Skip directly to site content Skip directly to page options Skip directly to A-Z link Skip directly to A-Z link Skip directly to A-Z link
Volume 8, Number 5—May 2002

Sentinel Surveillance: A Reliable Way To Track Antibiotic Resistance in Communities?

Stephanie J. Schrag*, Elizabeth R. Zell*, Anne Schuchat*, and Cynthia G. Whitney*
Author affiliations: *Centers for Disease Control and Prevention, Atlanta, Georgia, USA

Main Article

Table 2

Number of isolates required to estimate accurately %PNSP in a given area and percentage of sentinel laboratory groups that met sample size requirements

Area Actual %PNSP (target range) No. of isolates needed to estimate %PNSPa % of sentinel groups of 5 laboratories with > no. of required isolates
CA 15 (10-20) 94 100
CT 18 (13-23) 172 3
GA 33 (28-38) 243 40
MD 22 (17-27) 183 12
MN 20 (15-25) 163 70
NY 15 (10-20) 97 100
OR 21 (16-26) 120 100
TN 35 (30-40) 191 0

a No. of isolates, n, required to estimate the area’s actual %PNSP (P) within 5 percentage points (d=0.05) with 95% confidence (Z=1.96) is: n= (Z2 P(1-P))/d2, where d is the range of accepted variation around the actual %PNSP, and Z is the Z-score range within which values must fall. Because the total no. of isolates per area, N, was small, we corrected this estimate for finite population size: n=n/[1+(n-1)/N]. There is no power associated with this estimate (14).
%PNSP, percent of penicillin-nonsusceptible pneumocooccal isolates.

Main Article

Page created: April 18, 2012
Page updated: April 18, 2012
Page reviewed: April 18, 2012
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.