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Comparison of Rapid and Routine Methods of Identification and Antibiotic Susceptibility Testing of Microorganisms from Blood Culture Bottles Cover

Comparison of Rapid and Routine Methods of Identification and Antibiotic Susceptibility Testing of Microorganisms from Blood Culture Bottles

Open Access
|May 2020

Figures & Tables

Fig. 1.

Microscopic appearance of Gram-positive bacteria after Gram staining with the routine method at a magnification of 1000×.
Microscopic appearance of Gram-positive bacteria after Gram staining with the routine method at a magnification of 1000×.

Fig. 2.

Microscopic appearance of Gram-positive bacteria after Gram staining with the rapid method at a magnification of 1000×.
Microscopic appearance of Gram-positive bacteria after Gram staining with the rapid method at a magnification of 1000×.

Fig. 3.

Microscopic appearance of Gram-negative bacteria after Gram staining with the routine method at a magnification of 1000×.
Microscopic appearance of Gram-negative bacteria after Gram staining with the routine method at a magnification of 1000×.

Fig. 4.

Microscopic appearance of Gram-negative bacteria after Gram staining with the rapid method at a magnification of 1000×.
Microscopic appearance of Gram-negative bacteria after Gram staining with the rapid method at a magnification of 1000×.

Distribution of bacteria identified by both methods at the genus and species level_

Rapid methodn (%)Routine methodn (%)
Gram-positive bacteria (total) 116 Gram-positive bacteria (total) 116
Staphylococcus aureus   7 (6.0) Staphylococcus aureus   8 (6.9)
MRSA: 2, MSSA: 5 MRSA: 3, MSSA: 5
Coagulase-negative Staphylococci 71 (61.2)    Coagulase-negative Staphylococci
Staphylococcus epidermidis: 45 Staphylococcus epidermidis: 48 76 (65.5)
Staphylococcus hominis: 16 Staphylococcus hominis: 18
Staphylococcusschleiferi: 4 Staphylococcusschleiferi: 4
Staphylococcus haemolyticus: 2 Staphylococcus haemolyticus: 2
Staphylococcus capitis: 2 Staphylococcus capitis: 2
Staphylococcus warneri: 2 Staphylococcus warneri: 2
Enterococci 20 (17.2)    Enterococci 20 (17.2)
Enterococcus faecalis: 18 Enterococcus faecalis: 18
Enterococcus faecium: 2  3 (2.6) Enterococcus faecium: 2  2 (1.8)
Arcanobacterium haemolyticum   3 (2.6) Arcanobacterium haemolyticum   2 (1.8)
Bacillus cereus/subtilis   2 (1.8) Bacillus subtilis   2 (1.8)
Dermacoccus nishinomiyaensis   4 (3.5) Dermacoccus nishinomiyaensis   2 (1.8)
Micrococcus luteus/lylae   3 (2.6) Micrococcus luteus/lylae   2 (1.8)
Corynebacterium amycolatum   3 (2.6) Corynebacterium amycolatum   2 (1.8)
Corynebacterium jeikeium Corynebacterium jeikeium
Gram-negative bacteria (total) 30    Gram-negative bacteria (total) 30
Escherichia coli 15 (50) Escherichia coli 15 (50)
Pseudomonas aeruginosa   5 (16.7) Pseudomonas aeruginosa   5 (16.7)
Klebsiella pneumoniae   5 (16.7) Klebsiella pneumoniae   5 (16.7)
Stenotrophomonas maltophilia   3 (10.0) Stenotrophomonas maltophilia   3 (10.0)
Acinetobacter baumannii   2 (6.7) Acinetobacter baumannii   2 (6.7)
Yeasts   4    Yeasts   4
Candida parapsilosis   2 (50) Candida parapsilosis   2 (50)
Candida tropicalis   2 (50) Candida tropicalis   2 (50)

Categorical distribution of discrepancies in the antibiotic susceptibility results of the rapid method compared to the routine method_

AntibioticsAgreementn (%)mEsn (%)MEsn (%)VMEsn (%)Totaln
Amikacin    30 (100)     30
Ampicillin    94 (100)     94
Amoxicillin/Clavulanic acid114 (100)   114
Aztreonam    26 (86.7)  1 (3.3)   3 (10)    30
Cefepime24 (80)   6 (20)    30
Cefoxitin  85 (98.8)  1 (1.2)     86
Ceftazidime  30 (100)     30
Ceftriaxone  30 (100)     30
Ciprofloxacin108 (87.1)10 (8.1)   6 (4.8)  124
Colistin  30 (100)     30
Clindamycin    93 (98.9)  1 (1.1)     94
Daptomycin    88 (93.6)  6 (6.4)     94
Ertapenem  30 (100)     30
Erythromycin  94 (100)     94
Fusidic acid    85 (98.8)   1 (1.2)     86
Gentamicin123 (99.2)  1 (0.8)   124
Imipenem  30 (100)     30
Meropenem  30 (100)     30
Linezolid  94 (100)     94
Oxacillin  94 (100)     94
Piperacillin/Tazobactam    22 (73.3)  8 (26.7)     30
Rifampin  94 (100)     94
Teicoplanin  94 (100)     94
Tetracycline  86 (100)     86
Tigecycline    92 (97.9)  2 (2.1)     94
TMP/SX120 (96.8)  3 (2.4)   1 (0.8)  124
Vancomycin  94 (100)     94
Total1934 (97.4)33 (1.7)1 (0.1)16 (0.8)1984

Distribution of microorganisms detected by Gram staining after centrifugation according to the rapid method procedure_

