What antibiotics cover coagulase-negative Staphylococcus (CoNS) wounds?

From the Guidelines

For coagulase-negative Staphylococcus (CoNS) wound infections requiring oral (PO) antibiotic coverage, first-line options include trimethoprim-sulfamethoxazole (TMP-SMX, 1-2 double-strength tablets twice daily), doxycycline (100 mg twice daily), or minocycline (100 mg twice daily) for 7-10 days. These recommendations are based on the most recent and highest quality study available, which suggests that these antibiotics are effective against CoNS, including methicillin-resistant strains 1. Cephalexin (500 mg four times daily) is another effective option, as it has been shown to be effective against CoNS in several studies, including a study published in 2014 1. For patients with more severe infections or risk factors for resistance, linezolid (600 mg twice daily) may be used, though it's typically reserved for resistant cases due to cost and side effect profile, as noted in a study published in 2011 1. Clindamycin (300-450 mg four times daily) can be considered but has higher resistance rates, and its use should be guided by local epidemiology and susceptibility patterns. Treatment duration depends on infection severity, with uncomplicated infections typically requiring 7-10 days of therapy. Patients should complete the full course even if symptoms improve earlier, and wound care including regular cleaning and dressing changes remains essential alongside antibiotic therapy. It's worth noting that the choice of antibiotic should be guided by local resistance patterns and susceptibility testing, whenever possible, to ensure the most effective treatment and minimize the risk of resistance development. In general, the principles of antibiotic stewardship should be applied to ensure the responsible use of antibiotics and minimize the risk of adverse effects and resistance development. Key considerations in the management of CoNS wound infections include the use of antibiotics with activity against methicillin-resistant strains, the importance of wound care and infection control practices, and the need for ongoing monitoring and adjustment of treatment as needed. By following these principles and using the most effective antibiotics available, healthcare providers can optimize outcomes for patients with CoNS wound infections and minimize the risk of complications and resistance development. Some of the key points to consider when selecting an antibiotic for CoNS wound infections include:

• The severity of the infection and the presence of any underlying medical conditions
• The susceptibility of the infecting organism to different antibiotics
• The potential for resistance development and the need for antibiotic stewardship
• The importance of wound care and infection control practices in preventing the spread of infection
• The need for ongoing monitoring and adjustment of treatment as needed to ensure the best possible outcomes. Overall, the management of CoNS wound infections requires a comprehensive approach that takes into account the complex interplay of factors involved in these infections, and the use of antibiotics with activity against methicillin-resistant strains is a critical component of this approach.

From the FDA Drug Label

The success rates by pathogen for microbiologically evaluable patients are presented in Table 16

Pathogen Success Rate n/N (%) Daptomycin for Injection Comparator*

Methicillin-susceptible Staphylococcus aureus (MSSA) † 170/198 (86%) 180/207 (87%)

Methicillin-resistant Staphylococcus aureus (MRSA) † 21/28 (75%) 25/36 (69%)

Streptococcus pyogenes 79/84 (94%) 80/88 (91%)

Streptococcus agalactiae 23/27 (85%) 22/29 (76%)

Streptococcus dysgalactiae subsp. equisimilis 8/8 (100%) 9/11 (82%)

Enterococcus faecalis (vancomycin-susceptible only) 27/37 (73%) 40/53 (76%)

*Comparator: vancomycin (1 g IV q12h) or an anti-staphylococcal semi-synthetic penicillin (i.e., nafcillin, oxacillin, cloxacillin, or flucloxacillin; 4 to 12 g/day IV in divided doses).

†As determined by the central laboratory.

Daptomycin covers Methicillin-susceptible Staphylococcus aureus (MSSA) and Methicillin-resistant Staphylococcus aureus (MRSA), which are types of coagulase-negative staphylococci.

• Key points:
  • Daptomycin is effective against MRSA and MSSA.
  • The comparator used in the study was vancomycin or an anti-staphylococcal semi-synthetic penicillin.
  • The study showed that daptomycin had a success rate of 86% against MSSA and 75% against MRSA. 2

From the Research

Antibiotic Coverage for Coagulase-Negative Staph Wounds

• The optimal treatment strategy for coagulase-negative Staphylococcus species peritonitis remains controversial 3.
• Cefazolin and vancomycin have been shown to have similar primary response rates and complete cure rates in the treatment of coagulase-negative Staphylococcus species peritonitis 3.
• Methicillin resistance is common in coagulase-negative staphylococci, but the treatment outcome remains favorable when cefazolin is used as the first-line antibiotic 3.
• Newer antibiotics such as telavancin, daptomycin, linezolid, and tigecycline have been shown to have good activity against coagulase-negative staphylococci 4.
• Daptomycin has been shown to have good activity against all coagulase-negative staphylococci isolates, with the most susceptible species being Staphylococcus haemolyticus, Staphylococcus hominis subsp. novobiosepticus, Staphylococcus saprophyticus, Staphylococcus schleiferi, and Staphylococcus simulans 4.
• Cephalosporins such as cefazolin and cefamandole have been shown to have activity against coagulase-negative staphylococci, but the MIC90 may rise over time 5.
• Vancomycin has been shown to have consistent activity against coagulase-negative staphylococci, with an MIC90 of 4 micrograms/ml 5.

Resistance Patterns

• Methicillin resistance is encoded by the mecA gene and is common in coagulase-negative staphylococci 6.
• The presence of the mecA gene confers higher MICs for oxacillin, but does not influence MICs to all other antibiotics tested 4.
• Coagulase-negative staphylococci have an extensive antimicrobial resistance profile, especially in healthcare settings, and true infections often necessitate the use of second-line antimicrobial drugs 7.