Antimicrobial resistance and virulence-related genes of Streptococcus obtained from dairy cows with mastitis in Inner Mongolia, China

Figures & data

Table 1. Details of PCR primers used to amplify Streptococcus antimicrobial resistance genes and virulence factors.

	Primer sequence (5′–3′)
Target gene	Forward	Reverse	Tm (°C)	Amplicon size (bp)	Reference
soda	CCITAYICITAYGAYGCIYTIGARCC	ARRTARTAIGCRTGYTCCCAIACRTC	50	480	Hoshino et al. (2005)
ermB	ATTGGAACAGGTAAAGGGC	GAACATCTGTGGTATGGCG	50	442	Marimón et al. (2005)
mefA	AGTATCATTAATCACTAGTGC	TTCTTCTGGTACTAAAAGTGG	53	346	Marimón et al. (2005)
tetM	GAACTCGAACAAGAGGAAAGC	ATGGAAGCCCAGAAAGGAT	55	740	Lopardo et al. (2003)
tetO	AACTTAGGCATTCTGGCTCAC	TCCCACTGTTCCATATCGTCA	52	519	Lopardo et al. (2003)
tetL	TGAACGTCTCATTACCTG	ACGAAAGCCCACCTAAAA	50	993	Lopardo et al. (2003)
tetK	TCCTGGAACCATGAGTGT	AGATAATCCGCCCATAAC	50	189	Lopardo et al. (2003)
pbp2b	GATCCTCTAAATGATTCTCAGGTGG	CCATTAGCTTAGCAATAGGTGTTGG	55	1500	Charpentier & Tuomanen (2000)
bac	TGTAAAGGACGATAGTGTGAAGAC	CATTTGTGATTCCCTTTTGC	50	530	Dmitriev et al. (2002)
bca	TAACAGTTATGATACTTCACAGAC	ACGACTTTCTTCCGTCCACTTAGG	51	535	Dmitriev et al. (2002)
scpB	CCAAGACTTCAGCCACAAGG	CAATTCCAGCCAATAGCAGC	57	591	Dmitriev et al. (2002)
lmb	ACCGTCTGAAATGATGTGG	GATTGACGTTGTCTTCTGC	51	572	Dmitriev et al. (2002)
cyl	ACGGCTTGTCCATAGTAGTGTTTG	AACGACACTGCCATCAGCAC	52	345	Dmitriev et al. (2002)
glnA	ACGTATGAACAGAGTTGGCTATAA	TCCTCTGATAATTGCATTCCAC	52	471	Dmitriev et al. (2002)
cfb	ATGGGATTTGGGATAACTAAGCTAG	AGCGTGTATTCCAGATTTCCTTAT	52	193	Dmitriev et al. (2002)
scaA	ACGGTATCAACCTTGAAACTGG	TCAGTGTTGATTTCCCAGATGTA	52	256	Dmitriev et al. (2002)
hylB	ACAAATGGAACGACGTGACTAT	CACCAATTGGCAGAGCCT	52	346	Dmitriev et al. (2002)

Table 2. Minimum inhibitory concentrations (MIC: μg/mL) of Streptococcus from bovine mastitis (n = 81 isolates) for 15 antimicrobials agents.

	Distribution of isolates (%)
Antimicrobial	≤0.125	0.25	0.5	1	2	4	8	16	32	64	≥128
Penicillin	0	1.2	2.5	12.3	8.6	12	6.2	30.9	6.2	11.1	8.6
Amoxicillin	1.2	1.2	11.1	14.8	37	14	2.5	3.7	7.4	4.9	2.5
Ampicillin	4.9	13.6	56.8	9.9	1.2	2.5	0	0	3.7	4.9	2.5
Cefradine	13.6	2.5	6.2	6.2	4.9	1.2	1.2	8.6	29.6	13.6	12.3
Cefalotin	4.9	3.7	6.2	6.2	14.8	14	21	14.8	3.7	6.2	4.9
Meropenem	23.5	12.3	17.3	34.6	1.2	3.7	1.2	0	1.2	1.2	3.7
Erythromycin	9.9	6.2	17.3	14.8	4.9	3.7	7.4	2.5	6.2	6.2	21
Dirithromycin	30.9	8.6	9.9	9.9	3.7	12	13.6	7.4	3.7	0	0
Ofloxacin	1.2	6.2	25.9	24.7	13.6	4.9	14.8	3.7	2.5	2.5	0
Levofloxacin	33.3	7.4	9.9	18.5	22.2	7.4	3.7	0	0	0	0
Gatifloxacin	35.8	27.2	16	8.6	6.2	2.5	2.5	1.2	0	0	0
Chloramphenicol	0	0	1.2	4.9	22.2	17	21	4.9	16	7.4	4.9
Clindamycin	14.8	13.6	6.2	6.2	7.4	4.9	8.6	11.1	17.3	6.2	3.7
Vancomycin	4.9	7.4	33.3	27.2	16	6.2	0	0	0	2.5	2.5
Tetracycline	4.9	2.5	1.2	2.5	1.2	2.5	7.4	12.3	29.6	24.7	11.1

The breakpoints used are indicated by vertical lines (CLSI, 2013).

Table 3. Summary of minimum inhibitory concentrations (MIC: μg/mL) and antimicrobial resistance profile for Streptococcus from bovine mastitis (n = 81 isolates).

					% Isolates
		MIC (μg/mL)				Total			Resistance
Antimicrobial	Minimum	50%	90%	Maximum	I	R	I + R	S. agalactiae	S. dysgalactiae	S. uberis
Penicillin	0.25	16	64	≥128	–	95		67.9	11.1	16
Amoxicillin	≤0.125	2	32	≥128	–	91.4	–	66.7	8.6	16
Ampicillin	≤0.125	0.5	32	≥128	–	81.5	–	56.8	8.6	16
Cefradine	≤0.125	32	128	≥128	–	86.4	–	60.5	8.6	17.3
Cefalotin	≤0.125	8	64	≥128	–	85.2	–	60.5	7.4	17.3
Meropenem	≤0.125	0.5	4	≥128	–	46.9	–	30.9	6.2	9.9
Erythromycin	≤0.125	2	128	≥128	17.3	66.7	84	54.3	8.6	3.7
Dirithromycin	≤0.125	1	16	32	9.9	40.7	50.6	32.1	2.5	6.2
Ofloxacin	≤0.125	1	8	64	4.9	23.5	28.4	22.3	0	1.2
Levofloxacin	≤0.125	0.5	2	8	7.4	3.7	11.1	3.7	0	0
Gatifloxacin	≤0.125	0.25	2	16	6.2	6.2	12.4	4.9	1.2	0
Chloramphenicol	0.5	8	64	≥128	21	33.2	54.2	32.1	0	1.2
Clindamycin	≤0.125	4	32	≥128	6.2	65.4	71.6	63	0	2.4
Vancomycin	≤0.125	1	4	≥128	–	32.2	–	27.2	1.2	3.7
Tetracycline	≤0.125	32	128	≥128	2.5	85.1	87.6	61.7	9.9	13.6

I, intermediate resistance; R, resistance; –, not applicable. MIC₅₀ value is the MIC value that inhibited at least 50% of the isolates; MIC₉₀ value is the MIC value that inhibited at least 90% of the isolates.

Table 4. Resistance profiles for Streptococcus from bovine mastitis (n = 81 isolates).

	Isolates
Resistance to × classes of antimicrobials	Number	%
One	2	2.5
Two	7	8.5
Three	20	24.7
Four	27	33.3
Five	13	16
Six	9	11.1
Seven	3	3.7

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