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Potentiation of the action of metronidazole on Helicobacter pylori by omeprazole and bismuth subcitrate
International Journal of Antimicrobial Agents 14 (2000) 231 – 234 www.ischemo.org
Potentiation of the action of metronidazole on Helicobacter pylori by omeprazole and bismuth subcitrate Leif P. Andersen a,*, Hanne Colding b, Jette E. Kristiansen c a
Department of Clinical Microbiology 7806, National Uni6ersity hospital (Rigshospitalet), Tagens6ej 20, DK-2200 Copenhagen, Denmark b Institute for Medical Microbiology, Uni6ersity of Copenhagen, Copenhagen, Denmark c Department of Clinical Microbiology, Sonderborg Hospital, Sonderborg, Denmark
Abstract Treatment failures using triple therapy that include metronidazole, are common in patients infected with metronidazole-resistant Helicobacter pylori in the gastric mucosa. Higher eradication rates in such patients have been described when treatment regimens include bismuth salts compared to regimens that include proton pump inhibitors. In the present study, the synergistic effect of subinhibitory concentrations (0.25–0.5 MIC) of either bismuth subcitrate or omeprazole with metronidazole on the susceptibility of 42 H. pylori strains was investigated by agar dilution method and the Epsilometer test (Etest). With 0.5 MIC of either of the two drugs, the susceptibility of all H. pylori strains to metronidazole was reduced between two to 64 fold and six (27%) metronidazole-resistant strains (with MIC \4 mg/l) reverted to being metronidazole sensitive. These results suggested that either bismuth salts or proton pump inhibitors may be effective in the treatment of some infections with metronidazole-resistant H. pylori strains when used in sufficiently high doses. © 2000 Elsevier Science B.V. and International Society of Chemotherapy. All rights reserved. Keywords: Metronidazole; Helicobacter pylori; Omeprazole; Subcitrate
1. Introduction Helicobacter pylori affects more than 1 billion people world wide with local prevalence rates that range from 30 to 90% with no gender preference [1 – 3]. H. pylori causes human infection with oral – oral or faecal–oral transmission occurring mainly in childhood [1,4]. The organism produces chronic gastritis, gastric and duodenal ulceration [5–7] and is thought to initiate the development of gastric carcinomas and MALTlymphomas [8–10]. The management of chronic gastritis with antibiotics to which the organism is susceptible markedly decreases recurring peptic ulcers [11]. An increase in the rate of treatment failure ranging from 5 to 70% has been observed because of emerging resistance of the organism to conventional antibiotics [11– 13]. Treatment failure is attributed to inadequate management as well poor patient compliance [13] and is thus of an acquired nature. The clinical outcome, however, does not always correlate directly to the development of resistance to the antibiotics used [13]. * Corresponding author. Tel.: +45-35457784; fax + 45-35456831. E-mail address: [email protected] (L.P. Andersen)
The management of chronic gastritis and peptic ulcer disease prior to the understanding of the role of H. pylori as a causative organism involved the use of bismuth salts and H2-receptor antagonists such as cimetidine and ranitidine. Proton pump inhibitors (PPI) such as omeprazole, lansoprazole and pantoprazole as well as antibiotics were later added to the regimen, initially on empirical basis. Because chronic gastritis, now known to be primarily caused by H. pylori infection, responded to bismuth salts and PPI, the possibility that these agents had activity against H. pylori was investigated and subsequently demonstrated [14–18]. Compounds directly affecting the cell membrane presumably by affecting pump mechanisms located at the plasma membrane such as bismuth salts, anti-histamines and neuroleptics [14,15,19,20] as well as inhibitors of mammalian proton pumps have long been known to have anti-bacterial activity [16,17]. Neuroleptics such as chlorpromazine (a phenothiazine) not only have demonstrable activity against H. pylori, but reverses resistance of the organism to a few antibiotics [20,21].
0924-8579/00/$ 20 © 2000 Elsevier Science B.V. and International Society of Chemotherapy. All rights reserved. PII: S 0 9 2 4 - 8 5 7 9 ( 0 0 ) 0 0 1 3 3 - 3
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The possibility that bismuth salts and PPI employed in the management of chronic gastritis, enhance the activity of antibiotics to which H. pylori is susceptible or reverse antibiotic resistance, was thus investigated by testing the susceptibility of H. pylori to metronidazole in combination with the anti-ulcer drugs, in vitro.
