eMedicine Specialties > Emergency Medicine > Infectious Diseases

Felon

Glen Vaughn, MD, Director, Department of Emergency Medicine, Defiance Hospital

Updated: Oct 1, 2009

Introduction

Background

Felons are closed-space infections of the fingertip pulp.

Pathophysiology

Fingertip pulp is divided into numerous small compartments by vertical septa that stabilize the pad. Infection occurring within these compartments can lead to abscess formation, edema, and rapid development of increased pressure in a closed space. This increased pressure may compromise blood flow and lead to necrosis of the skin and pulp.

A paronychia can progress to a felon if left untreated.

Frequency

United States

Felons and paronychias account for approximately one third of all hand infections. Thumb and index finger are the most commonly affected digits.

Mortality/Morbidity

With skin necrosis, spontaneous decompression may occur. When skin does not yield, osteomyelitis, tenosynovitis, and septic arthritis may result.

Clinical

History

Wooden splinters or minor cuts are common predisposing causes, yet no history of injury exists in over one half of patients. Infection also may spread from a paronychia.
Initial minor injury causes cellulitis, which is first confined by tough fibrous septa that break up pulp into tiny compartments.
- This early infection causes tight or prickling pain.
- At this stage, infection may resolve spontaneously, particularly with antibiotics. The number of abortive cases is unknown because many patients never present to the hospital.
If resolution does not occur, abscess formation is accompanied by throbbing pain.

Physical

Felons are characterized by marked throbbing pain, tension, and edema of the fingertip pulp.

Causes

Staphylococcus aureus is the most common cause. Methicillin-resistant Staphylococcus aureus –infected felons have been reported.^1,2,3
Gram-negative organisms have been reported in immunosuppressed patients. Fingertip blood glucose measurements have been implicated as an etiology,
Eikenella corrodens has been reported in persons with diabetes who bite their fingernails.^1,4,5

Differential Diagnoses

Cellulitis
Fingertip Injuries
Herpetic Whitlow
Paronychia

Workup

Laboratory Studies

Laboratory studies are not required.

Imaging Studies

Felons that are untreated, are incorrectly treated, or have a prolonged course may lead to osteomyelitis. Perform radiographic evaluation in severe cases or in immunocompromised patients.

Treatment

Emergency Department Care

Adequate early treatment of a felon can prevent abscess formation.
As pain progresses, administer antibiotics with activity against staphylococcal and streptococcal organisms.
Decompress to preserve venous flow whenever tension is present, whether or not a frank abscess has formed.
Culture drainage if methicillin-resistant S aureus is prevalent.
Perform a midline incision of the pad, because this is least likely to injure nerves or circulation.
Update tetanus immunization.
Perform a digital block.
Make short skin incision with a number 11 blade over the area of maximum tenderness. Incise only the skin with scalpel.
Evacuate pus using a blunt instrument in order to decrease the chance of severing the nerve or entering the tendon sheath. Do not divide vertical fascial strands (septa). For further information, see Hand, Paronychia Drainage.

Drainage of puss from under perionychium in a paronychia.

Pack gauze loosely into the wound to prevent skin closure. Apply a loose dressing, splint finger, and elevate hand above the heart.
Incisions
- High lateral incisions, palmar longitudinal incisions, palmar transverse incisions, and hockey stick and fishmouth incisions have been recommended for drainage. Some of these incisions offer no benefit but increase the potential for serious injury.
- The felon should be incised in the area of maximum tenderness. The incision should not cross the distal interphalangeal (DIP) joint to prevent formation of a flexion contracture at the DIP flexion crease. Probing is not carried out proximally to avoid extension of infection into the flexor tendon sheath.
- A longitudinal incision in the midline is effective without serious iatrogenic complications that are observed with other traditionally recommended incisions.
- Lateral or transverse incisions frequently cause ischemia and anesthesia by injuring one or both neurovascular bundles.
- Fish-mouth incision can lead to an unstable painful fingertip.

Consultations

Consult a hand surgeon for more complex cases.

Medication

The goals of pharmacotherapy are to treat infections and prevent further complications.

Antibiotics

Empirical coverage for S aureus and streptococcal organisms should be provided. Given the rapid emergence of community-acquired methicillin-resistant S aureus, treatment with a drug more likely to be effective against this agent should be considered. Coverage for E corrodens may be indicated for immunosuppressed patients.

Dicloxacillin (Dycill, Dynapen)

Bactericidal antibiotic that inhibits cell wall synthesis; DOC to treat infections caused by penicillinase-producing staphylococci. May be used to initiate therapy when staphylococcal infection is suspected.

Dosing

Adult

250-500 mg PO qid

Pediatric

25-50 mg/kg/d PO qid

Interactions

Decreases efficacy of oral contraceptives; increases effects of anticoagulants; probenecid and disulfiram may increase penicillin levels

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

Monitor PT in patients taking anticoagulant medications; toxicity may increase in patients renally impaired

Erythromycin (EES, E-Mycin, Ery-Tab)

An alternative antibiotic that inhibits RNA-dependent protein synthesis, possibly by stimulating dissociation of peptidyl tRNA from ribosomes, which inhibits bacterial growth.
Indicated for the treatment of infections caused by susceptible strains, including streptococci and S aureus.
In children, age, weight, and severity of infection determine proper dosage. When twice a day dosing is desired, half-total daily dose may be taken every 12 h. For more severe infections, double dose.

