ASO and DNase-B Titers in Patients with Streptococcal Skin Infections in the Dalbavancin DISCOVER Program
1345
Michael Dunne, MD and Sailaja Puttagunta, MD
Durata Therapeutics, Branford, CT
ABSTRACT
RESULTS
Background
Elevated values of anti-Streptolysin O (ASO) and DNase-B antibody titers are known to be consistent
with antecedent group A streptococcal infections, especially acute streptococcal pharyngitis, acute
rheumatic fever or acute glomerulonephritis, but not much is known about their association with
streptococcal skin infections. We evaluated the presence of elevated ASO/DNase-B titers in patients
enrolled in 2 global phase 3 clinical trials comparing dalbavancin alone to vancomycin/linezolid for
the treatment of patients with acute bacterial skin and skin structure infections (ABSSSI).
Methods
Cultures obtained at a local laboratory at baseline were sent to a central laboratory for species
identification. ASO and DNase-B titers were measured at baseline and Day 28. ASO titers were
considered elevated if there was a 4 fold increase from baseline or if the titer was >200 kIU/L at any
time.
Results
52/107 (48.6%) of patients with a positive DNase and elevated ASO titer had a positive streptococcal
culture compared to 91/499 (18.2%) of those with a negative titers (p<0.001).
Table 1:
ABSSSI patients without a positive streptococcal culture at baseline
ABSSSI patients with a
positive streptococcal
culture at baseline
No positive
streptococcal culture at
Baseline
P value
Any non-streptococcal
positive culture
P
value1
No positive
culture
P
value2
77/145 (53.1)
148/472 (31.4)
<.001
136/437 (31.1)
<.001
6/27 (22.2)
0.003
Elevated DNase-B antibody
84/151 (55.6)
112/480 (23.3)
<.001
107/446 (24.0)
<.001
5/27 (18.5)
<.001
52/143 (36.4)
55/463 (11.9)
Elevated
<.001
53/430 (12.3)
<.001
2/27 (7.4)
0.003
DNase
N = 87
ASO and DNase
N = 54
ASO or DNase
N = 116
N = 40
45.5
44.2
42.9
45.8
50.2
54 (65.1)
62 (71.3)
40 (74.1)
76 (65.5)
79 (95.2)
82 (94.3)
51 (94.4)
African-American
2 (2.4)
2 (2.3)
Other
2 (2.4)
3 (3.4)
Mean age (years)
Male gender, n (%)
METHODS

Day 3 (48-72 Hours)
505/645 (78.3)
449/539 (83.3)*
23 (57.5)
≥ 20% reduction in
lesion size (ITT)
413/478(86.4)
370/419 (88.3)
217/252 (86.1)
566/645 (87.8)
496/539 (92.0)**
110 (94.8)
40 (100)
Day 14
1 (1.9)
3 (2.6)
0
2 (3.7)
3 (2.6)
0
Clinical status (CE)
377/414(91.1)
All patients enrolled in two Phase 3 ABSSSI studies had skin and blood culture specimens sent to
a central laboratory
ASO and DNase-B titers were measured at baseline and Day 28.
