S. IV 50:g,z51:-), S. Ealing, S. Carrau, andS. Abaetetuba, which did not correlate with the top 4serovars found in the present study.

In the current investigation, a total of 44 differentSalmonella serovars were identified. Of major impor-tance, S. Heron, S. Bredeney, S. Typhimurium, andS. Treforest, which are recovered from human caseswith Salmonella infections in Taiwan, were the top 4Salmonella serovars identified in reptiles. Similar tothe previous findings, the present study indicated that15.0% (22/147) of reptiles were co-colonized withdifferent Salmonella serovars.18,39 According to theco-infection prevalence and using combinations ofculture media for Salmonella isolation in the presentstudy, it may imply that 1 serovar dominates most ofthe animals. Nevertheless, it will be of major interestto understand whether reptiles with co-infection aremore likely to excrete Salmonella in the environment,and to threaten human health.

In the present study, except for 4 isolates, themajority of the salmonellae belonged to Salmonella

enterica subspecies II; the remaining ones belonged toS. enterica subsp. enterica. These results differed fromobservations reported in other studies, which foundmainly S. enterica subsp. II, IIIa, IIIb, IV, VI, and S.bongori associated with cold-blooded animals andtheir living environment.5 Although the reason forsuch a discrepancy is still unclear, S. enterica subsp.enterica was found to be common in reptiles in severalstudies.15,18,24,28 The present research findings mayimply that reptiles could play a role as importantvectors for Salmonella species commonly associatedwith human disease, and further research needs to beconducted to determine if water treatment and food

handling could be associated with this observation.It has been suggested that the distribution of

Salmonella in reptiles may reflect their living envi-ronments.24 In the present study, the isolation rate ofSalmonella in aqua turtles was significantly higherthan that in tortoises. Salmonella has high survivalrates in aquatic environments and is frequentlyisolated from water sources.3,9,11,40 A previous studyfurther indicated that Salmonella can persist in livingenvironments for up to 10 months.17 Therefore, if thewater is contaminated with Salmonella, it could be asource for Salmonella transmission in aquatic ani-mals, and eventually to humans.

Although the overall resistance prevalence was notvery high (014.7%), S. Typhimurium was the serovarwith the widest range of antimicrobial resistance.High resistance percentages (61.183.3%) in S.Typhimurium were observed to ampicillin, chloram-phenicol, gentamicin, streptomycin, trimethoprimsulfamethoxazole, and tetracycline, which are alltraditional antimicrobial agents used clinically inhumans. Cephalothin is frequently used for thetreatment of bacterial infection with multidrug

Table 4. Antimicrobial resistance of the top 5 Salmonella serovars identified from 347 Salmonella isolates in 476 animals.

Antimicrobial agent

Resistant (%)/intermediate (%)

S. Heron

(N 5 32)

S. Bredeney

(N 5 26)

S. Typhimurium

(N 5 18)

S. Treforest

(N 5 18)

S. 4,[5],12:i:-

(N 5 13)

Ampicillin 0.0/0.0 0.0/0.0 83.3/0.0 0.0/0.0 0.0/0.0Cephalothin 0.0/0.0 0.0/0.0 61.1/0.0 0.0/0.0 0.0/0.0Chloramphenicol 0.0/0.0 0.0/0.0 83.3/0.0 0.0/0.0 0.0/0.0

Ciprofloxacin 0.0/0.0 0.0/0.0 0.0/0.0 0.0/0.0 0.0/0.0Enrofloxacin 0.0/0.0 0.0/0.0 0.0/0.0 0.0/0.0 0.0/0.0

Gentamicin 0.0/0.0 0.0/0.0 61.1/0.0 0.0/0.0 0.0/0.0Nalidixic acid 0.0/0.0 0.0/0.0 61.1/0.0 0.0/0.0 0.0/0.0

Nitrofurantoin 0.0/0.0 0.0/0.0 27.8/44.4 0.0/5.6 0.0/0.0Norfloxacin 0.0/0.0 0.0/3.8 0.0/0.0 0.0/0.0 0.0/0.0Streptomycin 3.1/3.1 7.7/23.1 83.3/0.0 11.1/27.8 15.4/46.2

Trimethoprimsulfamethoxazole 0.0/0.0 0.0/0.0 61.1/0.0 0.0/0.0 0.0/0.0Tetracycline 0.0/0.0 0.0/0.0 83.3/0.0 0.0/0.0 0.0/0.0

48 Chen et al.



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resistance; however, 61.1% of the S. Typhimuriumisolates were resistant to cephalothin. This result issimilar to a previous report,32 which showed 66.7% ofSalmonella isolates resistant to cephalothin in reptiles.Although none of the S. Typhimurium isolates inreptiles were resistant to fluoroquinolones, such as

norfloxacin, enrofloxacin, and ciprofloxacin, 61.1%

of them were resistant to nalidixic acid. It is of majorimportance that nalidixic acid resistance was present

only in turtles. As the majority of reptile-associatedSalmonella cases have been from contact with turtlesin the United States, such resistance could impact thetreatment of human cases associated with turtle

exposure in Taiwan.

In the current study, serovars for 24.3% of theisolates could not be determined. Although theauthors laboratory has the capacity to identify mostknown Salmonella serovars, the result may imply thelimited spectrum of specific O- and H-antisera in the

authors laboratory for identification of all serotypes.It is reasonable to consider that unrecognizedserovars can be identified in reptiles. These untypableisolates are likely to be uncommon serovars, and willneed to be further identified. According to a study

conducted in Japan,24 although biochemical confir-mation was done for Salmonella isolates in reptiles, 58of the 112 Salmonella isolates tested were untypablewith commercial antisera. These reasons couldexplain the percentage of untypable isolates in the

present study.

Based on these observations, it was concluded

that raising reptiles as pets could be a possiblesource for Salmonella infections in humans and mayeventually threaten human health due to antimicro-bial-resistant Salmonella. The results offer valuable

information to educate people who are raising or areconsidering raising reptiles as pets and can beapplied in future risk assessment of Salmonella

infection in humans.

Acknowledgements

This project was supported by grant NSC 94-2313-B-005-047 from the National Science Council, Taiwan. Theauthors greatly appreciate the major assistance from the

Taipei Zoo, Taipei, Taiwan, for collecting reptile speci-mens.

Sources and manufacturers

a. DifcoTM, BD, Franklin Lakes, NJ.

b. SerotestH, S&A Reagents Lab Ltd., Bangkok, Thailand.

c. Denka Seiken Co. Ltd., Tokyo, Japan.

d. BBLTM, BD, Franklin Lakes, NJ.

e. OXOID Ltd., Cambridge, UK.

f. SAS Institute Inc., Cary, NC

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Prevalence and Antimicrobial Susceptibility of Salmonellae Isolates from Reptiles in Taiwan