2026-05-25T13:00:46Z https://www.peertechzpublications.org/oai-pmh

oai:www.peertechzpublications.org:10.17352/aprc.000028 2017-09-13 PTZ.APRC:VOL3

Ticarcillin Hypersusceptibility in Pseudomonas Aeruginosa in Cystic Fibrosis IT Hettiarachchi T O’Sullivan M Wootton A Smith J DuckersR Dhillon<p><strong>Background:</strong> A subpopulation of Pseudomonas aeruginosa (PsA) exists in cysticfibrosis (CF) patients that&nbsp; is&nbsp; hypersusceptible&nbsp; to&nbsp; ticarcillin,&nbsp; a&nbsp; carboxypenicillin,&nbsp; in&nbsp; vitro (Tichs strain)&nbsp; defined&nbsp; as&nbsp; a minimum inhibitory concentration (MIC) ≤4μg/ml. </p><p><strong>Methods:</strong> In a retrospective cohort study, isolates of PsA from CF (23),&nbsp; non-cystic fibrosis bronchiectasis (NCFB) (17) and control (18) patients were analysed. MICs for each isolate were determined using agar dilution against six antibiotics and interpreted using EUCAST breakpoints. Prevalence of Tichs in&nbsp; each&nbsp; cohort&nbsp; was&nbsp; calculated.&nbsp; A&nbsp; point&nbsp; prevalence&nbsp; survey&nbsp; was&nbsp; conducted&nbsp; in&nbsp; CF&nbsp; to&nbsp; review&nbsp; the&nbsp; patients’ clinical progress following PsA isolation. </p><p><strong>Results:</strong> Prevalence of the Tichs strain in PsA was 48%, 76% and 0% in the CF, NCFB and control cohorts respectively. A statistically significant difference in geometric mean MIC was seen between the Tichs and non-Tichs&nbsp; cohorts in CF for ticarcillin (as expected) and temocillin (p=0.041and p=0.036 respectively). A similar trend was observed in NCFB for ticarcillin (p=0.038) and temocillin (p=0.067), although statistical significance was not reached for the latter.In&nbsp; CF,&nbsp; the&nbsp; Tichs&nbsp; strain&nbsp; demonstrated&nbsp; lower&nbsp; MICs&nbsp; to&nbsp; all antibiotics&nbsp; tested&nbsp; apart&nbsp; from&nbsp; gentamicin compared&nbsp; to&nbsp; their&nbsp; non-Tichs counterparts. Those&nbsp; who&nbsp; had the Tichs strain&nbsp; in&nbsp; CF&nbsp; had&nbsp; fewer&nbsp; antibiotics (13.9&nbsp; days&nbsp; versus&nbsp; 23.5&nbsp; days,&nbsp; Tichs&nbsp; and&nbsp; non-Tichs respectively)&nbsp; although&nbsp; this&nbsp; result&nbsp; was&nbsp; not&nbsp; statistically significant p=0.202. <br></p><p><strong>Conclusion:</strong> Our&nbsp; data&nbsp; supports&nbsp; the&nbsp; existence&nbsp; of&nbsp; a&nbsp; Tichs strain&nbsp; of&nbsp; PsA&nbsp; in&nbsp; our&nbsp; CF&nbsp; and&nbsp; NCFB&nbsp; patient populations. This strain correlated with reduced MICs to temocillin in CF, to which PsA would normally be resistant, which may be of clinical relevance.</p> Archives of Pulmonology and Respiratory Care - Peertechz Publications 2017-09-13 Research Article https://doi.org/10.17352/aprc.000028 en Copyright © IT Hettiarachchi et al.