Diagnosing Gastric Helicobacter Infections in Dogs and Cats

Transcription

1 Article #4 CE Diagnosing Gastric Helicobacter Infections in Dogs and Cats Michael S. Leib, DVM, MS, DACVIM Robert B. Duncan, DVM, PhD, DACVP Virginia Maryland Regional College of Veterinary Medicine (Virginia Tech) ABSTRACT: Helicobacter spp are commonly identified in the stomachs of dogs and cats. The role of these bacteria in the pathogenesis of gastritis and chronic vomiting is not presently known. Spiral bacteria can be easily identified by histologic assessment or rapid urease testing of gastric biopsy samples or by evaluating gastric brush cytology specimens. Other diagnostic tests have been conducted in humans and experimentally in dogs and cats.this article reviews the procedures as well as advantages and disadvantages of available diagnostic tests for gastric Helicobacter spp in dogs and cats. Send comments/questions via fax , or web CompendiumVet.com Spiral bacteria were identified in the stomachs of humans and animals in the late 1800s. 1 However, it was not until the early 1980s that Warren and Marshall 2 proposed a relationship between Helicobacter pylori and gastric disease in humans. 3 Soon after, studies in dogs and cats clearly demonstrated that spiral bacteria were commonly found in the stomachs of clinically normal dogs and cats as well as dogs and cats with signs of gastrointestinal disease However, a direct causal relationship between spiral bacteria and gastric disease has not been established in dogs or cats. Although the potential pathogenic role of Helicobacter spp in dogs and cats is being investigated, we routinely determine whether the organisms are present in all dogs and cats with signs of chronic vomiting. A percentage of these patients have been treated for Helicobacter spp, and some have responded favorably. We want to emphasize that a thorough diagnostic evaluation to search for other potential causes of vomiting should always be conducted before considering Helicobacter spp to be etiologic agents. This article describes the common methods of identifying spiral bacteria in the stomachs of dogs and cats. Helicobacter spp are gram-negative, microaerophilic, motile, and curved or spiral bacteria with multiple terminal flagella. 12,13 They contain large quantities of the enzyme urease, which results in production of ammonia and bicarbonate from urea. This alters the ph surrounding the bacteria and helps them colonize the acidic environment of the stomach. 12,14 More than 30 Helicobacter spp have been identified in humans and animals. 13 In addition to the species found in the stomach, others have been identified in the intestine and liver. 15,16 H. pylori is the most common gastric species in humans. It has been shown to be a major cause of gastritis and peptic ulcers as well as to increase the risk of gastric cancer. 17,18 Infection rates in humans can approach 100% in developing countries and 25% to 60% in developed countries. 19 Infection is usually acquired in childhood and most often persists for life. Most infected humans remain asymptomatic. 20 However, peptic ulcers may develop in 10% and gastric cancer in 1% to 2% of those infected. March COMPENDIUM

2 222 CE Diagnosing Gastric Helicobacter Infections in Dogs and Cats Although H. pylori has been identified in research colony cats, infection of pet dogs and cats with other species occurs most commonly. Most Helicobacter spp commonly found in the stomachs of dogs and cats are larger than H. pylori (1.5 to 3 µm). 13 Large spiral bacteria (4 to 10 µm) identified in the stomachs of dogs were initially called Gastrospirillum hominis. They were later reclassified as Helicobacter heilmannii. 10,12 Other large gastric spiral bacteria such as Helicobacter felis, Helicobacter bizzozeronii, and Helicobacter salomonis have been identified and are indistinguishable from H. heilmannii using routine light microscopy Multiple species can be present in an individual animal. 27 Besides the potential role of Helicobacter spp in the pathogenesis of gastritis and chronic vomiting, zoonotic potential is another reason to identify these species in dogs and cats. Although most evidence suggests that the zoonotic potential is very low, some evidence supports potential zoonotic transmission. H. heilmannii is a rare cause of gastritis in humans, accounting for approximately and serology. 