Is Streptococcus (strep) a common cause of surgical site infections?

Streptococcus in Surgical Site Infections

Streptococcus is not a common cause of surgical site infections, with Staphylococcus aureus being the predominant pathogen in most surgical site infections. 1, 2

Epidemiology and Causative Pathogens

Surgical site infections (SSIs) occur in approximately 2-5% of patients undergoing surgery in the USA, with an estimated 160,000 to 300,000 cases diagnosed and treated annually 1. The causative pathogens vary based on the type of surgical procedure:

Clean Surgical Procedures

• Primary pathogen: Staphylococcus aureus (39.9-45.9% of all SSIs) 1, 2
• Streptococcal species are mentioned as potential pathogens but are much less common 2
• Coagulase-negative staphylococci (3.4-4.2%) 1

Other Common SSI Pathogens

• Pseudomonas aeruginosa (10.8-12.1%) 1, 2
• Escherichia coli (7-9.7%) 1, 2
• Enterococcus species (7.7-8.2%) 1, 2
• Klebsiella species (5.1-5.8%) 1, 2
• Enterobacter species (5.6-5.8%) 1, 2

Special Considerations for Streptococcus

• Group A Streptococcus (S. pyogenes) is rarely implicated in surgical site infections but when present, it can cause necrotizing incisional SSI that requires urgent intervention 1
• Group C Streptococcus (S. equisimilis) has been documented as an unusual cause of nosocomial surgical infection, typically transmitted from healthcare workers 3

Pathogen Distribution by Surgical Site

1. Clean surgical procedures:

   • S. aureus from patient's skin flora or exogenous environment is the most common cause 1
   • Streptococcal species are less commonly involved 2

2. Clean-contaminated or contaminated procedures:

   • Indigenous polymicrobial aerobic-anaerobic flora of the organ/tissue being operated on 1, 2
   • For contaminated operations of perioral, perirectal, and vulvovaginal tissues:
     • Bacteria similar to normal microbial flora of adjacent mucous membranes 1

3. Areas remote from mucosal surfaces:

   • Primarily indigenous skin microflora, especially if no body cavity has been entered 1

Risk Factors for Streptococcal SSIs

• Healthcare worker carriers: Surgeons, anesthesiologists, or other surgical team members may carry streptococcal species in their throat, anus, or vagina and transmit them during surgery 4
• Surgical procedures involving perioral, perirectal, and vulvovaginal tissues have higher risk of streptococcal infections due to normal flora 1
• Necrotizing soft tissue infections may rarely be caused by group A Streptococcus 1

Prevention and Management

Prevention

• Proper surgical technique and adherence to infection control practices 5, 6
• Appropriate preoperative antimicrobial prophylaxis 1, 6
• Screening of surgical team members during suspected outbreaks of streptococcal SSIs 4
• Maintaining normothermia during surgery 6
• Proper skin preparation with chlorhexidine gluconate and alcohol-based agents 6

Management

• For superficial SSIs: Opening the incision, evacuating infected material, and continuing dressing changes until healing 2
• For deep or organ/space SSIs: More extensive debridement and targeted antibiotic therapy 2
• For necrotizing streptococcal infections: Urgent surgical debridement and appropriate antibiotics 1, 2

Important Clinical Considerations

• While streptococcal species are not the most common cause of SSIs, they can cause severe infections when present, particularly necrotizing infections 1
• Outbreaks of streptococcal SSIs have been linked to carriers among surgical team members, with case fatality rates as high as 12% 4
• Relapse of carriage can occur several months after apparent eradication in healthcare workers 4
• The surgical team should maintain high vigilance for signs of necrotizing soft tissue infection, which may be caused by group A Streptococcus and requires urgent intervention 1, 2

In conclusion, while Streptococcus is not among the most common pathogens causing surgical site infections, it can cause serious infections in specific circumstances and should be considered in the differential diagnosis, particularly when there are signs of necrotizing infection or in the context of an outbreak.