Microarray analysis of the transcriptional responses of Clostridium difficile to environmental and antibiotic stress

Abstract

Clostridium difficile is a spore-forming anaerobic bacterium that is an emerging nosocomial threat; incidence of infection in hospitals is increasing, both in frequency and severity, resulting in considerable morbidity and mortality. In order to adapt to the intestinal environment, C. difficile must react to the many stresses involved with colonization, including exposure to antibiotics, which represents the most frequent precipitating agent of C. difficile infection. The responses of C. difficile to environmental shocks (heat, pH and oxidative shock) and to growth in the presence of subinhibitory concentrations of antibiotics (amoxicillin, clindamycin and metronidazole) were investigated using the C. difficile 630 microarray developed by the Bacterial Microarray Group at St George's, University of London, UK (BmG@S). Significantly regulated genes and operons were identified that are unique to or common between different stresses. The transcriptional profiles of C. difficile 630 are similar after growth in the presence of amoxicillin and clindamycin: both increased transcription of ribosomal protein genes and altered transcription of genes encoding surface-associated proteins. In contrast, metronidazole treatment resulted in minor changes in transcription patterns. The general stress response is observed after heat shock and acid shock. Heat shock also affected transcription of several biochemical pathways. Exposure to atmospheric oxygen induced a large number of electron transporters. This study provides a starting point for detailed analyses of numerous genes whose expression is affected by stress and may therefore be involved in adaptation to the host environment.

Pleiotropic Role of the RNA Chaperone Protein Hfq in the Human Pathogen Clostridium difficile

“…This included several genes probably in- During host infection, C. difficile is exposed to several stresses and responds to stress stimuli by inducing different mechanisms of defense (62). Among stress-related genes, we observed about 2-fold upregulation of genes encoding heat shock proteins, including groEL (CD0194) and grpE (CD2462) that are induced by clinically relevant heat stress and acid pH conditions in C. difficile (63,64) and by metabolic stresses in Clostridium acetobutylicum (65). Moreover, the expression of several genes that might be involved in the oxygen tolerance response and cell redox balance was altered in the CDIP53 strain compared to the CDIP51 strain.…”

ppGpp Conjures Bacterial Virulence

“…Bacillus anthracis, causing pulmonary anthrax, survives long periods in the environment as stresstolerant spores, and its differentiation into spores appears to be relA dependent (204). Clostridium difficile, an increasingly prevalent nosocomial pathogen that is frequently exposed to antimicrobial agents, upregulates a putative ppGpp synthesis/degradation protein in the presence of both amoxicillin and clindamycin (62). Here we discuss more extensive evidence for the direct involvement of ppGpp in the survival and pathogenesis of three firmicutes, the food-borne pathogen Listeria monocytogenes, hospital-acquired Enterococcus faecalis, and the versatile Streptococcus spp.…”

Clostridium difficile MazF Toxin Exhibits Selective, Not Global, mRNA Cleavage

“…They also analyzed the gene expression profile of C. difficile cells exposed to a subinhibitory concentration of metronidazole, the antibiotic traditionally enlisted as first-line therapy for CDI. The effects of other stress conditions on global gene expression were also analyzed, allowing the comparison of the classes of genes whose transcript levels increase upon exposure to each type of stress (10). In this data set, both toxin and antitoxin mRNA levels increased by 25% or more with clindamycin and amoxicillin exposure (Table 4).…”

“…In the first study, Fairweather and colleagues tested the effects of clindamycin or the ␤-lactam amoxicillin (at subinhibitory concentrations to preclude cell death) on global gene expression (10). They also analyzed the gene expression profile of C. difficile cells exposed to a subinhibitory concentration of metronidazole, the antibiotic traditionally enlisted as first-line therapy for CDI.…”