1. The identification of anaerobic bacteria using MALDI-TOF MS system VITEK MS
Wonmok Lee, Myungsook Kim, Heejung Yim, Dongeun Yong, Seok Hoon Jeong, and Kyungwon Lee
Department of Laboratory Medicine and
Research Institute of Bacterial Resistance,
Yonsei University College of Medicine, Seoul, Korea

2. Background
Matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS)
A rapid, inexpensive, and accurate method for identification of microorganisms
Protein spectral profiles (fingerprints) from whole bacterial cells
Comparing these fingerprints to a database of reference spectra by the use of various algorithms
Few minutes from colony to result for a sample

3. MALDI-TOF MS microorganisms identification
Choice a colony
Prepare on a MALDI plate
Generate protein
spectral profiles
Compare to reference database
Identified species

4. Aims
To evaluate the performance of a MALDI-TOF MS system for the identification of anaerobic bacteria isolated from clinical specimens

5. Materials and Methods Isolates
Clinical isolates : 274 anaerobic bacteria ( )
Identification of the bacterial isolates
Traditional identification method: Gram stain, colony morph., oxidase test, indole test, etc.
Rapid ID 32A system and/or VITEK 2 ANC card (bioMérieux)
16s rRNA gene sequencing  EzTaxon server 2.1
VITEK MS system (bioMérieux)
Axima Assurance mass spectrometer (Shimadzu Corporation)
MYLA software 2 (bioMérieux)
VITEK MS IVD V1 database
Advanced spectra classifier (ASC) algorithm

6. Gram-negative bacilli
Results
Gram-negative bacilli
(No. of isolates)
Agreement with:
No ID
Mis ID
Species
Genus
Bacteroides fragilis (92) 92
Bacteroides thetaiotaomicron (26) 26
Bacteroides uniformis (6) 6
Bacteroides vulgates (5) 5
Bacteroides ovatus (3) 3
Bacteroides faecis (2) 2
Bacteroides intestinalis (1) 1
Bacteroides nordii (1)
Bacteroides salyersiae (1)
Bacteroides sp (7)
Parabacteroides distasonis (3)
Parabacteroides gordonii (1)
Subtotal (148)
140 (94.6)
3 (2.0)
5 (3.4)

7. Gram-negative bacilli
(No. of isolates)
Agreement with:
No ID
Mis ID
Species
Genus
Prevotella bivia (5) 5
Prevotella buccae (4) 4
Prevotella melaninogenica (3) 3
Prevotella buccalis (1) 1
Prevotella denticola (1)
Prevotella intermedia (1)
Subtotal (15)
14 (93.3)
1 (6.7)

8. Gram-positive bacilli
(No. of isolates)
Agreement with:
No ID
Mis ID
Species
Genus
Clostridium perfringens (12) 12
Clostridium ramosum (6) 4 2
Clostridium bifermentans (2) 1
Clostridium tertium (2)
Clostridium butyricum (1)
Clostridium difficile (1)
Clostridium sporogenes (1)
Clostridium bolteae (1)
Clostridium citroniae (1)
Clostridium hastiforme (1)
Clostridium hathewayi (1)
Clostridium innocuum (1)
Clostridium sp (2)
Subtotal (32)
22 (68.8)
1 (3.1)
8 (25.0)

9. Gram positive bacilli
(No. of isolates)
Agreement with:
No ID
Mis ID
Species
Genus
Eggerthella lenta (26) 19 6 1
Actinomyces cardiffensis (1)
Actinomyces georgiae (1)
Bifidobacterium sp (2)
Bulleidia extructa (2) 2
Paraeggerthella hongkongensis (1)
Propionibacterium acnes (1)
Robinsoniella peoriensis (1)
Subtotal (35)
20 (57.1)
1 (2.9)
10 (28.6)
4 (11.4)

10. Gram positive cocci
(No. of isolates)
Agreement with:
No ID
Mis ID
Species
Genus
Finegoldia magna (11) 10 1
Peptoniphilus asaccharolyticus (9) 2 3 4
Parvimonas micra (5)
Peptostreptococcus anaerobius (1)
Peptoniphilus gorbachii (1)
Anaerococcus murdochii (1)
Anaerococcus vaginalis (2)
Anaerococcus sp (2)
Subtotal (32)
17 (53.1)
3 (9.4)
10 (31.3)
2 (6.3)
Gram-negative cocci
Veillonella dispar (2)
Veillonella sp (10) 9
Subtotal (12)
9 (75)
2 (16.7)
1 (8.3)

11. Organisms
(No. of isolates)
Agreement with:
No ID
Mis ID
Species
Genus
GNB (163)
154 (94.5)
3 (1.8)
5 (3.1)
1 (0.6)
GPB (67)
42 (62.7)
2 (3.0)
18 (26.9)
5 (7.5)
GPC (32)
17 (53.1)
3 (9.4)
10 (31.3)
2 (6.3)
GNC (12)
9 (75.0)
2 (16.7)
1 (8.3)
Total (274)
222 (81.0)
10 (3.6)
34 (12.4)
8 (2.9)

12. 16S rRNA 32A and/or ANC VITEK MS Agreement with: Others Species Genus
GNB (15)
13 (86.7)
2 (13.3)
8 (53.3)
3 (20.0)
4 (26.7)
GPB (20)
3 (15.0)
9 (45.0)
8 (40.0)
5 (25.0)
4 (20.0)
11 (55.0)
GPC (6)
1 (16.7)
4 (66.7)
5 (83.3)
GNC (12)
11 (91.7)
1 (8.3)
9 (75.0)
2 (16.7)
Total (52)
4 (7.5)
34 (64.2)
15 (28.3)
23 (43.4)
9 (17.0)
21 (39.6)
GNB: Bacteroides sp (11); Parabacteroides sp (1); Prevotella sp (3)
GPB: Clostridium sp (11); other GPR (9)
GPC: Bulleidia sp (2); Actinomyces sp (2); other GPC (2)
GNC: Veillonella sp (12)
Others: No ID or Mis ID
32a anc 와 16s 결과 비교
Vitek ms와 결과 비교

13. Summary & Conclusion
Anaerobic bacteria isolated frequently from clinical specimens were identified accurately as species level
Some of E. lenta, P. asaccharolyticus and organisms not registered reference DB were not identified exactly
B. fragilis
(96/96)
B. thetaiotaomicron
(26/26) VS
E. lenta
(19/26)
C. perfringens
(12/12)
P. asaccharolyticus
(2/9)
F. magna
(10/10)
Prevotella sp
(14/15)
The MALDI-TOF MS system is a fast and reliable method for the identification of most relevant anaerobic bacterial isolates in the clinical laboratory

14. Thank you.