14,38 43 Although noninvasive methods as well as polymerase chain reaction testing, scanning electron microscopy, and culture of gastric biopsy specimens have been investigated in dogs and cats, 8,9,21,23,27,44 50 they are not routinely available to practitioners. Presently, clinical diagnosis of Helicobacter infection in dogs and cats requires endoscopic examination or exploratory celiotomy. Spiral bacteria can be identified in gastric biopsy or brush cytology specimens or indirectly by rapid urease testing of gastric mucosal samples. 5 9,51 Results of histologic evaluation of biopsy samples require 24 to 72 hours. Results of gastric brush cytology and rapid urease testing are available much sooner. BRUSH CYTOLOGY Gastric brush cytology is the least expensive and most practical diagnostic method and has the quickest turnaround time. After an endoscopic examination has been completed and biopsy samples from the duodenum and stomach have been collected, a brush cytologic specimen Helicobacter spp may cause or contribute to gastritis and vomiting in dogs and cats. 0.1% of cases. 28 An epidemiologic survey of humans with H. heilmannii gastritis showed that contact with dogs and cats was a significant risk of infection. 28 In addition, there was an association between H. Heilmannii gastritis and gastric lymphoma, although this could be coincidental. 29 H. pylori has been identified in research colony cats, demonstrating that cats could serve as a reservoir. 21,22 Several studies have identified cat ownership as a risk factor for H. pylori infection in humans. 30,31 However, other studies have shown that contact with dogs or cats is not a risk factor for H. pylori infection Although the potential for zoonotic transmission appears slight, until this issue is conclusively resolved, it seems prudent to determine whether Helicobacter spp are present in dogs and cats during diagnostic evaluation of gastric disorders. Invasive methods of diagnosing Helicobacter infection in humans include bacterial culture, routine microscopic or ultrastructural examination, polymerase chain reaction testing, and rapid urease testing of gastric mucosal biopsy specimens, which are usually obtained via endoscopy. 14,38 40 Noninvasive methods of diagnosis include urea breath testing, fecal antigen determination, can be collected. A guarded cytology brush should be passed through the biopsy channel of the endoscope into the gastric body along the greater curvature. The cytology brush should be extended from the sheath and gently rubbed along the mucosa from the antrum toward the fundus along the greater curvature. Hemorrhagic areas associated with previous biopsy sites should be avoided. The brush should be retracted into the protective sheath and withdrawn from the endoscope. The brush should be extended from the sheath and gently rubbed across several glass microscope slides, which are air-dried and stained with a rapid Wright s stain. The slide should be magnified 100, immersed in oil, and examined. Areas with numerous epithelial cells and large amounts of mucus should initially be viewed. If present, spiral bacteria should be easily seen. They are usually at least as long as the diameter of an erythrocyte, and their classic spiral shape is obvious (Figure 1). The number of spiral bacteria can be highly variable (i.e., from one in every several fields to massive numbers in most fields). We examine at least 10 oil-immersion fields on two slides before the specimen is considered negative. Unlike diagnostic tests COMPENDIUM March 2005