2. Materials and methods
2.1. Bacterial strains Forty-two clinical isolates of H. pylori from patients in Denmark with peptic ulcer were included in the study. ATCC strains of H. pylori, Campylobacter jejuni, Escherichia coli and Staphylococcus aureus were used as controls.
2.2. Agents Bismuth subcitrate (Yamanouchi Pharma) dissolved in water and omeprazole (AstraHAssle AB) initially dissolved in 99% ethanol (1 – 2% of end volume) and further diluted in water in two-fold dilutions from 4 to 128 mg/l were added to Isosensitest (Oxoid, UK) agar plates containing 10% horse blood. Control plates without anti-ulcer compounds were used for each dilution row.
2.3. Susceptibility testing of H. pylori to bismuth subcitrate and omeprazole H. pylori was grown in microaerobic atmosphere on 7% lysed and defibrinated horse blood agar plates (chocolate agar plates) for 72 h. Cultures were harvested and suspended in saline to a final concentration of 109 colony forming units (CFU) per ml. The isosensitest plates were inoculated with a multipoint inoculator (Denley England) which provided an inoculum size of 106 CFU/spot. Results for the control strains with a variation of no more than two dilution steps were accepted. No growth was taken as the antibacterial activity and shown as the minimum inhibitory concentration (MIC). The tests were repeated twice. The resulting test variation was within two-fold for omeprazole and bismuth subcitrate.
2.4. Susceptibility testing of H. pylori to metronidazole Etests (Biodisk AB, Sweden) strips containing concentrations of 0.016 – 256 mg/l were used to determine the MIC of metronidazole. One Etest strip was placed on each agar plate inoculated with bacteria. The tests were repeated four times and the result of the test variation for each H. pylori strain was within threefold.
3. Results and discussion The MIC of bismuth subcitrate for the H. pylori strains was consistent and ranged from 32 to 64 mg/l for 40 of the strains. Three strains had MIC of 16 and another of 128 mg/l (Table 1). The MIC for omeprazole was also very consistent being 32–64 mg/l for all H. pylori strains (Table 1). The concentrations of bismuth subcitrate and omeprazole required for the inhibition of growth is high for all strains, showing that the strains studied were resistant to both subcitrate and omeprazole. The MIC of metronidazole for 20 strains ranged from 0.064 to 1 mg/l (sensitive) and for 22 strains ranged from 64 to \ 256 mg/l (resistant) with the exception of one with an MIC of 8 mg/l. The effect of combination of bismuth subcitrate or omeprazole with metronidazole is shown in the Table. In the presence of 0.25 MIC of bismuth subcitrate, there was a reduction of metronidazole MIC of greater than doubling dilutions in five strains, whereas 11 strains showed a similar MIC reduction in the presence of 0.25MIC of omeprazole. In the presence of 0.5 MIC of bismuth subcitrate, 18 strains had metronidazole MIC reduced by greater than two doubling dilutions, and 16 strains showed a similar MIC reduction in the presence of 0.5 MIC omeprazole. Three of 42 strains originally resistant to metronidazole (MIC] 64 mg/l) became susceptible (MIC5 4 mg/l) in combination with omeprazole. Both bismuth subcitrate and omeprazole at subinhibitory concentrations interacts with metronidazole in increasing the susceptibility of some H. pylori strains to metronidazole. Bismuth subcitrate is known to bind to the surface membrane of H. pylori and probably affected the permeability of the cell membrane. Omeprazole act on the proton pump by inhibiting secretion of the gastric acid. H. pylori also possess a proton pump and the effect of omeprazole could be a direct effect on this