Acute Mastoiditis in the Pneumococcal Conjugate Vaccine Era
Two-hundred, seventy-four hospitalizations for acute mastoiditis were identified between January 1999 and December 2008. We excluded 9 admissions for non-Colorado patients, 11 newborn admissions, 5 duplicate admissions, 5 admissions with cholesteatoma and 2 secondary admissions. Data remained for 242 admissions.
Children <2 years of age accounted for 44% (106/242) of all acute mastoiditis admissions ( Table 1 ). The annual incidence of acute mastoiditis appeared stable over the 10-year study period for children 2 to <18 years of age (Figure 1A). In contrast, variation occurred in children <2 years of age: the annual incidence per 100,000 children decreased from 11.0 in 2001 to 4.6 in 2002 ( Table 2 ). The lowest incidence occurred in 2003 at 4.5 before increasing to 12.0 by 2008. Linear regression demonstrated a significant increase in incidence of acute mastoiditis following PCV7 uptake by year from 2002 to 2008 (r = 0.972, P = 0.0003; Figure 1C).
The initial CHCO query yielded 248 admissions in 201 patients. We excluded 101 admissions with cholesteatoma, 21 with chronic suppurative otitis media, 26 deemed not related to acute mastoiditis and 7 duplicate records or repeat admissions related to a preceding mastoiditis episode. The final cohort included 91 patients with 94 admissions.
Children <2 years represented 53% (48/91) of acute mastoiditis hospitalizations at CHCO between 1999 and 2008. Patients received antibiotics before admission in 32/94 episodes (3/8, 2/13 and 10/28 children <2 years of age in the pre-PCV7, early post-PCV7 and late post-PCV7 periods, respectively, and 3/9, 5/15 and 9/21 children 2 to <18 years in these respective periods). Antibiotics were taken for an average duration of 5.4 days (standard deviation = 5.5) before admission. Most patients with previously intact tympanic membranes had a tympanostomy with tube insertion and/or mastoidectomy performed on admission at which time fluid/tissue was obtained for culture. Patients with preexisting, functioning tympanostomy tubes had fluid obtained from the lumen of the tubes for culture. One hundred and eighty cultures of middle ear fluid aspirates, mastoid fluid, otorrhea and abscess fluid (mastoid, postauricular, intraauricular, subperiostal) were obtained from all 91 patients ( Table 2 ). Only 2 had blood cultures, both negative for pathogens. There were 125 organisms (92 pathogens) isolated from 69 patients (72 admissions), including growth of pathogens from 19/32 patients who had received antibiotics before admission. S. pneumoniae was the most common pathogen, followed by S. pyogenes, anaerobes, P. aeruginosa and S. aureus. Haemophilus species represented only 3% (3/92) of isolated pathogens. S. pneumoniae was the predominant pathogen among children <2 years of age in all 3 periods, accounting for 49% (24/49) of all pathogens. In this age cohort, S. pneumoniae isolates comprised 30% (3/10) of pathogens in the pre-PCV7 period, 62% (8/13) in the early post-PCV7 period and 50% (13/26) in the late post-PCV7 period (P = 0.32).
Penicillin susceptibility testing was performed on 29 of 31 S. pneumoniae isolates. Thirty-eight percentage (5/13) of isolates tested in the late post-PCV7 period were nonsusceptible to penicillin (intermediate susceptibility in all 5 cultures) versus 0% (0/16) in both the pre-PCV7 and early post-PCV7 periods. Penicillin nonsusceptibility was observed only in children < 2 years of age ( Table 2 ). Paired comparisons for the whole group showed a significant increase in penicillin nonsusceptibility between the early and late post-PCV7 periods (P = 0.05) and across the entire study from 1999 to 2008 (P = 0.04).
Results
Colorado Population-based Estimates of Acute Mastoiditis Incidence and Demographics
Two-hundred, seventy-four hospitalizations for acute mastoiditis were identified between January 1999 and December 2008. We excluded 9 admissions for non-Colorado patients, 11 newborn admissions, 5 duplicate admissions, 5 admissions with cholesteatoma and 2 secondary admissions. Data remained for 242 admissions.
Children <2 years of age accounted for 44% (106/242) of all acute mastoiditis admissions ( Table 1 ). The annual incidence of acute mastoiditis appeared stable over the 10-year study period for children 2 to <18 years of age (Figure 1A). In contrast, variation occurred in children <2 years of age: the annual incidence per 100,000 children decreased from 11.0 in 2001 to 4.6 in 2002 ( Table 2 ). The lowest incidence occurred in 2003 at 4.5 before increasing to 12.0 by 2008. Linear regression demonstrated a significant increase in incidence of acute mastoiditis following PCV7 uptake by year from 2002 to 2008 (r = 0.972, P = 0.0003; Figure 1C).
CHCO Demographics and Microbiology
The initial CHCO query yielded 248 admissions in 201 patients. We excluded 101 admissions with cholesteatoma, 21 with chronic suppurative otitis media, 26 deemed not related to acute mastoiditis and 7 duplicate records or repeat admissions related to a preceding mastoiditis episode. The final cohort included 91 patients with 94 admissions.
Children <2 years represented 53% (48/91) of acute mastoiditis hospitalizations at CHCO between 1999 and 2008. Patients received antibiotics before admission in 32/94 episodes (3/8, 2/13 and 10/28 children <2 years of age in the pre-PCV7, early post-PCV7 and late post-PCV7 periods, respectively, and 3/9, 5/15 and 9/21 children 2 to <18 years in these respective periods). Antibiotics were taken for an average duration of 5.4 days (standard deviation = 5.5) before admission. Most patients with previously intact tympanic membranes had a tympanostomy with tube insertion and/or mastoidectomy performed on admission at which time fluid/tissue was obtained for culture. Patients with preexisting, functioning tympanostomy tubes had fluid obtained from the lumen of the tubes for culture. One hundred and eighty cultures of middle ear fluid aspirates, mastoid fluid, otorrhea and abscess fluid (mastoid, postauricular, intraauricular, subperiostal) were obtained from all 91 patients ( Table 2 ). Only 2 had blood cultures, both negative for pathogens. There were 125 organisms (92 pathogens) isolated from 69 patients (72 admissions), including growth of pathogens from 19/32 patients who had received antibiotics before admission. S. pneumoniae was the most common pathogen, followed by S. pyogenes, anaerobes, P. aeruginosa and S. aureus. Haemophilus species represented only 3% (3/92) of isolated pathogens. S. pneumoniae was the predominant pathogen among children <2 years of age in all 3 periods, accounting for 49% (24/49) of all pathogens. In this age cohort, S. pneumoniae isolates comprised 30% (3/10) of pathogens in the pre-PCV7 period, 62% (8/13) in the early post-PCV7 period and 50% (13/26) in the late post-PCV7 period (P = 0.32).
Penicillin susceptibility testing was performed on 29 of 31 S. pneumoniae isolates. Thirty-eight percentage (5/13) of isolates tested in the late post-PCV7 period were nonsusceptible to penicillin (intermediate susceptibility in all 5 cultures) versus 0% (0/16) in both the pre-PCV7 and early post-PCV7 periods. Penicillin nonsusceptibility was observed only in children < 2 years of age ( Table 2 ). Paired comparisons for the whole group showed a significant increase in penicillin nonsusceptibility between the early and late post-PCV7 periods (P = 0.05) and across the entire study from 1999 to 2008 (P = 0.04).
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