Cell wall deficiency and its effect on methicillin heteroresistance in Staphylococcus aureus

Маркова, Н.; Haydoushka, Irina; Michailova, Lilia; Ivanova, R.; Valcheva, Violeta; Jourdanova, Mimi; Popova, T.; Radoucheva, T.

doi:10.1016/j.ijantimicag.2007.09.015

Cited by 7 publications

(11 citation statements)

References 14 publications

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“…Several reports, including the earliest studies describing the phenomenon, applied this definition without specifying a particular antibiotic concentration range (3,4,7,8). In contrast, concentration ranges were indicated for heteroresistance in Acinetobacter baumannii, where subpopulations grew in 3 to 10 g/ml colistin while the culture's MIC ranged from 0.25 to 2 g/ml (9).…”

Section: Multiple Definitions Of Heteroresistancementioning

confidence: 99%

Antimicrobial Heteroresistance: an Emerging Field in Need of Clarity

2015

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SUMMARY “Heteroresistance” describes a phenomenon where subpopulations of seemingly isogenic bacteria exhibit a range of susceptibilities to a particular antibiotic. Unfortunately, a lack of standard methods to determine heteroresistance has led to inappropriate use of this term. Heteroresistance has been recognized since at least 1947 and occurs in Gram-positive and Gram-negative bacteria. Its clinical relevance may be considerable, since more resistant subpopulations may be selected during antimicrobial therapy. However, the use of nonstandard methods to define heteroresistance, which are costly and involve considerable labor and resources, precludes evaluating the clinical magnitude and severity of this phenomenon. We review the available literature on antibiotic heteroresistance and propose recommendations for definitions and determination criteria for heteroresistant bacteria. This will help in assessing the global clinical impact of heteroresistance and developing uniform guidelines for improved therapeutic outcomes.

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Section: Multiple Definitions Of Heteroresistancementioning

confidence: 99%

Antimicrobial Heteroresistance: an Emerging Field in Need of Clarity

2015

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“…In contrast to vancomycin resistance, resistance to β-lactams (methicillin resistance) is constitutively mediated by a affinity change in penicillin-binding proteins (enzymes involved in cell wall synthesis). Because many genes are involved in cell wall biosynthesis, explanation of the nature of heterogeneous expression of methicillin resistance is very difficult (Markova et al, 2008). Since 2001, an increase in the number of MRSA strains with heteroresistance to oxacillin has been observed in the Netherlands.…”

Section: Resultsmentioning

confidence: 99%

“…These strains can spread unnoticed, as their phenotypic heterogeneous resistance to beta-lactams affects the results of susceptibility testing (Wannet 2002). Coexistence of two subpopulations (susceptible and resistant) within a clinical isolate and expression of resistance only in a small number of cells leads to diagnostic problems in clinical laboratories (Markova et al, 2008). In methicillin-resistant Staphylococcus strain degree of heterogeneity is quite low: only 1 CFU of 10 4 -10 7 CFU are phenotypically resistant (De Lencastre et al, 1993).…”

