|
Five N. gonorrhoeae strains WHO A, B,
C, D and E with known susceptibility patterns to different antibiotics have
been selected as reference strains.
In addition, five provisional reference cultures, SEARO/WHO F,
G, H, I and J are available which provide a range of susceptibilies to a
number of different antibiotics currently in use.
These strains were selected with a view to control a 4-fold to
6-fold difference in chromosomal resistance to penicillin, the production of b-lactamase
and the presence of high-level resistance to tetracycline, quinolones and
spectinomycin, when used in combination.
The annular radius (in mm) and category of sensitivity of WHO
reference strains A–E and of the provisional reference cultures SEAR/WHO F–J
are listed in the following table.
|
Note
These values apply when using the CDS test system and
do not necessarily apply to other test systems (like NCCLS or E test) which
employ discs or inocula of different strengths.
|
WHO
reference strains of N. gonorrhoeae
SEARO/WHO A–J for gonococcal
susceptibility testing
|
Disc potency
|
Penicillin
P
0.5 IU
|
Ciprofloxacin
Cip NA
1 mg 30 mg
|
Ceftriaxone
Cro
0.5 mg
|
Spectinomycin
SH
100 mg
|
Tetracycline
TE
10 mg
|
|
|
|
|
|
|
|
|
MIC
|
AR
|
Cate-
|
MIC
|
AR
|
AR
|
Cate-
|
MIC
|
AR
|
Cate-
|
MIC
|
AR
|
Cate-
|
MIC
|
AR
|
Cate-
|
|
|
mg/L
|
mm
|
gory
|
mg/L
|
mm
|
mm
|
gory
|
mg/L
|
mm
|
gory
|
mg/L
|
mm
|
gory
|
mg/L
|
mm
|
gory
|
|
WHO A
|
0.008
|
14
|
S
|
0.016
|
17
|
13
|
S
|
<0.0005
|
15
|
S
|
>128
|
0
|
R
|
0.25
|
9
|
Not TRNG
|
|
WHO B
|
0.06
|
9
|
LS
|
0.016
|
14
|
14
|
S
|
0.004
|
11
|
S
|
<8
|
8
|
S
|
0.25
|
9
|
Not TRNG
|
|
WHO C
|
0.5
|
5
|
LS
|
0.016
|
16
|
13
|
S
|
0.016
|
10
|
S
|
16
|
9
|
S
|
1
|
6
|
Not TRNG
|
|
WHO D
|
1
|
0
|
R
|
0.03
|
13
|
12
|
S
|
0.016
|
8
|
S
|
16
|
10
|
S
|
4
|
3
|
Not TRNG
|
|
WHO E
|
>2.0
|
0
|
PPNG
|
0.016
|
15
|
14
|
S
|
0.004
|
12
|
S
|
16
|
9
|
S
|
1
|
8
|
Not TRNG
|
|
WHO
F
|
0.016
|
11
|
S
|
0.016
|
12
|
11
|
S
|
<0.03
|
14
|
S
|
<64
|
8
|
S
|
<8
|
8
|
Not TRNG
|
|
WHO G
|
0.5
|
4
|
LS
|
0.25
|
9
|
0
|
LS
|
<0.03
|
11
|
S
|
<64
|
8
|
S
|
32
|
0
|
TRNG
|
|
WHO H
|
0.25
|
6
|
LS
|
2
|
0
|
0
|
R
|
<0.03
|
12
|
S
|
<64
|
9
|
S
|
<8
|
5
|
Not TRNG
|
|
WHO
I
|
2
|
3
|
R
|
0.5
|
5
|
0
|
LS
|
<0.03
|
14
|
S
|
<64
|
11
|
S
|
<8
|
6
|
Not TRNG
|
|
WHO J
|
>2
|
0
|
PPNG
|
8
|
0
|
0
|
HLR
|
<0.03
|
11
|
S
|
<64
|
10
|
S
|
<8
|
5
|
Not TRNG
|
Category
 S Susceptible (sensitive)
LS Less sensitive
R Resistant
PPNG Penicillinase producing N.
gonorrhoeae (Resistant to penicillin by plasmid mediation)
TRNG Tetracycline resistant N.
gonorrhoeae (Resistant to tetracycline by plasmid mediation)
HLR High level resistance
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