Kocuria Infections: Overview and Treatment
What is Kocuria?
Kocuria species are catalase-positive, coagulase-negative Gram-positive coccoid bacteria that are normal skin commensals but have emerged as opportunistic pathogens, particularly in immunocompromised patients and those with indwelling devices. 1
These organisms belong to the family Micrococcaceae and were formerly classified as Micrococcus species before being reclassified. 1 While historically considered nonpathogenic saprophytes, they are increasingly recognized as causes of human infection. 2, 3
Clinical Manifestations
The most common types of Kocuria infections include:
- Bacteremia (36.3%) - most frequently reported, especially in patients with central venous catheters or undergoing hemodialysis 1, 4
- Skin and soft tissue infections (18.6%) 1
- Endophthalmitis (15.7%) - associated with poor visual outcomes 1
- Infective endocarditis (13.7%) - carries higher mortality 1
- Peritonitis (11.8%) - particularly peritoneal dialysis-associated 1, 3
Species Distribution and Risk Factors
K. kristinae is the most frequently isolated species (46.1%), followed by K. varians, K. rhizophila, and K. palustris. 5, 1
Key risk factors include:
- Immunocompromised states (chemotherapy, chronic kidney disease, malignancy) 4
- Presence of indwelling vascular catheters 2
- Peritoneal dialysis 3
- Neutropenia 4
Notably, infections can occur in immunocompetent patients, particularly with device-related infections. 2
Antimicrobial Treatment
First-Line Therapy
Empirical treatment should include intravenous vancomycin, ideally in combination with another antibiotic to which the organism is susceptible, pending antimicrobial susceptibility results. 5, 1
Vancomycin demonstrates the highest susceptibility rates (93% susceptible) and was the most commonly used antimicrobial (47% of cases). 1
Alternative Agents with High Susceptibility
Based on antimicrobial susceptibility data, the following agents show excellent activity:
- Linezolid - low resistance (7%) 5, 1
- Rifampicin 5
- Teicoplanin 5
- Tigecycline 5
- Cefotaxime and other cephalosporins (39.6% usage) 5, 1
- Meropenem 5
- Ampicillin/sulbactam 5
- Tetracyclines - resistance only 6.7% 1
- Quinolones (36.6% usage) 1
Treatment Duration and Adjunctive Measures
The median treatment duration is 14 days for most infections, though this should be extended for complicated cases such as endocarditis or osteomyelitis. 3
Device removal is critical for catheter-related infections and may be necessary for peritoneal dialysis-associated peritonitis, particularly with K. varians, which has higher relapse rates. 2, 3
For peritoneal dialysis-associated peritonitis:
- Intraperitoneal first-generation cephalosporins or glycopeptides are most commonly used 3
- Catheter removal was required in 2 of 12 reported episodes 3
- K. varians episodes are particularly prone to relapse 3
Antimicrobial Susceptibility Testing
Susceptibility testing should be performed and interpreted according to Staphylococcus species criteria, as no specific breakpoints exist for Kocuria. 2
Clinical Outcomes
Antibiotic treatment is almost universally effective, with only one death reported in the literature review of K. kristinae infections. 5 However, outcomes vary by infection type:
- Infective endocarditis carries the highest mortality 1
- Endophthalmitis is associated with increased rates of low visual acuity despite treatment 1
- Bacteremia and peritonitis generally have favorable outcomes with appropriate therapy 2, 3
Key Clinical Pitfalls
- Do not dismiss Kocuria as a contaminant in immunocompromised patients or those with indwelling devices 4
- Watch for relapses, particularly with K. varians peritonitis 3
- Ensure device removal when catheter-related infection is suspected, as antimicrobial therapy alone may be insufficient 2
- Consider combination therapy rather than monotherapy for serious infections 5