ASO titers were considered elevated if:
– a 4-fold increase from baseline or
– the titer was >200 kIU/L at any time
The demographic characteristics of patients, including measures related to the severity of their
clinical presentation of ABSSSI, were compared across test outcomes
Results of ASO and DNase-B titers were analyzed in sub-groups of patients with and without
positive streptococcal cultures at baseline to assess for:
– Sensitivity and specificity of each test
– Clinical response to treatment at early and late endpoints
19 (21.8)
10 (18.5)
34 (29.3)
22 (55.0)
Rest of World
58 (69.9)
68 (78.2)
44 (81.5)
82 (70.7)
18 (45.0)
Outpatients, n/N (%)
17/77 (22.1)
14/80 (17.5)
8/50 (16.0)
23/107 (21.5)
14/34 (41.2)
Diabetes*, n/N (%)
79/478 (16.5)
66/419 (15.8)
43/252 (17.1)
102/645 (15.8)
75/539 (13.9)
25.9
25.8
25.8
26.0
26.9
Median BMI (kg/m²)
Table 2. Severity of illness
Antibody Titer
Characteristic
Not Elevated
n/N (%)
ASO
n/N (%)
DNase
n/N (%)
ASO and DNase
n/N (%)
ASO or DNase
n/N (%)
265/476 (55.7)
246/419 (58.7)
154/252 (61.1)
357/643 (55.5)
247/537 (46.0)
633.0
584.0
641.8
597.6
443.2
Fever
403/472 (85.4)
362/415 (87.2)
221/249 (88.8)
544/638 (85.3)
462/536 (86.2)
Leukocytosis
189/455 (41.5)
163/400 (40.8)
100/240 (41.7)
252/615 (41.0)
186/521 (35.7)
Bands > 10%
106/366 (29.0)
100/320 (31.3)
67/199 (33.7)
139/487 (28.5)
78/403 (19.4)
CRP > 300, mg/L
43/457 (9.4)
35/407 (8.6)
27/242 (11.2)
51/622 (8.2)
18/525 (3.4)
CRP > 50, mg/L
285/457 (62.4)
257/407 (63.1)
167/242 (69.0)
375/622 (60.3)
267/525 (50.9)
Table 3. Duration of antibiotic therapy
Antibody Titer
Study Drug Therapy
(Days)
207/227 (91.2)
508/557 (91.2)
436/463 (94.2)***
Table 5. Correlation of ASO and DNase-B titers with positive streptococcal cultures
Elevated
Elevated
Not Elevated
DNase
ASO and DNase
ASO or DNase
Total Drug
11.0
11.1
11.1
10.9
11.1
Oral Drug
5.7
5.5
5.4
5.6
6.3
4.5
4.8
5.0
DNase
n/N (%)
ASO and DNase
n/N (%)
4.5
4.0
ASO
DNase
ASO and DNase
ASO or DNase
Sensitivity
53.5
53.7
35.3
70.7
Specificity
69.3
76.7
88.3
58.6
Positive predictive value
36.9
44.4
50.5
36.9
Negative predictive value
81.6
82.8
80.2
85.4
DISCUSSION
 SIRS criteria; Leukocytosis with increased immature white blood cells; Hs-CRP > 50
mg/L
Antibody Titer
ASO
n/N (%)
Characteristic
Antibody Titer
 A higher proportion of patients with elevated ASO and DNase-B titers had a more
severe clinical presentation of their ABSSSI based on a greater likelihood of having:
ASO or DNase
n/N (%)
Not Elevated
Positive streptococcal culture
83/155 (53.5)
87/162 (53.7)
54/153 (35.3)
116/164 (70.7)
40/153 (26.1)
No positive streptococcal
culture
395/1021 (38.7)
332/1084 (30.6)
198/1007 (19.7)
529/1098 (48.2)
499/1007 (49.6)
Positive Non-streptococcal
culture
142/462 (30.7)
109/469 (23.2)
53/453 (11.7)
198/478 (41.4)
264/453 (58.3)
Negative culture
253/559 (45.3)
223/615 (36.3)
145/554 (26.2)
331/620 (53.4)
235/554 (42.4)
All ‘positive’ vs ‘no positive’ comparisons: p< 0.001;
All ‘positive non-streptococcal’ vs ‘negative’ comparisons: p <0. 001
• Patients with elevated ASO and DNase-B titers also had lower clinical efficacy rates at
the early time-point (48 – 72 hours after initiation of therapy) compared to those with
normal titers.
 The highest likelihood of having a positive streptococcal antibody test was observed in
patients with a positive streptococcal culture, followed by those with negative cultures
and lowest in those with a culture positive for a non-streptococcal pathogen
• Patients with cellulitis were more likely to have a positive antibody test, suggesting
that the cellulitis event had a streptococcal etiology.
