By Dr. Brian Richman 

This is from a lecture I gave at Snowbird Utah Podiatry Seminar in 1993. Patients with an infection should be treated quickly, aggressively and appropriately to stop the progression of the infection. These patients usually need a surgical incision and drainage procedure and antibiotic therapy. The infectious process can spread quickly and if not treated appropriately can develop into a life or limb threatening situation. Patients can tolerate surgery, they cannot tolerate pus 
and/or infection. All patients are different and what might be the standard treatment for one patient might be totally different for another. ( The treatment suggestions and antibiotic doses are only guidelines and are not the standard of care, every patient needs individualized care. )

A. Important points to remember when treating any lower extremity infection:

  1. Every lower extremity infection is different.

  2. Surgical debridement, antibiotic delivery, local wound care, and close medical management are necessary to quell the infectious process. 

  3. Clinical judgment of the attending physician is the most important aspect of treating a lower extremity infection. 

  4. Antibiotic therapy will not compensate for inadequate primary wound care.

  5. The antibiotic choice initially should be based on gram stain results combined with clinical assessment.

  6. Diabetic infections are usually polymicrobial in nature.

  7. The first goal of primary care is prevention.

  8. Deep tissue cultures are more reliable than superficial cultures.

  9. Obtain anaerobic and aerobic cultures, send soft tissue and /or bone specimens when available.

  10. Usually empiric antibiotic coverage for gram positive organisms until results of gram stain, cultures, and sensitives are obtained.

  11. The best antibiotics in the world are no substitute for surgical debridement.

B. Types of Infection

  • Mild Infection
  • Local Infection
  • Moderate Infection
  • Regional Infection
  • Severe Infection
  • Systemic Infection 
Realize that mild infection can quickly develop into a moderate infection, and a moderate infection can develop into a severe infection if not treated properly.
C. Usual Hospital and Antibiotic Therapy for Lower Extremity Infections

Mild infections - outpatient basis and oral antibiotics
Moderate infections - inpatient basis and IV antibiotics
Severe infections - inpatient basis and IV antibiotics
If infection is not responding to present therapy within 48 hours re-evaluate treatment plan

D. Signs of Mild Infection

  1. Few organisms
  2. Slight erythema
  3. Usually afebrile
  4. Increase Serous Drainage
  5. Slight odor
  6. Ulcer doesn't have significant tracking 

E. Treatment for mild infection

  1. Patient may need surgical debridement
  2. Usually oral antibiotics on a outpatient basis
  3. Take appropriate labs, diagnostic tests, and cultures / sensitives
  4. Follow up with patient 3 days to a week

F. Signs of Moderate Infection

  1. Fever/Chills usually present
  2. Ascending Cellulitis
  3. Increase ESR
  4. Increase PMN'S
  5. Increase WBC usually with no left shift
  6. Odor may or may not be present

G. Treatment for Moderate Infection

  1. Usually parenteral antibiotics on a inpatient basis
  2. Patient may need surgical debridement and/or incision and drainage
  3. Follow up with patient daily
  4. Consults are a valuable resource
  5. Take appropriate labs/diagnostic tests/cultures/gram stain 
  6. Close Medical Management

H. Signs of Severe Infection ( often life or limb threatening )

  1. Increase ESR
  2. Massive Cellulitis
  3. Usually has severe odor
  4. Lymphangitis / lymphadenopathy
  5. Increase WBC with Left Shift
  6. High Fever / Chills / Nausea / Vomiting
  7. Polymicrobial
  8. Septic Shock / Septicemia
  9. Tissue Gas

I. Treatment for Severe Infection

  1. Parenteral Antibiotics needed ASAP
  2. Surgical Debridement and/or Incision and Drainage often a necessity
  3. Inpatient / Stabilize the patient medically
  4. Follow up with patient 2-3 times per day
  5. Medical consults are a necessity
  6. Take appropriate labs / diagnostic tests / cultures / gram stain
  7. Close Medical Management

J. Most Common Infective Organisms

Staphylococcus +++++ Gram Neg Anaerobes  ++
Streptococcus ++++ Proteus Mirablis  ++
Enterococcus +++ Proteus Non-Mirablis +
Gram Pos Anaerobes +++ Serratia +
E. Coli +++ Enterobacter +
Klebsiella +++ Pseudomonas +
Pseudomonas infections are very rare and antibiotic coverage should be implemented only after positive cultures and sensitivities which show only Pseudomonas isolated

