VETERINARSKI ARHIV 69 (4), 229-237, 1999

ISSN 1331-8055 Published in Croatia

Antibiograms of thermophilic Campylobacter and Salmonella species isolated from stray and pet animals and wildlife on Trinidad

Abiodun Adesiyun*

School of Veterinary Medicine, Faculty of Medical Sciences,
University of the West Indies, St. Augustine, Trinidad and Tobago

* Contact address:
Prof. Dr. Abiodun Adesiyun,
School of Veterinary Medicine, Faculty of Medical Sciences, University of the West Indies, Uriah Butler Highway, Champs Fleurs, St. Augustine, Trinidad and Tobago,
Phone: 1 868 645 2640 9; Fax: 1 868 645 7428

ADESIYUN, A.: Antibiograms of thermophilic Campylobacter and Salmonella species isolated from stray and pet animals and wildlife on Trinidad. Vet. arhiv 69, 229-237, 1999.

ABSTRACT

Campylobacter species isolated from wildlife (free-ranging or confined), stray and pet animals, and Salmonella spp. recovered from wildlife, were tested for their susceptibility to antimicrobial agents. Of the 191 isolates of Campylobacter tested, comprising 186 and 5 strains of C. jejuni and C. coli respectively, 21 (11.0%) exhibited resistance to one or more of the 6 antimicrobial agents tested. Resistance was highest to ampicillin (7.9%) and lowest to gentamicin and chloramphenicol (0.0%). Resistance to antimicrobial agents was highest among Campylobacter isolates from agouti (42.9%) and stray dogs (26.2%). Among the 54 Salmonella isolates tested, 50 (92.6%) each were resistant to tetracycline and streptomycin, 47 (87.0%) to nalidixic acid, 35 (64.8%) to kanamycin and 26 (48.1%) to neomycin. It was concluded that resistance to antimicrobial agents tested was low among Campylobacter isolates but comparatively very high among Salmonella isolates.

Key words: Campylobacter, Salmonella, wildlife, antibiogram, Trinidad

Introduction

Campylobacter jejuni and C. coli are well recognized human and animal pathogens (DOYLE, 1981; TUCKSON et al., 1988). In animals, Campylobacter spp. are widespread both as pathogens and commensals (SMIBERT, 1978). In Trinidad and Tobago, C. coli and C. jejuni have been isolated from dairy animals (ADESIYUN et al., 1998) and from different types of food (ADESIYUN, 1993; ADESIYUN and KRISHNAN, 1995).

Campylobacters from different sources have been shown to have variable resistance to antimicrobial agents depending on their sources (BRADBURY and MONROE, 1985). ADESIYUN et al. (1992) reported for the first time on antibiograms of Campylobacter spp. isolated from domestic animals on Trinidad. To date, no information is available on the sensitivity of antimicrobial agents of Campylobacter species isolated from wildlife in the country.

As with Campylobacter, Salmonella spp. have been documented to be important pathogens in humans and animals (LANCE et al., 1992; TODD, 1992). In Trinidad and Tobago, Salmonella have been isolated from livestock (ADESIYUN, 1994; ADESIYUN and BALBIRSINGH, 1996). The only report on antibiograms of Salmonella was for isolates from domestic animals in Trinidad (ADESIYUN et a., 1992), although with no documentation on isolates recovered from wildlife.

This study was conducted to determine the antibiograms of Campylobacter and Salmonella species from pet and stray animals and wildlife on Trinidad.

Materials and methods

Individual homes and veterinary clinics across the country served as sources of pet dogs and cats. Abandoned, submitted or stray dog samples were obtained from the Port of Spain, Trinidad and Tobago facility of the Trinidad and Tobago Society for Prevention of Cruelty to Animals (TTSPCA). In addition, stray dogs were obtained from the Port of Spain pound maintained by the Ministry of Health. Pet shops in San Juan, St Augustine and Port of Spain were sampled for pet birds. Mammalian and avian wildlife, either free-ranging or confined, were sampled from sources earlier described (ADESIYUN et al., 1998). Confined wildlife at the Emperor Valley Zoo, Port of Spain, and individual wildlife farms served as sources of confined wildlife.

