Sensitivity testing for Helicobacter pylori should be more widely available

BMJ 1996;313:1079-1080 (26 October)

Letters

Sensitivity testing for Helicobacter pylori should be more widely available

EDITOR,--Greg Rubin and Richard Stevens are right to ask forthe wider availability of non-invasive diagnostic tests formanaging Helicobacter pylori infection in primary care.¹ Webelieve that the implementation of management guidelines forpeptic ulcer disease also requires the wider availability oftests to determine the sensitivity of H pylori, because increasedprescribing of antimicrobial drugs to treat the infection maybe associated with increased drug resistance. Furthermore, ourdata indicate that if the global eradication of H pylori isdeemed desirable then simpler and more effective regimens needto be developed for infected patients.

Table 1 (see overleaf) gives details of seven patients withgastric or duodenal ulcer who received at least three differentcourses of eradication treatment, including the most commonlyused drugs, in an attempt to eradicate H pylori. In all caseswe used either histological examination (Giemsa staining) plusthe rapid urease test or breath testing to evaluate the patients'H pylori status at least six weeks after the completion of thetreatments. All the patients were fully informed and compliedwith the treatments.

Table 1--H pylori status of seven patients after three courses of eradication treatment
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                      First treatment                       Second treatment                               Third treatment                           H pylori
                                                                                                                                                      status    Duration
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                                                                                                                                                       after    of follow
Case                                          No                                               No                                             No       third       up
No         Drug                             of days         Drug                             of days       Drug                             of days  treatment  (months)
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1          Omeprazole 20 mg twice daily        14      Omeprazole 20 mg daily                    7     Omeprazole 20 mg twice daily             7    Positive      9
           Amoxycillin 1 g twice daily                 Tinidazole 500 mg twice daily                   Amoxycillin 1 g twice daily
                                                       Clarithromycin 250 mg                           Clarithromycin 250 mg
                                                         twice daily                                     twice daily
2          Omeprazole 20 mg twice daily        14      Omeprazole 20 mg twice daily             14     Omeprazole 20 mg twice daily             7    Negative     11
           Amoxycillin 1 g twice daily                 Amoxycillin 1 g twice daily                     Amoxycillin 1 g twice daily
           Tinidazole 500 mg twice daily                                                               Clarithromycin 250 mg
                                                                                                         twice daily
3          Bismuth 120 mg                      14      Omeprazole 20 mg twice daily             14     Omeprazole 20 mg daily                   7    Positive     13
             four times daily                          Amoxycillin 1 g twice daily                     Tinidazole 500 mg twice daily
           Tetracycline 250 mg                         Metronidazole 250 mg                            Clarithromycin 250 mg
             eight times daily                          four times daily                                 twice daily
           Metronidazole 250 mg
            six times daily
4          Omeprazole 20 mg daily               7      Omeprazole 20 mg daily                    7     Bismuth 120 mg                           7    Positive      9
           Tinidazole 500 mg twice daily               Amoxycillin 1 g twice daily                       four times daily
           Clarithromycin 250 mg                       Clarithromycin 250 mg                           Omeprazole 20 mg twice daily
             twice daily                                 twice daily                                   Amoxycillin 1 g twice daily
5          Omeprazole 20 mg twice daily        14      Omeprazole 20 mg daily                    7     Omeprazole 20 mg daily                   7    Negative     15
           Amoxycillin 1 g twice daily                 Tinidazole 500 mg twice daily                   Amoxycillin 1 g twice daily
           Metronidazole 250 mg                        Clarithromycin 250 mg                           Clarithromycin 250 mg
            six times daily                              twice daily                                     twice daily
6          Bismuth 120 mg                      14      Omeprazole 20 mg daily                    7     Omeprazole 20 mg twice daily             7    Positive     12
             four times daily                          Tinidazole 500 mg twice daily                   Amoxycillin 1 g twice daily
           Tetracycline 250 mg                         Clarithromycin 250 mg                           Clarithromycin 250 mg
             eight times daily                           twice daily                                     twice daily
           Metronidazole 250 mg
             six times daily
7          Omeprazole 20 mg daily               7      Omeprazole 20 mg twice daily              7     Bismuth 120 mg                          14    Positive     11
           Amoxycillin 1 g twice daily                 Amoxycillin 1 g twice daily                       four times daily
           Clarithromycin 250 mg                       Metronidazole 250 mg                            Tetracycline 250 mg
             twice daily                                 six times daily                                 eight times daily
                                                                                                       Metronidazole 250 mg
                                                                                                         six times daily

Failure of treatment may be due to the different antibioticsusceptibilities of the various strains of H pylori; phenotypicallyand genotypically different strains of H pylori can be presentin the stomach at the same time.² We do not yet know whether,in an individual patient, drug resistance occurs through theselection of resistant strains within a mixed population (thatis, primary resistance) or through previously sensitive strainsbecoming resistant (that is, secondary resistance). Becausewe found that a patient might have to be treated three or moretimes for H pylori to be eradicated, both mechanisms may actin the same patient. In some cases, after the selection of organismsthat are primarily resistant to certain antibiotics, secondaryresistance to other drugs might develop.

Before treating patients with H pylori infection it is thusalways important to consider the results of culture and sensitivitytests.³ The problem is that at present the tests are unavailablein most centres. In addition, the routine isolation of H pyloriis difficult,⁴ and the need to culture the bacterium from severalgastric sites in a single patient because of the possible coexistenceof several strains compounds this difficulty.

G CAMMAROTA Investigator in gastroenterology

A TURSI Investigator in gastroenterology

A PAPA Investigator in gastroenterology

G FEDELI Professor of gastroenterology

G GASBARRINI Director of internal medicine and gastroenterologyschools

Departments of Internal Medicine and Gastroenterology, CatholicUniversity of Rome, 00168 Rome, Italy

G Cammarota, A Tursi, A Papa, G Fedeli, G Gasbarrini