Ralstonia mannitolilytica is a rarely reported pathogen in cystic fibrosis. It is frequently resistant to antimicrobials and can be misidentified as
Burkholderia cepacia complex using biochemical techniques.
Methods
spara20">We identified 7 CF patients from 4 centres in Ireland, all with advanced lung disease that were colonized or infected with this organism. Each isolate was confirmed by gyrB sequence analysis and genetic relatedness was determined using PFGE. MIC testing was performed as well as combination testing using the multiple combination bactericidal test (MCBT). Whole genome sequencing was also performed.
Results
spara30">Four patients from the same institution had strains that were indistinguishable by PFGE. One patient died aged 14 years awaiting lung transplantation 18 months after acquisition; another patient underwent successful lung transplantation and remains culture negative. The remaining two patients are siblings who are at present requiring frequent courses of IV antibiotics and have significant decline in FEV1 since acquisition. Three other patient strains were unique by PFGE; one patient died age 38 y. Tigecycline and minocyline were the most active single agents showing inhibition by MIC to six and five strains, respectively. Minocycline/piperacillin–tazobactam was the most active combination but was not bactericidal against any strain. Tobramycin/piperacillin–tazobactam demonstrated bactericidal activity against three strains.
Conclusion
spara40">Ralstonia mannitolilytica is emerging as a significant pathogen in advanced CF. Early recognition and targeted treatment may reduce cross infection and improve clinical outcome in patients undergoing transplantation.