proton pump. The relation between the proton pump and metronidazole uptake in H. pylori is unknown but interference with efflux mechanisms may be possible. Another possible mechanism may be the interaction with fumarate reductase that is an important enzyme in the respiratory chain in H. pylori and is located in the cell membrane. Metronidazole-resistant H. pylori are found in 10– 15% of strains from developed countries up to 50% of strains in developing countries. Treatment failures using metronidazole regimen therapy are quite common in patients with metronidazole-resistant H. pylori. Regimens containing bismuth salts have a higher eradication rate than regimens containing proton pump inhibitors. Concentrations of 0.5 MIC of bismuth salts are achieved in the gastric mucosa but not with omeprazole in standard oral dosages (20–40 mg). High dosages (160 mg) of omeprazole have been used in patients with treatment failure and had a higher eradi-
Table 1 Susceptibility (MIC in mg/l) of H. pylori to bismuth subcitrate, omeprazole, metronidazole and their combinationsa Bismuth subcitrate
Omeprazole
Metronidazole (mtz)
Mtz+0.25 MIC bismuth subcitrate
Mtz+0.5 MIC bismuth subcitrate
Mtz+0.25 MIC omeprazole
Mtz+0.5 MIC omeprazole
v a˚ 2 4 5 6 o q 1 8 10 12 14 16 29 31 45 47 p 49 ø h l n b c d f g i r s x j k u 62 63 74 e M Z
32 32 32 32 32 64 32 32 32 32 64 16 32 32 16 32 32 32 128 32 32 32 32 32 32 32 32 32 32 32 32 32 16 32 32 32 32 64 32 32 32 32
64 32 64 64 64 64 64 32 64 64 64 64 64 64 64 64 64 64 64 64 32 64 64 64 64 64 64 64 64 64 64 32 64 64 64 32 64 64 64 64 64 32
0.064 0.064 0.125 0.125 0.125 0.125 0.125 0.125 0.19 0.25 0.25 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 1 8 64 64 64 128 128 128 128 128 128 128 128 128 256 256 256 \256 \256 \256 \256 \256 \256
0.064 0.064 0.016 0.032 0.047 0.125 0.125 0.125 (−) 0.19 0.25 0.25 0.25 0.38 0.5 0.64 0.5 0.5 0.016 1 8 64 64 64 64 128 128 128 128 128 64 128 64 256 256 128 64 128 \256 256 \256 \256
0.032 0.032 (−) (−) (−) (−) 0.016 0.064 (−) (−) (−) (−) (−) (−) (−) (−) (−) (−) (−) 0.064 4 32 16 8 16 32 32 32 32 64 64 48 16 16 32 128 0.094 1 48 64 32 48
0.064 0.064 (−) (−) (−) (−) 0.125 0.125 (−) 0.032 0.032 0.064 0.094 0.094 0.125 0.125 0.25 0.25 0.25 0.5 4 64 16 64 128 128 32 128 128 64 256 16 2 256 256 128 \256 \256 \256 256 256 \256
0.032 0.032 (−) (−) (−) (−) 0.064 0.064 (−) (−) (−) (−) (−) (−) (−) (−) (−) (−) 0.25 (−) 4 8 4 16 16 32 32 64 16 32 8 1 0.064 8 64 16 (−) (−) (−) 128 64 \256
(−), No growth observed in these plates; perhaps due to the inhibitory activity of sub MIC concentrations of bismuth subcitrate or omeprazole.
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Strain
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L.P. Andersen et al. / International Journal of Antimicrobial Agents 14 (2000) 231–234
cation rate in these patients than using standard doses of omeprazole. To reach the effective concentration of 0.5 MIC of omeprazole (as the synergistic concentration found in this study), in the gastric mucosa, an oral dose of 120–160 mg may have to be used. The standard dose of 20–40 mg b.i.d. omeprazole commonly used may not have an effect on metronidazole-resistant H. pylori. This study indicated that bismuth salts or high dosages of proton pump inhibitors such as omeprazole could be used in empirical triple therapy regimen which include metronidazole for the treatment of metronidazole-resistant H. pylori.
Acknowledgements The excellent technical assistance by Bente Jensen and Susanne Waldorf Larsen is greatly appreciated. This study was supported by The Danish Medical Research Council (Grant no. 12-1965), Astra Denmark A/S, Rhone-Poulenc Rorer AIS and Yamanouchi Pharma A/S.
