Figure 1Biofilm-forming capacity of 126 methicillin-resistant Staphylococcus aureus (MRSA) isolates by tissue culture plate (TCP) assay.
Table 1Comparison of antimicrobial susceptibilities between biofilm-forming and nonforming isolates
|
Antibiotic resistance profiles |
No. of isolates |
% |
Biofilm formers (86) |
OX-P |
12/86 |
13.9 |
OX-P-CLI |
4/86 |
4.7 |
OX-P-TET |
1/86 |
1.2 |
OX-P-CIP-CLI |
7/86 |
8.1 |
OX-P-CLI-TET |
1/86 |
1.2 |
OX-P-CIP-TET |
1/86 |
1.2 |
OX-P-CIP-CLI-SXT |
1/86 |
1.2 |
OX-P-CIP-CLI-TET |
57/86 |
66.2 |
OX-P-CIP-CLI-TET-SXT |
1/86 |
1.2 |
Biofilm non-formers (40) |
OX-P |
17/40 |
42.5 |
OX-P-CIP |
1/40 |
2.5 |
OX-P-TET |
1/40 |
2.5 |
OX-P-CIP-CLI |
3/40 |
7.5 |
OX-P-CIP-CLI-TET |
17/40 |
42.5 |
OX-P-CIP-CLI-TET-SXT |
1/40 |
2.5 |
Table 2Genotypic distribution between biofilm-forming and nonforming isolates
Characteristic |
No. (%) of MRSA isolates
|
p∗
|
Biofilm formers (n = 86) |
Biofilm non-formers (n = 40) |
agr group |
I |
25 (29.1) |
18 (45.0) |
0.357 |
II |
55 (64.0) |
20 (50.0) |
|
III |
3 (3.5) |
1 (2.5) |
|
SCCmec type |
I |
0 (0.0) |
0 (0.0) |
0.055 |
II |
60 (69.8) |
20 (50.0) |
|
III |
6 (7.0) |
1 (2.5) |
|
IV |
18 (20.9) |
18 (45.0) |
|
MLST |
ST1 |
2 (2.3) |
1 (2.5) |
|
ST5 |
60 (69.8) |
21 (52.5) |
0.060 |
ST8 |
1 (1.2) |
0 (0.0) |
|
ST72 |
16 (18.6) |
17 (42.5) |
0.005 |
ST239 |
7 (8.1) |
1 (2.5) |
0.434 |
Table 3Distribution of virulence-associated genes by functional category
Functional category |
No. of isolates by biofilm formation (%);
|
Positive, n = 86 |
Negative, n = 40 |
p∗ |
Adhesin-encoding genes |
icaA
|
83 (96.5) |
38 (95.0) |
0.652 |
icaD
|
86 (100) |
40 (100) |
|
cna
|
80 (93.0) |
36 (90.0) |
0.724 |
atl
|
86 (100) |
40 (100) |
|
fnbA
|
83 (96.5) |
39 (97.5) |
1.000 |
fnbB
|
64 (74.4) |
18 (45.0) |
0.001 |
Toxin-encoding genes |
SEs |
86 (100) |
40 (100) |
|
eta, etb, etd
|
1 (1.2) |
0 (0.0) |
1.000 |
tst
|
78 (90.7) |
34 (39.5) |
0.370 |
PVL
|
2 (2.3) |
0 (0.0) |
1.000 |
hla
|
83 (96.5) |
38 (95.0) |
0.652 |
hlb
|
86 (100) |
39 (97.5) |
0.317 |
Surface-associated genes |
cap5HK
|
75 (87.2) |
35 (87.5) |
0.964 |
cap8HK
|
9 (10.5) |
3 (7.5) |
0.751 |
Staphylococcal regulators |
sarA
|
86 (100) |
40 (100) |
|
arlRS
|
80 (93.0) |
39 (97.5) |
0.430 |
Table 4Summary of clinical characteristics
Characteristics |
Biofilm formers n (%) |
Bioflim non-formers n (%) |
p
|
OR (CI95) |
Age, years |
|
|
0.203 |
0.985 (0.964–1.008) |
Mean ± SD |
63.8 ± 12.5 |
56.7 ± 14.7 |
|
|
Median (range) |
69 (1–98) |
65 (1–80) |
|
|
Male:female |
56:30 |
26:14 |
0.990 |
|
MRSA isolates |
Onset of infection |
Nosocomial |
67 (77.9) |
24 (60.0) |
0.024 |
2.434 (1.111–5.331) |
Community onset |
19 (22.1) |
16 (40.0) |
|
|
Site of infection |
Endocarditis |
2 (2.3) |
0 (0) |
0.255 |
|
Lung infection |
7 (8.1) |
5 (12.5) |
0.407 |
|
SSTI/Bone |
8 (9.3) |
3 (7.5) |
0.857 |
|
CRI |
31 (36.0) |
21 (52.5) |
0.466 |
|
Other sites |
3 (3.5) |
0 (0) |
0.281 |
|
Primary |
33 (38.4) |
14 (35.0) |
0.629 |
|
Clinical outcome |
Crude mortality |
29 (37.7) |
16 (40.0) |
0.423 |
|
MRSA-related death |
16 (18.6) |
6 (15.0) |
0.203 |
|
Eradication of MRSA |
|
|
0.824 |
|
Success |
56 (72.7) |
26 (65.0) |
|
|
Failure |
19 (22.1) |
10 (25.0) |
|
|
Table 5Healthcare-associated risk factors associated with biofilm-forming capacity
Healthcare-associated risk factors |
Biofilm formers (%) |
Biofilm non-formers (%) |
p
|
Odds ratio (95% confidence interval) |
Presence of invasive device |
85.7 |
61.2 |
0.002 |
3.87 (1.60–8.96) |
Prior antibiotic use |
71.6 |
62.5 |
0.535 |
1.37 (0.49–3.89) |
Residence in LTCF |
12.5 |
10.0 |
0.704 |
1.30 (0.33–5.12) |
Prior hospitalization |
60.2 |
40.0 |
0.024 |
0.40 (0.18–0.88) |
Prior surgery |
36.4 |
17.5 |
0.121 |
0.47 (0.17–1.22) |
Receipt of hemodialysis |
26.1 |
30.0 |
0.278 |
1.65 (0.66–4.09) |
Prior MRSA colonization |
33.8 |
15.0 |
0.295 |
0.61 (0.24–1.54) |