3 Diagnosing Gastric Helicobacter Infections in Dogs and Cats CE 223 Figure 1. Gastric brush cytology specimens stained with Dip Quick Stain Solution (Jorgensen Laboratories, Loveland, CO). 10 µm 10 µm Large numbers of spiral bacteria from a cat. Cellular debris is scattered throughout. Higher magnification (of image on left) showing the spiral nature of the bacteria. that involve using a single (or several) small biopsy sample(s), brush cytology gathers surface mucus and epithelial cells from a much larger area, increasing the chance of identifying bacteria. Brush cytology was found to be more sensitive than urease testing or histopathologic examination of gastric tissue in identifying Helicobacter organisms in dogs and cats. 6,51,52 RAPID UREASE TEST The rapid urease test detects the presence of bacterial urease produced by Helicobacter spp in a biopsy sample. 13,14 We use the CLOtest (Ballard Medical Products, Draper, UT; Figure 2), which is commercially available. Individual tests cost approximately $6. The test consists of agar gel with urea and a ph indicator (i.e., phenol red) in a small, plastic well. Tests should be kept refrigerated before use. To conduct the test, a biopsy sample obtained from the angularis incisura of the stomach should be pushed into the gel. The test should be maintained at room temperature and examined frequently for 24 hours. If bacterial urease is present, urea will be hydrolyzed to ammonia, changing the ph of the gel. The gel should turn from yellow to magenta. The rate at which the gel changes color is proportional to the number of Helicobacter organisms present. When large numbers of bacteria are present in the biopsy sample, the rapid urease test quickly changes color, often within 15 Figure 2. Negative and positive results of a CLOtest. to 30 minutes. 7 If the color of the gel has not changed within 24 hours, the result should be interpreted as negative. A CLOtest with negative results can be reused within a short period if it is kept at room temperature. 53 Urease tests can also be made by placing 10% unbuffered urea in distilled water and 1% phenol red into a tube, but most practitioners prefer the convenience of commercially available tests. 6,11,46 March 2005 COMPENDIUM

4 224 CE Diagnosing Gastric Helicobacter Infections in Dogs and Cats Figure 3. Gastric mucosal samples stained with H & E. 10 µm 10 µm Numerous spiral bacteria are present within a gastric pit (arrows). Higher magnification showing spiral bacteria along the mucosal surface (arrows). We have occasionally observed false-positive test results perhaps because of urease-producing pharyngeal or intestinal bacteria and false-negative results because of the patchy distribution of bacteria within the stomach or administration of drugs that decrease acid secretion (increases in ph alter the activity of urease). 13,14,54 Falsenegative results should be suspected when spiral bacteria are observed in brush cytology specimens or during histopathologic assessment of biopsy samples. Including biopsy samples from multiple areas of the stomach can help reduce false-negative results in rapid urease testing. 55 Contamination of biopsy specimens with blood does not seem to alter test results. 56 False-positive results should be suspected when spiral bacteria are not observed in brush cytology specimens or during histopathologic assessment of multiple biopsy samples with routine and silver stains. We feel that, of the common diagnostic methods, rapid urease testing is the least valuable because of false-positive and negative results, cost, and turnaround time for test results (especially if negative). HISTOPATHOLOGIC IDENTIFICATION Histopathologic identification of Helicobacter spp within gastric biopsy samples using hematoxylin and eosin (H & E) or special stains has a specificity of 100% and a sensitivity of greater than 90% in human studies. 14,38,39 Because of the patchy distribution of organisms within the stomach, 12 examination of samples from multiple gastric locations can increase sensitivity. In our clinic, samples from the pylorus, angularis incisura, gastric body along the greater curvature, and cardia are routinely examined. In humans, the best site to detect H. pylori is the antrum. 40 In some studies in dogs and cats, organisms have been identified with a higher frequency in the body and fundus than in the antrum and pylorus. 6,7,51,57,58 Spiral bacteria can be seen within mucus covering the surface epithelium as well as within the gastric pits, glandular lumen, and parietal cells 5 7,10,21,22,48,49,59 (Figure 3). In cats, bacteria have been identified submucosally within gastric lymphoid follicles. 