First isolation of oleate-dependent Enterococcus faecalis small-colony variants from the umbilical exudate of a paediatric patient with omphalitis.
An oleate-dependent Enterococcus faecalis isolate representing small-colony variants (SCVs) was isolated from the umbilical exudate of a 31-month-old Japanese male patient in Nagano Children's Hospital, Azumino, Japan. The patient had been suffering from recurrent omphalitis since early infancy. The initial E. faecalis SCV isolate formed small colonies on sheep blood agar plates and tiny colonies on chocolate and modified Drigalski agar, although no visible growth was observed in HK-semi solid medium after 48 h incubation in ambient air. Moreover, the SCV isolate, the colonial morphology of which was reminiscent of Streptococcus species, could not be identified using the MicroScan WalkAway-40 and API 20 Strep systems, both of which yielded profile numbers that did not correspond to any bacterial species, probably as a result of insufficient growth of the isolate. The SCV isolate was subsequently identified as E. faecalis based on its morphological, cultural and biochemical properties, and this was confirmed by sequencing the 16S rRNA gene of the organism. Investigations revealed that the addition of oleate, an unsaturated fatty acid, enabled the isolate to grow on every medium with normal-sized colony morphology. Although it has long been known that long-chain fatty acids, especially unsaturated oleic acid, have a major inhibitory effect on the growth of a variety of microorganisms, including not only mycobacteria but also streptococci, this is, to the best of our knowledge, the first clinical isolation of an oleate-dependent E. faecalis SCV isolate. In addition, oleic acid might be considered to affect the cell membrane permeability of carbohydrates or antimicrobial agents such as β-lactams.
Department of Laboratory Medicine, Nagano Children's Hospital, Azumino 399-8288, Japan.
Noriko
N
Kubota
Department of Laboratory Medicine, Nagano Children's Hospital, Azumino 399-8288, Japan.
Kei
K
Kuzumoto
Department of Laboratory Medicine, Nagano Children's Hospital, Azumino 399-8288, Japan.
Eiko
E
Hidaka
Department of Surgery, Nagano Children's Hospital, Azumino 399-8288, Japan.
Katsumi
K
Yoshizawa
Department of Laboratory Medicine, Nagano Children's Hospital, Azumino 399-8288, Japan.
Kayoko
K
Yumoto
Division of Clinical Microbiology, Department of Biomedical Laboratory Sciences, School of Health Sciences, Shinshu University School of Medicine, Matsumoto 390-8621, Japan.|Division of Infection Control and Microbiological Regulation, Department of Health and Medical Sciences, Shinshu University Graduate School of Medicine, Matsumoto 390-8621, Japan.
Kozue
K
Oana
Department of Infection Control, Nagano Children's Hospital, Azumino 399-8288, Japan.|Department of Laboratory Medicine, Nagano Children's Hospital, Azumino 399-8288, Japan.
Yoshifumi
Y
Ogiso
Department of Infection Control, Nagano Children's Hospital, Azumino 399-8288, Japan.
Tomohiko
T
Nakamura
Division of Clinical Microbiology, Department of Biomedical Laboratory Sciences, School of Health Sciences, Shinshu University School of Medicine, Matsumoto 390-8621, Japan.|Division of Infection Control and Microbiological Regulation, Department of Health and Medical Sciences, Shinshu University Graduate School of Medicine, Matsumoto 390-8621, Japan.
Yoshiyuki
Y
Kawakami
D000362:Agar / Q000378:metabolism; D000818:Animals; D044466:Asian People; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002675:Child, Preschool; D003470:Culture Media / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics; D013293:Enterococcus faecalis / Q000235:genetics* / Q000302:isolation & purification*; D005227:Fatty Acids / Q000378:metabolism; D016908:Gram-Positive Bacterial Infections / Q000378:metabolism / Q000382:microbiology*; D006801:Humans; D008297:Male; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism; D019301:Oleic Acid / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012756:Sheep / Q000378:metabolism; D014470:Umbilical Cord / Q000378:metabolism / Q000382:microbiology*
D001426:Bacterial Proteins; D003470:Culture Media; D004269:DNA, Bacterial; C490371:FabZ protein, Enterococcus faecalis; D005227:Fatty Acids; D009097:Multienzyme Complexes; D012336:RNA, Ribosomal, 16S; D019301:Oleic Acid; D000362:Agar