Gastric Acid Suppressive Therapy and Community-Acquired Pneumonia, Etiology and Outcome

Abstract

Background: Community acquired pneumonia (CAP) is an infection of the pulmonary parenchyma that can be caused by various microbial pathogens. Co-morbidity and medication are related to specific pathogens. Patients on gastric acid suppressive therapy have an increased risk to develop CAP. We aimed to assess whether there are specific pathogens independently associated with gastric acid suppressive therapy and its impact on infection severity. Methods: From December 2007 to January 2010, all subjects consulting the emergency care unit of a general hospital in the south of the Netherlands with a suspected CAP were prospectively registered. Each patient underwent chest radiography. Sputum, urine, nose swabs and blood samples were obtained for microbial culture, antigen detection and polymerase chain reaction techniques, respectively. To study the severity of CAP upon presentation, the validated CURB-65 score was calculated. Furthermore, we assessed hospital or intensive care admission, length of hospitalization and in-hospital mortality. We evaluated the association between use of acid suppressive therapy and microbial aetiology of CAP and severity of illness with logistic regression analysis. Results: The final cohort comprised 463 patients with CAP, defined as presence of infiltrate on chest radiography and/ or microbial aetiology. Overall 136 patients (29%) used acid suppressive therapy, mainly proton pump inhibitors (97%). Patients with acid suppressive therapy more frequently had an infection with Streptococcus pneumoniae (28% vs. 14%) and Haemophilus influenzae (10% vs. 6%), and less frequently with Coxiella burnetii (8% vs. 19%) or H1N1 influenza A virus (2% vs. 7%) in comparison to those without acid suppressive therapy. After adjustment for baseline differences, the risk of proton pump inhibitor users being infected with S. pneumonia was 2.18 times (95%Confidence Interval(CI): 1.2-3.6) higher compared to those not on acid suppressive therapy. Patients using more than one defined daily dose of a PPI had a 1.48-fold increased risk of a S. pneumoniae infection compared with patients using the defined daily dose (95%CI:1.1-2.0). No risk between PPI use and any other microbial pathogen was found. Patients with acid suppressive therapy had on average higher CURB-65 scores, longer hospital stay and subsequently a case fatality rate of 11% vs. 4% compared to those not using acid suppressive therapy. Conclusions. Proton pump inhibitor therapy predisposes with community acquired S. pneumoniae pneumonia, and was associated with higher morbidity.