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Molecular Identification of Strains within the Mycobacterium abscessus Complex and Determination of Resistance to Macrolides and Aminoglycosides


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Fig. 1.

Mycobacterium abscessus subsp. abscessus. Photography of an auramine-stained acid-fast bacilli smear from liquid BBL culture. The visible bacilli forming cord-like structures.
Mycobacterium abscessus subsp. abscessus. Photography of an auramine-stained acid-fast bacilli smear from liquid BBL culture. The visible bacilli forming cord-like structures.

Fig. 2.

Mycobacterium abscessus subsp. abscessus. Photography of smear stained by Ziehl-Neelsen method for acid-fast bacilli (AFB). Counterstaining creates a compelling visual contrast of red acid-fast bacilli.
Mycobacterium abscessus subsp. abscessus. Photography of smear stained by Ziehl-Neelsen method for acid-fast bacilli (AFB). Counterstaining creates a compelling visual contrast of red acid-fast bacilli.

Fig. 3.

Growth of Mycobacterium abscessus after 7 days of incubation at 37°C in aerobic condition.
a) cream-colored, waxy colonies on Löwenstein-Jensen medium
b) mycobacterial colonies on non-selective media – Tryptic Soy Agar
c) mycobacterial colonies on Columbia agar with 5% of sheep blood.
Growth of Mycobacterium abscessus after 7 days of incubation at 37°C in aerobic condition. a) cream-colored, waxy colonies on Löwenstein-Jensen medium b) mycobacterial colonies on non-selective media – Tryptic Soy Agar c) mycobacterial colonies on Columbia agar with 5% of sheep blood.

Fig. 4.

Culture of rapidly growing non-tuberculous mycobacteria on selective NTM Elite agar (bioMérieux, France), after 5 days of incubation at 37°C under aerobic conditions.
a) colonies of Mycobacterium fortuitum subsp. fortuitum ATCC® 6841™, b) rough colonies of Mycobacterium abscessus subsp. abscessus.
Culture of rapidly growing non-tuberculous mycobacteria on selective NTM Elite agar (bioMérieux, France), after 5 days of incubation at 37°C under aerobic conditions. a) colonies of Mycobacterium fortuitum subsp. fortuitum ATCC® 6841™, b) rough colonies of Mycobacterium abscessus subsp. abscessus.

Fig. 5.

Prevalence of non-tuberculosis mycobacteria species isolated from patients in the Malopolska region of Poland, etween 2018–2022. Each year, the most prevalent species were Mycobacterium kansasii and Mycobacterium avium. Occurrence of Mycobacterium abscessus varies between the years and amounted to three strains in 2018, one in 2020, and eight in 2021.
Prevalence of non-tuberculosis mycobacteria species isolated from patients in the Malopolska region of Poland, etween 2018–2022. Each year, the most prevalent species were Mycobacterium kansasii and Mycobacterium avium. Occurrence of Mycobacterium abscessus varies between the years and amounted to three strains in 2018, one in 2020, and eight in 2021.

Fig. 6.

Analysis of the banding patterns received for 12 clinical strains (strips 1-12) with the use of GenoType NTM DR (Hain Lifescience GmbH, Germany). The strips coated with specific probes are complementary to selectively amplified nucleic acid sequences, that enable species determination as well as point mutations referring to resistance to aminoglycosides and macrolides.
Analysis of the banding patterns received for 12 clinical strains (strips 1-12) with the use of GenoType NTM DR (Hain Lifescience GmbH, Germany). The strips coated with specific probes are complementary to selectively amplified nucleic acid sequences, that enable species determination as well as point mutations referring to resistance to aminoglycosides and macrolides.

Fig. 7.

MIC value of selected antimycobacterial agents obtained by RAPMYCO2 plate. AN – amikacin, CIP – ciprofloxacin, DOX – doxycycline, LZD – linezolid, MXF – moxifloxacin, TGC – tigecycline, CLA – clarithromycin, IMI – imipenem
MIC value of selected antimycobacterial agents obtained by RAPMYCO2 plate. AN – amikacin, CIP – ciprofloxacin, DOX – doxycycline, LZD – linezolid, MXF – moxifloxacin, TGC – tigecycline, CLA – clarithromycin, IMI – imipenem

Results of susceptibility testing to antimycobacterial agents obtained by Sensititre™ RAPMYCO2 plates. Interpretation criteria following CLSI.

