Hydrogen sulphide, an avant-garde potential virulence factor of
Mycoplasma bovis isolated from the lungs of the Camelus dromedarius
exhibiting silent pneumonia: Virulence, antimicrobial resistance and
phylogeny
Abstract
The impact of asymptomatic carriers on the survival of Mycoplasma bovis
in the environment and the role of wildlife in transmitting M. bovis
still requires to be extensively studied. In this study, we have
extended the arsenal of factors implicated in pathogenicity of M. bovis
to shed light on the current knowledge gap. A number of 460 lung samples
(pneumonic; n=210 and apparently healthy; n=250) were randomly collected
from one hundred humped camels (Camelus domedarius). Biochemically,
13/210 of the recovered isolates (27.3%) from the pneumonic lungs were
recorded as putative mycoplasmas and to be confirmed by PCR to be M.
bovis. Infection with M. bovis was not detected in the apparently
healthy lungs. They were examined for their phenotypic virulence traits
and antimicrobial resistance. Haemolysis and hydrogen sulphide (H2S)
production was evident in 100% of the isolates. All 13 M. bovis
isolates were weak in their ability to form biofilm on polystyrene
surfaces and were 100% susceptible to florfenicol, spiromycin and
streptomycin while 100% resistant to ciprofloxacin. Five different
combinations of antibiotics representing one to three classes with the
Macrolide erythromycin being the most represented. Surprisingly, we did
not detect the uvrC and gapA virulence genes by PCR, however we did
detect the vsp gene in 2 out of 13 isolates. In addition, we detected
the parC gene encoding quinolone resistance in 2 out of 13 M. bovis
isolates, but did not detect the gyrA gene. Moreover, we have showed
H2S, a compound that has previously not been identified as a virulence
factor in M. bovis.