Gram-staining resultn (%)
Gram-positive cocci107 (70.4)
Gram-negative bacilli  30 (19.7)
Gram-positive bacilli    9 (5.3)
Gram-positive cocci + Gram-negative bacilli    2 (1.3)
Yeast (Candida spp.)    4 (2.6)
Total number of samples152 (100)

Analysis of the compatibility between the identification results of the rapid method when compared with the MALDI-TOF MS_

BacteriaFull consistencyn (%)Misidentifiedn (%)Not identifiedn (%)
Gram-positive bacteria104 (89.7)        12 (10.3)0
Gram-negative bacteria  30 (100)00
Yeasts    4 (100)00
Total138 (92)   12 (8)0

Distribution of the resistance profiles for Gram-positive and Gram-negative bacteria as a result of the antibiotic susceptibility testing when both methods were applied_

AntibioticsThe rapid method, n (%)The routine method, n (%)
SIRSIR
Amikacin    28 (93.3)2 (6.7)    28 (93.3)2 (6.7)
Ampicillin    18 (19.1)76 (80.9)    18 (19.1)76 (80.9)
Amoxicillin/Clavulanic acid    18 (15.8)96 (84.2)    18 (15.8)96 (84.2)
Aztreonam 18 (60)1 (3.3)11 (36.7) 15 (50)15 (50)    
Cefepime    20 (66.7)10 (33.3)    14 (46.7)16 (53.3)  
Cefoxitin36 (41.9)50 (58.1)35 (40.7)51 (59.3) 
Ceftazidime    10 (33.3)10 (33.3)10 (33.3)    10 (33.3)10 (33.3)10 (33.3) 
Ceftriaxone 18 (60)12 (40)    18 (60)12 (40)   
Ciprofloxacin    82 (66.1)42 (33.9)    66 (53.2)10 (8.1)48 (38.7)
Colistin   30 (100)   30 (100)
Clindamycin    50 (53.2)1 (1.1)43 (45.7)      51 (554.3)43 (45.7)
Daptomycin    71 (75.5)23 (24.5)    65 (69.1)29 (30.9)
Ertapenem    28 (93.3)2 (6.7)    28 (93.3)2 (6.7)
Erythromycin    14 (14.9)80 (85.1)    14 (14.9)80 (85.1)
Fusidic acid    35 (40.7)51 (59.3)    36 (41.9)50 (58.1)
Gentamicin    66 (53.2)58 (46.8)    66 (53.2)1 (0.8)57 (50)
Imipenem    28 (93.3)2 (6.7)    28 (93.3)2 (6.7)
Meropenem    28 (93.3)2 (6.7)    28 (93.3)2 (6.7)
Linezolid    94 (100)    94 (100)
Oxacillin    12 (12.8)82 (87.2)    12 (12.8)82 (87.2)
Piperacillin/Tazobactam    10 (33.3)10 (33.3)  10 (33.3)    16 (53.3)2 (6.7)12 (40)   
Rifampin  62 (66)32 (34)    62 (66)32 (34)   
Teicoplanin    94 (100)    94 (100)
Tetracycline    35 (40.7)51 (59.3)    35 (40.7)51 (59.3)
Tigecycline    84 (89.4)8 (8.5)2 (2.1)       86 (91.5)6 (6.4)2 (2.1)   
TMP/SX    55 (44.4)69 (55.6)    51 (41.1)3 (2.4)70 (56.5)
Vancomycin   94(100)   94 (100)
Total1102 (55.5)89 (4.5)793 (40)1077 (54.3)96 (4.8)811 (40.9)

Distribution of the identified species according to MALDI-TOF MS results when working with both methods_

OrganismsMALDI-TOFBiotyper scores< 1.7; 1.7–2.0; ≥ 2n n n TotalRapid methodnRoutine methodn
Gram-positive bacteria 116 116 116
Staphylococcus aureus 0 0 8 8    7    8
Staphylococcus epidermidis 0 12 36 48  45  48
Staphylococcus hominis 0 2 16 18  16  18
Staphylococcusschleiferi 0 0 4 4    4    4
Staphylococcus haemolyticus 0 0 2 2    2    2
Staphylococcus capitis 0 0 2 2    2    2
Staphylococcus warneri 0 0 2 2    2    2
Enterococcus faecalis 0 0 18 18  18  18
Enterococcus faecium 0 0 2 2    2    2
Arcanobacterium haemolyticum 0 1 1 2    3    2
Bacillus cereus/subtilis 0 0 0 0    1    0
Bacillus subtilis 0 0 2 2    2    2
Dermacoccus nishinomiyaensis 0 0 2 2    2    2
Micrococcus luteus/lylae 0 1 1 2    4    2
Corynebacterium amycolatum 0 1 1 2    3    2
Corynebacterium jeikeium 0 1 1 2    3    2
Gram-negative bacteria 30    30    30
Escherichia coli 0 0 15 15  15  15
Pseudomonas aeruginosa 0 1 4 5    5    5
Klebsiella pneumoniae 0 0 5 5    5    5
Stenotrophomonas maltophilia 0 0 3 3    3    3
Acinetobacter baumannii 0 0 2 2    2    2
Yeasts 4      4      4
Candida parapsilosis 0 0 2 2    2    2
Candida tropicalis 0 0 2 2    2
Total0 19 131 150150150
DOI: https://doi.org/10.33073/pjm-2020-019 | Journal eISSN: 2544-4646 | Journal ISSN: 1733-1331
Language: English
Page range: 165 - 176
Submitted on: Feb 13, 2020
Accepted on: Mar 29, 2020
Published on: May 15, 2020
Published by: Polish Society of Microbiologists
In partnership with: Paradigm Publishing Services
Publication frequency: 4 issues per year

© 2020 SADIK AKGUN, HAKAN SEZGIN SAYINER, published by Polish Society of Microbiologists
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.