Dataset Information

Association of methicillin-resistant Staphylococcus aureus (MRSA) USA300 genotype with mortality in MRSA bacteremia.

ABSTRACT: OBJECTIVES:To evaluate the association of USA300 genotype with outcomes in persons with MRSA bacteremia and examine the epidemiology of MRSA bacteremia over time. METHODS:Population-based surveillance for MRSA bacteremia was performed in 8-county Atlanta from 2005 to 2008. Cases of MRSA bacteremia were classified as healthcare-associated hospital-onset (HAHO), healthcare-associated community-onset (HACO), or community-associated (CA) disease. A survival analysis was performed on a nested cohort of cases with isolates characterized by pulse field gel electrophoresis (PFGE). RESULTS:4344 MRSA bacteremia cases were identified; 2579 (59.4%) HACO, 1144 (26.3%) HAHO; and 601 (13.8%) CA. Overall incidence rates of MRSA bacteremia declined from 33.9/100,000 in 2005-24.8/100,000 in 2008. Rates were highest in persons ? 65 years, blacks, males, and persons with AIDS. In multivariate analysis of 1104 cases, USA300 genotype was associated with increased in-hospital mortality (HR 1.63, 95% CI 1.19-2.23). USA300 strains were also associated with increased mortality when compared to USA100 strains (HR 1.79, 95% CI 1.24-2.58). CONCLUSIONS:MRSA bacteremia incidence declined over 4 years but CA disease rates remained stable. Persons with HIV, the elderly, and blacks were disproportionately affected. Bacteremia due to USA300 MRSA strains was associated with increased mortality, suggesting that USA300 strains may be more virulent.

SUBMITTER: Kempker RR

PROVIDER: S-EPMC2975870 | biostudies-literature | 2010 Nov

REPOSITORIES: biostudies-literature

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Association of methicillin-resistant Staphylococcus aureus (MRSA) USA300 genotype with mortality in MRSA bacteremia.

Kempker Russell R RR Farley Monica M MM Ladson Janine L JL Satola Sarah S Ray Susan M SM

The Journal of infection 20100922 5

<h4>Objectives</h4>To evaluate the association of USA300 genotype with outcomes in persons with MRSA bacteremia and examine the epidemiology of MRSA bacteremia over time.<h4>Methods</h4>Population-based surveillance for MRSA bacteremia was performed in 8-county Atlanta from 2005 to 2008. Cases of MRSA bacteremia were classified as healthcare-associated hospital-onset (HAHO), healthcare-associated community-onset (HACO), or community-associated (CA) disease. A survival analysis was performed on a ...[more]

PMID: 20868707

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Project description:Methicillin-resistant Staphylococcus aureus (MRSA) is a leading cause of health care-associated (HA) and community-associated (CA) infections. USA300 strains are historically CA-MRSA, while USA100 strains are HA-MRSA. Here, we update an antibiotic prediction rule to distinguish these two genotypes based on antibiotic resistance phenotype using whole-genome sequencing (WGS), a more discriminatory methodology than pulsed-field gel electrophoresis (PFGE). MRSA clinical isolates collected from 2007 to 2017 underwent WGS; associated epidemiologic data were ascertained. In developing the rule, we examined MRSA isolates that included a population with a history of incarceration. Performance characteristics of antibiotic susceptibility for predicting USA300 compared to USA100, as defined by WGS, were examined. Phylogenetic analysis was performed to examine resistant USA300 clades. We identified 275 isolates (221 USA300, 54 USA100). Combination susceptibility to clindamycin or levofloxacin performed the best overall (sensitivity 80.7%, specificity 75.9%) to identify USA300. The average number of antibiotic classes with resistance was higher for USA100 (3 versus 2, P < 0.001). Resistance to ≤2 classes was predictive for USA300 (area under the curve (AUC) 0.84, 95% confidence interval 0.78 to 0.90). Phylogenetic analysis identified a cluster of USA300 strains characterized by increased resistance among incarcerated individuals. Using a combination of clindamycin or levofloxacin susceptibility, or resistance to ≤2 antibiotic classes, was predictive of USA300 as defined by WGS. Increased resistance was observed among individuals with incarceration exposure, suggesting circulation of a more resistant USA300 clade among at-risk community networks. Our phenotypic prediction rule could be used as an epidemiologic tool to describe community and nosocomial shifts in USA300 MRSA and quickly identify emergence of lineages with increased resistance. IMPORTANCE Methicillin-resistant Staphylococcus aureus (MRSA) is an important cause of health care-associated (HA) and community-associated (CA) infections, but the epidemiology of these strains (USA100 and USA300, respectively) now overlaps in health care settings. Although sequencing technology has become more available, many health care facilities still lack the capabilities to perform these analyses. In this study, we update a simple prediction rule based on antibiotic resistance phenotype with integration of whole-genome sequencing (WGS) to predict strain type based on antibiotic resistance profiles that can be used in settings without access to molecular strain typing methods. This prediction rule has many potential epidemiologic applications, such as analysis of retrospective data sets, regional monitoring, and ongoing surveillance of CA-MRSA infection trends. We demonstrate application of this rule to identify an emerging USA300 strain with increased antibiotic resistance among incarcerated individuals that deviates from the rule.

