Susceptibilities to Levofloxacin in Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis Clinical Isolates from Children: Results from 2000-2001 and 2001-2002 TRUST Studies in the United States
Susceptibilities to Levofloxacin in Streptococcus pneumoniae,
Haemophilus influenzae, and Moraxella catarrhalis Clinical Isolates
from Children: Results from 2000-2001 and 2001-2002 TRUST Studies in the United
States
James A. Karlowsky,1* Clyde Thornsberry,2 Ian
A. Critchley,1 Mark E. Jones,3 Alan T. Evangelista,4
Gary J. Noel,5,6 and Daniel F. Sahm1
Focus Technologies, Herndon, Virginia 20171,1 Focus Technologies,
Franklin, Tennessee 37064,2 Focus Technologies, 1217 KP Hilversum,
The Netherlands,3 Ortho-McNeil Pharmaceutical, Raritan, New Jersey
08869,4 Johnson and Johnson Pharmaceutical Research and Development,
Raritan, New Jersey 08869,5 University of Medicine and Dentistry of
New Jersey, Newark, New Jersey 071036
Received 8 November 2002/ Returned for modification 22 February 2003/
Accepted 7 March 2003
Among respiratory tract isolates of Streptococcus pneumoniaefrom children, resistance to penicillins, cephalosporins, macrolides,and trimethoprim-sulfamethoxazole (SXT) increases on an annual
basis. Pediatric patients who do not respond to conventionaltherapy
for respiratory tract infections someday may be treatedwith
fluoroquinolones. In this study, MICs of ß-lactams,azithromycin,
SXT, and levofloxacin were determined and interpretedby using NCCLS
guidelines for isolates of S. pneumoniae (2,834from children
and 10,966 from adults), Haemophilus influenzae(629 from
children and 2,281 from adults), and Moraxella catarrhalis
(389 from children and 1,357 from adults) collected during the
2000-2001 and 2001-2002 respiratory illness seasons in the United
States as part of the ongoing TRUST surveillance studies. Ratesof
resistance to penicillin, azithromycin, and SXT were 7.5%higher among
patients 4 years
old than among patients 5 to 10,11 to 17, and 18 years old in both the 2000-2001
and the 2001-2002respiratory illness seasons. Levofloxacin
resistance was detectedin 2 of 2,834 isolates (0.07%) from patients
<18 years old.Levofloxacin MICs of 0.25 to 1 µg/ml accounted for
99.6,99.5, 99.3, 99.7, 98.4, and 98.0% of isolates from patients<2, 2 to 4, 5 to 10, 11 to 17, 18 to 64, and >64 yearsold.
Multidrug resistance was twice as common among patients4 years old
(25.3%) as among patients 5 to 10 years old (13.7%),11 to 17 years
old (11.9%), 18 to 64 years old (12.1%), and>64 years old (12.4%).
The most common multidrug resistancephenotype in S. pneumoniae
isolates for all age groups was resistanceto penicillin,
azithromycin, and SXT (70.3 to 76.6%). For H.influenzae and
M. catarrhalis isolates from patients <2,2 to 4, 5 to 10, 11
to 17, 18 to 64, and >64 years old, levofloxacinMICs at which 90% of
the isolates were inhibited were 0.015and 0.03 to 0.06 µg/ml,
respectively, in the 2000-2001and 2001-2002 respiratory illness
seasons. In the 2000-2001and 2001-2002 respiratory illness season
surveillance studiesin the United States, 99.9% of pediatric
isolates of S. pneumoniaewere susceptible to levofloxacin. If
fluoroquinolones becomea treatment option for pediatric patients,
careful monitoringof fluoroquinolone susceptibilities will be
increasingly importantin future surveillance studies.
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