References [1] Megraud F, Brassens-Rabbe MP, Denis F, et al. Seroepidemiology of Campylobacter pylori infection in various populations. J Clin Microbiol 1989;27:1870–3. [2] Andersen LP, Rosenstock SJ, Bonnevie O, et al. Seroprevalence of immunoglobulin G, M, and A antibodies to Helicobacter pylori in an unselected Danish population. Am J Epidemiol 1996;143:1157– 64. [3] Kosunen TU, Hook J, Rautelin HI. Age-dependent increase of Campylobacter pylori antibodies in blood donors. Scand J Gastroenterol 1989;24:110–4. [4] Klein PD, Graham DY, Gaillour A, et al. Water source as risk factor for Helicobacter pylori infection in Peruvian children. Gastrointestinal Physiology Working Group. Lancet 1991;337:1503– 6. [5] Kelly SM, Pitcher MC, Farmery SM, et al. Isolation of Helicobacter pylori from faeces of patients with dyspepsia in the UK. Gastroenterology 1994;107:1671–4.
.
[6] Marshall BJ, Warren JR. Unidentified curved bacilli in the stomach of patients with gastritis and peptic ulceration. Lancet 1984;1:1311 – 5. [7] Dunn BE, Cohen H, Blaser MJ. Helicobacter pylori. Clin Microbiol Rev 1997;10:720 – 41. [8] Andersen LP, Nielsen H. Peptic ulcer: an infectious disease? Ann Med 1993;25:563 – 8. [9] Lynch DA, Axon AT. Helicobacter pylori, gastric cancer and gastric epithelial kinetics: a review. Eur J Gastroenterol Hepatol 1995;7:S17 – 23. [10] Eidt S, Stolte M. The significance of Helicobacter pylori in relation to gastric cancer and lymphoma. Eur J Gastroenterol Hepatol 1995;7:318 – 21. [11] Hopkins RJ, Girardi LS, Tumey EA. Relationship between Helicobacter pylori eradication and reduced duodenal and gastric ulcer recurrence: a review. Gastroenterology 1996;110:1244–52. [12] Deltenre M, Jonas C, Otero J, et al. Strategies for Helicobacter pylori eradication in 1995: a review of international and Belgian experience. J Physiol Pharmacol 1996;47:59 – 69. [13] Bell GD, Powell KU, Burridge SM, et al. Reinfection or recrudescence after apparently successful eradication of Helicobacter pylori infection: implications for treatment of patients with duodenal ulcer disease. Q J Med 1993;86:375 – 82. [14] Kristiansen JE. Antimicrobial activity of non-antibiotics: unusual properties of non-antibiotic drugs create unexpected therapeutic possibilities and lead to new basic insights. Features. ASM News 1991;57:135 – 9. [15] Andreasen JJ, Andersen LP. In vitro susceptibility of Campylobacter pylori to cimetidine, sucralfate, bismuth and sixteen antibiotics. Acta Pathol Microbiol lmmunol Scand Sect B 1987;95:147 – 9. [16] Belli WA, Fryklund J. Partial characterization and effect of omeprazole on ATPase activity in Helicobacter pylori by using permeabilized cells. Antimicrob Agents Chemother 1995;39:1717 – 20. [17] lwahi T, Hiroshi H, Nakao M, et al. Lansoprazole, a novel benzimidazole proton pump inhibitor, and its related compounds have selective activity against Helicobacter pylori. Antimicrob Agents Chemother 1991;35:490 – 6. [18] Labenz J, Tillenburg B, Peitz U, et al. Helicobacter pylori augments the pH-increasing effect of omeprazole in patients with duodenal ulcer. Gastroenterology 1996;110:725 – 32. [19] Kristiansen JE. Experiments to illustrate the effect of chlorpromazine on the permeability of the bacterial cell wall. Acta Pathol Microbiol Immunol Scand Sect B 1979;87:317 – 9. [20] Kristiansen JE. Chlorpromazine: non-antibiotics with antimicrobial activity — new insights in managing resistance? Curr Opin Invest Drugs 1993;2:587 – 91. [21] Kristiansen JE, Amaral L. The potential management of resistant infections with non-antibiotics. J Antimicrob Chemother 1997;40:319 – 27.