K. Oral Antibiotics with Good Gram Positive Coverage

  1. Dicloxacillin 500 mg PO QID ( most effective when taken on an empty stomach 1-2 hours before eating. )
    1. Oral drug of choice for mild staphylococcal infection
    2. Effective, inexpensive, and relatively safe
  2. Augmentin (Amoxicillin / clavulanic acid) 500 mg PO TID or 875 mg PO BID
    1. spectrum of activity includes Enterococcus
    2. excellent anaerobic coverage including B. Fragilis
    3. oral drug of choice for empiric therapy of animal and human bite wound infections 
  3. Clindamycin 300mg PO BID/TID or 600 mg - 900 mg IV Q 8 hours
    1. good for penicillin allergic patients
    2. good for staphylococcal infection 
  4. Keflex ( cehalexin ) 500 mg PO BID/TID/QID
    Duricef ( cefadroxil ) 500 mg PO BID
    Ceftin ( cefuroxine axetil ) 250 mg PO BID 
    Velocef ( cephradine ) 500 mg PO QID
    1. Oral agents that are good for gram pos organisms
  5. Tetracycline 250 - 500 mg PO QID
    1. Bacteriostatic
    2. Good for staphylococcus and streptococcus
    3. Contraindicated in pregnant patients
    4. Not effective for diabetic infections
  6. Erythromycin 250 mg -500 mg PO QID
    1. Not very effective for foot infections
    2. Macrolide class of antibiotic
    3. Resistance common
  7. Rifampin 300 mg PO BID
    1. Used in combination therapy for tuberculosis
    2. Rapid resistance when used alone
    3. Excellent against staphylococcus
  8. Zithromax - ( Z Pack)
    1. Oral alternative in patients allergic to penicillin and cephalosporins
    2. Good for staphylococcus and streptococcus
  9. Ciprofloxin 500 mg - 750 mg PO BID
    1. Broad spectrum coverage for gram positive organisms
    2. Available in IV
    3. Other quinolones - Floxin, Levaquin

L. IM antibiotics - Rocephin 1 gram Q 24 hours

  1. This is a great antibiotic when you want something stronger than oral antibiotics but not severe enough for IV antibiotics.
  2. Can be injected to a localized area ( i.e. foot )

M. Parenteral Antibiotics

  1. Cefazolin ( Ancef ) 1 gram IV Q 12 hours
    1. First generation cephalosporin
    2. Good for most gram positive organisms except Enterococcus
    3. Commonly used for prophylaxis in lower extremity surgery
  2. Vancomycin 1 gram IV Q 24 hours
    1. Infuse slowly at least 60 minutes
    2. Drug of choice for MSRA infections
    3. For the treatment of normally susceptible gram positive infections
      in patients with an allergy to penicillin or cephalosporins
    4. Drug of choice for diabetic patients on dialysis
  3. Unasyn ( Ampicillin/sulbactam ) 3 grams IV Q 6 hours
    1. Empiric therapy of moderately severe diabetic foot infections when gram stain reveals predominately gram positive organisms
    2. Good for mixed infections including Enterococcus, staphylococcus, and anaerobic infections.
  4. Timentin ( ticarcillin / clavulanic acid ) 3.1 grams IV Q6-8 hours
    1. Useful when the gram stain shows mixed gram positive and gram negative flora
    2. Drug of choice for parenteral therapy of human and animal bite wound infections
  5. Clindamycin 600 mg - 900 mg IV Q 8 hours
    1. Good for staphylococcal infections
    2. Good for penicillin or cephalosporin allergic patients
  6. Cefotan ( cefotetan ) 1 to 2 grams IV Q 12 hours
    1. Second generation cephalosporin
    2. Similar to cefoxitin but more active against gram positive and gram negative organisms
    3. Longer half life
  7. Mefoxin ( cefoxitin ) 2 grams IV Q 6-8 hours
    1. Most active cephalosporin against anaerobic organisms including Bacteroides
    2. More active against gram negative organisms than cefazolin
  8. Primaxin ( imipenem / cilastatin ) 500 mg IV Q 6-8 hours
    1. Drug of choice for empiric therapy of severe life of
      limb threatening infections in diabetic patients
    2. Good for gas forming infections such as necrotizing fasciitis
    3. Covers most gram positive aerobes and anaerobes 
  9. Aztreonam ( azactam ) 1 to 2 grams IV Q 8 hours
    1. Monobactam antibiotic
    2. Only active against gram negative aerobes including Pseudomonas Aeruginosa
    3. No activity against gram positive organisms or anaerobes
    4. Can be used in penicillin or cephalosporin allergic patients with Pseudomonas infections
  10. Piperacillin 3 grams Q 4-6 hours
    1. very good against Pseudomonas
    2. doesn't work against Staphylococcus
    3. should not be used unless there is a documented or highly suspected Pseudomonal infection 
  11. Aminoglycosides
    1. have a significant risk for ototoxicity and nephrotoxicity
    2. should not be used in patients with diabetes
    3. should not be used in patients with underlying renal disease
    4. ineffective against anaerobes

N. Antibiotics with good Staphylococcal coverage

Dicloxacillin PO Nafcillin IV
Augmentin PO Cefazolin  IV
Keflex PO  Unasyn IV
Clindamycin PO and IV Timentin IV
Rocephin IM Vancomycin IV

O. References

1. Warren Joseph, Handbook of Lower Extremity Infections.
Churchill Livingstone, New York 1990.

2. Lower Extremity Infections, Clinics of Podiatric Medicine and Surgery
July Vol 7:3 1990. W.B. Saunders Philadelphia.

3. Lipsky B, Pecoraro R, Foot Ulceration and Infections in Elderly Diabetics.
Diabetes mellitus in the Elderly. Clinics of Geriatric Medicine
Vol 6, No 4, 747-769 November 1990.

4. Warren Joseph, Treatment of Lower Extremity Infections in Diabetics.
Practical Therapeutics: Drugs Vol 42, No 6, 984-996 1991.


2001, Dr. Brian Richman, All right reserved