Oral and Airway Microbiota in HIV-Infected Pneumonia Patients

Abstract

cDespite the increased frequency of recurrent pneumonia in HIV-infected patients and recent studies linking the airway bacterial community (microbiota) to acute and chronic respiratory infection, little is known of the oral and airway microbiota that exist in these individuals and their propensity to harbor pathogens despite antimicrobial treatment for acute pneumonia. This pilot study compared paired samples of the oral and airway microbiota from 15 hospitalized HIV-infected patients receiving antimicrobial treatment for acute pneumonia. Total DNA was extracted, bacterial burden was assessed by quantitative PCR, and amplified 16S rRNA was profiled for microbiome composition using a phylogenetic microarray (16S rRNA PhyloChip). Though the bacterial burden of the airway was significantly lower than that of the oral cavity, microbiota in both niches were comparably diverse. However, oral and airway microbiota exhibited niche specificity. Oral microbiota were characterized by significantly increased relative abundance of multiple species associated with the mouth, including members of the Bacteroides, Firmicutes, and TM7 phyla, while airway microbiota were primarily characterized by a relative expansion of the Proteobacteria. Twenty-two taxa were detected in both niches, including Streptococcus bovis and Chryseobacterium species, pathogens associated with HIV-infected populations. In addition, we compared the airway microbiota of five of these patients to those of five non-HIV-infected pneumonia patients from a previous study. Compared to the control population, HIV-infected patients exhibited relative increased abundance of a large number of phylogenetically distinct taxa, which included several known or suspected pathogenic organisms, suggesting that recurrent pneumonia in HIV-infected populations may be related to the presence of these species.

Multicenter Comparison of Lung and Oral Microbiomes of HIV-infected and HIV-uninfected Individuals

“…Alterations in the oral microbiome have important implications for disease processes (29), such as periodontal diseases (30), but may precede changes in the lung. Previous work by one of the LHMP collaborators identified increased abundances for a large number of taxa in oral samples from HIV-infected patients with pneumonia, in comparison to HIV-uninfected control subjects (31). A culture-based study identified abundant Streptococcus spp.…”

Comparison of the Respiratory Microbiome in Healthy Nonsmokers and Smokers

“…Understanding the microbial composition of the lung in healthy individuals is necessary to understand changes that may occur with respiratory diseases such as chronic obstructive pulmonary disease (COPD) or in immunosuppressed individuals such as those with HIV infection. Culture-independent techniques investigating various respiratory samples have produced conflicting conclusions about the composition of the lower respiratory tract microbiome (6)(7)(8)(9)(10). Controversy persists over the existence of distinct organisms in the lung and whether bacteria in the lungs represent microaspiration of oral microbiota or whether upper respiratory contamination of lower respiratory tract samples is caused by passing a bronchoscope through the oral cavity to obtain lung samples.…”

“…Before bronchoscopy, 10 to 50 ml of sterile 0.9% saline were washed through the bronchoscope and collected as a control for DNA in the bronchoscope. Bronchoalveolar lavage (BAL) was performed according to standardized procedures developed to minimize oral contamination (10). Participants gargled with an antiseptic mouthwash (Listerine) immediately before topical anesthesia.…”

Lung Microbiome for Clinicians. New Discoveries about Bugs in Healthy and Diseased Lungs

“…Iwai and colleagues compared the oral and airway microbiome in HIV-infected patients treated with antimicrobials for acute pneumonia (89). The lungs exhibited a significantly higher relative abundance of multiple members of the Proteobacteria, including several known pathogens such as Klebsiella pneumoniae and Pseudomonas species, which may contribute to the high prevalence of recurrent pneumonia in HIVinfected patients.…”