From the Guidelines
The most common bacteria responsible for cellulitis in diabetic patients are Staphylococcus aureus (including methicillin-resistant S. aureus or MRSA) and beta-hemolytic streptococci (particularly Group A and Group B streptococci). Diabetic patients are also at increased risk for polymicrobial infections involving gram-negative organisms such as Escherichia coli, Pseudomonas aeruginosa, and anaerobes, especially in chronic wounds or ulcers. These infections tend to be more severe in diabetic patients due to impaired immune function, peripheral vascular disease, and neuropathy that often accompanies diabetes.
When treating cellulitis in diabetic patients, empiric antibiotic therapy should typically cover both gram-positive and gram-negative organisms. For mild to moderate infections, oral options include amoxicillin-clavulanate (875/125 mg twice daily), trimethoprim-sulfamethoxazole (1-2 DS tablets twice daily) plus amoxicillin, or in cases of suspected MRSA, doxycycline (100 mg twice daily) or linezolid (600 mg twice daily) 1. Severe infections often require intravenous antibiotics such as vancomycin, piperacillin-tazobactam, or a carbapenem. Proper wound care, blood glucose control, and prompt treatment are essential components of management to prevent complications.
Some key points to consider in the management of cellulitis in diabetic patients include:
- The importance of covering both gram-positive and gram-negative organisms with empiric antibiotic therapy
- The use of oral antibiotics for mild to moderate infections, with options including amoxicillin-clavulanate, trimethoprim-sulfamethoxazole, and doxycycline or linezolid for suspected MRSA
- The need for intravenous antibiotics for severe infections, with options including vancomycin, piperacillin-tazobactam, and carbapenems
- The importance of proper wound care, blood glucose control, and prompt treatment to prevent complications.
It's also important to note that the management of cellulitis in diabetic patients should be individualized based on the severity of the infection, the presence of underlying medical conditions, and the results of culture and susceptibility testing 1.
From the FDA Drug Label
The cure rates by pathogen for microbiologically evaluable patients are presented in Table 19. Table 19 Cure Rates at the Test-of-Cure Visit for Microbiologically Evaluable Adult Patients with Diabetic Foot Infections Pathogen Cured ZYVOX n/N (%) Comparator n/N (%) Staphylococcus aureus 49/63 (78) 20/29 (69) Methicillin-resistant S aureus 12/17 (71) 2/3 (67) Streptococcus agalactiae 25/29 (86) 9/16 (56)
The most common bacteria responsible for cellulitis in diabetic patients are:
- Staphylococcus aureus
- Streptococcus agalactiae
- Methicillin-resistant S aureus 2
From the Research
Most Common Bacteria for Cellulitis in Diabetic Patients
The most common bacteria responsible for cellulitis in diabetic patients include:
- Gram-positive bacteria, such as Staphylococcus aureus and beta-hemolytic streptococci, which are the most common pathogens in previously untreated mild and moderate infections 3
- Polymicrobial infections, which are often seen in severe, chronic, or previously treated infections 3
- Pseudomonas aeruginosa, which is a common gram-negative bacterium isolated from diabetic foot ulcers 4, 5
- Other bacteria, such as Enterococcus spp., Escherichia coli, and Peptostreptococcus spp., which can also be isolated from diabetic foot ulcers 5
Bacterial Resistance
Some bacteria isolated from diabetic foot ulcers can exhibit resistance to antibiotics, including:
- Methicillin-resistant Staphylococcus aureus (MRSA), which is a common multiresistant microorganism 4, 5
- Extended-spectrum β-lactamase (ESBL) producers, which can be found among gram-negative bacteria such as Klebsiella species 4
- Resistance to amoxicillin/clavulanic acid and ciprofloxacin, which can be seen in E. coli strains 5
Diagnosis and Treatment
Diagnosis of diabetic foot infection is based on clinical signs and symptoms of local inflammation, and infected wounds should be cultured after debridement 3 Treatment of cellulitis in diabetic patients typically involves aggressive surgical debridement and wound management, effective antibiotic therapy, and correction of metabolic abnormalities 3