60 Spiral bacteria associated with the mucosal surface or within gastric pits are relatively easy to detect with routine H & E staining of tissue. However, if the distribution of bacteria favors gastric glands and glandular epithelial cells, bacteria are much more readily detected with the silver technique. Therefore, if bacteria cannot be identified with H & E staining, a modified Steiner s silver stain should be used (Figure 4). Because of similarities in morphologic characteristics, it is not possible to identify specific species using routine histologic staining techniques. Besides identifying Helicobacter spp, histopathologic evaluation of biopsy samples allows assessment of underlying inflammation (Figure 5) and neoplasia, 6,7,10,21,22,58,61 which may be the cause of a patient s clinical signs. BACTERIAL CULTURE Although bacterial culture of gastric biopsy specimens is commonly used to detect H. pylori in humans, culture is far less useful in dogs and cats. 8,62 H. heilmannii has not been successfully cultured. 57 H. bizzozeronii, H. felis, COMPENDIUM March 2005

5 Diagnosing Gastric Helicobacter Infections in Dogs and Cats CE µm Figure 4. Modified Steiner s silver stain of a gastric mucosal sample. Dark staining spiral bacteria are clearly visible (arrows). 100 µm Figure 5. Moderate lymphoplasmacellular gastritis in a gastric mucosal sample from a dog and stained with H & E. and H. salomonis have been cultured from dogs with and without clinical signs. 6 Even in humans, H. pylori is considered difficult to culture because of demanding transport and handling requirements. 14,40 Culture of gastric biopsy specimens from dogs and cats in clinical practice is not routinely conducted. UREA BREATH TESTING Urea breath testing is commonly used to assess the effectiveness of treatment in humans and diagnose amount of abnormal CO 2 liberated by the urease produced by gastric Helicobacter spp. Helicobacter spp can be easily identified during the diagnostic workup of dogs and cats with chronic vomiting. infection in children. 38,39,63 Urea breath testing has been used experimentally in dogs and cats, 8,52,64 but because of equipment limitations, radiation regulations, and difficulty collecting breath samples from patients, this testing is not routinely available to veterinary practitioners. To conduct the test, radioactive carbon 14 C- or heavy 13 C-labeled urea should be placed within the stomach via intubation in animals or ingestion in humans. If Helicobacter spp are present, urease will hydrolyze the urea and release the 13 C or 14 C, which diffuses into blood and is expired as carbon dioxide (CO 2 ). 63 Breath samples should be collected for up to 60 minutes and analyzed for abnormal CO 2 ( 14 C requires a scintillation counter and 13 C a mass spectrometer). 63 Tests with positive results contain a large CONCLUSION The role of Helicobacter spp in gastritis and chronic vomiting in dogs and cats remains unknown. However, it seems prudent to determine whether spiral bacteria are present in the stomachs of dogs and cats evaluated for chronic vomiting. A diagnosis of spiral bacteria is best made by examining gastric cytology samples and confirmed by histologic evaluation of gastric biopsy samples. Rapid urease tests can also be used to indirectly identify the organism. Specific treatments cannot be recommended until the potential role of Helicobacter spp in dogs and cats with chronic vomiting has been studied further. REFERENCES 1. Kidd M, Modlin IM: A century of Helicobacter pylori. Digestion 59:1 15, Warren J, Marshall B: Unidentified curved bacilli on gastric epithelium in active chronic gastritis. Lancet 1: , Marshall B, Armstrong J, McGechie D, et al: Attempt to fulfill Koch s postulates for pyloric Campylobacter. Med J Aust 142: , Geyer C, Colbatzky F, Lechner J, et al: Occurrence of spiral-shaped bacteria in gastric biopsies of dogs and cats. Vet Rec 133:18 19, Hermanns W, Kregel K, Breuer W, et al: Helicobacter-like organisms: Histopathological examination of gastric biopsies from dogs and cats. J Comp Pathol 112: , March 2005 COMPENDIUM

