Most Common Organism and Discharge Type in Hand Surgical Site Infections
Staphylococcus aureus is the most common organism causing surgical site infections in the hand, and greenish discharge is characteristic of Pseudomonas aeruginosa infection. 1
Primary Causative Organisms
Staphylococcus aureus remains the dominant pathogen in hand infections, accounting for the majority of cases, with methicillin-resistant S. aureus (MRSA) representing an increasingly significant proportion. 1, 2
MRSA has become the single most prevalent organism in hand infections, with rates reaching 61% of all hand infections by 2003 in some institutions, and representing 78% of all S. aureus isolates. 2
Streptococcus species are the second most common bacterial cause of hand infections. 1
In surgical site infections overall, S. aureus accounts for 39.9-45.9% of complicated skin and soft tissue infections, making it the leading pathogen. 3
Discharge Characteristics and Organism Correlation
Greenish discharge is pathognomonic for Pseudomonas aeruginosa infection, which is the second most common organism in complicated skin and soft tissue infections after S. aureus. 3
Pseudomonas aeruginosa accounts for 10.8-12.1% of complicated skin and soft tissue infections in surveillance studies. 3
Purulent drainage (regardless of color) is diagnostic of surgical site infection and requires prompt drainage. 4
The presence of greenish discharge in a patient with previous surgical scar, pain, redness, and swelling strongly suggests Pseudomonas infection requiring specific antibiotic coverage. 3
Clinical Context for This Patient
Given the presentation of greenish discharge with pain, redness, and swelling at a previous surgical site, this represents a surgical site infection most likely caused by Pseudomonas aeruginosa, though polymicrobial infection including S. aureus cannot be excluded. 3
Wound cultures should be obtained before initiating antibiotic therapy to guide subsequent treatment. 5
The infection requires both surgical drainage and antibiotic therapy covering both gram-positive organisms (including MRSA) and Pseudomonas. 6
Treatment Implications
Empiric antibiotic therapy must cover MRSA and Pseudomonas aeruginosa in this clinical scenario of post-surgical hand infection with greenish discharge. 6, 2
Recommended regimen includes vancomycin or linezolid for MRSA coverage plus piperacillin-tazobactam for Pseudomonas coverage. 6
Incision and drainage is mandatory as the primary intervention, with antibiotics serving as adjunctive therapy. 3, 5
MRSA strains demonstrate 100% sensitivity to linezolid and tigecycline, with vancomycin remaining effective (though 1.12% of strains may show intermediate resistance). 7
Common Pitfalls
Failing to recognize that greenish discharge indicates Pseudomonas infection and treating only for gram-positive organisms will result in treatment failure. 3
Delaying surgical drainage while relying solely on antibiotics leads to progression of infection and increased morbidity. 5
Underestimating the prevalence of MRSA in hand infections (now exceeding 60% in many institutions) and using beta-lactam monotherapy results in inadequate coverage. 2
Not obtaining cultures before antibiotic initiation prevents targeted therapy adjustment and antimicrobial stewardship. 5