Single center experience with infections due to Parvimonas micra previously known as Micromonas micros

Author(s):
Hugo Bonatti; Sridhar Gona; Aaron George

Background:

Parvimonas micra (PM) previously known as Micromonas micros is fastidious, anaerobic, gram positive coccus, which is found in normal human oral and gastrointestinal flora. It has been associated with periodontal disease and and abcsesses after septic dissemination. Still little data on intraabdominal infections caused by this emerging pathogen are available.

Hypothesis:

Parvimonas micra may be an underestimated surgical pathogen.

Methods:

Our institutional database was searched for all cases of PM infections during a 4-year period.

Results:

A total of 40 isolates of PM in 39 patients were identified. There were 29 men and 10 women with a median age of 61 (range 9.7 to 88.7) years. There were five monomicrobial infections and in 35 cases PM was isolated as part of a polymicrobial infection. Isolated co-pathogens included Gram positive cocci (Staphylococcus aureus 6, streptococci 13 (predominantly anginosus group, Anaerococcus prevotii 1), Gram negative rods (E. coli 10, Pseudomonas aeruginosa 4, others 6), Bacteroides/Prevotella spp 24 and other anaerobes 5. Seven patients had bacteremia; there were nine intraabdominal infections, one pleural empyema, eight perianal abscesses and 14 soft tissue infections. Treatment consisted in the majority of cases of surgical/interventional source control and antibiotics such as Betalactams and Clindamycin as well as metronidazole. Four patients in this series died; three of them had monomicrobial blood stream infections with PM and suffered from severe comorbid conditions.

Conclusions:

We report a large series of infections due to PM from a rural hospital with the vast majority being surgical cases. The pathogen needs to be considered to cause serious infections in humans.