Methicillin resistance and vancomycin heteroresistance in Staphylococcus aureus in cystic fibrosis patients (original) (raw)
Related papers
Journal of Cystic Fibrosis, 2011
Background: Chronic methicillin resistant Staphylococcus aureus (MRSA) infection in CF is associated with faster FEV1 decline and greater mortality. Screening for infection involves swabs from both upper respiratory (nose, throat) and peripheral sites (groin, axilla), as well as sputum culture. There are no data to indicate which is superior. Methods: Microbiology results of pts attending our adult tertiary care centre who have had any positive MRSA result between 01/01/09 and 01/08/2010 were reviewed. Patients were considered continuously infected between their earliest and last MRSA culture. Results: 17pts (5%) had at least 1 MRSA isolate: 6 known chronic MRSA; 3 intermittent; 6 detected on routine outpatient sputum culture; 2 detected on ward screening. 307 microbiology samples were taken during periods of MRSA positivity: 180 (59%) were swabs (throat = 71, nose = 35, groin = 59 and axilla = 15) and 127 sputa. Of these, 70 (55%) sputa were MRSA positive. Nose swabs grew MRSA in 24%, throat 23%, groin 19% and axilla 0% cases. 28 sets of concurrent samples from 12 pts were discordant. Nose swabs were positive in 17/28 (61%) of these, throat swabs in 8/14 (57%). Peripheral swabs grew MRSA in 5/27 (19%), all also positive in nose +/− sputum. Concurrent sputa were MRSA positive in 15/23 (65%). Discussion: Upper respiratory tract swabs constitute an important tool for MRSA surveillance. Little additional information however is derived from non-respiratory swabs, and their routine use could be discontinued in units with low MRSA prevalence. In those who expectorate easily, sputum is the most effective method of detecting MRSA. There is a considerable false negative rate for all sample methods.
Curr Microbiol, 2011
Twenty seven S. aureus isolates were obtained from cystic fibrosis (CF) patients at a tertiary care hospital in Brazil. Nineteen (70.4%) were methicillin-susceptible S. aureus (MSSA) and eight (29.6%) methicillin-resistant S. aureus (MRSA). Of the MRSA isolates, four had SCCmec type III and four had SCCmec type IV. PVL genes were not detected in any of the MSSA or MRSA isolates. New studies are necessary to evaluate the exact impact of these different MRSA clones in CF patients.
Methicillin-resistant Staphylococcus aureus: impact at a national cystic fibrosis centre
Journal of Hospital Infection, 1998
In many patient populations there has been a progressive increase in the prevalence of methicillin-resistant Staphylococcus UUY~US (MRSA). We examined the prevalence and consequences of acquiring MRSA in the adult cystic fibrosis (CF) population at Royal Brompton. Patients who became colonized by MRSA between 1965 and 1997 were identified from an existing database and case-notes were reviewed. Clinical and microbiological data were recorded. Twentysix patients became colonized with MRSA during this period. Median age at acquisition was 23.4 years (range 11.8-43.3 years) and median FEVl (percent predicted) was 28.9% (range 12-81%). Twenty patients (77%) had an FEVl of 140% predicted. MRSA was probably acquired by four patients at Royal Brompton. In 17 patients isolates were first identified whilst under the care of a total of 11 other institutions. Since the first case of MRSA infection in 1982, there has been an increase in prevalence to a current rate of nine cases in the first seven months of 1997. The commonest site of colonization was the lower airway (96%); the nose (23%) and skin sites (15%) were more rarely affected. Duration of colonization was frequently brief with nine cases (35%) lasting less than one month. The identification of MRSA appeared to be of little clinical significance, and did not generally affect outcomes. Only three patients were MRSA positive at the time of death, and in only one of these was MRSA considered a possible contributing factor. Keyzcovds Cystic fibrosis; methicillin-resistant Staphylococcus mucus; transplantation.
Clinical Microbiology and Infection, 2013
Staphylococcus aureus small-colony variants (SCVs) are being isolated more frequently in cystic fibrosis (CF) patients. We aimed to determine the prevalence of S. aureus SCVs and their phenotypic and genotypic properties in CF patients admitted to a university hospital. Specimens of 248 patients were examined during a period of 11 months. Colonies supposed to be SCVs were evaluated on Columbia blood agar, mannitol salt agar, and brain-heart infusion agar with 5% NaCl (BHIA 5% NaCl). Strains were confirmed by S. aureus nucA PCR. Antibiotic susceptibilities of SCVs and simultaneously isolated S. aureus strains were determined for oxacillin, gentamicin, trimethoprim-sulphamethoxazole, vancomycin, ciprofloxacin, linezolid, and tigecycline. Genetic relatedness between SCVs and normal S. aureus strains was determined with a pulsed-field gel electrophoresis (PFGE) method. S. aureus SCVs were detected in 20 of 248 patients (8.1%). The highest SCV isolation rate was obtained with MSA, followed by BHIA 5% NaCl. Auxotrophism for thymidine was demonstrated in six SCVs. The tigecycline susceptibilities of 48 SCV strains isolated in this study showed higher MIC values than those of 33 simultaneously isolated normal S. aureus strains. Whereas SCVs and normal S. aureus strains showed identical genotypes in 14 of the patients, five patients showed different genotypes. This first study from Turkey evaluating S. aureus SCVs in CF patients has indicated the importance of considering and reporting SCVs in chronic infections such as CF. The presence of SCVs will probably indicate persistent infection, and this might impact on antibiotic treatment decisions, as they are more resistant to antibiotics.
Current Microbiology, 2016
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.
Journal of Antimicrobial Chemotherapy, 2007
Epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) is poorly defined in cystic fibrosis (CF) patients, and S. aureus detection may be hampered by the presence of small colony variants (SCVs). We conducted a multicentre survey to determine the prevalence of S. aureus and MRSA colonization in Belgian CF patients and characterize the phenotype and clonal distribution of their staphylococcal strains. S. aureus isolated from CF patients attending nine CF centres were collected. Oxacillin resistance was detected by oxacillin agar screen and mecA PCR. Antibiotic susceptibility was tested by microdilution. MRSA strains were genotyped by PFGE and SCCmec typing and compared with hospital-associated MRSA strains. Laboratories used a diversity of sputum culture procedures, many of which appeared substandard. S. aureus was isolated from 275/627 (44%) CF patients (20% to 72% by centre). The prevalence of SCV colonization was 4%, but SCVs were almost exclusively recovered from patients in two centres performing an SCV search. Phenotypically, 14% of S. aureus isolates were oxacillin-resistant: 79% carried mecA and 19% were SCVs lacking mecA. The mean prevalence of 'true' MRSA colonization was 5% (0% to 17% by centre). By PFGE typing, 67% of CF-associated MRSA were related to five epidemic clones widespread in Belgian hospitals. This first survey of S. aureus colonization in the Belgian CF population indicated a diversity in local prevalence rates and in proportion of oxacillin-resistant and SCV phenotypes, probably related to variation in bacteriological methods. These findings underscore the need for standard S. aureus detection methods and MRSA control policies in Belgian CF centres.