Reptile-associated salmonellosis remains a primary concern of public health officials in the United States.1–5 The increased numbers of reptiles imported into the United States during the 1990s and the recent findings of illegal hatchling (< 10.2 cm in length) turtle and terrapin sales in major US markets have been blamed for the increased incidence of reptileassociated salmonellosis.6 Currently, no federal or state regulations exist that are attributed to managing the risk associated with Salmonella spp in captive reptiles. Instead, the general consensus is that reptiles should be kept only by responsible adults and that households with young children or immunocompromised individuals should not keep reptiles.7 Although these recommendations have been accepted as a method to minimize the likelihood of developing reptile-associated salmonellosis from imported wild reptiles and captivebred nonchelonian reptiles by the Pet Industry Judicial Action Committee and the CDC, 1 segment of the pet reptile industry, the aquatic chelonian farmers, remains unable to participate in the market.
Aquatic chelonians have been raised in captivity on commercial farms for > 70 years. An increased incidence of turtle-associated salmonellosis in young children during the late 1960s and early 1970s led the FDA to enact a regulation that restricted the inter- and intrastate sale of chelonians < 10.2 cm in length. In response to the regulation, aquatic chelonian farmers from Louisiana initiated research to identify methods to eliminate Salmonella spp in hatchling turtles. Initial research focused on the use of common veterinary antimicrobials. Treatment of hatchlings with oxytetracycline in their tank water for up to 14 days reduced shedding in treated turtles, but did not affect enteric colonization.8 Treatment of freshly laid eggs with oxytetracycline or chloramphenicol with a temperature-differential egg dip method was also successful at eliminating Salmonella spp in eggs < 1 day old, but did not clear eggs > 2 days old.8 Large-scale experimentation on commercial turtle farms with surface decontamination and pressure- or temperature-differential treatment of eggs with gentamicin dip solutions for eggs > 2 days old, followed by hatching eggs on Salmonella-free bedding, substantially reduced Salmonella spp infections and shedding rates in hatchling turtles.9 Forty percent of the eggs not treated with the gentamicin was found to harbor Salmonella spp, whereas only 0.15% of the treated eggs had positive results.
Unfortunately, the use of antimicrobials has led to the development of antimicrobial-resistant strains of Salmonella spp. One study10 isolated Salmonella spp from 6 of 28 (21%) RES turtle (Trachemys scripta elegans) lots exported to Canada from Louisiana. Of the 37 Salmonella strains isolated, 30 (81%) were gentamicin resistant. Another study11 collected environmental specimens and live hatchlings directly from 2 Louisiana turtle farms and found isolates of Salmonella enterica subsp arizonae and S enterica serotype Poona that were resistant to erythromycin, gentamicin, tetracycline, and sulfonamide. Findings of these studies suggest that the application of a single antimicrobial agent is not sufficient to suppress or eliminate Salmonella spp from captive-bred chelonians and that it leads to the development and dissemination of antimicrobial resistance in turtles and their environment.
Almost since the inception of the 1975 regulation, aquatic chelonian farmers have been in discussions with the FDA to determine possible methods to reverse the regulation and reopen the pet turtle market in the United States. The FDA's response to farmers has been that they must find 3 nonantibiotic methods to eliminate Salmonella spp from RES turtles. Recent research suggests that a PHMB compound may be used to suppress or eliminate Salmonella spp in the aquatic environment of captive RES hatchings.12 This group of compounds may also prove valuable as a method to treat RES turtle eggs.
Polyhexamethylene biguanide is a sanitizing agent that is considered safe for human and animal use. This compound has been used as a mouth rinse for humans,13 a microbicide for chicken eggs,14 and a treatment for fungal keratitis.15 The antimicrobial effect of this compound varies with concentration, being bacteriostatic at low concentrations and bacteriocidal at higher concentrations. Many derivatives of PHMB exist. One such derivative of PHMB (polyiminoimidocarbonylimino-hexamethylene hydrochloride)a is a commercially available swimming pool sanitizer and algistatic agent that can be used as a safe alternative to chlorine for swimming pools.
