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Ceftazidime treatment in cystic fibrosis: resistant organisms in sputum and faeces
A M Dalzell1, D Sunderland, C A Hart
1Royal Liverpool Children's Hospital, Alder Hey.
Abstract:
Ceftazidime was used as the only intravenous agent for treating lower respiratory tract infections in patients with cystic fibrosis. The risks of inducing beta lactamases and conferring antibiotic resistance are high when monotherapy is used; so the emergence of resistant bacteria was studied prospectively in the sputum of 120 patients. The mean age of patients was 9.0 (range 0.3-25) years and there were equal number of male and female patients. Pseudomonas aeruginosa was the only ceftazidime resistant bacterium to be isolated from the respiratory tract, and was identified only in chronically colonised patients. Ceftazidime resistance occurred in 103 (14%) of 750 P aeruginosa isolates, and in 16 of 36 chronically colonised patients. Ceftazidime resistant organisms were isolated from the faeces of 17 of 64 patients investigated. Eighty two per cent of the resistant faecal organisms were single isolates: the same resistant organism in faeces was isolated from successive samples in only two patients. In no case was the ceftazidime resistant enteric isolate the same as that from sputum. Patients chronically colonised by P aeruginosa did not harbour ceftazidime resistant enteric organisms any more than non-colonised patients. The use of ceftazidime as a single intravenous agent in treating chest exacerbations in cystic fibrosis does not induce a reservoir of ceftazidime resistant bacteria.
Insights
Ceftazidime monotherapy for cystic fibrosis respiratory infections did not induce resistant bacteria. Studies showed resistant Pseudomonas aeruginosa only in chronically colonized patients, not from fecal samples.
Area of Science:
- Infectious Diseases
- Microbiology
- Pulmonology
Background:
- Cystic fibrosis (CF) patients often experience recurrent respiratory tract infections.
- Antibiotic monotherapy, like ceftazidime, carries a risk of inducing antibiotic resistance.
- Pseudomonas aeruginosa is a common and problematic pathogen in CF lung infections.
Purpose of the Study:
- To prospectively investigate the emergence of ceftazidime-resistant bacteria during monotherapy in CF patients.
- To determine if ceftazidime treatment selects for resistant organisms in sputum and feces.
Main Methods:
- Prospective study of 120 CF patients treated with intravenous ceftazidime monotherapy.
- Bacterial cultures and susceptibility testing performed on sputum and fecal samples.
- Analysis of ceftazidime resistance patterns in Pseudomonas aeruginosa and other bacteria.
Main Results:
- Ceftazidime resistance was primarily observed in Pseudomonas aeruginosa isolates from sputum.
- Resistance was mainly found in chronically colonized patients, not in new infections.
- No evidence of ceftazidime-resistant enteric organisms being induced or transferred from feces to sputum.
Conclusions:
- Intravenous ceftazidime monotherapy for CF chest exacerbations does not appear to induce a reservoir of resistant bacteria.
- The risk of resistance appears linked to chronic colonization rather than short-term monotherapy.
- Further monitoring of resistance patterns in CF patients is warranted.