The procedure used was as earlier described (ADESIYUN et al., 1998). In addition, for pound dogs, pet dogs and cats, and TTSPCA dogs, rectal swabs were collected and transported to the laboratory in Ames Transport Medium (ATM) (Difco, Michigan, U.S.A.) and processed within 2 hours of collection. Cloacal swabs were taken from pet shop canaries.

The procedure used for isolation and identification of Campylobacter and Salmonella was as earlier described (ADESIYUN et al., 1998).

For Campylobacter spp., the following antimicrobial agents and concentrations were used: streptomycin (10 µg), neomycin (30 µg), kanamycin (30 µg), ampicillin (10 µg) chloramphenicol (30 µg) and gentamicin (10 units). In addition, nalidixic acid (30 µg) and cephalothin (30 µg) were used for the identification of Campylobacter. The disc diffusion method described by BAUER et al. (1996) was used, with the plates incubated at 42 ^°C in 8% CO₂ in a CO₂ incubator (from Scientific Inc. Maretta, Ohio, U.S.A.) for 24 h.

To determine the antibiotic sensitivity of Salmonella isolates, the following antimicrobial agents and concentrations were used: tetracycline (30 µg), streptomycin (10 µg), kanamycin (30 µg), ampicillin (10 µg), gentamicin (10 units), nalidixic acid (30 µg), chloramphenicol (30 µg) and sulphamethoxazole/trimethoprim (30 µg). The disc diffusion method (BAUER et al., 1966) was used with inoculated Mueller-Hinton agar plates incubated aerobically overnight at 37 °C.

For both micro-organisms, the test interpretation suggested by the disc manufacturer was used to determine resistance and sensitivity to antimicrobial agents.

Results

The sources of Campylobacter isolates tested are shown in Table 1. Overall, 5 (2.6%) and 186 (97.4%) of 191 isolates were C. coli and C. jejuni, respectively. Of the 191 Campylobacter isolates studied, 21 (11.0%) exhibited resistance to one or more of the six antimicrobial agents tested (Table 2). Fifteen (7.9%), 7 (3.7%), 2 (1.0%) and 1 (0.5%) strains were resistant to ampicillin, kanamycin, streptomycin and neomycin, respectively. Resistance was comparatively high among Campylobacter isolates from agouti (42.9%) and pound stray dogs (26.2%). Of all the animals species sampled from a total of 21 sources, only 6 (28.6%) animal types exhibited resistance to antimicrobial agents. All isolates were sensitive to chloramphenicol and gentamicin.

Table 1. Sources of Campylobacter isolates from animals on Trinidad

*Trinidad and Tobago Society for Protection of Cruelty to Animals

Table 2. Prevalence of resistance of Campylobacter isolates from
animals on Trinidad to antimicrobial agents

-=Not resistant; ^aAll 191 of Campylobacter were sensitive to chloramphenicol and gentamycin; ^bResistant to one or more of the antimicrobial agents tested; ^cTrinidad and Tobago Society for Protection of Cruelty to Animals; S=Streptomycin; N=Neomycin; K=Kanamycin; AMP=Ampicillin

Table 3 shows the antibiograms of Salmonella strains isolated from confined and free-ranging wildlife species. Resistance was high among the 54 isolates of Salmonella tested to tetracycline, 50 (92.6%); streptomycin, 50 (92.6%); nalidixic acid, 47 (87.0%) and kanamycin, 35 (64.8%). There was no relationship between the serotypes of Salmonella and resistance to antimicrobial agents.

Table 3. Antibiogram of Salmonella isolates isolated from
animals sources on Trinidad

-=Not resistant; ^aAll 53 of Salmonella were resistant to one or more of the antimicrobial agents tested; ^bConsisted of S. uganda (1), S. newport (1), S. archavaleta (1), S. miami (6), S. mundonobo (1), S. panama (2), S. brandenburg (1), and S. mbandaka (1); NT=Not serotyped; TE=tetracycline; S=streptomycin; N=neomycin; K=kanamycin; AMP=ampicillin; CN=gentamycin; NA=nalidixic acid; C=chloramphenicol; SXT=sulphamethoxazole/trimethoprim

