HAND INFECTIONS

Most hand infections are bacterial and are the result of minor wounds that have been neglected. Human bite wounds are the second most common cause of hand infections. Hematogenous spread of infection from other sites to the hand is rare but can occur.

A complete history and physical examination is necessary to exclude other associated medical conditions (eg, diabetes, arthritis, immunosuppression1 ) that may compromise therapy. The history should ascertain the mechanism of injury, as this may provide some clues about the organism(s) most likely responsible for the infection. Radiographic evaluation may be indicated if the history and physical examination suggest a possibility of fracture, osteomyelitis, or foreign body

Diagnostic Studies-

In most cases, the diagnosis of infection is made on clinical grounds. Diagnostic studies are frequently necessary to support the diagnosis. If the diagnosis is in doubt, diagnostic studies may be of benefit.The following studies may be performed:
Complete blood count (CBC) may reveal leukocytosis with left shift.
Serum glucose levels may be helpful, particularly in patients with diabetes.
Plain radiographs may be helpful to rule out fractures, foreign bodies, and osteomyelitis. The presence of gas on radiographs suggests the presence of gas-forming organisms, such Clostridium perfringens.
In the presence of obvious purulent drainage, perform wound cultures. In suspected septic arthritis, joint aspiration helps confirm the diagnosis and identify the organisms involved. Use caution in aspiration of joints through infected tissues, as this may result in inoculation of the joint space with organisms.
Ultrasonography may help confirm the clinical suspicion of abscess, septic arthritis, or pyogenic flexor tenosynovitis.
CT scan, MRI, and bone scan may be used to diagnose osteomyelitis.
Tzanck smear is useful when the diagnosis of viral infection is suspected in the presence of a blister that has not resolved spontaneously.

TYPES OF INFECTIONS-

Bite wounds
Bite wounds to the hand may cause cellulitis and abscess. Human bite wounds are particularly virulent because of the gram-positive and anaerobic bacteria present in the mouth. They are frequently the result of punching an opponent in the mouth, with the teeth causing the laceration. Frequently, the tooth penetrates the metacarpophalangeal joint, where the cartilage is particularly sensitive to infection. Every puncture wound near the proximal knuckle must be treated aggressively with exploration, irrigation, antibiotics, and drainage. Human saliva contains more than 109 bacteria per milliliter. The risk of infection is, therefore, great. Because of this risk, human bite wounds to the hand should usually not be closed.3
The infection progresses rapidly, with swelling, tenderness, and erythema presenting within 24 hours of the injury. The cellulitis usually progresses to an abscess if untreated. In the evaluation, wound cultures and radiographs should be obtained to exclude fractures or foreign bodies (eg, teeth).
Bites from cats and dogs are much less likely than human bites to result in infection. Cat bites are less frequent than dog bites but are more likely to cause infection. Animal bite wounds can be closed loosely after debriding the wound edges, provided that they are seen early, thoroughly irrigated, and followed very closely, and that oral antibiotics are administered. Advanced cases require intravenous antibiotics

Midpalmar space infection
The midpalmar space is a potential space between the middle, ring, and small finger flexor tendons and volar interosseous muscles. It extends from the hypothenar muscles ulnarly to the midpalmar septum radially. The accumulation of pus converts this potential space into a true space. The infection usually results from direct open trauma, or it may spread from a pyogenic flexor tenosynovitis. S aureus and streptococci are cultured most frequently.
Radial to the midpalmar septum is the thenar space, which is also a potential space. This space is volar to the adductor pollicis muscle over the second and third metacarpals. It also can be expanded by the accumulation of pus, which is characterized by painful swelling in the thenar space and passive abduction of the thumb. The hypothenar space is a potential space within the fascia of the hypothenar muscles. Infection within this space is rare. It manifests as tenderness and swelling over the hypothenar region