USE OF PCR AND CULTURE TO DETECT HELICOBACTER-PYLORI IN NATURALLY INFECTED CATS FOLLOWING TRIPLE ANTIMICROBIAL THERAPY

Helicobacter pylori causes gastritis and peptic ulcers and is linked t o gastric cancer. Domestic cats from a commercial source were found to be naturally infected with H. pylori, and studies were undertaken to eradicate H. pylori from infected cats by using triple antimicrobial t herapy. Eight cats infected with H. pylori were used in the study. Six cats received a 21-day course of oral amoxicillin, metronidazole, and omeprazole, and two cats served as controls. Two weeks and 4 weeks po sttreatment (p.t.), all six treated cats were negative at several site s (saliva, gastric juice, and gastric mucosa) for H. pylori by culture . However, as determined by PCR with primers specific for the 26-kDa p roduct, the majority of cats at 2 and 4 weeks p.t. had gastric fluid s amples which were positive for H. pylori and three of three cats at 2 weeks p.t. had dental plaque which was positive for H.pylori. At 6 wee ks p.t., all six cats had H. pylori-negative cultures for samples from several gastric sites taken at necropsy, and only one cat had H.pylor i cultured from gastric juice. PCR analysis revealed that five of six cats had H. pylori DNA amplification products from plaque, saliva, and /or gastric fluid samples, Negative bacterial cultures for cats for wh ich there was demonstrable PCR amplification of H. pylori DNA may refl ect the inability of in vitro culture techniques to isolate small numb ers of H. pylori organisms, focal colonization at sites not cultured, or a failure of the antibiotics to successfully eradicate H. pylori fr om extragastric sites which allowed subsequent recolonization of the s tomach after cessation of therapy. Alternatively, the treatment strate gy may have induced in vivo viable but nonculturable coccoid forms of Ii. pylori. The H. pylori cat model should allow further studies to te st these hypotheses as well as the efficacies of other combined therap eutic regimens. Also, because 100% of these cats were naturally infect ed with H. pylori, this model should prove useful in exploring mechani sms whereby human populations in underdeveloped countries, which have H. pylori infection rates approaching 100%, have a high rate of recurr ence of H. pylori infection after use of prescribed antibiotic therapi es that successfully eradicate H. pylori in individuals in developed c ountries.