Antibiotic susceptibility of coagulase-negative staphylococci isolated from very low birth weight babies: comprehensive comparisons of bacteria at different stages of biofilm formation

Qu, Yue; Daley, Andrew J; Istivan, Taghrid S; Garland, Suzanne M; Deighton, Margaret A

doi:10.1186/1476-0711-9-16

Annals of Clinical Microbiology and Antimicrobials

Table 2 Antibiotic susceptibilities of five biofilm-positive isolates^a grown in different modes.

From: Antibiotic susceptibility of coagulase-negative staphylococci isolated from very low birth weight babies: comprehensive comparisons of bacteria at different stages of biofilm formation

Isolate and mode of growth	Initial bacterial density (CFU/ml)	Penicillin (μg/ml)		Gentamicin (μg/ml)		Oxacillin (μg/ml)		Vancomycin (μg/ml)		Ciprofloxacin (μg/ml)		Rifampicin (μg/ml)
		MIC	MBC	MIC	MBC	MIC	MBC	MIC	MBC	MIC	MBC	MIC	MBC
RP62A
Log Planktonic	(2.6-7.3)× 10⁵	8	8	16	32	64	64	2	2	0.06	0.12	0.008	0.03
Monolayer	(6.0-15.6) × 10⁵	32	128 ^c	64	64	16	64	2	8	0.12	0.12	0.002	0.008
Stat Planktonic	(0.2-0.5) × 10⁹	^b	> 1024		1024		> 1024		32		≤1		32
Biofilm	(0.9-1.9) × 10⁹	>1024^e	>1024	64	>1024	64	>1024	16	>*1024*^d	0.25	>*1024*	0.004	0.015
Isolate 3
Log Planktonic	(2.9-8.3) × 10⁵	8	16	0.25	0.25	0.25	0.25	2	4	0.12	0.25	0.008	0.015
Monolayer	(5.0-11.0) × 10⁵	32	64	0.25	0.5	0.12	0.5	2	8	0.25	0.5	0.002	0.004
Stat Planktonic	(0.6-2.2) × 10⁹		>1024		32		>1024		> 1024		1024		256
Biofilm	(0.3-1.3) × 10⁹	>1024	>1024	16	16	0.25	2	16	16	0.25	2	0.5	4
Isolate 8a
Log Planktonic	(2.6-5.5) × 10⁵	128	128	32	32	8	8	1	2	0.25	0.25	0.008	0.03
Monolayer	(6.4-11.1) × 10⁵	>128	>128	32	64	64	64	1	8	0.12	0.5	0.004	0.015
Stat Planktonic	(4.4-4.9) × 10⁸		>1024		>1024		>1024		>1024		1024		2
Biofilm	(0.6-1.8) × 10⁸	1024	>1024	256	>1024	256	>1024	8	>1024	0.12	>1024	0.004	4
Isolate 9
Log Planktonic	(3.1-5.2) × 10⁵	32	64	32	32	8	16	1	2	0.25	0.25	0.015	0.03
Monolayer	(4.6-10.8) × 10⁵	>128	>128	32	>128	16	32	2	8	0.25	0.5	0.004	0.015
Stat Planktonic	(0.7-0.8) × 10⁹		>1024		>1024		>1024		>1024		>1024		256
Biofilm	(1.1-1.7) × 10⁹	>1024	>1024	64	>1024	>128	>1024	8	>1024	0.25	>1024	0.008	4
Isolate 11
Log Planktonic	(2.7-8.5) × 10⁵	8	8	64	>128	32	64	1	1	0.06	0.12	>128	>128
Monolayer	(3.2-17.8) × 10⁵	32	64	>128	>128	32	64	1	2	0.06	0.12	>128	>128
Stat Planktonic	(0.8-1.6) × 10⁹		>1024		>1024		>1024		>1024		512		1024
Biofilm	(0.2-0.6) × 10⁹	>1024	>1024	256	>1024	256	>1024	8	>1024	0.25	16	64	>1024

^α Biofilm-positive isolates (OD₆₀₀ >0.24).
^b MICs for CoNS at stationary phase are not provided as the values could not be determined by standard methods.
^c Values underlined indicate a significant increase in the MICs or MBCs between log-planktonic and adherent monolayer modes of growth.
^d Values in italic indicate a significant change in the MBCs between stationary-planktonic and biofilm modes of growth.
^e Values in bold indicate a significant increase in MICs or MBCs between log-planktonic/adherent monolayer and biofilm modes of growth

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ISSN: 1476-0711

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