A new formalin-inactivated vaccine prepared by sucrose density gradient centrifugation of tissue culture-grown Rickettsia rickettsii was evaluated for safety and immunogenicity in a placebo-controlled, double-blind study. Most of the 52 seronegative adult vaccinees, 88% after the first and 66% after the second dose, experienced brief, mild (mostly local) reactions, but only 50% exhibited a systemic immune response to vaccination. Six unvaccinated volunteers (controls) and 16 of these vaccinees were challenged with R rickettsii one month after vaccination. Vaccine efficacy was 25%; all six controls and 12 of 16 vaccinees developed typical Rocky Mountain spotted fever. The incubation period was longer, the duration of constitutional symptoms shorter, and the height of fever lower in ill vaccinees than in controls. The vaccine provided only partial protection against Rocky Mountain spotted fever but ameliorated the illness.
A method was devised for predicting the serum bactericidal activity of new drugs. Six healthy volunteers received 2 g moxalactam, cefoperazone and cefotaxime, respectively, as 30-min infusions in a crossover manner at one-week intervals. The pharmacokinetics of each drug was characterized and the bactericidal activity of the serum 1 h after infusion was measured against panels of six strains of Pseudomonas aeruginosa, six strains of Escherichia coli, six strains of Staphylococcus aureus, and four strains of Klebsiella pneumoniae. The minimum bactericidal concentration of each antibiotic was determined for each organism by the standard NCCLS reference method and the method of Stratton and Reller. On the basis of these values and a serum concentration-time curve constructed from individual patient pharmacokinetic parameters, the bactericidal activity of the serum 1 h after infusion was predicted. These predictions showed a 90% agreement with measured values calculated according to the method of Stratton and Reller, whereas an agreement of 74% was obtained with the reference method. This difference was statistically significant (p less than 0.001).
Enteritis necroticans is a necrotizing process manifesting as segmental gangrene of the bowel, triggered by Clostridium perfringens toxins under specific dietary conditions. It is a rare disease in developed countries and is probably underdiagnosed. A case of enteritis necroticans presenting with midgut necrosis with sepsis and hemolysis is reported herein. Bacteriologic culture of blood and peritoneal content revealed C perfringens. Dietary history, including the ingestion of meat together with sweet potatoes, should increase clinical suspicion of enteritis necroticans. Early recognition and timely surgical intervention are required for successful treatment. Clinicians are encouraged to be aware of this clinically fulminant yet rarely recognized surgical entity.
Cytomegalovirus (CMV) colitis usually occurs in patients with advanced immunosuppression when the CD4 count is <50 cells/μL. We reported a case of recurrent CMV colitis in a patient with HIV who presented with profuse lower gastrointestinal bleed. This was a case of immune reconstitution inflammatory syndrome (IRIS) manifesting as CMV colitis and has been reported only once in the literature previously. This patient had a CD4 count of 157 cells/μL and undetectable viral load after being on antiretroviral therapy (ART) for 5 months, which was consistent with IRIS. The diagnosis of CMV was confirmed by a colonoscopy and a biopsy. This case highlights the fact that CMV colitis can manifest despite a moderately preserved CD4 count and the clinicians must have a high index suspicion for IRIS syndrome especially when someone was recently started on ART. Since effective treatment is available, it is important not to miss the diagnosis of CMV colitis.
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