• Even patients with negative cultures who had cellulitis were also more likely to have
elevated antibodies
 The combination of both a high ASO and positive DNase titer is highly (>85%)
predictive of the likelihood of having a positive streptococcal culture at baseline
Table 6. ASO and DNase –B Titers by Sub-type of ABSSSI
Antibody Titer
Elevated
Not Elevated
n/N (%)
ASO
n/N (%)
DNase
n/N (%)
ASO and DNase
n/N (%)
ASO or DNase
n/N (%)
Positive Streptococcal Culture
29/47 (61.7)
27/53 (50.9)
18/47 (38.3)
38/53 (71.7)
9/47 (19.1)
Positive Non- Streptococcal Culture
36/134 (26.9)
35/138 (25.4)
13/130 (10.0)
58/142 (40.8)
77/130 (59.2)
Negative Culture
199/424 (46.9)
168/478 (35.1)
108/420 (25.7)
259/482 (53.7)*
172/420 (41.0)
Cellulitis
Major Abscess
ASO
IV Drug
338/370 (91.4)
*p value = 0.009; **p value = 0.008; ***p value = 0.099
25 (30.1)
Mean lesion size
Not Elevated
n/N (%)
191/252 (75.8)
North America
(cm2)
ASO or DNase
n/N (%)
326/419 (77.8)
Geographic Region, n (%)
SIRS criteria
ASO and DNase
n/N (%)
370/478(77.4)
Race, n (%)
Caucasian
DNase
n/N (%)
Clinical Response (ITT)
Elevated
Conclusion
• A higher proportion of patients with documented streptococcal skin infections had elevated ASO
and/or DNase-B titers than patients who did not have streptococci isolated from cultures at
baseline. ABSSSI patients with an elevated ASO and DNase titer are more likely to have a
streptococcal etiology for their infection but additional investigation to improve its sensitivity and
specificity is warranted.

Not Elevated
ASO
N = 83
value calculated for patients with a positive streptococcal culture vs those with a positive non-streptococcal culture
2p value calculated for patients with a positive streptococcal culture vs those with negative cultures


ASO
n/N (%)
Antibody Titer
1p

Elevated
Clinical Success
*Fasting blood glucose > 7 mmol/L
Elevated ASO titer
Elevated ASO and DNase-B
antibodies
Antibody Titer
Table 1. Demographics for Patients with Streptococcal ABSSSI
Characteristic
Table 7. Sensitivity and Specificity of ASO and DNase-B titers for the diagnosis of culture positive streptococcal
skin infections
Table 4. Efficacy Outcomes
Positive Streptococcal Culture
23/49 (46.9)
21/50 (42.0)
9/48 (18.8)
35/51 (68.6)
15/48 (31.3)
Positive Non- Streptococcal Culture
58/195 (29.7)
33/195 (16.9)
19/190 (10.0)
72/200 (36.0)
121/190 (63.7)
Negative Culture
29/71 (40.8)
29/72 (40.3)
21/71 (29.6)
37/72 (51.4)
34/71 (47.9)
 The absence of either an elevated ASO or DNase titer is highly (>85%) predictive of not
having a culture confirmed streptococcal etiology to the ABSSSI
CONCLUSION
• A higher proportion of patients with documented streptococcal skin infections had
elevated ASO and/or Dnase-B titers than patients who did not have streptococci isolated
from cultures at baseline.
– ABSSSI patients with an elevated ASO and DNase titer are more likely to have a
streptococcal etiology for their infection
• Patients with elevated ASO and Dnase-B titers have a more severe clinical presentation
of their ABSSSI and a lower clinical success rate
• Additional investigation is warranted:
Wound Infection
Positive Streptococcal Culture
31/59 (52.5)
39/59 (66.1)
27/58 (46.6)
43/60 (71.7)
16/58 (27.6)
Positive Non- Streptococcal Culture
48/133 (36.1)
41/136 (30.1)
21/133 (15.8)
68/136 (50.0)
66/133 (49.6)
Negative Culture
25/64 (39.1)
26/65 (40.0)
16/63 (25.4)
35/66 (53.0)
29/63 (46.0)
– to improve the sensitivity and specificity of these tests
– to examine the presence of streptococcal toxin production and antibody titers
*Elevated ASO or DNase vs not elevated for negative culture in cellulitis: p <0.001
Presented at ID Week 2014 • October 8-12, Philadelphia, PA
Funding provided by Durata Therapeutics, Inc
.