Coagulase-negative staphylococci (CoNS) are the most frequently isolated bacteria from the blood and the predominant cause of nosocomial infections. Macrolides, lincosamides and streptogramin B (MLSB) antibiotics, especially erythromycin and clindamycin, are important therapeutic agents in the treatment of methicillin-resistant staphylococci infections. Among CoNS, Staphylococcus hominis represents the third most common organism. In spite of its clinical significance, very little is known about its mechanisms of resistance to antibiotics, especially MLSB. Fifty-five S. hominis isolates from the blood and the surgical wounds of hospitalized patients were studied. The erm(C) gene was predominant in erythromycin-resistant S. hominis isolates. The methylase genes, erm(A) and erm(B), were present in 15 and 25% of clinical isolates, respectively. A combination of various erythromycin resistance methylase (erm) genes was detected in 15% S. hominis isolates. The efflux gene msr(A) was detected in 18% of isolates, alone in four isolates, and in different combinations in a further six. The lnu(A) gene, responsible for enzymatic inactivation of lincosamides was carried by 31% of the isolates. No erythromycin resistance that could not be attributed to the genes erm(A), erm(B), erm(C) and msr(A) was detected. In S. hominis, 75 and 84%, respectively, were erythromycin resistant and clindamycin susceptible. Among erythromycin-resistant S. hominis isolates, 68% of these strains showed the inducible MLSB phenotype. Four isolates harbouring the msr(A) genes alone displayed the MSB phenotype. These studies indicated that resistance to MLSB in S. hominis is mostly based on the ribosomal target modification mechanism mediated by erm genes, mainly the erm(C), and enzymatic drug inactivation mediated by lnu(A).
- MeSH
- antibakteriální látky farmakologie MeSH
- bakteriální proteiny genetika metabolismus MeSH
- lidé MeSH
- linkosamidy farmakologie MeSH
- makrolidy farmakologie MeSH
- methyltransferasy genetika metabolismus MeSH
- mikrobiální testy citlivosti MeSH
- mnohočetná bakteriální léková rezistence MeSH
- stafylokokové infekce mikrobiologie MeSH
- Staphylococcus hominis klasifikace účinky léků enzymologie genetika MeSH
- streptograminy farmakologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Staphylococcus hominis is the third species of coagulase-negative staphylococci (CoNS) most frequently isolated from specimens of patients with hospital-acquired infections. Many infections caused by CoNS appeared to be associated with biofilms. Nevertheless, the knowledge of the ability of S. hominis to form a biofilm is limited. The aim of this study was to analyze the formation of the biofilm by 56 S. hominis strains isolated from clinical cases. The biofilm three-dimensional structure was reconstructed by confocal laser scanning microscopy. We found that most of S. hominis strains carried icaADBC genes encoding polysaccharide intercellular adhesin (PIA), which plays a crucial role in the formation of biofilms in staphylococci strains. However, only a half of the ica-positive strains had an ability to form a biofilm in vitro. In this study, we also accessed the sensitivity of biofilms of S. hominis strains to sodium metaperiodate, proteinase K and DNase. We found that polysaccharides and proteins are the major components of the extracellular matrix of the biofilm formed by S. hominis. DNase did not have a significant effect on biofilms, which suggested that nucleic acid plays a minor role in the mature biofilm.
- MeSH
- bakteriální proteiny genetika metabolismus MeSH
- biofilmy * MeSH
- lidé MeSH
- stafylokokové infekce mikrobiologie MeSH
- Staphylococcus hominis genetika fyziologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Staphylococcus epidermidis is a commensal inhabitant of the healthy human skin, but in the recent years, it has been recognized as a nosocomial pathogen especially in immunocompromised patients. The pathogenesis of S. epidermidis is thought to be based on its capacity to form biofilms on the surface of medical devices, where bacterial cells may persist, protected from host defence and antimicrobial agents. Rifampin has been shown to be one of the most active antimicrobial agents in the eradication of the staphylococcal biofilm. However, this antibiotic should not be used in monotherapy. Therefore, one of the objectives of our research was to study the efficacy of the tigecycline/rifampin combination against methicillin-resistant S. epidermidis embedded in biofilms. Of the 80 clinically significant S. epidermidis isolates, 75 strains possess the ability to form a biofilm. These bacteria formed the biofilm via ica-dependent mechanisms. However, other biofilm-associated genes, including aap (encoding accumulation-associated protein) and bhp (coding cell wall-associated protein), were present in 85 and 29 % of isolates, respectively. The biofilm structures of S. epidermidis strains were also analyzed in confocal laser scanning microscopy (CLSM) and the obtained image demonstrated differences in their architecture. In vitro studies showed that the MIC value for tigecycline against S. epidermidis growing in the biofilm ranged from 0.125 to 2 μg/mL. Tigecycline in combination with rifampin demonstrated higher activity against bacteria embedded in biofilms than tigecycline alone.
- MeSH
- antiinfekční látky farmakologie terapeutické užití MeSH
- biofilmy účinky léků růst a vývoj MeSH
- DNA bakterií chemie genetika MeSH
- kombinovaná farmakoterapie normy MeSH
- konfokální mikroskopie MeSH
- lidé MeSH
- mikrobiální testy citlivosti MeSH
- minocyklin analogy a deriváty farmakologie terapeutické užití MeSH
- polymerázová řetězová reakce MeSH
- rifampin farmakologie terapeutické užití MeSH
- stafylokokové infekce farmakoterapie mikrobiologie MeSH
- Staphylococcus epidermidis genetika růst a vývoj MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Many serious diseases caused by Staphylococcus aureus appear to be associated with biofilms. Therefore, we investigated the biofilm-forming ability of the methicillin-resistant S. aureus (MRSA) isolates collected from hospitalized patients. As many as 96 % strains had the ability to form biofilm in vitro. The majority of S. aureus strains formed biofilm in ica-dependent mechanism. However, 23 % of MRSA isolates formed biofilm in ica-independent mechanism. Half of these strains carried fnbB genes encoding surface proteins fibronectin-binding protein B involved in intercellular accumulation and biofilm development in S. aureus strains. The biofilm structures were examined via confocal laser scanning microscopy (CLSM) and three-dimensional structures were reconstructed. The images obtained in CLSM revealed that the biofilm created by ica-positive strains was different from biofilm formed by ica-negative strains. The MRSA population showed a large genetic diversity and we did not find a single clone that occurred preferentially in hospital environment. Our results demonstrated the variation in genes encoding adhesins for the host matrix proteins (elastin, laminin, collagen, fibronectin, and fibrinogen) and in the gene involved in biofilm formation (icaA) within the majority of S. aureus clones.
- MeSH
- biofilmy * MeSH
- konfokální mikroskopie MeSH
- lidé MeSH
- methicilin rezistentní Staphylococcus aureus genetika fyziologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
