Identification of biochemically atypical Staphylococcus aureus clinical isolates with three automated identification systems.
Between January and April 2002, a total of 271 strains of Staphylococcus aureus were isolated from clinical specimens at Toho University Omori Hospital, Japan, including 201 (74.2 %) which were identified as meticillin-resistant S. aureus (MRSA). However, 34 (12.5 %) were biochemically atypical, because they did not produce acid on mannitol salt agar or did not agglutinate in Staphaurex testing but were categorized as MRSA by PCR analysis and by antibiotic susceptibility. Three automatic identification systems, AutoScan-4 (Dade Behring), BD Phoenix (Becton Dickinson) and Vitek 2 (bioMérieux), were evaluated by testing these atypical S. aureus isolates. The AutoScan-4 and Phoenix systems identified all 34 isolates as S. aureus. Without additional tests such as Staphaurex, observation of colony pigment and haemolysins on sheep blood agar, Vitek 2 identified only 16 isolates (47.1 %) as S. aureus with good or better confidence levels and misidentified one of the remaining isolates as Staphylococcus chromogenes. This study shows that it is possible to identify these physiologically atypical S. aureus isolates correctly by using the Phoenix and AutoScan-4 fully automatic identification systems.
Ishii
Yoshikazu
Y
Department of Microbiology and Infectious Diseases, Toho University School of Medicine, 5-21-16 Omori-nishi, Ota-ku, Tokyo 1438540, Japan.
Alba
Jimena
J
Department of Microbiology and Infectious Diseases, Toho University School of Medicine, 5-21-16 Omori-nishi, Ota-ku, Tokyo 1438540, Japan.
Maehara
Chikako
C
Clinical Laboratory Department, Toho University Omori Hospital, Japan.
Murakami
Hinako
H
Clinical Laboratory Department, Toho University Omori Hospital, Japan.
Matsumoto
Tetsuya
T
Clinical Laboratory Department, Toho University Omori Hospital, Japan.|Department of Microbiology and Infectious Diseases, Toho University School of Medicine, 5-21-16 Omori-nishi, Ota-ku, Tokyo 1438540, Japan.
Tateda
Kazuhiro
K
Clinical Laboratory Department, Toho University Omori Hospital, Japan.|Department of Microbiology and Infectious Diseases, Toho University School of Medicine, 5-21-16 Omori-nishi, Ota-ku, Tokyo 1438540, Japan.
Furuya
Nobuhiko
N
Clinical Laboratory Department, Toho University Omori Hospital, Japan.|Department of Microbiology and Infectious Diseases, Toho University School of Medicine, 5-21-16 Omori-nishi, Ota-ku, Tokyo 1438540, Japan.
Iwata
Morihiro
M
Clinical Laboratory Department, Toho University Omori Hospital, Japan.
Yamaguchi
Keizo
K
Clinical Laboratory Department, Toho University Omori Hospital, Japan.|Department of Microbiology and Infectious Diseases, Toho University School of Medicine, 5-21-16 Omori-nishi, Ota-ku, Tokyo 1438540, Japan.
D000900:Anti-Bacterial Agents; D001331:Automation; D015373:Bacterial Typing Techniques / Q000295:instrumentation* / Q000379:methods*; D006801:Humans; D016106:Methicillin Resistance; D012680:Sensitivity and Specificity; D013203:Staphylococcal Infections / Q000382:microbiology; D013211:Staphylococcus aureus / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism
D000900:Anti-Bacterial Agents