Incremental increase in fitness cost with increased beta-lactam resistance in pneumococci evaluated by competition in an infant rat nasal colonization model
UNSPECIFIED (2006) Incremental increase in fitness cost with increased beta-lactam resistance in pneumococci evaluated by competition in an infant rat nasal colonization model. In: 4th International Symposium on Pneumococci and Pneumococcal Diseases, MAY 09-13, 2004, Helsinki, FINLAND.Full text not available from this repository.
Background. We evaluated the impact of resistant penicillin-binding protein ( PBP) allele acquisition on the ability of penicillin-resistant ( PEN-R) pneumococcal strains to compete with penicillin-susceptible ( PEN-S) ancestors for upper-respiratory-tract ( URT) colonization. Methods. PEN-S serotype 2, 6B, and 9V strains were transformed into derivatives expressing an increasing number of PEN-R PBP forms ( 2X, 2X-1A, and 2X-1A-2B for serotype 2 and 2X, 2X-2B, and 2X-2B-1A for 6B and 9V). Infant rats were inoculated intranasally with a mix of a PEN-R and PEN-S strains. For consecutive days, samples were collected for assessment of the ratio of PEN-S to PEN-R cells colonizing the URT. The selective index ( SI), defined as the change in the natural logarithm of the ratio of PEN-S to PEN-R strains from the inoculum to the nasal-wash samples, quantified differences in fitness. Results. SIs significantly > 0 ( indicating a cost of resistant allele acquisition) were observed 4-5 days after colonization in all but serotype 6B pbp2x transfomants. Additional replacements with low-affinity forms of pbp2b and pbp1a genes reduced further ability to compete in all strains. Conclusions. The cost of penicillin-resistance acquisition for the Streptococcus pneumoniae strain competing with its susceptible ancestor to colonize the URT increases with the number of resistant pbp alleles acquired.
|Item Type:||Conference Item (UNSPECIFIED)|
|Subjects:||Q Science > QR Microbiology > QR180 Immunology
Q Science > QR Microbiology > QR355 Virology
Q Science > QR Microbiology
|Journal or Publication Title:||JOURNAL OF INFECTIOUS DISEASES|
|Publisher:||UNIV CHICAGO PRESS|
|Date:||1 May 2006|
|Number of Pages:||8|
|Page Range:||pp. 1296-1303|
|Title of Event:||4th International Symposium on Pneumococci and Pneumococcal Diseases|
|Location of Event:||Helsinki, FINLAND|
|Date(s) of Event:||MAY 09-13, 2004|
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