Coombs’ reaction

Vasculitis may be related to penicillin hypersensitivity. The Coombs reaction frequently becomes positive during prolonged therapy, but hemolytic anemia is rare. Reversible neutropenia has been noted, occurring in up to 30% of patients treated with 8-12 g nafcillin for longer than 21 days. Eosinophilia occasionally accompanies other allergic reactions to penicillin. 

Patients with a history of a mild or a temporally distant penicillin reaction appear to be at low risk of allergic reaction following cephalosporin administration. However, patients who have had a recent severe, immediate reaction to a penicillin should be given a cephalosporin with great caution, if at all. A positive Coombs reaction appears frequently in patients who receive large doses of a cephalosporin, but hemolysis is rare. Cephalosporins rarely have produced bone marrow depression characterized by granulocytopenia. 

Hypersensitivity reactions with P-lactam antibiotics, especially penicillin, may encompass any of the type I through IV Gell-Coombs classifications. The most common reactions are maculopapular and urticarial eruptions.7 While rare (less than 0.05%), anaphylaxis to penicillins causes the greatest concern because they are responsible for the majority of drug-induced anaphylaxis deaths in patients, accounting for 75% of all ana-i phylaxis cases in the United States.5,8 The treatment of ana-I phylaxis is given in Table 51-2.9... 

Adverse reactions CNS Convulsions, confusion, drowsiness, myoclonus, fever Dermatologic Rash Metabolic Electrolyte imbalance Hematologic Positive Coombs test, hemolytic anemia Local Rain, thrombophlebitis Renal Acute interstitial nephritis Miscellaneous Anaphylaxis, hypersensitivity, Jarisch-Herxheimer reaction CNS Seizures, confusion, drowsiness, myoclonus, CNS stimulation Cardiovascular Myocardial depression, vasodilation, conduction disturbances Hematologic Positive Coombs test, hemolytic anemia, neutropenia Local Thrombophlebitis, sterile abscess at injection site Renal Interstitial nephritis Miscellaneous Pseudoanaphylactic reactions, hypersensitivity, Jarisch-Herxheimer reaction, serum sickness... 

The answer is a. (Katzung, p 162.) Many drugs can cause an immunohemolytic anemia. Methyldopa may cause a positive Coombs test in as many as 20% of patients, along with hemolytic anemia. Other drugs with similar actions on red blood cells are penicillins, quinidine, procainamide, and sulfonamides. These form a stable or unstable hapten on the red cell surface, which induces an immune reaction I immunoglobulin G (IgG) antibodies] and leads to dissolution of the membrane. 

Coombs, R.R.A. and Gell, P.G.H. (1975). Classification of allergic reactions responsible for clinical hypersensitivity and disease. In Clinical Aspects of Immunology. (Gell, P.G.H., Coombs, R.R.A. and Lachman, D.J., Eds.). Blackwell Scientific Publications, Oxford, p. 761. 

In case of benzene, the potassium salt of its anion-radical can be separated as a precipitate after benzene reduction by potassium in the presence of low concentrations of 18-crown-6-ether. For benzene, the heavy-form content is greatest in the solution, not in the precipitate. It is in the solution where most of the nonreduced neutral molecules remain. Since the neutral molecules are inert toward protons, the anion-radicals combine with the protons to give dihydro derivatives (products of the Birch reaction). Therefore, it is possible to conduct the separation chemically. The easiest way is to protonate a mixture after the electron transfer, than to separate the aromatic compounds from the respective dihydroaromatics (cyclohexadiene, dihydronaphthalene, etc.) (Chang and Coombe 1971, Stevenson and Alegria 1976 Stevenson et al. 1986a, 1986c, 1988). 

R. G. Coombes, in Comprehensive Organic Chemistry The Synthesis and Reactions of Organic Compounds, Ed. I. O. Sutherland, Pergamon Press, Oxford, 325-356 (1979). 

Drug/Lab test interactions False-positive urine glucose reactions may occur with penicillin therapy if Clinitest, Benedict s Solution, or Fehling s Solution are used. It is recommended that enzymatic glucose oxidase tests (such as Clinistix or Tes-Tape) be used. Positive Coombs tests have occurred. High urine concentrations of some penicillins may produce false-positive protein reactions (pseudoproteinuria) with the P.870... 

False-positive protein reactions False-positive Coombs test... 

Adverse Reactions Diarrhea, nausea Eosinophilia, positive Coombs test, thrombocytosis, agranulocytosis, hemolytic anemia, leukopenia, thrombocytopenia, prolonged prothrombin time Elevation of hepatic enzymes Rash, anaphylactic reaction Phlebitis at injection site... 

Rajan TV. 2003. The Gell-Coombs classification of hypersensitivity reactions A reinterpretation. Trends Immunol. 24 376-379. 

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