Usefulness of Multiple-Locus VNTR Fingerprinting in detection of clonality of community- and hospital-acquired Staphylococcus aureus isolates

Abstract

Staphylococcus aureus has become a major source of hospital infections and the risk of colonisation and infection by community-acquired methicillin-resistant S. aureus (CA-MRSA) is increasingly higher. Because of the importance of S. aureus to public health, many molecular typing methods have been developed to determine its transmission routes and source of infection during epidemiological investigations. In this study we evaluated the usefulness of multiplex PCR based Multi-Locus VNTR Fingerprinting (MLVF) as the first step method for rapid differentiation of Croatian and Polish S. aureus isolates in hospital and community settings. This is a first report of the usefulness of MLVF in typing of hospital-acquired methicillin-sensitive S. aureus (HA-MSSA) and four CA-MRSA isolates. A total of 47 isolates of S. aureus recovered in Croatia in 2004 and in Poland in 2006 and 2007 were tested. The MLVF results were compared to those produced by other typing methods, such as Pulsed-Field Gel Electrophoresis (PFGE), Multi-Locus Sequence Typing (MLST) and spa typing. The MLVF analysis showed almost the same clonality results as the remaining typing methods although some differences were found. Epidemiological data about the relation among S. aureus isolates and the results produced by typing methods applied in the present study indicate that because of the advantages in ease and speed of Variable Number of Tandem Repeats (VNTR) procedure over PFGE, spa typing and MLST, MLVF can be used as a first screening method followed by additional typing.

Comparison of Fingerprinting Methods for Typing Methicillin-Resistant Staphylococcus aureus Sequence Type 398

“…In this set of AA-MRSA isolates, the MLVA was not able to distinguish among isolates with the same PFGE profile. In agreement with our results, previously published reports of MLVA typing of clinical MRSA isolates had more discriminatory power than those of spa typing and MLST (12,15,16,17). In contrast, most studies comparing the MLVA with PFGE have shown that the discriminatory power of PFGE was comparable to that of the MLVA or only slightly better.…”

“…In addition, three recently developed MLVA techniques, successfully applied to Staphylococcus aureus and more specifically to HA-MRSA and CA-MRSA, were evaluated and optimized for use with ST398 strains. Both the initial Polish system (15,16,17,23,24) and the Swiss system (10) are based on tandem repeats in genes, whereas the British system is based on staphylococcal interspersed repeat units, called SIRUs (11,12). In this study, only primers with discriminatory power were included in this optimized MLVA specific for AA-MRSA.…”

“…This method has proven to be useful for typing both Staphylococcus aureus and clinical MRSA isolates with good reproducibility and good discriminatory power. Because the MLVA is also simple, inexpensive, and easy to interpret, it is useful as a typing method for large-scale epidemiological studies (10,11,12,15,16,17,23,24,27).…”

Core genome conservation of Staphylococcus haemolyticus limits sequence based population structure analysis

“…The selection of our strain collection is biased, based on isolates which differs by PFGE. This has previously been reported to affect the discriminatory ability of MLVF (Holmes et al, 2010;Luczak-Kadlubowska et al, 2008). Furthermore, a better resolution might have been obtained if we had targeted more than five tandem repeat loci.…”

Overview of molecular typing methods for outbreak detection and epidemiological surveillance

“…In the spa sequence typing method, each identified repeat is associated to a code and a spa-type is deduced from the order of specific repeats. Although spa-typing has a lower discriminatory ability than PFGE [45,46], its cost-effectiveness, ease of use, speed, excellent reproducibility, appropriate in vivo and in vitro stability, standardised international nomenclature, high-throughput by using the StaphType software, and full portability of data via the Ridom database (http:// spaserver.ridom.de) makes this method the currently most useful instrument for characterising S. aureus isolates at the local, national and international levels [47][48][49][50][51][52]. Importantly, this approach ensures strict criteria for internal and external quality assurance of data submitted to the database that is curated by SeqNet.org [50,53].…”