Potentiation of the action of metronidazole on Helicobacter pylori by omeprazole and bismuth subcitrate Leif P. Andersen a,*, Hanne Colding b, Jette E. Kristiansen c a
Department of Clinical Microbiology 7806, National Uni6ersity hospital (Rigshospitalet), Tagens6ej 20, DK-2200 Copenhagen, Denmark b Institute for Medical Microbiology, Uni6ersity of Copenhagen, Copenhagen, Denmark c Department of Clinical Microbiology, Sonderborg Hospital, Sonderborg, Denmark
Abstract Treatment failures using triple therapy that include metronidazole, are common in patients infected with metronidazole-resistant Helicobacter pylori in the gastric mucosa. Higher eradication rates in such patients have been described when treatment regimens include bismuth salts compared to regimens that include proton pump inhibitors. In the present study, the synergistic effect of subinhibitory concentrations (0.25–0.5 MIC) of either bismuth subcitrate or omeprazole with metronidazole on the susceptibility of 42 H. pylori strains was investigated by agar dilution method and the Epsilometer test (Etest). With 0.5 MIC of either of the two drugs, the susceptibility of all H. pylori strains to metronidazole was reduced between two to 64 fold and six (27%) metronidazole-resistant strains (with MIC \4 mg/l) reverted to being metronidazole sensitive. These results suggested that either bismuth salts or proton pump inhibitors may be effective in the treatment of some infections with metronidazole-resistant H. pylori strains when used in sufficiently high doses. © 2000 Elsevier Science B.V. and International Society of Chemotherapy. All rights reserved. Keywords: Metronidazole; Helicobacter pylori; Omeprazole; Subcitrate
1. Introduction Helicobacter pylori affects more than 1 billion people world wide with local prevalence rates that range from 30 to 90% with no gender preference [1 – 3]. H. pylori causes human infection with oral – oral or faecal–oral transmission occurring mainly in childhood [1,4]. The organism produces chronic gastritis, gastric and duodenal ulceration [5–7] and is thought to initiate the development of gastric carcinomas and MALTlymphomas [8–10]. The management of chronic gastritis with antibiotics to which the organism is susceptible markedly decreases recurring peptic ulcers [11]. An increase in the rate of treatment failure ranging from 5 to 70% has been observed because of emerging resistance of the organism to conventional antibiotics [11– 13]. Treatment failure is attributed to inadequate management as well poor patient compliance [13] and is thus of an acquired nature. The clinical outcome, however, does not always correlate directly to the development of resistance to the antibiotics used [13]. * Corresponding author. Tel.: +45-35457784; fax + 45-35456831. E-mail address: [email protected] (L.P. Andersen)
The management of chronic gastritis and peptic ulcer disease prior to the understanding of the role of H. pylori as a causative organism involved the use of bismuth salts and H2-receptor antagonists such as cimetidine and ranitidine. Proton pump inhibitors (PPI) such as omeprazole, lansoprazole and pantoprazole as well as antibiotics were later added to the regimen, initially on empirical basis. Because chronic gastritis, now known to be primarily caused by H. pylori infection, responded to bismuth salts and PPI, the possibility that these agents had activity against H. pylori was investigated and subsequently demonstrated [14–18]. Compounds directly affecting the cell membrane presumably by affecting pump mechanisms located at the plasma membrane such as bismuth salts, anti-histamines and neuroleptics [14,15,19,20] as well as inhibitors of mammalian proton pumps have long been known to have anti-bacterial activity [16,17]. Neuroleptics such as chlorpromazine (a phenothiazine) not only have demonstrable activity against H. pylori, but reverses resistance of the organism to a few antibiotics [20,21].
0924-8579/00/$ 20 © 2000 Elsevier Science B.V. and International Society of Chemotherapy. All rights reserved. PII: S 0 9 2 4 - 8 5 7 9 ( 0 0 ) 0 0 1 3 3 - 3
232
L.P. Andersen et al. / International Journal of Antimicrobial Agents 14 (2000) 231–234
The possibility that bismuth salts and PPI employed in the management of chronic gastritis, enhance the activity of antibiotics to which H. pylori is susceptible or reverse antibiotic resistance, was thus investigated by testing the susceptibility of H. pylori to metronidazole in combination with the anti-ulcer drugs, in vitro.
2. Materials and methods
2.1. Bacterial strains Forty-two clinical isolates of H. pylori from patients in Denmark with peptic ulcer were included in the study. ATCC strains of H. pylori, Campylobacter jejuni, Escherichia coli and Staphylococcus aureus were used as controls.
2.2. Agents Bismuth subcitrate (Yamanouchi Pharma) dissolved in water and omeprazole (AstraHAssle AB) initially dissolved in 99% ethanol (1 – 2% of end volume) and further diluted in water in two-fold dilutions from 4 to 128 mg/l were added to Isosensitest (Oxoid, UK) agar plates containing 10% horse blood. Control plates without anti-ulcer compounds were used for each dilution row.