Discussion

The overall prevalence (11.0%) of resistance among Campylobacter isolates to antimicrobial agents detected in pet and stray animals and wildlife in the present study is considerably lower than reported for Campylobacter species from other animal species in the same environment (ADESIYUN et al., 1992). In a study of livestock (cattle, sheep, goats and pigs) on Trinidad, ADESIYUN et al. (1992) found resistance in 245 (77.8%) of 315 isolates of Campylobacter. Similarly, in a study of Trinidadian dairy cows 73% of 26 isolates of Campylobacter were resistant to antimicrobial agents (ADESIYUN et al., 1996). Resistance to individual antibiotics was also significantly different among isolates from livestock as reported (ADESIYUN et al., 1992) compared to those found in the present study. For livestock isolates of Campylobacter, 73% were resistant to ampicillin, 19.2% to neomycin, 11.5% to kanamycin, 2.7% to chloramphenicol and 3.8% to gentamicin compared to prevalence of resistance of 7.9%, 0.5%, 3.7% 0% and 0% for corresponding antibiotics in the present study. It was also significant to observe that only 29% of the animal sources (6 of 21) yielded Campylobacter spp. which exhibited resistance to antimicrobial agents. Sources of Campylobacter have been reported to affect their antibiograms (BRADBURY and MONROE, 1985). The relatively lower prevalence of resistance detected in the present study may be partly explained by the fact that all animals sampled were apparently healthy and most of the animals were free-ranging wildlife or stray animals. Use or misuse of antimicrobial agents to control infections in humans and animals has been reported to result in the development of resistance to antimicrobial agents among bacteria (WALTON, 1971).

The prevalence of resistance to ampicillin (7.9%) found in this study, however, agrees with the findings of CABRITA et al. (1992) who reported a resistance prevalence of 5.5% to ampicillin for isolates from wildlife (black rats, sparrows and ducks). Similarly, the finding that all dog (pet and stray) isolates tested were sensitive to gentamicin agrees with the report by MODOLO et al. (1991). Resistance to antimicrobial agents among Salmonella isolates was very high, as 93% exhibited resistance to one or more of the 9 antimicrobial agents tested. In an earlier study on

In conclusion, the prevalence of resistance amongst Campylobacter isolates studied was relatively low, while Salmonella strains demonstrated comparably high resistance to the antimicrobial agents tested.

Acknowledgements
Our thanks go to the Pan American Health Organization (PAHO) for funding the project. The technical assistance of G. Ramirez and N. Seepersadsingh is also appreciated, and we are additionally grateful for the co-operation received from the management of the Emperor Valley Zoo. Ms. Colette Marina Gall is thanked for typing the manuscript.

References

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Received: 24 August 1999
Accepted: 18 October 1999

ADESIYUN, A.: Antibiogrami termofilnih vrsta roda Campylobacter i Salmonella izdvojenih iz zivotinja lutalica, kucnih ljubimaca i divljih zivotinja na Trinidadu. Vet. arhiv 69, 229-237, 1999.

SAZETAK

Vrste roda Campylobacter izdvojene iz slobodno zivucih i u zatocenistvu drzanih divljih zivotinja, lutalica i kucnih ljubimaca, te vrste roda Salmonella izdvojene iz divljih zivotinja, pretrazene su na osjetljivost prema antimikrobnim tvarima. Od 191 pretrazenog izolata bakterija iz roda Campylobacter, od kojih je 186 pripadalo vrsti C. jejuni, a 5 C. coli, 21 izolat (11,0%) je bio rezistentan prema jednom ili vise od sest upotrijebljenih antibiotika. Otpornost je najcesce ustanovljena prema ampicilinu (7,9%), a nije utvrdena prema gentamicinu i kloramfenikolu. Najcesce su bili otporni izolati podrijetlom iz agutija (42,9%) i pasa lutalica (26,2%). Od 54 pretrazena izolata salmonela, 50 (92,6%) ih je bilo otporno prema tetraciklinu i streptomicinu, 47 (87,0%) prema nalidiksicnoj kiselini, 35 (64,8%) prema kanamicinu i 26 (48,1%) prema neomicinu. Zakljucuje se da je otpornost prema upotrijebljenim antibiotskim tvarima rijetka u kampilobaktera, a vrlo ucestala u salmonela.

Kljucne rijeci: Campylobacter, Salmonella, divlje zivotinje, antibiogram, Trinidad