A Comparison of Tissue versus Swab Culturing of Infected Diabetic Foot Wounds

Table 3

Microbial load and diagnostic utility of swab cultures.

Microorganism	Deep tissue (+)		Deep tissue (−)		Diagnostic utility of swab culture in identifying pathogens
	Swab (+)	Swab (−)	Swab (+)	Swab (−)	SE (%)	SP (%)	Accuracy (%)
Presence of pathogens	46	4	3	3	92.0	50.0	87.5
Gram-positive organisms	29	3	5	19	90.6	79.2	85.7
S. aureus	12	4	3	37	75.0	92.5	87.5
Enterococcus	6	4	2	44	60.0	95.7	89.3
Streptococci	5	3	7	41	62.5	85.4	82.1
CNS	5	1	4	46	83.3	92.0	91.1
Arcanobacterium pyogenes	1	0	0	55	100.0	100.0	100.0
Corynebacterium	0	0	2	54	—	96.4	96.4
Globicatella sanguis	0	0	1	55	—	98.2	98.2
Gram-negative organisms	22	3	3	28	88.0	90.3	89.3
Proteus	7	4	1	44	63.6	97.8	91.1
Pseudomonas	3	0	2	51	100.0	96.2	96.4
Klebsiella	2	1	1	52	66.7	98.1	96.4
Enterobacter	2	0	2	52	100.0	96.3	96.4
E. coli	1	2	2	51	33.3	96.2	92.9
Morganella	1	2	0	53	33.3	100.0	96.4
Citrobacter	1	2	0	53	33.3	100.0	96.4
Serratia	0	2	0	54	0.0	100.0	96.4
Acinetobacter	0	1	0	55	0.0	100.0	98.2
Myroides odoratimimus	0	0	1	55	—	98.2	98.2
Ralstonia pickettii	0	1	0	55	0.0	100.0	98.2
Kluyvera ascorbata	0	1	0	55	0.0	100.0	98.2
Fungi	4	1	1	50	80.0	98.0	96.4

S. aureus: Staphylococcus aureus; CNS: Coagulase-Negative Staphylococcus.
SE: sensitivity; SP: specificity; (+): positive; (−): negative.