Department of Pediatrics, Georgetown University School of Medicine, 4431 Albemarle St. NW, Washington, DC 20016, USA
Received 27 August 2003; returned 14 October 2003; revised 2 November 2003; accepted 7 November 2003
![]() |
Abstract |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Methods: Analysis of nasopharyngeal cultures obtained from 70 patients, 42 with AMS and 28 with RMS.
Results: Thirty-eight potentially pathogenic organisms were recovered in 36 (86%) of the children from the AMS group, and 40 were isolated from 26 (93%) of the children from the RMS group. The organisms isolated were Streptococcus pneumoniae (21 isolates), Haemophilus influenzae non-type b (17), Moraxella catarrhalis (15), Streptococcus pyogenes (13) and Staphylococcus aureus (12). Resistance to the eight antimicrobial agents used was found in 34 instances in the AMS group compared to 93 instances in the RMS group (P < 0.005). The difference between AMS and RMS was significant with S. pneumoniae resistance to amoxicillin (P < 0.0025), to co-amoxiclav (P < 0.0025), to trimethoprimsulfamethoxazole (P < 0.05), to cefixime (P < 0.05), and to azithromycin (P < 0.05), and for H. influenzae to amoxicillin (P < 0.025).
Conclusions: These data illustrate the higher recovery rate of antimicrobial-resistant S. pneumoniae and H. influenzae from the nasopharynx of children who had maxillary sinusitis that recurred after amoxicillin therapy than those with AMS.
Keywords: sinusitis, Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, antimicrobial resistance
![]() |
Introduction |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
This study was carried out to investigate the antimicrobial susceptibility of the organisms isolated from the nasopharynx of children who present with maxillary sinusitis or maxillary sinusitis that recurred after amoxicillin therapy.
![]() |
Materials and methods |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
The diagnostic criteria applied for maxillary sinusitis were the presence of purulent rhino-sinusitis for at least 10 days and radiological abnormalities of the maxillary sinus in the form of total opacity or mucosal swelling greater than 6 mm (established by plain film or computed tomography). These were carried out as previously described.3 RMS was defined as an AMS episode that followed a previous maxillary sinus infection after an infection-free interval of 46 weeks. All patients of the RMS group were treated with amoxicillin (45 mg/kg per day) given twice a day for 14 days for their previous infection. Excluded were children who had ear effusion or infection, otorrhoea, tympanostomy tubes, craniofacial anomalies, chronic sinusitis and other chronic medical problems. Also excluded from the AMS group were those who had received antimicrobials in the past 3 months.
A total of 70 patients were studied, 42 with AMS and 28 with RMS. Patient ages ranged from 3 years and 8 months to 13 years and 5 months (average age 8 years and 9 months) and 41 were males. No differences were noted in the age, gender and day care attendance distribution between the two groups. No siblings were allowed to be included in the study.
Nasopharyngeal cultures were obtained using sterile calcium alginate swabs and were immediately plated on media supportive of growth of aerobic and facultative anaerobes. Sheep blood agar, chocolate agar and MacConkey agar plates were inoculated. The plates were incubated at 37°C aerobically (MacConkey) or under 5% CO2 and examined at 24 and 48 h. Potentially pathogenic organisms (Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Streptococcus pyogenes and Staphylococcus aureus) were identified by techniques described previously.4 ß-Lactamase activity was determined on all isolates by the nitrocefin method.4
MICs of eight antimicrobial agents were determined (Table 1) by the agar dilution method with MuellerHinton agar (BBL Microbiology Systems, Cockeysville, MD, USA) supplemented with 5% sheep blood. The NCCLS breakpoints were used for MIC interpretation.5 For MIC determinations, suspensions with a turbidity equivalent to that of a 0.5 McFarland standard were prepared by suspending growth from blood agar plates in 2 mL of MuellerHinton broth (BBL). Suspensions were further diluted 1:10 to obtain a final inoculum of 104 cfu/spot. Plates were inoculated with a Steers replicator and incubated overnight in ambient air at 37°C. Standard quality control strains were included in each run. Additionally, MICs of azithromycin were read after an additional 24 h of incubation. Intermediate resistance to penicillin was defined as an MIC of 0.11.0 mg/L and high resistance to penicillin was defined as an MIC of 2.0 mg/L. Statistical analysis was done using the t-test and the 2 test with continuity correction.
|
![]() |
Results |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Of the two penicillin-resistant S. pneumoniae isolates recovered in the AMS group, one was intermediately resistant and one was highly resistant. Of the eight S. pneumoniae isolates in the RMS group, five were intermediately resistant and three highly resistant.
