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Lack of effective bactericidal activity of new quinolones against Brucella spp
J A García-Rodriguez1, J E García Sánchez, I Trujillano
1Department of Microbiology, Facultad de Medicina, Hospital Clinico Universitario, Salamanca, Spain.
Abstract:
The in vitro activities of six fluoroquinolones against 43 Brucella spp. were compared by testing three different inocula at two medium pH values. The influence of the test conditions was moderate. The activities of all quinolones were lower at pH 5 and with a high inoculum size. Results indicate the lack of effective bactericidal activity of quinolones against most strains of Brucella spp., particularly B. abortus.
Insights
Fluoroquinolones show limited effectiveness against Brucella species in vitro. Their bactericidal activity is reduced by lower pH and higher bacterial concentrations, especially against Brucella abortus.
Area of Science:
- Microbiology
- Pharmacology
- Infectious Diseases
Background:
- Brucella species are Gram-negative bacteria causing brucellosis, a zoonotic disease.
- Fluoroquinolones are broad-spectrum antibiotics used to treat bacterial infections.
Purpose of the Study:
- To evaluate the in vitro activity of six fluoroquinolones against Brucella species.
- To determine the impact of inoculum size and medium pH on fluoroquinolone efficacy.
Main Methods:
- In vitro susceptibility testing of six fluoroquinolones against 43 Brucella isolates.
- Testing performed with three different inoculum sizes and two medium pH values (e.g., neutral and acidic).
Main Results:
- Fluoroquinolone activity was generally low against most Brucella strains.
- Activity decreased significantly at pH 5 and with higher inoculum sizes.
- Brucella abortus strains were particularly less susceptible to fluoroquinolones.
Conclusions:
- Fluoroquinolones exhibit limited bactericidal activity against most Brucella species in vitro.
- Optimizing testing conditions like pH and inoculum size is crucial for accurate susceptibility assessment.
- Fluoroquinolones may not be a primary choice for treating brucellosis, especially infections caused by B. abortus.