MIC values (μg/ml) (Interpretation S/I/R)
No. Species AN FOX CIP DOX LZD MXF SXT IMI TGC CLA after 5d CLA after 14 d
1 Mabs 16 (S) 64 (I) > 4 (R) > 16 (R) ≤ 1 (S) 4 (R) 4/76 (R) 16 (I) MIC = 1 0,06 (S) 0,125 (S)
2 Mabs 16 (S) >128 (R) > 4 (R) > 16 (R) 4 (S) 2 (I) > 8/152 (R) 16 (I) MIC = 0,5 0,06 (S) > 16 (R)
3 Mabs 16 (S) 32 (I) > 4 (R) > 16 (R) 4 (S) > 8 (R) 4/76 (R) 16 (I) MIC = 0,5 0,5 (S) > 16 (R)
4 Mabs 16 (S) >128 (R) > 4 (R) > 16 (R) 16 (I) > 8 (R) > 8/152 (R) 16 (I) MIC = 2 0,06 (S) > 16 (R)
5 Mabs 16 (S) 64 (I) > 4 (R) > 16 (R) 16 (I) > 8 (R) > 8/152 (R) 16 (I) MIC = 1 0,06 (S) > 16 (R)
6 Mabs 16 (S) 64 (I) > 4 (R) > 16 (R) 4 (S) > 8 (R) > 8/152 (R) 16 (I) MIC = 2 4 (I) > 16 (R)
7 Mmas - - - - - - - - - - -
8 Mmas 16 (S) >128 (R) > 4 (R) > 16 (R) 16 (I) 4 (R) 4/76 (R) 16 (I) MIC = 0,25 0,06 (S) 0,125 (S)
9 Mabs 16 (S) >128 (R) > 4 (R) > 16 (R) 16 (I) 4 (R) 4/76 (R) 16 (I) MIC = 0,5 0,06 (S) 0,125 (S)
10 Mmas 16 (S) 32 (I) > 4 (R) 1 (S) 1 (S) 2 (I) 2/38 (S) 16 (I) MIC = 0,5 0,06 (S) 0,06 (S)
11 Mbol 4(S) 32 (I) > 4 (R) > 16 (R) 4 (S) > 8 (R) > 8/152 (R) 16 (I) MIC = 0.25 0.06 (S) > 16 (R)
12 Mabs 4 (S) 33 (I) > 4 (R) > 16 (R) 8 (S) > 8 (R) > 8/152 (R) 16 (I) MIC = 0.12 4 (I) > 16 (R)

Interpretation of susceptibility pattern of rapidly growing mycobacteria according to the CLSI recommendations.

Antimycobacterial agents MIC breakpoints (μg/ml)
S I R
Amikacin ≤ 16 32 ≥ 64
Cefoxitin ≤ 16 32-64 ≥ 128
Doxycycline ≤ 1 2-4 ≥ 32
Ciprofloxacin ≤ 1 2 ≥ 4
Clarithromycin ≤ 2 4 ≥ 8
Linezolid ≤ 8 16 ≥ 32
Moxifloxacin ≤ 1 2 ≥ 4
Trimthoprim/sulfamethoazole ≤ 2/38 ≥ 4/76
Imipenem ≤ 4 8-16 ≥ 32
Tigecycline*

Results of molecular identification of resistance mechanisms to amikacin obtained by GenoType NTM in relation to phenotypic susceptibility testing results.

