USE OF C-REACTIVE PROTEIN IN DIFFERENTIATION BETWEEN ACUTE BACTERIAL AND VIRAL OTITIS-MEDIA

Objectives. The objectives of this investigation were: (1) to determin e degree of elevation of serum C-reactive protein (CRP) in uncomplicat ed acute otitis media (AOM); (2) to compare serum CRP levels in bacter ial and viral otitis media; and (3) to determine whether a single seru m CRP level, obtained early in the course of AOM, could be used to dif ferentiate between viral and bacterial otitis media. Design and method s. Sera were obtained from otherwise healthy infants and children with AOM who were 3 months to 7 years of age between 1989 and 1991. Tympan ocentesis, bacterial and viral studies of the middle ear fluids, virol ogic studies of nasal wash specimens, measurements of serum antibody t iters to respiratory viruses, blood counts, and quantitation of serum CRP concentrations were performed. After the initial tympanocentesis, an oral antibiotic was given for the next 10 days. The patients were c linically reevaluated over next 4 weeks. Outcome measures. Serum CRP c oncentrations were compared among subjects with AOM who were divided i nto four groups based on the results of bacteriologic and virologic st udies: group I, Bacterial infection (n = 82); group II, bacterial and viral infections (n = 69); group III, viral infection (n = 12); and gr oup IV,no identifiable pathogen (n = 22). Results. There was no statis tical difference in serum CRP values among the four groups. The ranges of CRP were less than 0.6 to 22.8, less than 0.6 to 17.8, less than 0 .6 to 2.0, and less than 0.6 to 6.8 mg/dL in groups I through IV, resp ectively. However, when CRP values in bacteria-positive cases were com pared with CRP concentrations in bacteria-negative cases (1.58 +/- 3.1 6 vs 0.64 +/- 1.24 mg/dL), the difference was statistically significan t. Furthermore, a significantly higher proportion of bacteria-positive cases had serum CRP concentrations greater than 2 mg/dL, compared wit h those in bacteria-negative cases. There was no correlation between i nitial CRP values and clinical findings and/or the clearance of bacter ia from the middle ear. After 10 days of antibiotic treatment, CRP val ues returned to normal (<0.6 mg/dL) in all cases. Conclusion. In AOM, the range of serum CRF varied from less than 0.6 to 22.8 mg/dL. High C RP values (>2.0 mg/dL) were associated with 22% of cases of bacterial AOM but only with 6% of nonbacterial AOM. High levels of serum CRP wer e found to be very specific in detecting bacterial AOM, and no cases o f viral AOM without a concurrent bacterial infection were found to exh ibit high serum levels of CRP.