Age, Sex, Underlying Chronic Disease
The patients ranged in age from seventeen to seventy-four years and four of five were male. Chronic disease was present in three patients including arteriosclerotic heart disease in two. One of these patients also had chronic pyelonephritis. A third patient had viral hepatitis, short stature, and bilateral ureteroceles with hydronephrosis.
Pathogenesis
In all five patients, Pseudomonas osteomyelitis appeared to develop secondary to a contiguous focus of infection. Sites of infection included the left tibia, left knee, right hip area, lumbar vertebrae, and sternum. In four patients, infection developed following bone trauma including fractures in two and operative sterniotomy and intra-articular corticosteroid injection in single instances. In one of these patients (Case 3), Pseudomonas aeruginosa was isolated from urine while a Foley catheter was in place in the presence of a ruptured bladder. This apparently led to infection of a right pelvic hematoma and subsequently to right hip and pubic ramus osteomyelitis. The fifth patient was the only one without underlying bone disease. Osteomyelitis of the fourth and fifth lumbar vertebrae appeared to develop secondary to upper urinary tract infection.
Antibiotics were administered prior to the development of infection in three patients (Cases 2, 3, and 4) and may have played a role in the development of Pseudomonas aeruginosa superinfection.
Clinical Manifestations
The duration of symptoms ranged from three weeks to ten months and included pain and tenderness in all five, draining sinuses in three, and prolonged fever in two (fever was noted in patient 3 only one week prior to admission). In none of the patients were metastatic lesions noted.
Laboratory Findings
Only one of the five patients was anemic, with a hemoglobin of 9.7 grams per 100 milliliters. The white blood cell count was consistently below 12,000 per mm3 with a normal differential. Quantitative immunoglobulin studies in three patients (Cases 2, 3, and 5) revealed an elevated IgA level of 600 milligrams per 100 milliliters in one (Case 3) and an increased 1gM of 480 milligrams per 100 milliliters in a second patient (Case 5) which probably resulted from concomitant infectious hepatitis. Protein electrophoresis in a fourth patient revealed a normal gamma globulin level of 1,120 milligrams per 100 milliliters. Pseudomonas agar-gel precipitins were detected in the sera of three of four patients studied (Cases 2, 3, and 5). The organism recovered from patient 3 was identified as Fisher-Devlin-Gnabasik immunotype 7 and correlated with a type 7 hemagglutinating antibody titer of 1-2048. Precipitins were not detected in the serum of patient 4 but hemagglutinating antibodies were demonstrated to several immunotypes including a 1-52 titer with immunotype 6 lipopolysaccharide antigen.
Pseudomonas aeruginosa was recovered directly from bone or joint in all five patients. In vitro sensitivity studies revealed sensitivity to polymyxin B. gentamicin, and carbenicillin (isolate not tested with carbenicillin in Case 5). The minimum inhibitory concentrations of the strains isolated from two patients (Cases 2 and 3) were 50 and 62.5 micrograms per milliliter, respectively.
Characteristic findings of osteomyelitis were noted in roentgenographic examinations and included osteolysis in five, periosteal reaction in four, and osteoblastic activity and soft-tissue swelling in one each. In two patients serial roentgenograms revealed development of osteomyelitis in areas of previously normal bone (Figs. 1-A through 2-D).
Therapy
Four of the five patients were apparently cured of their infection at twelve to twenty-four-month follow-up periods. In one patient this followed the use of gentamicin intramuscularly, eighty milligrams every twelve hours for three weeks and eighty milligrams daily for an additional three weeks. The remaining four patients were treated with intravenous carbenicillin with apparent cure in three. This antibiotic was administered in an average dose of 2.5 grams every two hours for twenty-two days to six weeks.
Saucerization was performed in three patients (Cases 1, 2, and 4) and ingress and egress polyethylene tubes were positioned in the surgical wound for local antibiotics instillation. In Case 1, forty milligrams of gentamycin was administered daily by this route for three weeks while two patients (Cases 2 and 4) received one gram of carbenicillin daily for the same period.
Improvement was accompanied by decrease of pain and tenderness within two to four weeks, cessation of drainage, and roentgenographic changes in three of four patients. One patient (Case 3) continued to complain of pain and did not show signs of improvement on roentgenogram although he became afebrile. He was one of two patients in whom systemic antibiotic administration was not accompanied by saucerization and local antibiotics. He was subsequently lost to follow-up and is regarded as a probable treatment failure. The other patient (Case 5) not treated surgically did improve clinically and roentgenographically (Fig. 2-D).
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Control of infection, defined as complete absence of symptoms and signs of the infection for at least six months, was achieved in four of the five patients.