November 10, 1994: Vol26n10: Research shows bacterial resistance to antibiotics

By LOIS BAKER
News Bureau Staff
Three types of bacteria responsible for up to 90 percent of middle-ear
infections in children have developed significant resistance to
commonly prescribed antibiotics, a study by researchers at UB and the
University of Massachusetts has shown.
	 The data, reported recently in Pediatric Infectious Disease
Journal, provide a clear warning that antibiotic resistance is
becoming a significant problem in treating the ailment, said Howard
Faden, UB professor of pediatrics, a specialist in childhood
infectious diseases and lead researcher on the study.
	Otitis media -- middle-ear infection -- is one of the most
common infections of early childhood, accounting for approximately 30
percent of visits to pediatricians. Infectious-disease researchers
have identified three bacteria type -- Streptococcus pneumoniae,
nontypeable Haemophilus influenzae, and Moraxella catarrhalis -- as
pathogens that cause 50-90 percent of these infections. Studies in the
past four years have reported that standard antibiotics used to defeat
these organisms were becoming less effective, because bacteria were
developing resistance to the medicines.
	To assess the extent of bacterial resistance, the researchers
collected nasal mucus specimens from 216 infants who had not received
any prior antibiotic therapy. Research has shown a direct connection
between nasal colonization by the organisms and development of otitis
media.
	The researchers identified the pathogens and subjected them to
antimicrobial agents commonly used to fight middle-ear infections --
amoxicillin-clavulanate, ampicillin, cefaclor, cefpodoxime, cefprozil,
cefuorxime, penicillin, and trimethoprim-sulfamethoxazole (TMP/SMX).
	Results showed that: 
	o 96 percent of M. catarrhalis strains were resistant to
penicillin, 90 percent to ampicillin, and 19 percent to TMP/SMX.
	o 32 percent of nontypeable H. influenzae strains were
resistant to ampicillin and 17 percent did not respond to cefaclor.
	o In contrast to some reports of strong resistance of
pneumococci bacteria to penicillin -- more than 30 percent in Kentucky
and 26 percent among Native Americans in Alaska -- this study showed
penicillin and its derivatives remain highly effective against this
pathogen. Only 1.2 percent of S. pneumoniae were resistant and another
4.7 percent were somewhat resistant. However, 20 percent of the
strains were resistant to TMP/SMX.
	Faden said rates of bacterial resistance to antibiotics vary
widely geographically, and are related to patterns of antibiotic use
in any given region. "We learned from this study that there are some
commonly used drugs that are no longer valuable," he said. "For
example, it is clear from this study that
trimethoprim-sulfamethoxazole should not be prescribed for otitis
media, and that in our community, amoxicillin is still very effective
for simple ear infections.
 	"Surveys of resistance should be done on a regular basis to
keep up with changes in susceptibility patterns," Faden said.
	 Gary Doern, University of Massachusetts at Worcester,
conducted the resistance testing. Judy Wolf of UB and Michael Blocker,
University of Massachusetts, assisted in the research. The study was
supported by a grant from the National Institute of Child Health and
Human Development.