What is the recommended treatment for Corynebacterium striatum infections?

Treatment of Corynebacterium striatum Infections

Vancomycin is the first-line antibiotic for Corynebacterium striatum infections, particularly for severe infections or multidrug-resistant strains, which are increasingly common with this organism. 1, 2

Antibiotic Selection

First-Line Therapy

• Vancomycin is the preferred agent for clinically significant C. striatum infections, as all tested strains demonstrate universal susceptibility to this glycopeptide 3, 4
• Linezolid represents an alternative option, with 100% susceptibility demonstrated in recent surveillance studies 4
• The recommendation for vancomycin is particularly strong given that C. striatum exhibits multidrug resistance patterns in the majority of clinical isolates 5, 3, 4

Alternative and Combination Regimens

• Amoxicillin (or aminopenicillins) combined with rifampin may be considered for bone and joint infections when susceptibility testing confirms aminopenicillin activity, with cure rates of 67% (8/12 cases) reported 6
• Combination therapy with vancomycin plus rifampin for the first 2 weeks, followed by vancomycin monotherapy, successfully treated multidrug-resistant pneumonia in an immunocompromised host 5
• Gentamicin may be selected for empirical treatment, as resistance rates are lower (34.6%) compared to other agents 4

Treatment Duration

• Standard duration is 7-14 days for most serious infections caused by Gram-positive organisms, including C. striatum 1
• Extend therapy beyond 14 days if endovascular infection or metastatic infection is present 1
• For catheter-related infections, treat for 10-14 days with appropriate systemic antibiotics 2
• Bone and joint infections may require prolonged therapy, with successful outcomes reported after median follow-up of 487.5 days 6
• For catheter exit site infections in peritoneal dialysis patients, a 1-month course of vancomycin (1g IV every 5 days) achieved cure without catheter removal 7

Device Management

• Remove indwelling catheters when possible for catheter-related C. striatum infections 2
• However, catheter salvage is achievable with appropriate antibiotic therapy in select cases, as demonstrated in peritoneal dialysis catheter infections treated with prolonged vancomycin 7

Antimicrobial Resistance Patterns

C. striatum demonstrates concerning multidrug resistance:

• Universal resistance to penicillin, cefotaxime, ciprofloxacin, and tetracycline 4
• High resistance rates to clindamycin (87.7%) and erythromycin (79%) 4
• Universal susceptibility to vancomycin and linezolid across all tested strains 3, 4
• Variable susceptibility to aminopenicillins (10/12 strains susceptible in bone and joint infections), though this class is not routinely tested per EUCAST/CASFM guidelines 6

Critical Diagnostic Considerations

Distinguishing True Infection from Contamination

• Abundant Gram-positive rods on direct microscopy plus pure culture growth strongly suggests true infection rather than contamination 7, 5
• Presence of leukocyte reaction on Gram stain supports pathogenicity 7
• Repeated isolation from multiple specimens increases likelihood of true infection 5
• Clinical signs of infection with pure culture growth establishes cause-and-effect relationship 7

High-Risk Patient Populations

• Malignancy and neutropenia significantly increase odds of true C. striatum bloodstream infection versus contamination 3
• Immunocompromised patients (solid organ transplant recipients, those on immunosuppressive therapy) are at elevated risk 5, 6
• Patients with indwelling medical devices (catheters, prosthetic joints, osteosynthetic devices) 7, 6
• Previous antibiotic exposure predisposes to C. striatum infection 7

Essential Microbiological Testing

• Perform species-level identification when coryneforms are isolated from blood or sterile sites, rather than dismissing as "diphtheroids" 3
• Antimicrobial susceptibility testing is mandatory for clinically significant isolates due to high rates of multidrug resistance 7, 3
• Prolonged culture incubation may be necessary for optimal recovery 6
• Consider testing aminopenicillin susceptibility despite lack of routine guideline recommendations, as this may expand treatment options 6

Common Pitfalls to Avoid

• Do not dismiss C. striatum as a contaminant when isolated in pure culture with clinical signs of infection, particularly in immunocompromised hosts 7, 5, 3
• Avoid empirical beta-lactam monotherapy given universal resistance to penicillin and cephalosporins 4
• Do not use fluoroquinolones or tetracyclines as these demonstrate universal resistance 4
• Failing to perform susceptibility testing can lead to treatment failure with inappropriate antibiotics 7, 3