M. hyorhinis infection - antimicrobial activity of Tiamutin® (tiamulin)
M. hyorhinis is highly sensitive in vitro to tiamulin[?]. See table below.
MIC range, MIC50 and MIC90 (mcg/ml) of various antibiotics for Mycoplasma hyorhinis (serial broth dilution method)
MIC for field strains (n=20)
Antimicrobial
MIC range
MIC50
MIC90
Doxycycline
<0.03-0.5
<0.03
0.12
Tylosin
0.06-05
0.12
0.25
Chlortetracycline
1-8
2
4
Lincomycin
0.25-1
0.5
1
Enrofloxacin
0.5-2
1
2
Tiamutin® (tiamulin)
<0.03-0.25
0.06
0.12
In comparison with other antibiotics tested the pleuromutilins, valnemulin and tiamulin, have also been shown to have higher potency against M.hyorhinis in vitro[?]. See table below.
MIC range, MIC50 and MIC90 (mcg/ml) of tested antibiotics for Mycoplasma hyorhinis
Antimicrobial
MIC range
MIC50
MIC90
Doxycycline
0.06-8.0
0.5
8.0
Valnemulin
0.06-0.5
0.06
0.25
Tylosin
4.0-32.0
8.0
32.0
Lincomycin
1.0-8.0
2.0
8.0
Chlortetracycline
4.0-32.0
16.0
32.0
Tilmicosin
4.0-32.0
16.0
32.0
Tiamutin® (tiamulin)
0.06-2.0
0.125
1.0
Isolates of M. hyorhinis were isolated from pigs in Thailand which died from pneumonia and/or polyserositis, polyarthritis and convulsions in the years 1999-2004 and were sub-cultured in modified Hayflick's broth to determine the minimum inhibitory concentrations (MIC's) for 10 antimicrobial agents[?].
The MIC's were performed by the microdilution method and the concentrations of the antimicrobial drugs were two-fold serial dilutions from 50-0.024µg/ml (chlortetracycline, oxytetracycline and tilmicosin) and 12.5-0.006µg/ml (aivlosin, doxycycline, josamycin, lincomycin, tiamulin, tylosin and valnemulin). The MIC's are shown below.
In vitro sensitivity (mcg/ml) of M. hyorhinis isolates to various antimicrobial agents
Thongkamkoon, P. (2005)
Antimicrobial
MIC (µg/ml) from M.hyorhinis (n=26)
MIC range
MIC50
MIC90
Aivlosin
0.024-6.25
0.097
0.19
Chlortetracycline
6.25-5.0
25
25
Doxycycline
0.097-3.12
0.78
1.56
Josamycin
0.19-6.25
0.39
0.78
Lincomycin
0.19->12.5
0.78
0.78
Oxytetracycline
1.56-25
6.25
12.5
Tiamutin® (tiamulin)
0.024-0.39
0.097
0.19
Tilmicosin
0.19-50
0.78
3.12
Tylosin
0.39-6.25
0.78
1.56
Valnemulin
<0.006
<0.006
<0.006
MIC90 - all drugs inhibited growth in at least 24 of 26 isolates tested.
Irrespective of some variations in the analytical methods used in the studies, the obtained MIC values indicated the consistent efficacy of valnemulin and tiamulin and the high sensitivity of M. hyorhinis to both antimicrobials.