6 226 CE Diagnosing Gastric Helicobacter Infections in Dogs and Cats 6. Happonen I, Linden J, Saari S, et al: Detection and effects of helicobacters in healthy dogs and dogs with signs of gastritis. JAVMA 213: , Yamasaki K, Suematsu H, Takahashi T: Comparison of gastric lesions in dogs and cats with and without gastric spiral organisms. JAVMA 212: , Neiger R, Dieterich C, Burnens A, et al: Detection and prevalence of Helicobacter infection in pet cats. J Clin Microbiol 36: , Papasouliotis K, Gruffydd-Jones TJ, Werrett G, et al: Occurrence of gastric Helicobacter-like organisms in cats. Vet Rec 140: , Eaton KA, Dewhirst FE, Paster BJ, et al: Prevalence and varieties of Helicobacter species in dogs from random sources and pet dogs: Animal and public health implications. J Clin Microbiol 34: , Otto G, Hazell SH, Fox JG, et al: Animal and public health implications of gastric colonization of cats by Helicobacter-like organisms. J Clin Microbiol 32: , Lecoindre P, Chevallier M, Peyrol S, et al: Gastric helicobacters in cats. J Feline Med Surg 2:19 27, Neiger R, Simpson K: Helicobacter infection in dogs and cats: Facts and fiction. J Vet Intern Med 14: , Flatland B: Helicobacter infection in humans and animals. Compend Contin Educ Pract Vet 24: , Fox JG, Lee A: The role of Helicobacter species in newly recognized gastrointestinal tract disease of animals. Lab Anim Sci 47: , Fox JG, Schauer D, Wadstrom T: Enterohepatic Helicobacter spp. Curr Opin Gastroenterol 17(suppl 1):S28 S31, Pakodi F, Abdel-Salam O, Debreceni A, et al: Helicobacter pylori: One bacterium and a broad spectrum of human disease! An overview. J Physiol 94: , Uemura N, Okamoto S, Yamamoto S, et al: Helicobacter pylori infection and the development of gastric cancer. N Eng J Med 345: , Goodman K, Correa P: The transmission of Helicobacter pylori. A critical review of the evidence. Int J Epidemiol 24: , Brown LM: Helicobacter pylori: Epidemiology and routes of transmission. Epidemiol Rev 22: , Handt LK, Fox JG, Dewhirst FE, et al: Helicobacter pylori isolated from the domestic cat: Public health implications. Infect Immun 62: , Esteves MI, Schrenzel MD, Marini RP, et al: Helicobacter pylori gastritis in cats with long-term natural infection as a model of human disease. Am J Pathol 156: , Perkins SE, Yan LL, Shen Z, et al: Use of PCR and culture to detect Helicobacter pylori in naturally infected cats following triple antimicrobial therapy. Antimicrob Agents Chemother 40: , Jalava K, Kaartinen M, Utriainen M, et al: Helicobacter salomonis sp nov, a canine gastric Helicobacter sp related to Helicobacter felis and Helicobacter bizzozeronii. Int J Syst Bacteriol 47: , Hanninen M, Happonen I, Saari S, et al: Culture and characteristics of Helicobacter bizzozeronii, a new canine gastric Helicobacter sp. Int J Syst Bacteriol 46: , Hanninen M, Happonen I, Jalava K: Transmission of canine gastric Helicobacter salomonis infection from dam to offspring and between puppies. Vet Microbiol 62:47 58, Strauss-Ayali D, Scanziani E, Deng D: Helicobacter spp infection in cats: Evaluation of humoral immune response and prevalence of gastric Helicobacter spp. Vet Microbiol 79: , Meining A, Kroher G, Stolte M: Animal reservoirs in the transmission of Helicobacter heilmannii. Scand J Gastroenterol 33: , Stolte M, Kroher G, Meining A, et al: A comparison of Helicobacter pylori and H. heilmannii gastritis. A matched control study involving 404 patients. Scand J Gastroenterol 32:28 33, Webb PM, Knight T, Elder JB, et al: Is Helicobacter pylori transmitted from cats to humans? Helicobacter 1:79 81, Rothenbacher D, Bode G, Peschke F, et al: Active infection with Helicobacter pylori in an asymptomatic population of middle aged to elderly people. Epidemiol Infect 120: , Rothenbacher D, Bode G, Winz T, et al: Helicobacter pylori in out-patients of a general practitioner: Prevalence and determinants of current infection. Epidemiol Infect 119: , Fiedorek S, Malaty H, Evans D, et al: Factors influencing the epidemiology of Helicobacter pylori infection in children. Pediatrics 88: , McIsaac W, Leung G: Peptic ulcer disease and exposure to domestic pets. Am J Public Health 89:81 84, Begue R, Gonzales J, Correa-Gracian H, et al: Dietary risk factors associated with the transmission of Helicobacter pylori in Lima, Peru. Am J Trop Med