Characterization of Staphylococcus aureus small colony variant strains isolated from Italian patients attending a regional cystic fibrosis care centre.
Small colony variant (SCV) Staphylococcus aureus are a subpopulation of auxotroph, slow-growing strains causing persisting and relapsing infections in cystic fibrosis (CF) patients. Twenty-eight SCV and 29 normal S. aureus strains were isolated from 42 out of 222 Italian CF patients. The isolates were characterized for: susceptibility to antibiotics, methicillin-resistance (MR), Panton Valentine leukocidin, auxotrophy, hypermutability and biofilm formation. Clonal identity of SCV and normal strains was determined by pulsed-field gel electrophoresis. We found that 27 out of 28 SCVs were thymidine-dependent. Furthermore, in contrast to normal phenotype, SCVs were characterized by antibiotic resistance. We also found that 39.3% SCV vs 20.7% normal strains were strong mutators. Moreover, SCVs showed a higher capability to form biofilm compared to normal strains (100% vs 59%). Importantly, we found evidence of clonal spread of SCV strain among CF patients. Using molecular typing, we found that five patients shared the same type A and five out of seven MR-SCV belonged to the same clone (Clone C). The particular virulence and spreading ability of MR-SCV observed highlights the importance of accurate identification and susceptibility testing of these strains. It is important to adopt the optimal approach to treat patients and to prevent cross-infection in CF centres.
Microbiology Laboratory of Giannina Gaslini Institute, Largo G. Gaslini 5, 16147 Genoa, Italy.
Patrizia
P
Morelli
Microbiology Laboratory of Giannina Gaslini Institute, Largo G. Gaslini 5, 16147 Genoa, Italy.
Alessandra
A
De Alessandri
DINOGMI Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics and Mother-Infant Sciences, L.go P. Daneo 3, 16132 Genoa, Italy.
Graziana
G
Manno
Microbiology Section, DISC, University of Genoa, Largo R. Benzi 10, 16132 Genoa, Italy.
Anna
A
Marchese
Microbiology Laboratory of Giannina Gaslini Institute, Largo G. Gaslini 5, 16147 Genoa, Italy.
Marta
M
Bassi
Microbiology Laboratory of Giannina Gaslini Institute, Largo G. Gaslini 5, 16147 Genoa, Italy.
Raffaele
R
Lobello
Microbiology Laboratory of Giannina Gaslini Institute, Largo G. Gaslini 5, 16147 Genoa, Italy; Microbiology Section, DISC, University of Genoa, Largo R. Benzi 10, 16132 Genoa, Italy.
Laura
L
Minicucci
Microbiology Laboratory of Giannina Gaslini Institute, Largo G. Gaslini 5, 16147 Genoa, Italy.
Roberto
R
Bandettini
D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002648:Child; D002675:Child, Preschool; D003550:Cystic Fibrosis / Q000150:complications* / Q000208:ethnology* / Q000382:microbiology; D005260:Female; D006801:Humans; D007558:Italy; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D013203:Staphylococcal Infections / Q000209:etiology / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification*; D055815:Young Adult
D000900:Anti-Bacterial Agents
Antibiotic resistance; Biofilm; Cystic fibrosis; Small colony variants; Staphylococcus aureus; hypermutability