Effect of pH and Antibiotics on Microbial Overgrowth in the Stomachs and Duodena of Patients Undergoing Percutaneous Endoscopic Gastrostomy Feeding

Abstract

Enteral nutrition via a percutaneous endoscopic gastrostomy (PEG) tube is often part of management in patients with dysphagia due to neurological or oropharyngeal disease. Gastrostomy placement can affect normal innate defense mechanisms in the upper gut, resulting in bacterial overgrowth. In this study microbiological investigations were done with gastric and duodenal aspirates from 20 patients undergoing PEG tube placement and PEG tubes from 10 patients undergoing tube replacement. Aspirate and PEG tube microbiotas were assessed by using viable counts and selective solid media followed by aerobic and anaerobic incubation to assess cell viabilities. The antibiotic susceptibility profiles of the isolates were determined by the disk diffusion method, and gas chromatography was used to study the bacterial metabolic products in the aspirates. The aspirates and PEG tubes contained mainly streptococci, staphylococci, lactobacilli, yeasts, and enterobacteria. Enterococci were detected only in PEG tube biofilms and not in aspirates. Gastric pH affected the composition of the aspirate microbiotas but not the total microbial counts. Staphylococci, Escherichia coli, and Candida spp. were isolated only from antibiotic-treated patients, despite the sensitivities of the bacteria to the agents used. Antibiotic treatment had no effect on the incidence of infection or the length of hospital stay in these patients.

Polymicrobial Interactions: Impact on Pathogenesis and Human Disease

“…A comprehensive study of the microbiota of patients receiving EN via a PEG tube was carried out by O'May et al An array of 11 selective solid media was used to isolate microorganisms from the luminal surface of PEG tubes and from gastric and duodenal aspirates from the same individuals (154). The genera isolated were similar to those isolated in previous studies, comprising mainly Candida spp., Enterobacteriaceae, streptococci, staphylococci, and lactobacilli.…”

“…In the case of PEG-mediated polymicrobial disease, a failure of antimicrobial therapy requires an alternative treatment strategy, given the evidence that the administration of antibiotics may actually increase overgrowth by potentially pathogenic microorganisms (154). Smith et al used the above-mentioned in vitro model to investigate the use of a synbiotic for just such a purpose (A. R. Smith, S. Macfarlane, G. A. O'May, N. Reynolds, and G. T. Macfarlane, submitted for publication).…”

Bacterial-Fungal Interactions: Hyphens between Agricultural, Clinical, Environmental, and Food Microbiologists

“…A common effect is an alteration of the pH, since although some microorganisms (e.g., streptococci, lactobacilli, and Candida) can occupy environments under a broad range of pH conditions, most are susceptible to acidic pHs below 4 (288). Thus, changes in pH can affect microbial community structure by either promoting or inhibiting the growth of acid-sensitive organisms, as demonstrated in the phyllosphere, the human gut, and cheese and wine production (5,13,78,113,289). On cheese surfaces, for example, yeast lactate metabolism and the production of alkaline metabolites such as ammonia cause deacidification that favors the growth of less-acid-tolerant bacterial strains that are essential for cheese ripening (79).…”

“…BFIs also contribute to the increasing number of nosocomial (hospitalacquired) infections; for example, Curvale-Fauchet et al (86) reported that a high proportion of hospital intravascular catheters were simultaneously colonized by the pathogenic lipophilic yeast Malassezia and bacteria, including staphylococci. These mixed biofilms, which have also been evidenced with C. albicans (195,289), can be more resistant to antibiotic treatments; for example, the presence of Staphylococcus epidermidis was shown to delay the diffusion of antifungal drugs in mixed Candida-Staphylococcus biofilms (6). Bacterial-fungal associations with potentially detrimental impacts on human health may also occur in moldy houses (170).…”

From Structure to Function: the Ecology of Host-Associated Microbial Communities

“…Although it is not clear which portion of the detected communities are transient or resident, studies using clone libraries and pyrosequencing suggest that the bacterial community may contain up to a few hundred members (14,24). Members of the community are affiliated with the Firmicutes, Actinobacteria, Bacteroidetes, Proteobacteria, and Fusobacteria phyla (14,24,244,289). Less abundant members belong to the TM7 phylum, Deferribacteres, Deinococcus/Thermus, and others (14,24).…”