Hyg 59: , Bode G, Rothenbacher D, Brenner H, et al: Pets are not a risk factor for Helicobacter pylori infection in young children: Results of a population-based study in Southern Germany. Pediatr Infect Dis J 17: , Webb PM, Knight T, Greaves S, et al: Relation between infection with Helicobacter pylori and living conditions in childhood: Evidence for person-toperson transmission in early life. Br Med J 308: , Cutler A, Havstad S, Ma C, et al: Accuracy of invasive and noninvasive tests to diagnose Helicobacter pylori infection. Gastroenterology 109: , Rollan A, Giancaspero R, Arrese M, et al: Accuracy of invasive and noninvasive tests to diagnose Helicobacter pylori infection after antibiotic treatment. Am J Gastroenterol 92: , Leodolter A, Megraud F: Diagnosis of Helicobacter pylori infection. Curr Opin Gastroenterol 17(suppl 1):S19 S23, Chiba N, Veldhuyzen Van Zanten SJ: 13 C-urea breath tests are the noninvasive method of choice for Helicobacter pylori detection. Can J Gastroenterol 13: , Fanti L, Mezzi G, Cavallero A, et al: A new simple immunoassay for detecting Helicobacter pylori infection: Antigen in stool specimens. Digestion 60: , Vaira D, Malfertheiner P, Megraud F, et al: Noninvasive antigen-based assay for assessing Helicobacter pylori eradication: A European multicenter study. Am J Gastroenterol 95: , Shinozaki J, Sellon R, Cantor G, et al: Fecal polymerase chain reaction with 16S ribosomal RNA primers can detect the presence of gastrointestinal Helicobacter in dogs. J Vet Intern Med 16: , Stoffel MH, Friess AE, Burnens A, et al: Distinction of gastric Helicobacter spp in humans and domestic pets by scanning electron microscopy. Helicobacter 5: , Rossi G, Rossi M, Vitali C, et al: A conventional beagle dog model for acute and chronic infection with Helicobacter pylori. Infect Immunol 67: , Fox JG, Batchelder M, Marini R, et al: Helicobacter pylori induced gastritis in the domestic cat. Infect Immunol 63: , Radin MJ, Eaton K, Krakowka S, et al: Helicobacter pylori gastric infection in gnotobiotic beagle dogs. Infect Immunol 58: , Lee A, Krakowka S, Fox JG, et al: Role of Helicobacter felis in chronic canine gastritis. Vet Pathol 29: , Simpson K, Strauss-Ayali D, McDonough P, et al: Gastric function in dogs with naturally acquired gastric Helicobacter spp infection. J Vet Intern Med 13: , Happonen I, Saari S, Castren L, et al: Comparison of diagnostic methods for detecting gastric Helicobacter-like organisms in dogs and cats. J Comp Pathol 115: , Cornetta AM, Simpson KW, Strauss-Ayali D, et al: Use of [ 13 C] urea breath test for detection of gastric infection with Helicobacter spp in dogs. Am J Vet Res 59: , Lee C, Tu T, Dai Y, et al: Negative CLOtest pellet can be reused. Gastrointest Endosc 50: , Adamsson I, Nord CE, Sjostedt S, et al: The value of different detection methods of Helicobacter pylori during treatment. J Clin Gastroenterol 27: , Weston A, Campbell D, Hassanein R, et al: Prospective, multivariate evaluation of CLOtest performance. Am J Gastroenterol 92: , COMPENDIUM March 2005

7 Diagnosing Gastric Helicobacter Infections in Dogs and Cats CE Laine L, Sidhom O, Emami S, et al: Effect of blood on rapid urease testing of gastric mucosal biopsy specimens. Gastrointest Endosc 47: , Scanziani E, Simpson K, Monestiroli S, et al: Histological and immunohistochemical detection of different Helicobacter species in the gastric mucosa of cats. J Vet Diagn Invest 13:3 12, Simpson KW, McDonough PL, Strauss-Ayali D, et al: Helicobacter felis infection in dogs: Effect on gastric structure and function. Vet Pathol 36: , Simpson KW, Strauss-Ayali D, Straubinger RK, et al: Helicobacter pylori infection in the cat: Evaluation of gastric colonization, inflammation and function. Helicobacter 6:1 14, Serna JH, Genta RM, Lichtenberger LM, et al: Invasive Helicobacter-like organisms in feline gastric mucosa. Helicobacter 2:40 43, Happonen I, Linden J, Westermarck E: Effect of triple therapy on eradication of canine gastric helicobacters and gastric disease. J Small Anim Pract 41:1 6, Cattoli G, van Vugt R, Zanoni RG, et al: Occurrence and characterization of gastric Helicobacter spp. in naturally infected dogs. Vet Microbiol 70: , Savarino