Dosing

Adult

250-1000 mg PO qid

Pediatric

30-50 mg/kg/d PO qid

Interactions

Coadministration may increase toxicity of theophylline, digoxin, carbamazepine, and cyclosporine; may potentiate anticoagulant effects of warfarin; coadministration with lovastatin and simvastatin increases risk of rhabdomyolysis

Contraindications

Documented hypersensitivity; hepatic impairment

Precautions

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

Caution in liver disease; estolate formulation may cause cholestatic jaundice; GI adverse effects are common (give doses pc); discontinue use if nausea, vomiting, malaise, abdominal colic, or fever occur

Cephalexin (Keflex, Biocef)

Another alternative antibiotic. First-generation cephalosporin that inhibits bacterial replication by inhibiting bacterial cell wall synthesis. Bactericidal and effective against rapidly growing organisms forming cell walls.

Dosing

Adult

250-500 mg PO qid

Pediatric

25-50 mg/kg/d PO qid

Interactions

Coadministration with aminoglycosides increases nephrotoxic potential

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

Adjust dose in renal impairment

Nafcillin (Unipen)

Indicated for severe infections.
Treats infections caused by penicillinase-producing staphylococci. Used to initiate therapy in any patients with possible penicillin G-resistant staphylococcal infection. Do not use for treatment of penicillin G-susceptible staphylococcal organisms.
Use parenteral therapy initially in severe infections. Severe infections may require very high doses.
Change to oral therapy as condition improves.
Because of occasional occurrence of thrombophlebitis associated with the parenteral route, particularly in elderly patients, administer parenterally only for a short term (24-48 h) and change to oral route if clinically possible.

Dosing

Adult

1-2 g IV q4h

Pediatric

100-200 mg/kg/d IV qid

Interactions

Associated with warfarin resistance when administered concurrently; effects may decrease with bacteriostatic action of tetracycline derivatives

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

To optimize therapy, determine causative organisms and susceptibility; >10 d treatment to eliminate infection and prevent sequelae (eg, endocarditis, rheumatic fever); take cultures after treatment to confirm that infection is eradicated

Sulfamethoxazole and trimethoprim (Bactrim DS, Septra DS)

Inhibits bacterial growth by inhibiting synthesis of dihydrofolic acid.

Dosing

Adult

160 mg TMP PO/IV q12h

Pediatric

<2 years: Do not administer
>2 years: 6-12 mg TMP/kg/d PO/IV divided bid

Interactions

May increase PT when used with warfarin (perform coagulation tests and adjust dose accordingly); coadministration with dapsone may increase blood levels of both drugs; coadministration of diuretics increases incidence of thrombocytopenia purpura in elderly persons; phenytoin levels may increase with coadministration; may potentiate effects of methotrexate in bone marrow depression; hypoglycemic response to sulfonylureas may increase with coadministration; may increase levels of zidovudine

Contraindications

Documented hypersensitivity; megaloblastic anemia due to folate deficiency

Precautions

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

Do not use during last trimester of pregnancy due to potential toxicity to newborn (eg, jaundice, hemolytic anemia, kernicterus)
Dosage adjustments (adult adjustments)
CrCl (mL/min) 80-50: Recommended IV dose q18h
CrCl 50-10: Recommended IV dose q24h
CrCl <10: Not recommended
During peritoneal dialysis: 0.16-0.8 g q48h
Discontinue at first appearance of skin rash or sign of adverse reaction; obtain CBCs frequently; discontinue therapy if significant hematologic changes occur; goiter, diuresis, and hypoglycemia may occur with sulfonamides; prolonged IV infusions or high doses may cause bone marrow depression (if signs occur, give 5-15 mg/d leucovorin); caution in folate deficiency (eg, chronic alcoholics, elderly, those receiving anticonvulsant therapy, or those with malabsorption syndrome); hemolysis may occur in G-6-PD deficient individuals; AIDS patients may not tolerate or respond to TMP-SMZ; caution in renal or hepatic impairment (perform urinalyses and renal function tests during therapy); give fluids to prevent crystalluria and stone formation

Follow-up

Further Outpatient Care

Splint and elevate finger.
Provide follow-up care within 2 days.
Remove packing in 2 days.

Complications

Osteomyelitis involving the diaphysis of distal phalanx is a common complication.
The most serious complication is acute tenosynovitis, which may result from contiguous spread of infection. This is usually iatrogenic from inadvertent nicking of flexor tendon sheath with scalpel.
Other complications include skin necrosis, deformity of the fingertip, septic arthritis, and instability of the finger pad.

Prognosis

Prognosis is excellent when treated early and appropriately.

