In vivo toxin expression is increased by proton pump inhibitor (PPI) in the dominant strain of the 2003–4 Montreal Clostridiumdifficile epidemic

Abstract number: 1134_04_136

Louie T.J., MacCannell D.R., Loo V., Krulicki W., Ward L., Louie R., Emery J.

The recently publicized massive outbreak of C. difficile associated disease (CDAD) in Montreal is largely clonal in nature, with a single, binary-toxin (CDT) positive strain accounting for a major proportion of clinical cases, with attendant morbidity and mortality. A recent epidemiologic study showed that concurrent use of proton pump inhibitor (PPI) was associated with a 2.1–2.7 fold increased risk of infection. The Calgary region experienced a large ermB + clonal outbreak in 2000–2001, also with associated increased disease severity.


We examined the impact of pantoprazole on C. difficile toxin expression of cytotoxin B in a Sprague-Dawley animal model simulating human intestinal ecology and antibiotic selection pressure.


In two parallel experiments, 73 rats were infected with either the dominant, binary toxin-positive (M13) from the Montreal CDAD outbreak, a less-prevalent, binary toxin negative (M18) Montreal strain or the binary toxin-negative Calgary outbreak strain (C2007). Animals (200 g) were individually housed in wire mesh cages; barrier/contact precautions were maintained between groups to prevent cross infection. Cultures of all rats confirmed no initial colonization. After 7 days of conditioning on a mixed meat/grain diet (maintained for 20 days), the animals were given 103 CFU of CD spores on days 8–9, followed by Cefotaxime (15 mg q8h) with or without pantoprazole (2 mg IP/day) from days 10–20. The animals were sacrificed on day 21, and vegetative and spore counts were quantitatively assessed. Toxin titres were determined by standard cell culture methods, and pH of cecal contents was measured ex-vivo.


The increase in toxin titre upon exposure to pantoprazole was statistically significant (p < 0.01) in the pooled M13 group (Montreal dominant clone). Conversely, toxin titres in C2007 and M18 both decreased upon exposure to the PPI, but while the decrease in C2007 was significant (p < 0.05), the change in M18 was not.

Exp #1
M13 Cefotasxime (n=8)4000 (±645 6)1.1E9 (±2.6E8)3.4E7 (±1.5E7) 
M13 Cefotaxime +   Pantoprazole (n=8)10625 (±2652.0)4.8E8 (±1 0E8)7.8E6 (±3 4E6) 
C2007 Cefotaxime (n=8)6500 (±2665 9)5.3E8 (±1 0E8)1.1E7 (±2.1E6) 
C2007 Cefotaxime +   Pantoprazole (n=8)3750 (±700.7)5.1E8 (±1 0E8)1.1E7 (±2.1E6) 
Exp #2
M13Cefotaxime (n=8)4125 (±934.2)3.4E8 (±8.4E7)5.1E3 (±1.1E3)6.08 (±0.04)
M13 Cefotaxime +   Pantoprazole (n=8)8000 (±1851.6)4.0E8 (±1.4E8)8.5E6 (±7.4E6)6.93 (±0.33)
M18 Cefotaxime (n=8)6375 (±3741.4)5.5E8 (±2.2E8)9.3E3 (±3.8E3)7.04 (±0.11)
MI8 Cefotaxime +   Pantoprazole (n=8)2625 (±532 4)4 1E8 (±7.2E7)2.8E4 (±)1.2E46.98 (±0.12)
C2007 Untreated   Control (n=9)NilNilNil6.33 (±0.07)


In this animal model, the dominant strain of the 2003–4 Montreal CDAD epidemic demonstrated a 2 to 2.5 fold increase in-vivo toxigenicity in the presence of pantoprazole. It is unclear if the function of colonic Na + /K + ATPase pumps accounts for this difference. The effect appears to be strain specific. Since toxigenicity is variably linked to disease severity, these observations support of the possibility that PPIs could increase disease severity.

Session Details

Date: 01/08/2007
Time: 00:00-00:00
Session name: XXIst ISTH Congress
Location: Oxford, UK
Presentation type:
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