V, Vigneri S, Celle G: The 13 C urea breath test in the diagnosis of Helicobacter pylori infection. Gut 45:I18 I22, Neiger R, Seiler G, Schmassmann A: Use of a urea breath test to evaluate short-term treatments for cats naturally infected with Helicobacter heilmannii. Am J Vet Res 60: , ARTICLE #4 CE TEST This article qualifies for 2 contact hours of continuing CE education credit from the Auburn University College of Veterinary Medicine. Subscribers may purchase individual CE tests or sign up for our annual CE program. Those who wish to apply this credit to fulfill state relicensure requirements should consult their respective state authorities regarding the applicability of this program. To participate, fill out the test form inserted at the end of this issue or take CE tests online and get real-time scores at CompendiumVet.com. 1. Which statement regarding spiral bacteria is incorrect? a. They were described in the stomachs of humans and animals more than 100 years ago. b. They were first implicated as a cause of peptic ulcers in humans in the early 1980s. c. In humans, H. pylori has been shown to increase the risk of gastric cancer. d. They are uncommon in the stomachs of normal dogs and cats. 2. Which statement regarding Helicobacter spp is incorrect? a. They are gram positive. b. They are microaerophilic. c. They are motile. d. They are urease positive. 3. Which Helicobacter sp has not been identified in the stomachs of dogs? a. H. heilmannii c. H. felis b. H. pylori d. H. bizzozeronii 4. Which of the following is considered a noninvasive test to detect Helicobacter spp? a. histologic examination of gastric mucosal biopsies b. rapid urease test c. electron microscopic examination of gastric mucosal biopsies d. urea breath testing 5. Which statement regarding evaluation of gastric brush cytology specimens is incorrect? a. They are insensitive in identifying spiral bacteria. b. Evaluation is inexpensive. c. There is a rapid turnaround time for results. d. Identification of spiral bacteria requires simple staining methods available in all practices. 6. The rapid urease test a. is expensive (approximately $25 per test). b. detects the presence of bacterial urease from Helicobacter organisms. c. needs to be incubated at 98.6 F (37 C) for 2 to 3 days. d. can have false-negative results if a large number of Helicobacter spp are present within the biopsy sample. 7. Which of the following is not a potential advantage of identifying spiral bacteria by histologic evaluation of gastric mucosal samples? a. Spiral bacteria are usually clearly visible with H & E staining if present on the mucosal surface or within gastric pits. b. Underlying inflammatory or neoplastic conditions can be identified. c. The turnaround time for results is rapid (i.e., usually less than 12 to 24 hours). d. It is easy to increase diagnostic sensitivity by evaluating samples from multiple regions of the stomach. 8. Bacterial culture of Helicobacter spp in dogs and cats is a. not commonly conducted because H. heilmannii has not been successfully cultured. b. the diagnostic test of choice because of high sensitivity and specificity. c. very convenient because it can be conducted with fresh feces. March 2005 COMPENDIUM

8 228 d. not commonly conducted because of the long period necessary to grow the organisms, resulting in very long turnaround times (7 to 10 days). 9. Which statement regarding the urea breath test is incorrect? a. It is considered a noninvasive test. b. It can easily be conducted in small animal practices. c. 14 C- or 13 C-labeled urea is hydrolyzed by bacterial urease in the stomachs of animals with gastric Helicobacter spp and can be measured as CO 2 in expired air. d. It has been used in adult humans to monitor treatment efficacy and in children to make a diagnosis. 10. Based on cost, ease of performance, sensitivity, specificity, turnaround time, and practicality, which test is best in diagnosing gastric Helicobacter infection in dogs and cats? a. histologic assessment of gastric biopsy samples b. rapid urease testing of gastric biopsy samples c. assessment of gastric brush cytologic specimens d. bacterial culture of gastric biopsy samples COMPENDIUM March 2005