Comparison of DNA sequencing of the protein A gene polymorphic region with other molecular typing techniques for typing two epidemiologically diverse collections of methicillin-resistant Staphylococcus aureus.

The aim of this study was to compare the recently developed typing approach for methicillin-resistant Staphylococcus aureus (MRSA) based on the DNA sequencing of the protein A gene polymorphic region (spaA typing) with a combination of three well-established molecular typing techniques: ClaI-mecA vicinity polymorphisms, ClaI-Tn554 insertion patterns, and SmaI pulsed-field gel electrophoresis (PFGE) profiles. In order to evaluate the applicability of this typing technique in different types of studies, two groups of MRSA clinical isolates were analyzed: a collection of 185 MRSA isolates circulating in Hungary recovered from 17 hospitals in seven cities during a 3-year period (1994 through 1996), and a selection of 53 MRSA strains isolated in a single hospital in Hungary between 1997 and 1998. The 238 MRSA clinical strains from Hungary were first classified in clonal types (defined as ClaI-mecA::ClaI-Tn554::SmaI-PFGE patterns), and 65 of the 238 strains, representing major MRSA clones and some sporadic clones, were further analyzed by spaA typing. Our results showed that the lineages most recently introduced in the hospital setting showed little variability in spaA types, whereas the MRSA clones circulating for a longer period of time and spread among several hospitals showed a higher degree of variability. The implementation of the spaA typing method was straightforward, and the results obtained were reproducible, unambiguous, and easily interpreted. This method seems to be adequate for outbreak investigations but should be complemented with other techniques in long-term surveillance or in studies comparing distant clonal lineages.

Current state and tendencies of antibiotic resistance in Hungary.

This survey is based on data for 245 903 isolates reported by Public Health Network laboratories in 1983. Facultatively pathogenic Gram-negative bacteria comprised two-third of the isolates, and--except Escherichia coli--were resistant in a high percent to the most frequently used antibiotics. Oxacillin and vancomycin were the most effective against Staphylococcus aureus being in 94.7% resistant to penicillin. In contrast to other streptococci, all Streptococcus pyogenes strains were sensitive to penicillin. The majority of the Gram-positive strains were resistant to tetracycline. A comparison to results reported earlier (1974 to 1983) showed an increasing resistance rate mainly to ampicillin, carbenicillin, co-trimoxazole and gentamicin, which were introduced in therapy during this period. Resistance rate of almost all species has increased to gentamicin, e.g. that of Proteus mirabilis has risen tenfold. Emergence of Haemophilus influenzae resistant to ampicillin, and increasing resistance rates of P. mirabilis and Streptococcus pneumoniae to almost all drugs are remarkable findings. The increasing or variable usage of drugs that have been used for a long time did not influence resistance markedly. In some instances the resistance rates even diminished, e.g. the tetracycline resistance of agents associated with enteric diseases. A restricted use of chloramphenicol reflected in a decreased resistance of some species. Multiresistant Gram-negative strains--which are resistant to all drugs frequently used in Hungary--were isolated in 12.7% from a representative clinical material. The frequent occurrence of multiresistant P. mirabilis and Acinetobacter isolates is a new phenomenon. Surprisingly, the percentage of multiresistant E. coli strains was very low. Amikacin and netilmicin were found to be the most effective against multiresistant isolates.