The purpose of the study reported here was to determine whether a combination of NaOCl (household bleach)b and PHMB could be used to treat RES turtle eggs and suppress or eliminate Salmonella spp in turtle eggs and hatchlings. The first hypothesis tested was that eggs treated with any of 3 treatment combinations would be less likely to have Salmonella-positive culture results than controls. The second hypothesis was that no difference would be found in the Salmonella status of the 3 treatment groups. The third hypothesis was that no difference would be found in Salmonella-culture results between the 3 geographic regions in Louisiana. The final hypothesis was that no difference would be found in Salmonella-culture results between specimen collection times.
Delayed secondary enrichment
Baquacil, Avecia Inc, Wilmington, Del.
Clorox, Clorox Co, Oakland, Calif.
Proper pH 7.5, Aquarium Pharmaceuticals, Chalfont, Pa.
Becton, Dickinson & Co, Sparks, Md.
XLT4 agar base, Remel, Lenexa, Kan.
Eugon urea broth, Remel, Lenexa, Kan.
Lysine iron agar, Remel, Lenexa, Kan.
Triple sugar iron agar, Remel, Lenexa, Kan.
API 20E test strips, bioMeriux Vitek Inc, Hazelwood, Mo.
Ketaset, Fort Dodge Inc, Fort Dodge, Iowa.
Beuthanasia, Schering Plough Animal Health Care, Union, NJ.
SPSS 11.0, SPSS Inc, Chicago, Ill.
Cosmocil CQ, ICI Americas Inc, Wilmington, Del.
Ackman DM, Drabkin P, Birkhead G, et al. Reptile-associated salmonellosis in New York State. Pediatr Infect Dis J 1995;14:955–959.
Nowinski RJ, Albert MC. Salmonella osteomyelitis secondary to iguana exposure. Clin Orthop Relat Res 2000;372:250–253.
Rodgers GL, Long SS, Smergel E, et al. Salmonella infection associated with a pet lizard in siblings with sickle cell anemia: an avoidable risk. J Pediatr Hematol Oncol 2002;24:75–76.
Wells EV, Boulton M, Hall W, et al. Reptile-associated salmonellosis in preschool aged children in Michigan, January 2001–June 2003. Clin Infect Dis 2004;39:687–691.
Wybo I, Potters D, Plaskie K, et al. Salmonella enterica subspecies Houtenae serotype 44:z4, z23: as a rare cause of meningitis. Acta Clin Belgica 2004;59:232–234.
Bradley T, Angulo F, Mitchell MA. Public health education on Salmonella spp and reptiles. J Am Vet Med Assoc 2001;219:754–755.
Siebling RJ, Neal PM, Granberry WD. Evaluation of methods for the isolation of Salmonella and Arizona organisms from pet turtles treated with antimicrobial agents. Appl Microbiol 1975;29:240–245.
Siebling RJ, Caruso D, Neuman S. Eradication of Salmonella and Arizona species from turtle hatchlings produced from eggs treated on commercial turtle farms. Appl Environ Microbiol 1984;47:658–662.
D’Aoust JY, Daley E, Crozier M, Sewell AM. Pet turtles: a continuing international threat to public health. Am J Epidemiol 1990;132:233–238.
Shane SM, Gilbert R, Harrington KS. Salmonella colonization in commercial pet turtles (Pseudemys scripta elegans). Epidemiol Infect 1990;105:307–315.
Mitchell M, Bauer R, Nehlig R, et al. Evaluating the efficacy of Baquacil against Salmonella sp. in the aquatic habitat of red-eared slider (Trachemys scripta elegans). J Herp Med Surg 2005;15:9–14.
Rosin M, Welk A, Bernhardt O, et al. Effect of polyhexamethylene biguanide mouthrinse on bacterial counts and plaque. J Clin Periodont 2001;28:1121.
Cox NA, Bailey JS, Berrang MA. Chemical treatment of Salmonella contaminated fertile hatching eggs using an automated egg spray sanitizing machine. J Appl Poult Res 1994;3:26–30.
Panda A, Ahuja R, Biswas NR, et al. Role of 0.02% polyhexamethylene biguanide and 1% povidone iodine in experimental Aspergillus keratitis. Cornea 2003;22:138–141.
Izadjoo MJ, Pantoja COA, Siebling RJ. Acquisition of Salmonella flora by turtle hatchlings on commercial turtle farms. Can J Microbiol 1987;33:718–724.
Michael-Marler S, Brown ML, Siebling RJ. Eradication of Arizona hinshawii from artificially infected turtle eggs. Appl Environ Microbiol 1983;45:748–754.