Molecular Epidemiology of Methicillin-Resistant and Methicillin-Susceptible Staphylococcus aureus Isolated from the Eye

Figures & data

TABLE 1  Summary of ocular S. aureus characteristics.

	MRSA		MSSA
	Type II	Type IV
Number of isolates	22	16	16
Source of isolates by state (number of sites)	AL (2), FL (1), GA (1), ID (1), MA (2), MD (1), MI (3), NY (2), OH (2), PA (4), SC (1), TN (2)	FL (1), GA (1), ID (1), MA (1), MD (4), MI (1), NC (1), NY (2), OH (4)	AL (1), FL (2), GA (1), MA (2), MD (1), MI (1), MO (1), NY (3), OH (2), PA (2)
SCCmec type (n)	II (22)	IVa (15)	NA
		IVb (1)
PVL positive, n (%)	0 (0.0%)	12 (75.0%)	3 (18.8%)
Number of spa types	4	5	12
% Resistant to 1+ drug class^a	100.0%	100.0%	62.5%
% Resistant to 2+ drug classes	100.0%	93.8%	37.5%
% Resistant to 3+ drug classes	100.0%	62.5%	18.8%
% Resistant to 4+ drug classes	95.5%	6.3%	6.3%
% Resistant to 5+ drug classes	36.4%	0.0%	0.0%
% Resistant to 6+ drug classes	4.5%	0.0%	0.0%
% Resistant to 7+ drug classes	0.0%	0.0%	0.0%

^aDrug classes tested included fluoroquinolones, macrolides, lincosamides, aminoglycosides, tetracyclines, rifamycins, glycopeptides, oxazolidinones, β-lactams.

TABLE 2  Antimicrobial susceptibilities of ocular S. aureus, including 16 MSSA, 22 MRSA SCCmec type II, and 16 MRSA SCCmec type IV isolates.

Agent	Organism	MIC (μg/ml)			% Susceptible
		Range	50%	90%
Besifloxacin	MSSA	0.016–4	0.03	4	NA^a
	MRSA (type II)	0.5–8	4	4	NA^a
	MRSA (type IV)	0.016–1	0.25	0.5	NA^a
Moxifloxacin	MSSA	0.03–64	0.06	32	62.5
	MRSA (type II)	2–64	32	64	0
	MRSA (type IV)	0.016–2	2	2	37.5
Gatifloxacin	MSSA	0.06–64	0.125	32	62.5
	MRSA (type II)	2–128	64	128	0
	MRSA (type IV)	0.031–2	2	2	37.5
Ciprofloxacin	MSSA	0.125–256	0.5	256	56.3
	MRSA (type II)	32–256	256	256	0
	MRSA (type IV)	0.125–64	16	32	37.5
Levofloxacin	MSSA	0.125–512	0.25	512	56.3
	MRSA (type II)	8–1024	512	512	0
	MRSA (type IV)	0.125–8	4	8	37.5
Azithromycin	MSSA	0.5–> 256	0.5	> 256	56.3
	MRSA (type II)	> 256	> 256	> 256	0
	MRSA (type IV)	0.5–> 256	128	128	6.3
Erythromycin	MSSA	0.25–> 256	0.5	> 256	56.3
	MRSA (type II)	> 256	> 256	> 256	0
	MRSA (type IV)	0.25–64	64	64	6.3
Clindamycin	MSSA	0.063–> 256	0.125	> 256	87.5
	MRSA (type II)	0.063–> 256	0.25	> 256	54.5
	MRSA (type IV)	0.063–0.125	0.063	0.063	100
Tobramycin	MSSA	0.25–256	0.5	256	81.3
	MRSA (type II)	0.5–256	256	256	13.6
	MRSA (type IV)	0.5–32	1	2	93.8
Tetracycline	MSSA	0.5–32	0.5	4	93.8
	MRSA (type II)	0.25–64	0.5	0.5	95.5
	MRSA (type IV)	0.25–0.5	0.5	0.5	100
Rifampin	MSSA	0.002–0.016	0.008	0.008	100
	MRSA (type II)	0.004–0.125	0.008	0.008	100
	MRSA (type IV)	0.004–0.008	0.004	0.008	100
Vancomycin	MSSA	1	1	1	100
	MRSA (type II)	1	1	1	100
	MRSA (type IV)	0.5–1	1	1	100
Linezolid	MSSA	2–4	2	4	100
	MRSA (type II)	2–4	4	4	100
	MRSA (type IV)	2	2	2	100
Oxacillin	MSSA	0.25–0.5	0.25	0.5	100
	MRSA (type II)	> 8	> 8	> 8	0
	MRSA (type IV)	4–> 8	> 8	> 8	0

^aSince besifloxacin was developed as an exclusively topical ophthalmic agent, no breakpoints exist.

TABLE 3  spa clusters, spa types, repeat patterns, and (n) number for ocular S. aureus.

MRSA SCCmec type II (n=22)
spa CC002 cluster
t002	26-23-17–34-17–20-17-12–17-16	(18)
t045	26-17–20-17-12-17-16	(1)
t067	26-23-17–34-17–20-17-12-17	(2)
t242	26-23-17-13-17-20-17-12-17-16	(1)
MRSA SCCmec type IV (n=16)
spa CC008 cluster
t008	11–19-12–21-17–34-24–34-22–25	(12)
t024	11–12–21-17–34-24–34-22–25	(1)
t334	11–12–21-17–34-22–25	(1)
t622	11–19-12–21-17–34-22–25	(1)
t1578	11–19-12-21-17–34-24–34-17	(1)
MSSA (n=16)
spa CC002 cluster
t002	26-23-17–34-17–20-17-12-17-16	(5)
t242	26-23-17-13–17–20-17-12-17-16	(1)
spa CC008 cluster
t008	11–19-12-21-17-34-24–34-22-25	(1)
t064	11–19-12-05-17-34-24-34-22-25	(1)
spa CC084 cluster
t084	07-23-12–34–34-12–12–23-02-12–23	(1)
t346	07-23-12-34-12-12–23-02-12–23	(1)
t491	26-23-12-34-34-12-12–23-02-12-23	(1)
spa CC240/773 cluster
t240	04-44-33-31-12-16–34-16-12-22–34	(1)
t773	04-44-33-31-16-12–25-22–34	(1)
Singletons
t004	09-02-16-13-13-17-34-16-34	(1)
t005	26-23-13–23-31-05-17–25-17–25-16–28	(1)
t160	07-23-21-24–33-22-17	(1)