ISOLATION, IDENTIFICATION AND ANTIMICROBIAL SUSCEPTIBILITY OF BRUCELLA BLOOD CULTURE ISOLATES
Journal
Prilozi (Makedonska akademija na naukite i umetnostite. Oddelenie za medicinski nauki)
Date Issued
2010
Author(s)
Jankoska G
Abstract
Isolation of slowly growing and fastidious Brucella spp strains from
clinical specimens is difficult, because of varying factors, including species specificities, stadium of disease, and previous antibiotic treatment of the patients. The use of
automated blood culture systems has overcome some cultivation problems. The automated identification system such as VITEK 2 compact allows more precise identification,
as well.
Aim: To present our own experience in the isolation of Brucella species from
blood cultures, by the Bact/Alert automated system, identification by the VITEK 2
compact system and antimicrobial susceptibility of isolated strains.
Material and Methods: Patients from various regions of Macedonia hospitalized in the University Infectious Diseases and Febrile Condition Clinic in Skopje. FAN
blood culture bottles (aerobic and anaerobic) of the Bact/Alert system were used, inoculated with 5–10 ml of blood, incubated under continuous agitation and monitored for up
to 5 days or until they became positive (in our cases for 2–3 days). Confirmations of all
isolates were made by the VITEK 2 automated system on GN cards.
Results: During a period of three years, 113 blood cultures from patients with
diagnosis of brucellosis hospitalized at the above-mentioned clinic were examined. A
total of 16 blood cultures from different patients were positive (14.2%), showing Gram
negative bacilli, oxidase positive small colonies on Columbia agar media. The isolates
were identified as four biochemically different types of B. mellitensis, mainly within 8
hours. Susceptibility testing by the disk diffusion method on Muller Hinton agar showed
sensitivity of all strains to cephalosporin, tetracycline, aminoglycoside and quinolone
antibiotic groups.
Conclusion: With the BacT/Alert system Brucella spp. were isolated in 14.2%
of suspected cases of brucellosis. Isolation was done within 2–3 days. Only B. meliten-
sis from the Brucella genus could be identified by the VITEK 2 system and some biochemical differences could be detected. The VITEK 2 system is not able to determine
the susceptibility of B. melitensis. The Disk-diffusion method used in this study showed
sensitivity to all tested antibiotics, although not recommended by CLSI for the Brucella
genus.
clinical specimens is difficult, because of varying factors, including species specificities, stadium of disease, and previous antibiotic treatment of the patients. The use of
automated blood culture systems has overcome some cultivation problems. The automated identification system such as VITEK 2 compact allows more precise identification,
as well.
Aim: To present our own experience in the isolation of Brucella species from
blood cultures, by the Bact/Alert automated system, identification by the VITEK 2
compact system and antimicrobial susceptibility of isolated strains.
Material and Methods: Patients from various regions of Macedonia hospitalized in the University Infectious Diseases and Febrile Condition Clinic in Skopje. FAN
blood culture bottles (aerobic and anaerobic) of the Bact/Alert system were used, inoculated with 5–10 ml of blood, incubated under continuous agitation and monitored for up
to 5 days or until they became positive (in our cases for 2–3 days). Confirmations of all
isolates were made by the VITEK 2 automated system on GN cards.
Results: During a period of three years, 113 blood cultures from patients with
diagnosis of brucellosis hospitalized at the above-mentioned clinic were examined. A
total of 16 blood cultures from different patients were positive (14.2%), showing Gram
negative bacilli, oxidase positive small colonies on Columbia agar media. The isolates
were identified as four biochemically different types of B. mellitensis, mainly within 8
hours. Susceptibility testing by the disk diffusion method on Muller Hinton agar showed
sensitivity of all strains to cephalosporin, tetracycline, aminoglycoside and quinolone
antibiotic groups.
Conclusion: With the BacT/Alert system Brucella spp. were isolated in 14.2%
of suspected cases of brucellosis. Isolation was done within 2–3 days. Only B. meliten-
sis from the Brucella genus could be identified by the VITEK 2 system and some biochemical differences could be detected. The VITEK 2 system is not able to determine
the susceptibility of B. melitensis. The Disk-diffusion method used in this study showed
sensitivity to all tested antibiotics, although not recommended by CLSI for the Brucella
genus.
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