TEM-1-encoding small plasmids impose dissimilar fitness costs on Haemophilus influenzae and Haemophilus parainfluenzae

• DOI: 10.1099/mic.0.000183
• Publication Date: 2015-09-18T05:12:21Z
• Authors: Annette Søndergaard; Niels Nørskov-Lau...; Marianne Lund
• Keywords: Haemophilus parainfluenzae

Only two beta-lactamases, TEM-1 and ROB-1, have been observed in Haemophilus influenzae, while four different TEM but no ROB enzymes found parainfluenzae. In order to investigate the mechanisms behind dissemination of small beta-lactamase-encoding plasmids H. influenzae parainfluenzae, we assessed fitness cost three TEM-1- (pPN223, pA1209, pA1606), one TEM-15- (pSF3) ROB-1-bearing (pB1000) plasmid when expressed either bacterial species. All were stable parainfluenzae except pB1000, which showed on average (sample mean) 76% curing after 5 days subculture. Competition assays between isogenic strains with without competitive disadvantage pPN223 pA1606 or pA1209 contrast, pSF3 pB1000 associated significant disadvantages both Some may be related differences copy number mRNA expression beta-lactamase genes, as revealed by quantitative PCR analysis. conclusion, encoding beta-lactamases isolated from can stably transferred The fast this study correlates fact that ROB-1 has never reported for TEM-1-encoding are lowest level cost, confer levels hosts.