Alteration of Normal Gastric Flora in Critical Care Patients Receiving Antacid and Cimetidine Therapy

Abstract

One hundred fifty-three critical care patients with documented cimetidine and antacid use were prospectively studied with serial gastric pH determinations and semiquantitative gastric fluid cultures. This study documents the abnormal gastric colonization of patients with therapeutically altered gastric acidity by hospital acquired gram negative rods (GNR). Three hundred twenty-four gastric fluid cultures from 153 patients revealed 152 (47%) positive cultures for GNR, 78 (24%) sterile specimens, and 94 (29%) positive for mixed oropharyngeal flora. One hundred forty (59%) of the 236 cultures at a pH of 4 or greater were positive for GNR. In contrast, only 12 (14%) of the 88 cultures at a pH of less than 4 were positive for GNR (p<.001). Forty-six (52%) of 88 cultures at a pH of less than 4 were sterile as compared to only 32 (14%) of 236 sterile cultures at a pH of 4 or greater (p<.001). At low pH, cultures are predominately sterile and at a pH of 4 or greater the flora dramatically changes to hospital acquired GNR. This artificially maintained reservoir of gram negative rods in the critically ill patient is a potential reservoir of organisms causing nosocomial bacteremia or pneumonia in this high risk population.

Colonização e translocação bacteriana orofaríngea, gástrica e traqueal em crianças submetidas à ventilação pulmonar mecânica

“…(15) The predominance of the species of normal microbiota such as, coagulase-negative Staphylococcus, viridans Streptococcus and Moraxella spp, in the oropharynx and trachea cultures of the children included in this study was similar to the results shown by an epidemiological study developed in populations of children at risk for the acquisition of gram-negative aerobic bacilli. (16) There was also predominance of pathogenic bacteria such as Enterobacter spp, K. pneumoniae and P. aeruginosa, in the cultures of oropharyngeal and tracheal secretions, a result similar to that found in other studies that demonstrated that colonization of the oropharynx by gram-negative pathogens is an almost universal occurrence in critical patients submitted to MPV. (8,13,17) Risk factors for the development of pneumonia may be divided into three categories: those related to the host, equipment and devices, and to the professionals.…”

Multivariate analysis of the factors associated with the risk of pneumonia in intensive care units

“…The risk of using antacids and H2-blockers for the development of pneumonia in hospitalized patients has been analyzed in various studies. Donowitz et al [9] carried out semiquantitative cultures in the gastric fluid of 153 patients in use of cimetidine or antacids. In 47% of these patients there was a growth of Gram-negative bacilli, while in patients with gastric pH < 4, cultures were sterile.…”

Stomach as a source of colonization of the respiratory tract during mechanical ventilation: association with ventilator-associated pneumonia

“…Alkalinization of gastric contents in the critically ill patient may result from the intrinsic decrease of gastric acid production or from the use of antacids or histamine type 2 (H 2 ) antagonists, which neutralize or block secretion of gastric acid. DU MOULIN et al [13] and DONOWITZ et al [14] were among the first authors to demonstrate the relationship between alkalinization of gastric contents and overgrowth of bacteria. Figure 2 shows the correlation between gastric pH and concentrations of Gram-negative bacilli in the gastric contents from critical care patients receiving antacids (r=0.4; p<0.001).…”