Analysis and Characterization of Staphylococcus aureus Small Colony Variants Isolated From Cystic Fibrosis Patients in Austria.

Cystic fibrosis (CF) is the most common hereditary lung disease in the Caucasian population, characterized by viscous bronchial secretion, consecutive defective mucociliary clearance, and unavoidable colonization with microorganisms. Besides Pseudomonas aeruginosa, Staphylococcus aureus is the most common bacterial species colonizing the CF respiratory tract. Under antibiotic pressure S. aureus is able to switch to small colony variants (SCV). These small colony variants can invade epithelial cells, overcome antibiotic therapy inside the cells and can be the starting point for extracellular recolonization. The aim of the present study was the isolation and characterization of S. aureus small colony variants from Austrian cystic fibrosis patients. Samples collected from 147 patients were screened for the presence of S. aureus wild-type and small colony variants. Antibiotic susceptibility testing and determination of the small colony variants causing auxotrophism were performed. Wild-type isolates were assigned to corresponding small colony variants with spa typing. In total, 17 different small colony variant isolates and 12 corresponding wild-type isolates were obtained. 13 isolates were determined thymidine auxotroph, 2 isolates were auxotroph for hemin, and none of the tested isolates was auxotroph for both, respectively. The presence of SCVs is directly related to a poor clinical outcome, therefore a monitoring of SCV prevalence is recommended. This study revealed rather low SCV ratios in CF patients compared to other countries.

Prevalence of emm types and antimicrobial susceptibility of Streptococcus dysgalactiae subsp. equisimilis in Austria.

OBJECTIVES: An increase of severe infections caused by Streptococcus dysgalactiae subsp. equisimilis (SDSE) similar to infections caused by Streptococcus pyogenes has been reported over the last years. Little is known about infections with SDSE in Austria. Therefore, we investigated a collection of 113 SDSE invasive and non-invasive isolates from different infection sites and type of infections as well as patients' characteristics. METHODS: The isolates were phenotypically identified and emm typed using the enlarged emm database from the Centers for Disease Control and Prevention. Additionally, 13 antimicrobial agents were tested using EUCAST guidelines and virulence genes were investigated. RESULTS: Severe SDSE infections were most common in elderly men with underlying diseases especially diabetes mellitus. With VitekMS identification of SDSE isolates was successful to the species level only. Emm typing revealed 24 different emm types, one new type and one new subtype. StG485, stG6, stC74a, stG643, and stG480 were the predominant types in this study, stC74a and stG652 in invasive infections and stG643, stC74a and stG485 in non-invasive infections. Resistance was observed to tetracycline (62%), macrolides (13%) with one M phenotype, and clindamycin (12%) presenting 6 constitutive MLS(B) phenotypes and 8 inducible MLS(B) phenotypes. Levofloxacin resistance was detected only in one isolate. All isolates tested for virulence genes were positive for scpA, ska, saga and slo. Superantigenic genes were negative except speG(dys) (positive 17/34; 50%). CONCLUSION: This paper presents the first report of SDSE infections in Austria. Severe SDSE infections were found mainly in elderly men with underlying diseases. SDSE isolates demonstrated substantial emm type diversity without association with infections site or invasiveness. Analysis of virulence genes showed no significant difference between invasive and non-invasive infections.

Genetic and Phenotypic Characteristics of Staphylococcus aureus Isolates from Cystic Fibrosis Patients in Austria.

BACKGROUND: Cystic fibrosis (CF) is the most common life-limiting inherited disease in Caucasian populations. While pathological changes can be seen in various organs, morbidity and mortality are mainly related to the respiratory tract, with patients suffering from chronic bronchopulmonary infections with characteristic pathogens including Staphylococcus aureus. OBJECTIVES: To date, there is only very limited data on the genetic and phenotypic characteristics of S. aureus in CF patients. Therefore, in our study, we characterized 58 S. aureus isolates collected from CF patients in Austria by spa typing, DNA microarray profiling, as well as antimicrobial susceptibility testing in order to determine common genomic and antimicrobial resistance features. The tested strain collection exhibited high genomic diversity. RESULTS: The 58 isolates were assigned to 16 clonal complexes and 48 spa types and differed greatly regarding their virulence and resistance gene profiles. The predominant clonal complexes were MLST CC30 (22%), CC15 (16%), CC45 (14%), and CC5 (12%), complexes that are highly prevalent worldwide among S. aureus strains isolated from humans colonized or infected with S. aureus. DNA microarray profiles showed a wide variety of genes encoding antimicrobial resistance and virulence factors such as various leukocidins, haemolysins, enterotoxins, exfoliative toxins, toxic shock syndrome toxin, as well as genes involved in adhesion and immune evasion. CONCLUSIONS: While a large number of strains exhibited resistance to one or several antimicrobial agents, methicillin-resistant S. aureus was found at a low prevalence of 3% (n = 2) only. The two methicillin-resistant S. aureus isolates were assigned to CC152/t355 (SCCmecV) and CC5/t001 (SCCmecI). This is the first study to genetically characterize S. aureus isolates in CF patients in Austria.

Occurrence and genotyping using automated repetitive-sequence-based PCR of methicillin-resistant Staphylococcus aureus ST398 in Southeast Austria.

In this retrospective study, the occurrence and genetic relatedness of methicillin-resistant Staphylococcus aureus (MRSA) ST398 in Austrian MRSA patients was investigated. From 2002 to 2008, 14 MRSA ST398 were detected. First occurrence of MRSA ST398 was already found in 2004. Spa ribotyping assigned 12 isolates to spa type t011 and 1 each to spa type t034 and spa type t1451. Isolated MRSA ST398 was nontypeable by pulsed-field gel electrophoresis (NT-MRSA) using restriction enzyme SmaI; therefore, genotyping was performed using automated repetitive-sequence-based PCR (rep-PCR) on the DiversiLab system. Rep-PCR results assigned 10 (71%) of the 14 MRSA ST398 into 1 cluster with a similarity >95%; there was 1 cluster consisting of 2 isolates with a similarity >99% and 2 unique MRSA ST398 isolates. In conclusion, MRSA ST398 was continuously detected in Southeast Austria; first in 2004 with up to 5 MRSA ST398 isolates in 2008. Automated rep-PCR proved as a reliable technique in determining genetic relatedness of NT-MRSA ST398 and demonstrates clonal spread of MRSA ST398 in the investigated region.