Susceptibilities of Haemophilus influenzae, Streptococcus pneumoniae, including serotype 19A, and Moraxella catarrhalis paediatric isolates from 2005 to 2007 to commonly used antibiotics.
OBJECTIVE
The aim of this study was to evaluate susceptibility to common paediatric antibiotics for Streptococcus pneumoniae, non-typeable Haemophilus influenzae and Moraxella catarrhalis isolated from 2005 through 2007.


METHODS
Microdilution MIC assays were performed using CLSI-approved methods. S. pneumoniae 19A strains were identified by quellung reaction.


RESULTS
Among 143 non-typeable H. influenzae, 42% produced beta-lactamase. By 2007 breakpoints (PK/PD:CLSI), percentage susceptibility for non-typeable H. influenzae was: ceftriaxone = cefixime = high-dose amoxicillin/clavulanate (all 100%:100%) > standard-dose amoxicillin/clavulanate (91.6%:100%) > cefuroxime axetil (88.1%:99.3%) > cefdinir (83.9%:100%) > trimethoprim/sulfamethoxazole (73.4%:73.4%) >high-dose amoxicillin (58%:58%) > standard-dose amoxicillin (55.2%:58%) > cefprozil (28.7%:83.2%) > cefaclor (3.5%:83.2%) > azithromycin (0%:87.4%). Of 208 S. pneumoniae (42 serotype 19A), 86 were penicillin-susceptible, 60 were penicillin-intermediate and 62 were penicillin-resistant by 2007 CLSI breakpoints. Percentage susceptibility for all S. pneumoniae/19A by PD breakpoints was: ceftriaxone (95.2%/86.1%) > high-dose amoxicillin (89.4%/58.3%) > clindamycin (85%/58.3%) > standard-dose amoxicillin (73.5%/33.3%) > cefuroxime axetil (69.2%/36.1%), cefprozil (67.3%/33.3%) > cefdinir (59.1%/33.3%) > cefixime (57.7%/33.3%) > azithromycin (56.7%/33.3%) > trimethoprim/sulfamethoxazole (50.5%/25%) > penicillin (41.3%/19.4%) > cefaclor (28.8%/8.3%). Percentage M. catarrhalis (n = 62) susceptibility by PK/PD breakpoints was: high-dose amoxicillin/clavulanate = cefixime (100%) > azithromycin (98.4%) > ceftriaxone (96.8%) > standard-dose amoxicillin/clavulanate (88.7%) > cefdinir (80.6%) > cefprozil = cefuroxime axetil (37.1%) > high-dose amoxicillin (11.2%) > cefaclor (6.5%) > standard-dose amoxicillin (4.8%).


CONCLUSIONS
Despite high rates of beta-lactamase production among non-typeable H. influenzae and M. catarrhalis, multiple oral treatment options exist for non-typeable H. influenzae and M. catarrhalis. Multidrug-resistant serotype 19A S. pneumoniae ( approximately 20%) limits treatment options for ambulatory S. pneumoniae respiratory disease.
Harrison
Christopher J
CJ
Pediatric Infectious Diseases Section, Children's Mercy Hospital and Clinics, and the University of Missouri-Kansas City, Kansas City, MO, USA. cjharrison@cmh.edu
Woods
Charles
C
Stout
Gordon
G
Martin
Brittanie
B
Selvarangan
Rangaraj
R
D000293:Adolescent; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002648:Child; D002675:Child, Preschool; D024901:Drug Resistance, Multiple, Bacterial; D006192:Haemophilus Infections / Q000382:microbiology; D006193:Haemophilus influenzae / Q000187:drug effects* / Q000201:enzymology / Q000302:isolation & purification; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008826:Microbial Sensitivity Tests; D001936:Moraxella catarrhalis / Q000187:drug effects* / Q000201:enzymology / Q000302:isolation & purification; D045828:Moraxellaceae Infections / Q000382:microbiology; D011008:Pneumococcal Infections / Q000382:microbiology; D013296:Streptococcus pneumoniae / Q000187:drug effects* / Q000201:enzymology / Q000302:isolation & purification; D001618:beta-Lactamases / Q000096:biosynthesis
D000900:Anti-Bacterial Agents; D001618:beta-Lactamases