A Series of Soft Tissue Infections due to the Rare Pathogen Myroides

Authors:
Aaron George, Hugo Bonatti, Pooja Ajith

Body of Abstract:
Background: Myroides is a genus of Gram-negative, rod-shaped obligate aerobic bacteria that naturally occur in environmental sources like soil and water. They produce a yellow pigment (flexirubin) and exhibit a distinct fruity odor on nutrient agar. The high rate of natural antibiotic resistance is of major concern.
Patients and Methods: The institutional database of a rural hospital was searched for all cases of Myroides infections during a 4-year period.
Results: Nine patients (4m/5f) with infections caused by Myroides spp were identified. Median age was 65.1 (range 50.1 to 84.3) years. Obesity rate was 63%, 22% had DM, 33% had hypertension, 44% had COPD with one third being active smokers. Two patients had blood stream infections; the remaining 7 patients had soft tissue infections all involving the lower extremities. 67% of specimens were sent by medical teams, 22% by the emergency department and 11% by surgical services. Four infections including both sepsis cases were monomicrobial. Isolated copathogens in the 5 polymicrobial infections included Staphylococcus aureus 3 (2 MRSA), streptococci (2), Acinetobacter baumannii, Stenotrophomonas maltophilia and Bacteroides fragilis 1each. Growth of Myroides spp was reported light (14%), moderate (29%) and heavy (56%). Treatment consisted of 4th generation cephalosporines or carbapenems and debridement/drainage for the surgical infections.
Conclusion: Myroides spp are rare pathogens but are capable of causing serious infections in humans. In our setting, lower extremity soft tissue infections in elderly patients with comorbid conditions were the most common presentation.