[A case report of lung abscess caused by Capnocytophaga gingivalis infection]

The Metabolic Potential of the Human Lung Microbiome

The human lung microbiome remains largely underexplored, despite its potential implications in the pharmacokinetics of inhaled drugs and its involvement in lung diseases. Interactions within these bacterial communities and with the host are complex processes which often involve microbial small molecules. In this study, we employed a computational approach to describe the metabolic potential of the human lung microbiome. By utilizing antiSMASH and BiG-SCAPE software, we identified 1831 biosynthetic gene clusters for the production of specialized metabolites in a carefully compiled genome database of lung-associated bacteria and fungi. It was shown that RiPPs represent the largest class of natural products within the bacteriome, while NRPs constitute the largest class of natural products in the lung mycobiome. All predicted BGCs were further categorized into 767 gene cluster families, and a subsequent network analysis highlighted that these families are widely distributed and contain many uncharacterized members. Moreover, in-depth annotation allowed the assignment of certain gene clusters to putative lung-specific functions within the microbiome, such as osmoadaptation or surfactant synthesis. This study establishes the lung microbiome as a prolific source for secondary metabolites and lays the groundwork for detailed investigation of this unique environment.

Capnocytophaga gingivalis Bacteremia After Upper Gastrointestinal Bleeding in Immunocompromised Patient

Odontogenic bacteremia, most commonly involving gram-positive oral flora, can result from daily self-care practices or professional dental procedures. Though usually transient and quickly cleared by the immune system, the presence of periodontal disease increases the frequency of exposure and risk of persistence of oral-systemic infections. Comorbidities such as asplenia, alcoholism, and immunocompromise increase the risk of complications of hematogenous spread and severe systemic illness. Capnocytophaga is a genus of anaerobic fastidious gram-negative bacilli, which is a common member of human oral flora, and its density is proportional to mass of dental plaques and periodontal diseases. Capnocytophaga spp that colonize humans are less virulent and are uncommon causes of bacteremia when compared with the Capnocytophaga typical of canines. C gingivalis has been rarely reported as a cause of disease in immunocompromised or immunocompetent hosts. In this article, we present a case of an immunocompromised 70-year-old man with poor oral hygiene, on methotrexate and prednisone for rheumatoid arthritis and sarcoidosis, who was admitted for chronic obstructive pulmonary disease exacerbation and developed C gingivalis bacteremia and septic shock after an episode of upper gastrointestinal bleeding. Poor oral hygiene in our patient is believed to have increased his risk as an immunocompromised patient to developing C gingivalis bacteremia. This case highlights the importance of oral care in immunocompromised patients especially while hospitalized, and those about to receive transplant, chemotherapy, or on immune modulators.

Multidrug-resistant oral Capnocytophaga gingivalis responsible for an acute exacerbation of chronic obstructive pulmonary disease: Case report and literature review

INTRODUCTION

Capnocytophaga genus was recently known to highly contribute to the beta-lactam (BL) and macrolide-lincosamide-streptogramin (MLS) resistance gene reservoir in the oral microbiota (BL: bla_CSP-1 and bla_CfxA; MLS: erm(F) and erm(C)). But fluoroquinolone (FQ) resistance remains uncommon in literature, without available data on resistance mechanisms.

CASE REPORT

For the first time, a case of acute exacerbation of chronic obstructive pulmonary disease (COPD) was described in a 78-year-old immunocompetent patient due to a multidrug-resistant Capnocytophaga gingivalis isolate with significant microbiological finding. C.gingivalis acquired resistance to third generation cephalosporins (bla_CfxA3 gene), MLS (erm(F) gene), and fluoroquinolones. Genetics of the resistance, unknown as regards fluoroquinolone, was investigated and a substitution in QRDR of GyrA was described (Gly80Asn substitution) for the first time in the Capnocytophaga genus.

LITERATURE REVIEW

A comprehensive literature review of Capnocytophaga spp. extra-oral infection was conducted. Including the present report, on 43 cases, 7 isolates were BL-resistant (17%), 4 isolates were MLS-resistant (9.5%) and 4 isolates were FQ-resistant (9.5%). The studied clinical isolate of C.gingivalis was the only one to combine resistance to the three groups of antibiotics BL, MLS and FQ. Four cases of Capnocytophaga lung infection were reported, including three infections involving C. gingivalis (two FQ resistant) and one involving C. sputigena.

CONCLUSION

This multidrug-resistant C. gingivalis isolate illustrated the role of oral flora as a reservoir of antibiotic resistance and its contribution to the limitation of effective antibiotics in severe respiratory infections.