Section: Resultsmentioning

confidence: 99%

Single Cell Level Survey on Heterogenic Glycopeptide and β-Lactams Resistance

Jarzembowski¹,

Jóźwik²,

Wiśniewska³

et al. 2012

Antibiotic Resistant Bacteria - A Continuous Challenge in the New Millennium

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Antibiotic Resistant Bacteria-A Continuous Challenge in the New Millennium been found in E. faecalis. Vancomycin resistance is usually determined by one of the two related gene clusters, vanA and vanB, that encode a dehydrogenase (VanH or VanHB) and ligase (VanA or VanB). Expression of VanA-and VanB-type resistance is regulated by the VanRS and VanRBSB two-component regulatory systems, respectively (Arthur et al., 1992; Evers and Courvalin, 1996). www.intechopen.com Single Cell Level Survey on Heterogenic Glicopeptide and -Lactams Resistance 2. Material and methods The study was performed on reference and clinical strains listed in Tab 1. Fourteen MRSA strains were isolated from patients of various wards of the University Clinical Centre in Gdańsk and 12 Enterococcus faecalis from patients of Kościerzyna Medical Centre. The staphylococcal strains were isolated in the hospital laboratory during the period March 2008 to March 2009 and were sent to the Microbiology Department of the Medical University of Gdańsk for epidemiological typing. One isolate per patient was included in the study. Bacteria were cultured from swabs: wound (4 isolates), nose (2 isolates) and fluids: tracheostomy tube fluid (3 isolates), blood (1 isolate), abscess fluid (1 isolate), pus (1 isolate), bronchial fluid (1 isolate), urine (1 isolate). The data about clinical recognitions were not available. The isolates were cultured on sheep blood agar and were identified as S.aureus by colony morphology, a positive plasma coagulase reaction and by biochemical tests (API, bioMerieux, France). Resistance to methicillin was primary tested using disc diffusion method with cefoxitin disc (Clinical and Laboratory Standards Institute,2006) and then was confirmed by detection of mec A gene by the Polymerase Chain Reaction (PCR) as described previously (Barski et al., 1996). DNA of bacterial isolates was extracted according to the previous report (Barski et al., 1996). For further analyses, the isolates were subcultured on nutrient broth and stored with glycerol at-70°C. Spa typing and BURP analyses. The polymorphic X region of the protein A gene (spa) was amplified from the isolates by PCR with primers and according to procedure described by Kobayashi (1999). Spa types were determined by using Ridom Staph Type software, according to Harmsen et al (2003). The spa types were clustered into spa-CCs (clonal complexes) using the algorithm BURP-based upon repeat pattern (Rupptisch et al., 2006). Phage typing was performed according to Blair and Williams (1961). Two sets of phages were used as follows: a basic set of 23 phages with additional phages 88,89,187 and an additional set of phages MR8, MR12, MR25, 30, 33, 38, M3, M5, 622, 56B supplied by the Central Public Health Laboratory in London for use on MRSA strains (Richardson et al., 1999). The phages were used in concentrations at routine test dilution (RTD) and 100xRTD. Reactions for phages were noted as described by Blair and Williams (1961). The phage type was defined by all the phages with strong reacti...

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“…This chromosomal genetic element appears in both MRSA and MRCoNS with production of low-affinity penicillin-binding protein, and consequently, resulting in cross-resistance to most β-lactam antimicrobials and the significant limitation in their use. 10,11 It is possible to identify S. aureus and/ or detect the presence of mecA using polymerase-chain reaction (PCR) assay in isolated staphylococcal strains or directly in blood cultures or in animal samples. 10,12 The aim of this study was to develop a new algorithm for rapid detection of MRSA/MRSCoN and methicillin sensitive S. aureus (MSSA) directly in growth-positive blood cultures and/or in abscess punctures by mecA detection and species-specific identification of S. aureus by PCR and to recommend adequate therapy based on the susceptibility of the MRSA isolates.…”

Section: Introductionmentioning

confidence: 99%

Molecular-genetic Method for Fast Direct Detection of Staphylococcus Aureus and Methicillin Resistance in Blood Cultures and Punctures

Gergova

Tsitou

Mitov

2019

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Citation: Gergova RT, Tsitou VMS, Mitov IG. Molecular-genetic method for fast direct detection of Staphylococcus aureus and methicillin resistance in blood cultures and punctures. Folia Med (Plovdiv) 2019;61(4):559-65. AbstractBackground: Invasive infections caused by methicillin resistant Staphylococcus aureus and coagulase-negative staphylococci (MRSA/ MRSCoN) require fast, adequate treatment.The aim of this study was to develop a faster protocol for direct detection of MRSA/MRSCoN in blood cultures and in abscess punctures based on mecA and species specific identification of S. aureus by polymerase-chain reaction (PCR). Materials and methods:We examined 77 growth-positive BACTEC blood cultures and 50 abscess punctures by routine microbiological assay and simultaneous PCR detection of MRSA/MRSCoN. The specificity of the PCR was evaluated by using DNA from another 15 microbial species for negative controls. We determined the minimum inhibitory concentration (MIC) of oxacillin, vancomycin, tigecycline, linezolid, levofloxacin, clindamycin, and erythromycin against the S. aureus isolates using the E-test. Results:In the blood cultures, the two methods detected 39.3% of MRSA, and 93.9% of MRCoNS. In the punctures, the PCR assay identified 20.9% of MRSA and 79.2% of MSSA. In the puncture cases, there were three PCR MRSA positive and culture negative samples. Screening for susceptibility to 14 antimicrobial agents demonstrated significantly higher (p<0.05) methicillin resistance in blood culture isolates than in the puncture ones (39.3% and 20.0%, respectively). Conclusion:The new PCR protocol was very fast and specific. It was more sensitive in detecting MRSA from abscess punctures than the routine microbiological techniques. This protocol will speed up the right choice of empirical therapy, which is extremely important for saving patients' lives.

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Cell wall deficiency and its effect on methicillin heteroresistance in Staphylococcus aureus

Cited by 7 publications

References 14 publications

Antimicrobial Heteroresistance: an Emerging Field in Need of Clarity

Antimicrobial Heteroresistance: an Emerging Field in Need of Clarity

Single Cell Level Survey on Heterogenic Glycopeptide and β-Lactams Resistance

Molecular-genetic Method for Fast Direct Detection of Staphylococcus Aureus and Methicillin Resistance in Blood Cultures and Punctures

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