Miscellaneous

Medicolegal Pitfalls

Failure to adequately treat infection can result in serious complications.
Failure to check pressure and accumulation of pus in a closed compartment may lead to osteomyelitis and skin necrosis.
Failure to perform judicious incisions may result in unstable tender fingertips or flexion contractures of DIP flexor crease.
Failure to address the possibility of methicillin-resistant S aureus may result in worsening infection.

Special Concerns

Instability of distal phalangeal skin and fat pad is a significant handicap that has resulted from traditional insistence on division of septa.

Multimedia

Media file 1: Differential diagnosis for a felon includes herpetic whitlow.

Media file 2: A paronychia can progress to a felon if left untreated.

Media file 3: Drainage of puss from under perionychium in a paronychia.

References

Connolly B, Johnstone F, Gerlinger T, Puttler E. Methicillin-resistant Staphylococcus aureus in a finger felon. J Hand Surg [Am]. Jan 2000;25(1):173-5. [Medline].
Barkin JA, Miki RA, Mahmood Z, Landy DC, Owens P. Prevalence of methicillin resistant Staphylococcus aureus in upper extremity soft tissue infections at jackson memorial hospital, miami-dade county, Florida. Iowa Orthop J. 2009;29:67-73. [Medline].
Pallin DJ, Egan DJ, Pelletier AJ, Espinola JA, Hooper DC, Camargo CA Jr. Increased US emergency department visits for skin and soft tissue infections, and changes in antibiotic choices, during the emergence of community-associated methicillin-resistant Staphylococcus aureus. Ann Emerg Med. Mar 2008;51(3):291-8. [Medline].
Newfield RS, Vargas I, Huma Z. Eikenella corrodens infections. Case report in two adolescent females with IDDM. Diabetes Care. Sep 1996;19(9):1011-3. [Medline].
Glickel SZ. Hand infections in patients with acquired immunodeficiency syndrome. J Hand Surg [Am]. Sep 1988;13(5):770-5. [Medline].
Bolton H, Fowler PJ, Jepson RP. Natural history and treatment of pulp space infection and osteomyelitis of the terminal phalanx. J Bone Joint Surg. 1949;4:499-504.
Canales FL, Newmeyer WL, Kilgore ES. The treatment of felons and paronychias. Hand Clin. Nov 1989;5(4):515-23. [Medline].
Clark DC. Common acute hand infections. Am Fam Physician. Dec 1 2003;68(11):2167-76. [Medline].
Elston DM. Optimal antibacterial treatment of uncomplicated skin and skin structure infections: applying a novel treatment algorithm. J Drugs Dermatol. Nov-Dec 2005;4(6 Suppl):s15-9. [Medline].
Hijjawi JB, Dennison DG. Acute felon as a complication of systemic paclitaxel therapy: case report and review of the literature. Hand (N Y). Sep 2007;2(3):101-3. [Medline].
Kilgore ES Jr, Brown LG, Newmeyer WL. Treatment of felons. Am J Surg. Aug 1975;130(2):194-8. [Medline].
Perry AW, Gottlieb LJ, Zachary LS, Krizek TJ. Fingerstick felons. Ann Plast Surg. Mar 1988;20(3):249-51. [Medline].
Roberge RJ, Weinstein D, Thimons MM. Perionychial infections associated with sculptured nails. Am J Emerg Med. Oct 1999;17(6):581-2. [Medline].
Watson PA, Jebson PJ. The natural history of the neglected felon. Iowa Orthop J. 1996;16:164-6. [Medline].
Zyluk A, Puchalski P. [Severe infections within the upper extremity--analysis of the causes and methods of treatment]. Chir Narzadow Ruchu Ortop Pol. 2006;71(4):239-44. [Medline].

Keywords

felon, paronychia, fingertip infection, finger infection, closed-space infections, fingertip pulp, paronychias, hand infections, osteomyelitis, tenosynovitis, septic arthritis, Staphylococcus aureus, S aureus, Eikenella corrodens, E corrodens, wood splinter, minor cut, cellulitis, skin necrosis

Contributor Information and Disclosures

Author

Glen Vaughn, MD, Director, Department of Emergency Medicine, Defiance Hospital
Disclosure: Nothing to disclose.

Medical Editor

Jeffrey Glenn Bowman, MD, MS, Consulting Staff, Highfield MRI, Columbus, Ohio
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment

Managing Editor

Jon Mark Hirshon, MD, MPH, Associate Professor, Department of Emergency Medicine, University of Maryland School of Medicine
Jon Mark Hirshon, MD, MPH is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American College of Emergency Physicians, American Public Health Association, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

CME Editor

John D Halamka, MD, MS, Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center
John D Halamka, MD, MS is a member of the following medical societies: American College of Emergency Physicians, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Chief Editor

Steven C Dronen, MD, FAAEM, Director of Emergency Services, Director of Chest Pain Center, Department of Emergency Medicine, Ft Sanders Sevier Medical Center
Steven C Dronen, MD, FAAEM is a member of the following medical societies: American Academy of Emergency Medicine and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Further Reading