Higher biofilm formation in multidrug-resistant clinical isolates of Staphylococcus aureus.
The biofilm-forming capacity of Staphylococcus aureus contributes to antibiotic resistance, but whether antibiotic-resistant strains have the capacity to form biofilms has not yet been determined. Therefore, we recovered 101 clinical isolates of S. aureus and performed antibiotic susceptibility testing for 30 antibiotics using a VITEK II automatic system. We then carried out a biofilm assay on 96-well polystyrene plates. In addition, the presence of IS256 involved in the variation of biofilm phases of S. aureus was determined by polymerase chain reaction. The prevalence of IS256 was significantly related to multidrug resistance as well as biofilm expression, with biofilm positivity in 27 (39.7%) of the 68 IS256-positive strains and 3 (9.1%) of the 33 IS256-negative strains. In our analysis of the relationship between meticillin resistance and biofilm formation, we found that the rate of biofilm positivity was 37.9% (25/66) for meticillin-resistant strains and 14.3% (5/35) for meticillin-susceptible strains (P<0.05). Staphylococcal cassette chromosome mec (SCCmec) typing found that SCCmec type IV was most prevalent, comprising 14 (56.0%) of the 25 biofilm-positive, meticillin-resistant strains. A statistical analysis testing the relationship between multidrug resistance and biofilm formation revealed a significantly higher rate of biofilm development in strains with greater multiresistance compared with strains with less multiresistance. Our results suggest that the multidrug-resistant clinical isolates of S. aureus have a greater likelihood of developing biofilms on medical devices.
Department of Microbiology, Medical School, Chosun University, 375 Seosuk-dong, Dong-gu, Gwangju 501-759, Republic of Korea.
An Sung
AS
Kwon
Gwang Chul
GC
Park
So Yeon
SY
Ryu
Dong Hoon
DH
Lim
Dong Yoon
DY
Lim
Chul Hee
CH
Choi
Yoonkyung
Y
Park
Yong
Y
Lim
D015373:Bacterial Typing Techniques; D018441:Biofilms / Q000254:growth & development*; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial; D005838:Genotype; D006801:Humans; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction; D013203:Staphylococcal Infections / Q000382:microbiology; D013211:Staphylococcus aureus / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification / Q000502:physiology*
D004251:DNA Transposable Elements; D004269:DNA, Bacterial