No. of strain Species GenoType NTM-DR results Phenotypic results of susceptibility to amikacin
Type of bands (WT or mutation) Molecular mechanisms of resistance (Yes/No)
1 Mabs rrs rrs WT No (S)
2 Mabs rrs rrs WT No (S)
3 Mabs rrs rrs WT No (S)
4 Mabs rrs rrs WT No (S)
5 Mabs rrs rrs WT No (S)
6 Mabs rrs rrs WT No (S)
7 Mmas rrs rrs WT No nt
8 Mmas rrs rrs WT No (S)
9 Mabs rrs MUT1 (A1408G) Yes (S)
10 Mmas rrs rrs WT No (S)
11 Mb ol rrs rrs WT No (S)
12 Mabs rrs rrs WT No (S)

j.pjm-2023-048.tab.007

Strip 1 – a clinical strain of Mycobacterium abscessus subs. abscessus (band characteristic for M. abscessus subsp. abscessus; SP4, SP5, SP6, SP9, SP10); no point mutation was detected;
Strips 2-6, 10, 12 - –clinical strains of M. abscessus subs. abscessus (band characteristic for M. abscessus subsp. abscessus; SP4, SP5, SP6, SP9, SP10); point mutation erm(41)T28 referring to macrolide resistance;
Strips 7, 9 – clinical strains of M. abscessus subs. massiliense (band characteristic for M. abscessus subsp. massiliense; SP4, SP5, SP8, SP9); point mutation erm(41)T28 no clinical implication in case of M. masiliense;
Strips 8 – clinical strains of M. abscessus subs. abscessus (band characteristic for M. abscessus subsp. abscessus; SP4, SP5, SP6, SP9, SP10); point mutations were detected: erm(41)T28 and rrl MUT referring to macrolide resistance as well as point mutation A1408G referring to amikacin resistance;
Strip 11 – clinical strains of M. abscessus subs. bolletii (band characteristic for M. abscessus subsp. bolletii; SP4, SP5, SP6, SP7, SP9, SP10), point mutation erm(41)T28 referring to macrolide resistance.

Interpretation of the mutation type conferring to the macrolides and aminoglicosides resistance according to the GenoType NTM-DR VER 1.0 test instructions.

Discernible phenotypic pattern resistance Target nucleic acid sequence Nascent mutation band Mutation
Macrolides 2058–2059 rrl MUT1 A2058C
rrl MUT2 A2058G
A2058T
rrl MUT3 A2059C
rrl MUT4 A2059T
Aminoglycosides 1406–1409 rrs MUT1 A1408G
T1406A
C1409T

Results of susceptibility testing to amikacin and clarithromycin obtained by manually conducted microdilution method. Interpretation criteria following CLSI.

No. Species AN Interpretation* CLA after 5 days of incubation Interpretation* CLA after 14 days of incubation Interpretation*
1 Mabs 16 (S) 0.06 (S) 0,5 (S)
2 Mabs 8 (S) 0.06 (S) > 64 (R)
3 Mabs 16 (S) 0.06 (S) = 32 (R)
4 Mabs 16 (S) 0.06 (S) = 32 (R)
5 Mabs 16 (S) 0.06 (S) = 32 (R)
6 Mabs 16 (S) 0.06 (S) = 32 (R)
7 Mmas
8 Mmas 16 (S) 0.06 (S) = 0.125 (S)
9 Mabs 16 (S) 0.06 (S) = 0.125 (S)
10 Mmas 16 (S) 0.06 (S) = 0.06 (S)
11 Mbol 0.5 (S) 0.06 (S) > 64 (R)
12 Mabs 0.250 (S) 4 (R) = 16 (R)

Results of molecular identification of resistance mechanisms to clarithromycin by GenoType NTM in relation to phenotypic susceptibility testing results.

No. of strain Species GenoType NTM-DR results Phenotypic results of susceptibility to clarithromycin
Type of bands (WT or mutation) Molecular mechanisms of resistance (Yes/No)
1 Mabs erm(41) C28 rrlWT No (S)
2 Mabs erm(41)T28 rrlWT Yes (R)
3 Mabs erm(41)T28 rrlWT Yes (R)
4 Mabs erm(41)T28 rrlWT Yes (R)
5 Mabs erm(41)T28 rrlWT Yes (R)
6 Mmas erm(41)T28 rrlWT Yes (R)
7 Mmas erm(41)T28* rrlWT No nt
8 Mmas erm(41)T28* rrlWT No (S)
9 Mabs erm(41)T28 rrlMUT Yes (S)
10 Mb ol erm(41)T28* rrlWT No (S)
11 Mabs erm(41)T28 rrlWT Yes (R)
12 Mabs erm(41)T28 rrlWT Yes (R)
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Life Sciences, Microbiology and Virology