Chapter 135. Gas Gangrene and Other Clostridial Infections (Part 5)

Diagnosis The diagnosis of clostridial disease, in association with positive cultures, must be based primarily on clinical findings. Because of the presence of clostridia in many wounds, their mere isolation from any site, including the blood, does not necessarily indicate severe disease. Smears of wound exudates, uterine scrapings, or cervical discharge may show abundant large gram-positive rods as well as other organisms. Cultures should be placed in selective media and incubated anaerobically for identification of clostridia. The diagnosis of clostridial myonecrosis can be established by frozen-section biopsy of muscle.The urine of patients with severe clostridial sepsis may contain protein...
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Chapter 135. Gas Gangrene and Other Clostridial Infections (Part 5) Chapter 135. Gas Gangrene and Other Clostridial Infections (Part 5) Diagnosis The diagnosis of clostridial disease, in association with positive cultures,must be based primarily on clinical findings. Because of the presence of clostridiain many wounds, their mere isolation from any site, including the blood, does notnecessarily indicate severe disease. Smears of wound exudates, uterine scrapings,or cervical discharge may show abundant large gram-positive rods as well as otherorganisms. Cultures should be placed in selective media and incubatedanaerobically for identification of clostridia. The diagnosis of clostridialmyonecrosis can be established by frozen-section biopsy of muscle. The urine of patients with severe clostridial sepsis may contain protein andcasts, and some patients may develop severe uremia. Profound alterations ofcirculating erythrocytes are seen in severely toxemic patients. Patients havehemolytic anemia, which develops extremely rapidly, along with hemoglobinemia,hemoglobinuria, and elevated levels of serum bilirubin. Spherocytosis, increasedosmotic and mechanical red blood cell fragility, erythrophagocytosis, andmethemoglobinemia have been described. DIC may develop in patients withsevere infection. In patients with severe sepsis, Wrights or Grams staining of asmear of peripheral blood or buffy coat may demonstrate clostridia. X-ray examination sometimes provides an important clue to the diagnosisby revealing gas in muscles, subcutaneous tissue, or the uterus. However, thefinding of gas is not pathognomonic for clostridial infection. Other anaerobicbacteria, frequently mixed with aerobic organisms, may produce gas. Clostridial Infections: Treatment (Table 135-1) Traumatic wounds should be thoroughly cleansed anddebrided. Traditionally, the antibiotic of choice for severe clostridial infection hasbeen penicillin G (20 million units per day in adults). Penicillin G treatment of gasgangrene has become more controversial because of increasing resistance to thisdrug and data obtained from animal models of infection. In a mouse model of gasgangrene, antibiotics inhibiting toxin synthesis appeared to be preferable to cellwall–active drugs; clindamycin treatment enhanced survival more than therapywith penicillin; and the combination of clindamycin and penicillin was superior topenicillin alone. For severe clostridial sepsis, clindamycin may be used at a doseof 600 mg every 6 h in combination with high-dose penicillin (3–4 million unitsevery 4 h). Although no clinical trials validate this choice, it is gaining acceptancein the infectious disease community. Table 135-1 Treatment of Clostridial Infectionsa Condition Antibiotic Penicillin Adjunctiv Treatment Allergy e Treatment/Note Contaminatio None — —n Gas gangrene Penicillin, Chloramphenico Surgical 3–4 million units l, metronidazole, debridement with IV q4h, plus imipenem, doxycycline wide excision is (see text)b essential. Clindamyci Consider n, 600 mg IV q6h hyperbaric oxygen. Clostridial Penicillin, Chloramphenico Transientsepsis 3–4 million units l, metronidazole, bacteremia may IV q4h, plus imipenem, doxycycline be clinically (see text)b insignificant. Clindamyci n, 600 mg IV q6h Suppurative Penicillin, As above, plus Empiricaldeep-tissue 3–4 million units gentamicin or a therapy should beinfections (e.g., IV q4h, plus quinolone given. Therapyabdominal wall, should be based Gentamicin,gynecologic) on Grams stain 5 mg/kg IV q24h, ...