Project description:Methicillin-resistant Staphylococcus aureus (MRSA) USA300 isolates have been recognized globally, not only in community but also in healthcare settings. USA300 isolates were initially resistant only to methicillin, but resistance to non-?-lactams has emerged with time. To evaluate the prevalence and antimicrobial susceptibility of USA300 isolates in Stockholm, we conducted a nine-year retrospective study. Of 5359 consecutive MRSA cases in Stockholm, isolates from 285 cases were USA300 strains according to the pulsed-field gel electrophoresis pattern. Of these cases, repeated isolates with altered antibiotic resistance patterns were observed in six individuals. Therefore, antimicrobial susceptibility testing was performed on totally 291 isolates. To study the phylogenetic relatedness of isolates in transmission events and genomic resistance traits, 35 isolates were further studied by whole genome sequencing (WGS). The incidence of MRSA was increased from 17.6 per 100,000 inhabitants in 2008 to 37.3 per 100,000 inhabitants in 2016, while the proportion of USA300 cases declined from 6.6% in 2008 to 2.6% in 2016. Among the USA300 isolates, 73.5% were community-associated, 21.3% healthcare-associated, and 5.2% had unknown acquisition. The highest resistance rate among non-?-lactams was found in erythromycin (86%), followed by fluoroquinolones (68-69%). 57% of the isolates were resistant to both erythromycin and fluoroquinolone. Simultaneous resistance to four non-?-lactam antibiotic classes was found in six isolates. Four isolates were susceptible to all non-?-lactam antibiotics. Ceftaroline, daptomycin, linezolid, mupirocin, rifampicin, teicoplanin, telavancin, trimethoprim-sulfamethoxazole and vancomycin retained full activity in the study. WGS analysis indicated that isolates from an outbreak were phylogenetically closely related. In conclusion, USA300 MRSA isolates in Stockholm have neither been limited to the community setting, nor remained susceptible to non-?-lactam agents. WGS is becoming a useful tool in tracing transmission events. The results herein provide the most up-to-date and comprehensive information regarding status of USA300 strains in this geographic area.

Project description:The herbal products proved to be more promising antimicrobials even though their antimicrobial activity is milder than commercially available antibiotics. Moreover, herbal drugs may act synergistically with antibiotics to kill microbes. In this study, we aimed to enhance the activity of penicillin against MRSA through combination with the active saponin fraction isolated from the Zygophyllum album plant. Three different types of metabolites (saponins, sterols, and phenolics) have been extracted from Zygophyllum album with ethanol and purified using different chromatographic techniques. The antibacterial activity of crude extract and the separated metabolites were checked against MRSA isolates, Saponin fraction (ZA-S) was only the active one followed by the crude extract. Therefore, the compounds in this fraction were identified using ultra-high-performance liquid chromatography connected to quadrupole time-of-flight mass spectrometry (UHPLC/QTOF-MS) operated in positive and negative ionization modes. UHPLC/QTOF-MS revealed the presence of major six ursane-type tritepenoidal saponins (Quinovic acid, Quinovic acid 3β-O-β-D-quinovopyranoside, Zygophylloside C, Zygophylloside G, Zygophylloside K and Ursolic acid), in addition to Oleanolic acid. Interaction studies between saponin fraction and penicillin against MRSA were performed through the checkerboard method and time-kill assay. According to checkerboard results, only three combinations showed a fractional inhibitory concentration index less than 0.5 at concentrations of (62.5 + 312.5, 62.5 + 156.25, and 62.5 + 78.125 of penicillin and ZA-S, respectively). Time kill assay results showed that the highest reduction in log10 colony-forming unit (CFU)/ml of initial inoculum of MRSA after 24 h occurred by 3.7 at concentrations of 62.5 + 312.5 (µg/µg)/ml of penicillin and ZA-S, respectively. Thus, the combination between saponin fraction of Zygophyllum album and penicillin with these concentrations could be a potential agent against MRSA that can serve as possible model for new antibacterial drug.

Dataset Information

Association of methicillin-resistant Staphylococcus aureus (MRSA) USA300 genotype with mortality in MRSA bacteremia.

Publications

Association of methicillin-resistant Staphylococcus aureus (MRSA) USA300 genotype with mortality in MRSA bacteremia.

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