Veterinarska stanica, Vol. 53 No. 5, 2022.
Original scientific paper
https://doi.org/10.46419/vs.53.5.11
Bovine mastitis caused by rapid-growth environmental mycobacteria
Luka Cvetnić
; Hrvatski veterinarski institut, Zagreb, Hrvatska
Silvio Špičić
; Hrvatski veterinarski institut, Zagreb, Hrvatska
Gordan Kompes
; Hrvatski veterinarski institut, Zagreb, Hrvatska
Boris Habrun
; Hrvatski veterinarski institut, Zagreb, Hrvatska
Vera Katalinić-Janković
; Hrvatski zavod za javno zdravstvo, Hrvatska
Marija Cvetnić
; Veterinarski fakultet Sveučilišta u Zagrebu, Hrvatska
Maja Zdelar-Tuk
; Hrvatski veterinarski institut, Zagreb, Hrvatska
Irena Reil
; Hrvatski veterinarski institut, Zagreb, Hrvatska
Sanja Duvnjak
; Hrvatski veterinarski institut, Zagreb, Hrvatska
Željko Cvetnić
Miroslav Benić
orcid.org/0000-0001-7594-520X
; Hrvatski veterinarski institut, Zagreb, Hrvatska
Abstract
Rapid-growth mycobacteria were isolated from two cases of cow mastitis with similar clinical appearance and within a narrow time frame. Mycobacteria were isolated on blood esculine agar. The isolated mycobacteria were Gram stained, Ziehl-Nielsen stained and tested for growth at 25°C, 37°C and 42°C, iron uptake, growth on Löwenstein-Jensen (LJ) agar with and without 5% NaCl, arylsulphatase (3 days), tween 80 hydrolysis, tellurite reduction, nitrate reductase and niacin synthesis. Molecular identification was performed using the Mycobacteria GenoType CM and AS tests (Hain Diagnostika, Nehren, Germany). One isolate was additionally sequenced for the hsp65, rpoB, 16S rRNA gene sequence and transcribed spacer sequence (ITS) DNA. Susceptibility testing of isolates was performed on the Sensititre Rapmycol plate (TREK Diagnostic Systems Ltd.) for trimethoprim/sulfamethoxasole, linezolid, ciprofloxacin, imipenem, moxifloxacin, cefepime, cefoxitin, amoxicillin / clavulanic acid, amikacin, ceftriaxone, doxycycline, minocycline, tigecycline, tobramycine and clarythromycine. Gram-positive acid-resistant rods were observed in stained smears. Both strains grew at 25°C, 37°C and 42°C on LJ medium, and on LJ medium containing 5 % NaCl. The conventional biochemical tests for iron uptake, arylsulphatase (3 days), Tween 80 hydrolysis, tellurite reduction and nitrate reductase were positive, while the niacin test was negative. Both isolates were identified by the GenoType Mycobacterium CM as Mycobacterium fortuitum II/ Mycobacterium mageritense, while application of the GenoType Mycobacterium AS kit identified both isolates as belonging to the species Mycobacterium smegmatis. Analysis of the isolate sequences (strain DS) for 16S ribosomal RNA confirmed a 100% identical result with Mycobacterium smegmatis strain INHR2. According to the CLSI criteria, both strains were sensitive to sulfametoxazole/trimethoprim, linezolid, doxicycline, amikacin and tobramycin. The strains differed in their sensitivity to cefoxitim, and both strains were resistant to clarithromycin. There was a strong difference between the isolates in sensitivity toward cefoxitime and tigecycline.
Keywords
Hrčak ID:
268262
URI
Publication date:
20.12.2021.
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