Resistance to the eight antimicrobial agents used was found in 34 instances (of a total of 304 possibilities) in the AMS group compared to 93 instances (of a total of 320 possibilities) in the RMS group (P < 0.005) (Table 1). The difference between AMS and RMS was significant with S. pneumoniae resistance to amoxicillin (P < 0.0025), to co-amoxiclav (P < 0.0025), to trimethoprimsulfamethoxazole (P < 0.05), to cefixime (P < 0.05), and to azithromycin (P < 0.05), and for H. influenzae to amoxicillin (P < 0.025) (Table 1).
![]() |
Discussion |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
These findings support previous reports where such a relationship was found in recovery of pathogens from middle ear aspirates in children.6,7 Brook & Gober7 evaluated the antimicrobial susceptibility of the pathogens isolated from the middle ear of 22 children with otitis media and from sinus aspirates of 20 patients with maxillary sinusitis who failed to respond to antimicrobial therapy and correlated it with previous antimicrobial therapy. Resistance of at least two tube dilutions (tested in parallel) to the antimicrobial agents used was found in 23 of the 47 (49%) isolates that were found in 20 (48%) of the patients. These included 10 of 15 (67%) isolates of S. pneumoniae, four of 14 (29%) H. influenzae, four of seven (57%) S. aureus, and five of six (83%) M. catarrhalis. A statistically significant higher recovery of resistant organisms was noted in those treated 26 months previously, and in those with sinusitis who smoked. The data illustrate the relationship between resistance to antimicrobials and failure of patients with otitis media and sinusitis to improve.
S. pneumoniae, H. influenzae and M. catarrhalis are showing increasing resistance to a variety of antibiotics. S. pneumoniae has growing resistance to penicillin, orally administered third generation cephalosporins (i.e. cefixime), trimethoprimsulfamethoxazole and the macrolides and H. influenzae and M. catarrhalis resist ß-lactam antibiotics through the production of ß-lactamase.8 Selection of antimicrobial agents can be improved by knowledge of the resistance pattern of the organisms in the community and by consideration of the effect of previous antimicrobial therapy or prophylaxis9 that may select resistant strains. Increased resistance to several antimicrobials can be expected in children with RMS who had failed antimicrobial therapy. The selective use of collection of endoscopic sinus aspirates for smear, culture and susceptibility studies, can assist in the proper selection of antimicrobial therapy.10
![]() |
Footnotes |
---|
![]() |
References |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
2 . Dagan, R., Leibovitz, E., Cheletz, G. et al. (2001). Antibiotic treatment in acute otitis media promotes superinfection with resistant Streptococcus pneumoniae carried before initiation of treatment. Journal of Infectious Diseases 183, 8806.[CrossRef][ISI][Medline]
3 . Brook, I., Frazier, E. H. & Foote, P. A. (1996). Microbiology of the transition from acute to chronic maxillary sinusitis. Journal of Medical Microbiology 45, 3725.[Abstract]
4 . Murray, P. R., Baron, E. J., Pfalter, M. A. et al. (1999). Manual of Clinical Microbiology, 7th edn. American Society for Microbiology, Washington, DC, USA.
5 . National Committee for Clinical Laboratory Standards. (2000). Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria that Grow Aerobically5th Edition: Approved Standard M7-A5. NCCLS, Wayne, PA, USA.
6 . Dagan, R., Abramson, O., Leibovitz, E. et al. (1996). Impaired bacteriologic response to cephalosporins in acute otitis media caused by pneumococci with intermediate resistance to penicillin. Pediatric Infectious Disease Journal 15, 9805.[CrossRef][ISI][Medline]
7 . Brook, I. & Gober, A. E. (1999). Resistance to antimicrobials used for the therapy of otitis and sinusitis: effect of previous antimicrobial therapy and smoking. Annals of Otology, Rhinology and Laryngology 108, 6457.[ISI][Medline]
8 . Ednie, L. M., Spangler, S. K., Jacobs, M. R. et al. (1997). Susceptibilities of 228 penicillin- and erythromycin-susceptible and -resistant pneumococci to RU 64004, a new ketolide, compared with susceptibilities to 16 other agents. Antimicrobial Agents and Chemotherapy 41, 10336.[Abstract]
9 . Brook, I. & Gober, A. E. (1996). Prophylaxis with amoxicillin or sulfisoxazole for otitis media: effect on the recovery of penicillin-resistant bacteria from children. Clinical Infectious Diseases 22, 1435.[ISI][Medline]
10 . Brook, I., Frazier, E. H. & Foote, P. A. (1997). Microbiology of chronic maxillary sinusitis: comparison between specimens obtained by sinus endoscopy and by surgical drainage. Journal of Medical Microbiology 46, 4302.[Abstract]