Table 4.
Distribution of Acute Otitis Media Pathogens in Nasopharyngeal Cultures, According to Type of Visit.*
| Variable | Index Episode | End-of-Treatment Assessment for Index Episode | Recurrent Episode† | Routine Nonillness† | Final | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| 10-Day Group | 5-Day Group | 10-Day Group | 5-Day Group | 10-Day Group | 5-Day Group | 10-Day Group | 5-Day Group | 10-Day Group | 5-Day Group | |
| Visits | ||||||||||
|
| ||||||||||
| No. of visits with culture obtained/total no. of visits | 256/257 | 258/258 | 233/236 | 222/224 | 148/162 | 119/125 | 415/421 | 359/361 | 225/225 | 195/195 |
|
| ||||||||||
| S. pneumoniae | ||||||||||
|
| ||||||||||
| No. of positive cultures (%)‡ | 125 (49) | 138 (53) | 28 (12) | 36 (16) | 72 (49) | 57 (48) | 146 (35) | 144 (40) | 88 (39)§ | 70 (36) |
| Susceptible | 84 (33) | 94 (36) | 5 (2) | 10 (5) | 41 (28) | 24 (20) | 82 (20) | 89 (25) | 54 (24) | 48 (25) |
| Intermediate | 20 (8) | 28 (11) | 10 (4) | 12 (5) | 14 (9) | 13 (11) | 33 (8) | 31 (9) | 24 (11) | 11 (6) |
| Resistant | 21 (8) | 16 (6) | 13 (6) | 14 (6) | 17 (11) | 20 (17) | 31 (7) | 24 (7) | 9 (4) | 11 (6) |
|
| ||||||||||
| Simple odds ratio (95% CI)¶ | NA | NA | 0.6 (0.3–1.0) | 0.6 (0.4–1.1) | 1.4 (0.8–2.3) | 1.9 (1.1–3.1) | 1.0 (0.6–1.5) | 0.9 (0.6–1.4) | 0.9 (0.6–1.5) | 0.6 (0.4–1.1) |
| P value | NA | 0.76 | 0.43 | 0.79 | 0.31 | |||||
|
| ||||||||||
| Conditional odds ratio (95% CI)|| | NA | NA | 9.4 (3.3–26.6) | 5.6 (2.5–12.5) | 1.6 (0.8–2.8) | 2.9 (1.6–5.6) | 1.6 (1.0–2.6) | 1.3 (0.8–2.2) | 1.2 (0.7–2.2) | 1.0 (0.5–1.8) |
| P value | NA | 0.43 | 0.15 | 0.59 | 0.57 | |||||
|
| ||||||||||
| H. influenzae | ||||||||||
|
| ||||||||||
| No. of positive cultures (%)** | 84 (33) | 61 (24) | 77 (33) | 65 (29) | 39 (26) | 41 (34) | 49 (12) | 42 (12) | 21 (9) | 25 (13) |
| Susceptible | 53 (21) | 37 (14) | 39 (17) | 37 (17) | 28 (19) | 27 (23) | 33 (8) | 30 (8) | 14 (6) | 16 (8) |
| Nonsusceptible | 31 (12) | 24 (9) | 38 (16) | 28 (13) | 11 (7) | 14 (12) | 16 (4) | 12 (3) | 7 (3) | 9 (5) |
|
| ||||||||||
| Simple odds ratio (95% CI)¶ | NA | NA | 1.4 (0.8–2.4) | 1.4 (0.8–2.5) | 0.6 (0.3–1.2) | 1.3 (0.6–2.6) | 0.3 (0.2–0.5) | 0.3 (0.2–0.7) | 0.2 (0.1–0.5) | 0.5 (0.2–1.0) |
| P value | NA | 0.99 | 0.12 | 0.76 | 0.23 | |||||
|
| ||||||||||
| Conditional odds ratio (95% CI)|| | NA | NA | 1.7 (0.9–3.1) | 1.2 (0.6–2.4) | 0.7 (0.3–1.5) | 0.8 (0.4–1.8) | 0.8 (0.4–1.7) | 0.6 (0.3–1.4) | 0.8 (0.3–2.4) | 0.9 (0.3–2.3) |
| P value | NA | 0.46 | 0.77 | 0.61 | 0.98 | |||||
In the analyses for Streptococcus pneumoniae and Haemophilus influenzae, the denominator for the percentage calculations is the number of visits with culture obtained, unless otherwise noted. P values are for the comparison of the 10-day group with the 5-day group.
Data shown are for all such visits combined.
Susceptibility to penicillin was determined as follows: when the minimum inhibitory concentration (MIC) was available, susceptibility was defined as an MIC of less than 0.1 μg per milliliter, intermediate as an MIC of 0.1 to 1 μg per milliliter, and resistant as an MIC of more than 1 μg per milliliter; when the MIC was not available, susceptibility was defined as an oxacillin-disk zone size of more than 20 mm, intermediate as a zone size of 9 to 20 mm, and resistant as a zone size of 8 mm or less.
Sensitivity was not available for one isolate, so the denominator to calculate the percentages in the sensitivity distribution is 224 rather than 225.
The simple odds ratio constitutes the odds for a specific treatment group, as compared with the status of that group at the index episode, of being colonized at a later time with a nonsusceptible organism.13 Results are presented without regard to multiple observations in individual children.
The conditional odds ratio constitutes the odds for a specific treatment group, as compared with the status of that group at the index episode, of being colonized at a later time with a nonsusceptible organism conditional on overall carriage of that organism (i.e., both susceptible and nonsusceptible strains) at that time.13 Results are presented without regard to multiple observations in individual children.
Susceptibility was defined as a beta-lactamase–negative result and an ampicillin E test MIC of 1 μg per milliliter or less; nonsusceptibility was defined as either a beta-lactamase–positive result or a beta-lactamase–negative result and an ampicillin E test MIC of more than 1 μg per milliliter.