Comparison of traditional and molecular methods of typing isolates of Staphylococcus aureus

Abstract

Fifty-nine Staphylococcus aureus isolates and 1 isolate of Staphylococcus intermedius were typed by investigators at eight institutions by using either antibiograms, bacteriophage typing, biotyping, immunoblotting, insertion sequence typing with IS257/431, multilocus enzyme electrophoresis, restriction analysis of plasmid DNA, pulsed-field or field inversion gel electrophoresis, restriction analysis of PCR-amplified coagulase gene sequences, restriction fragment length polymorphism typing by using four staphylococcal genes as probes, or ribotyping. Isolates from four well-characterized outbreaks (n = 29) and a collection of organisms from two nursing homes were mixed with epidemiologically unrelated stock strains from the Centers for Disease Control and Prevention. Several isolates were included multiple times either within or between the sets of isolates to analyze the reproducibilities of the typing systems. Overall, the DNA-based techniques and immunoblotting were most effective in grouping outbreak-related strains, recognizing 27 to 29 of the 29 outbreak-related strains; however, they also tended to include 3 to 8 epidemiologically unrelated isolates in the same strain type. Restriction fragment length polymorphism methods with mec gene-associated loci were less useful than other techniques for typing oxacillin-susceptible isolates. Phage typing, plasmid DNA restriction analysis, and antibiogram analysis, the techniques most readily available to clinical laboratories, identified 23 to 26 of 29 outbreak-related isolates and assigned 0 to 6 unrelated isolates to outbreak strain types. No single technique was clearly superior to the others; however, biotyping, because it produced so many subtypes, did not effectively group outbreak-related strains of S. aureus.

Antibiotic resistance in staphylococci associated with cats and dogs

“…Other applications of PFGE in canine staphylococci include typing of MRS (Pak et al 1999;Yamashita et al 2005). The discriminatory ability of PFGE is very high and has been shown to be superior to bacteriophage typing, antibiogram and ribotyping (Tenover et al 1994;Bannerman et al 1995). Results from PFGE are more reliable and very reproducible.…”

“…MLEE has been applied to many bacterial species including Staph. aureus (Selander et al 1986) but the discriminatory ability depends to a large extent on the number of enzymes used (Tenover et al 1994).…”

Guidelines for the validation and application of typing methods for use in bacterial epidemiology

“…Unfortunately, new molecular typing methods are often proposed for general use without sufficient prior critical evaluation. For example, they may not have been standardised, a minimal number of isolates may have been used for validation, their agreement with epidemiological data may not have been assessed, or the suitability of a specific method-microbe combination for a specific bacterial taxon may not have been addressed [19][20][21][22][23][24][25][26][27][28]. Finally, basic terminology-including fundamental terms such as 'isolate', 'strain', 'type' or 'clone'-is often used differently by different workers in the field of bacterial epidemiology.…”

Molecular diversity of live-attenuated prototypic vaccine strains and clinical isolates of Staphylococcus aureus

“…In the past decade, numerous molecular techniques with dissimilar discriminatory capacity were used for discrimination of S. aureus isolates in epidemiological studies [7]. Identi¢cation and comparison of S. aureus isolates from mastitic cow milk were established by several molecular methods [8,9].…”