2.3. Susceptibility testing of H. pylori to bismuth subcitrate and omeprazole H. pylori was grown in microaerobic atmosphere on 7% lysed and defibrinated horse blood agar plates (chocolate agar plates) for 72 h. Cultures were harvested and suspended in saline to a final concentration of 109 colony forming units (CFU) per ml. The isosensitest plates were inoculated with a multipoint inoculator (Denley England) which provided an inoculum size of 106 CFU/spot. Results for the control strains with a variation of no more than two dilution steps were accepted. No growth was taken as the antibacterial activity and shown as the minimum inhibitory concentration (MIC). The tests were repeated twice. The resulting test variation was within two-fold for omeprazole and bismuth subcitrate.
2.4. Susceptibility testing of H. pylori to metronidazole Etests (Biodisk AB, Sweden) strips containing concentrations of 0.016 – 256 mg/l were used to determine the MIC of metronidazole. One Etest strip was placed on each agar plate inoculated with bacteria. The tests were repeated four times and the result of the test variation for each H. pylori strain was within threefold.
3. Results and discussion The MIC of bismuth subcitrate for the H. pylori strains was consistent and ranged from 32 to 64 mg/l for 40 of the strains. Three strains had MIC of 16 and another of 128 mg/l (Table 1). The MIC for omeprazole was also very consistent being 32–64 mg/l for all H. pylori strains (Table 1). The concentrations of bismuth subcitrate and omeprazole required for the inhibition of growth is high for all strains, showing that the strains studied were resistant to both subcitrate and omeprazole. The MIC of metronidazole for 20 strains ranged from 0.064 to 1 mg/l (sensitive) and for 22 strains ranged from 64 to \ 256 mg/l (resistant) with the exception of one with an MIC of 8 mg/l. The effect of combination of bismuth subcitrate or omeprazole with metronidazole is shown in the Table. In the presence of 0.25 MIC of bismuth subcitrate, there was a reduction of metronidazole MIC of greater than doubling dilutions in five strains, whereas 11 strains showed a similar MIC reduction in the presence of 0.25MIC of omeprazole. In the presence of 0.5 MIC of bismuth subcitrate, 18 strains had metronidazole MIC reduced by greater than two doubling dilutions, and 16 strains showed a similar MIC reduction in the presence of 0.5 MIC omeprazole. Three of 42 strains originally resistant to metronidazole (MIC] 64 mg/l) became susceptible (MIC5 4 mg/l) in combination with omeprazole. Both bismuth subcitrate and omeprazole at subinhibitory concentrations interacts with metronidazole in increasing the susceptibility of some H. pylori strains to metronidazole. Bismuth subcitrate is known to bind to the surface membrane of H. pylori and probably affected the permeability of the cell membrane. Omeprazole act on the proton pump by inhibiting secretion of the gastric acid. H. pylori also possess a proton pump and the effect of omeprazole could be a direct effect on this proton pump. The relation between the proton pump and metronidazole uptake in H. pylori is unknown but interference with efflux mechanisms may be possible. Another possible mechanism may be the interaction with fumarate reductase that is an important enzyme in the respiratory chain in H. pylori and is located in the cell membrane. Metronidazole-resistant H. pylori are found in 10– 15% of strains from developed countries up to 50% of strains in developing countries. Treatment failures using metronidazole regimen therapy are quite common in patients with metronidazole-resistant H. pylori. Regimens containing bismuth salts have a higher eradication rate than regimens containing proton pump inhibitors. Concentrations of 0.5 MIC of bismuth salts are achieved in the gastric mucosa but not with omeprazole in standard oral dosages (20–40 mg). High dosages (160 mg) of omeprazole have been used in patients with treatment failure and had a higher eradi-
