Characterization of methicillin-resistant Staphylococcus aureus from healthy carrier chickens

Figures & data

Table 1.  Comparison of MRSA isolates detected using DBEM or SBEM.

	DBEM
SBEM	Number of positive results	Number of negative results	Total number
Number of positive results	1	5	6
Number of negative results	2	324	326
Total number	3	329	332

Table 2.  Total number and prevalence of MRSA-positive farms using DBEM or SBEM.

Isolation method^a	Number of positive farms	Prevalence (%)	Farm type
DBEM	3	0.8 (n = 372)	Broilers
SBEM	6	1.8 (n = 332)	2 layers and 4 broilers
DBEM and SBEM^b	8	2.4 (n = 332)	Layers and broilers
n, total number of broiler or layer farms. ^aPrevalence is computed out of 372 farms for DBEM, and out of 332 farms for SBEM. ^bDBEM and SBEM is the comparison of both methods used in parallel.

Table 3.  MRSA prevalence in different farms for DBEM and SBEM.

Isolation method^a	Broilers (%)	Layers (%)
DBEM	3.3 (n = 92)	0.0 (n = 280)
SBEM	4.8 (n = 81)	0.8 (n = 251)
n, total number of broiler or layer farms. ^aPrevalence is computed out of 92 broilers and 280 layers for DBEM, and computed out of 81 broilers and 251 layers for SBEM.

Table 4.  Comparison of sensitivity, specificity, positive and negative predictive values for the isolation methods used in this study.

	DBEM (95% CI)	SBEM (95% CI)
Sensitivity	0.375 (3.9 to 71.0)	0.75 (45.0 to 100.0)
Specificity	1	1
PPV	1	1
NPV	0.985 (97.2 to 99.8)	0.994 (98.5 to 100.0)

Table 5.  Genotyping of MRSA.

Strain	spa type	Sequence type	ccr complex	mec	SCCmec type	Origin	Isolation method
M72	t037	ST239	A3/B3	A	III	Layer	SBEM
M86	t037	ST239	A3/B3	A	III	Layer	SBEM
M118b	t899	ST398	A2/B2	B	IV	Broiler	SBEM
M213	t011	ST398	A2/B2	B	IV	Broiler	SBEM + DBEM
M282	t037	ST239	A3/B3	B	III	Broiler	DBEM
M286	t011	ST398	C2	C	V	Broiler	DBEM
M363	t011	ST398	C2	C	V	Broiler	SBEM
M371	t011	ST398	A2/B2	B	IV	Broiler	SBEM

Table 6.  Antimicrobial resistance of all MRSA strains isolated in this study.

Strain	CHL	CIP	CLI	ERY	FOX	FUS	GEN	KAN	LZD	MUP	PEN	RIF	SMX	STR	SYN	TET	TIA	TMP	VAN
M72	64^a	≤0.25	≤0.12	>8	>16	≤0.5	≤1	>64	2	≤0.5	>2	>0.5	512	>32	≤0.5	>16	≤0.5	≤2	≤1
M86	64	≤0.25	≤0.12	>8	>16	≤0.5	≤1	>64	≤1	1	>2	>0.5	512	>32	≤0.5	>16	≤0.5	≤2	≤1
M282	64	≤0.25	≤0.12	>8	>16	≤0.5	≤1	>64	≤1	≤0.5	>2	>0.5	>512	>32	≤0.5	>16	≤0.5	≤2	≤1
M118	≤4	2	>4	4	16	1	8	64	2	≤0.5	>2	0.03	≤64	8	1	>16	>4	>32	≤1
M213	64	0.5	>4	>8	>16	2	>16	>64	≤1	≤0.5	>2	>0.5	256	>32	≤0.5	>16	1	>32	≤1
M286	16	2	>4	>8	16	≤0.5	≤1	≤4	2	≤0.5	>2	≤0.016	≤64	8	1	>16	≤0.5	>32	≤1
M363	32	2	>4	>8	16	≤0.5	>16	>64	≤1	≤0.5	>2	≤0.016	256	>32	4	>16	>4	>32	≤1
M371	8	>8	>4	>8	16	≤0.5	>16	64	2	≤0.5	>2	≤0.016	≤64	8	1	>16	2	>32	≤1
CHL, chloramphenicol; CIP, ciprofloxacin; CLI, clindamycin; ERY, erythromycin; FOX, cefoxitin; FUS, fusidic acid; GEN, gentamicin; KAN, kanamycin; LZD, linezolid; MUP, mupirocin; PEN, penicillin; RIF, rifampicin; SMX, sulfamethoxazole; STR, streptomycin; SYN, quinupristin/dalfopristin; TET, tetracyclin; TIA, tiamulin; TMP, trimethoprim; VAN, vancomycin. ^aResults in bold indicate resistance breakpoints.