Pulsed-field gel electrophoresis as a replacement for bacteriophage typing of Staphylococcus aureus

Abstract

Bacteriophage typing (BT) (World Health Organization method) has been used at the Centers for Disease Control and Prevention for over 30 years to type isolates of Staphylococcus aureus. Since studies have shown that BT patterns have poor reproducibility and because BT fails to type a high percentage (15 to 20%) of isolates, the Centers for Disease Control and Prevention has converted from using BT to using pulsed-field gel electrophoresis (PFGE) for strain typing S. aureus. We compared the results of BT with results of PFGE for typing 300 isolates of S. aureus, including strains from several well-characterized outbreaks. Ninety-six isolates were BT group I, 19 were group II, 82 were group III, 7 were group V, and 96 were nontypeable. PFGE identified subgroups within each phage group and thus was more discriminating than BT, which identified no subgroups. PFGE was able to type all isolates and distinguish related from unrelated strains of S. aureus. Our modified, standardized PFGE methodology should enable typing laboratories to obtain rapid, reliable results in 3 to 4 days when starting with an isolated colony on agar media.

Replacement of methicillin-resistant Staphylococcus aureus clones in Hungary over time: a 10-year surveillance study

“…Phage typing is still used to characterise S. aureus [41], but this collection showed low typeability, with 35.4% of the isolates not being assigned to any group (i.e., belonging to mixed phage groups or not typeable). There was poor concordance between phage typing and the DNA-based approaches used, as has been observed previously [42].…”

Clonal dissemination of epidemic methicillin-resistant Staphylococcus aureus in Belgium and neighboring countries

“…Phage typing has long been used as a reference S. aureus typing method, but it is hampered by a substantial proportion of non-typable MRSA isolates and by variability of patterns, thereby leading to its replacement by PFGE typing in some reference laboratories [13]. For clonal delineation of S. aureus, PFGE analysis has emerged as one of the most discriminating methods.…”

“…Epidemiologic typing of MRSA can be achieved by a number of molecular methods [5][6][7][8][9][10][11][12]. Pulsed-field gel electrophoresis (PFGE) of genomic macrorestriction fragments has been recommended as a standard [13]. The advantages of PFGE include full typability, good reproducibility within centers, recognizable stability of genomic pattern relatedness over years and high discriminatory power.…”

Assessment of ica operon carriage and biofilm production in Staphylococcus epidermidis isolates causing bacteraemia in bone marrow transplant recipients

“…DNA isolation and PFGE were performed as described previously with minor modifications [11]. S. epidermidis isolates were grown from a single colony overnight at 37°C.…”