Table 1 Susceptibility (MIC in mg/l) of H. pylori to bismuth subcitrate, omeprazole, metronidazole and their combinationsa Bismuth subcitrate
Omeprazole
Metronidazole (mtz)
Mtz+0.25 MIC bismuth subcitrate
Mtz+0.5 MIC bismuth subcitrate
Mtz+0.25 MIC omeprazole
Mtz+0.5 MIC omeprazole
v a˚ 2 4 5 6 o q 1 8 10 12 14 16 29 31 45 47 p 49 ø h l n b c d f g i r s x j k u 62 63 74 e M Z
32 32 32 32 32 64 32 32 32 32 64 16 32 32 16 32 32 32 128 32 32 32 32 32 32 32 32 32 32 32 32 32 16 32 32 32 32 64 32 32 32 32
64 32 64 64 64 64 64 32 64 64 64 64 64 64 64 64 64 64 64 64 32 64 64 64 64 64 64 64 64 64 64 32 64 64 64 32 64 64 64 64 64 32
0.064 0.064 0.125 0.125 0.125 0.125 0.125 0.125 0.19 0.25 0.25 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 1 8 64 64 64 128 128 128 128 128 128 128 128 128 256 256 256 \256 \256 \256 \256 \256 \256
0.064 0.064 0.016 0.032 0.047 0.125 0.125 0.125 (−) 0.19 0.25 0.25 0.25 0.38 0.5 0.64 0.5 0.5 0.016 1 8 64 64 64 64 128 128 128 128 128 64 128 64 256 256 128 64 128 \256 256 \256 \256
0.032 0.032 (−) (−) (−) (−) 0.016 0.064 (−) (−) (−) (−) (−) (−) (−) (−) (−) (−) (−) 0.064 4 32 16 8 16 32 32 32 32 64 64 48 16 16 32 128 0.094 1 48 64 32 48
0.064 0.064 (−) (−) (−) (−) 0.125 0.125 (−) 0.032 0.032 0.064 0.094 0.094 0.125 0.125 0.25 0.25 0.25 0.5 4 64 16 64 128 128 32 128 128 64 256 16 2 256 256 128 \256 \256 \256 256 256 \256
0.032 0.032 (−) (−) (−) (−) 0.064 0.064 (−) (−) (−) (−) (−) (−) (−) (−) (−) (−) 0.25 (−) 4 8 4 16 16 32 32 64 16 32 8 1 0.064 8 64 16 (−) (−) (−) 128 64 \256
(−), No growth observed in these plates; perhaps due to the inhibitory activity of sub MIC concentrations of bismuth subcitrate or omeprazole.
233
a
L.P. Andersen et al. / International Journal of Antimicrobial Agents 14 (2000) 231–234
Strain
234
L.P. Andersen et al. / International Journal of Antimicrobial Agents 14 (2000) 231–234
cation rate in these patients than using standard doses of omeprazole. To reach the effective concentration of 0.5 MIC of omeprazole (as the synergistic concentration found in this study), in the gastric mucosa, an oral dose of 120–160 mg may have to be used. The standard dose of 20–40 mg b.i.d. omeprazole commonly used may not have an effect on metronidazole-resistant H. pylori. This study indicated that bismuth salts or high dosages of proton pump inhibitors such as omeprazole could be used in empirical triple therapy regimen which include metronidazole for the treatment of metronidazole-resistant H. pylori.
Acknowledgements The excellent technical assistance by Bente Jensen and Susanne Waldorf Larsen is greatly appreciated. This study was supported by The Danish Medical Research Council (Grant no. 12-1965), Astra Denmark A/S, Rhone-Poulenc Rorer AIS and Yamanouchi Pharma A/S.
References [1] Megraud F, Brassens-Rabbe MP, Denis F, et al. Seroepidemiology of Campylobacter pylori infection in various populations. J Clin Microbiol 1989;27:1870–3. [2] Andersen LP, Rosenstock SJ, Bonnevie O, et al. Seroprevalence of immunoglobulin G, M, and A antibodies to Helicobacter pylori in an unselected Danish population. Am J Epidemiol 1996;143:1157– 64. [3] Kosunen TU, Hook J, Rautelin HI. Age-dependent increase of Campylobacter pylori antibodies in blood donors. Scand J Gastroenterol 1989;24:110–4. [4] Klein PD, Graham DY, Gaillour A, et al. Water source as risk factor for Helicobacter pylori infection in Peruvian children. Gastrointestinal Physiology Working Group. Lancet 1991;337:1503– 6. [5] Kelly SM, Pitcher MC, Farmery SM, et al. Isolation of Helicobacter pylori from faeces of patients with dyspepsia in the UK. Gastroenterology 1994;107:1671–4.
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