Predictors of Clinical Virulence in Community-Onset Methicillin-Resistant Staphylococcus aureus Infections: The Importance of USA300 and Pneumonia

Hota, Bala; Lyles, Rosie D.; Rim, Jean Y.; Popovich, Kyle J.; Rice, Thomas W.; Aroutcheva, Alla; Weinstein, Robert A.

doi:10.1093/cid/cir472

Cited by 38 publications

(28 citation statements)

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“…Prior studies provided little information on the association between multiple microbiologic molecular characteristics and clinical outcome, or they did not focus on pneumonia per se. Hota et al (12) recently reported that USA300 infection was negatively associated with severe clinical courses in patients with community-onset infections, but theirs was a single-center study, and only 18% of all patients had pneumonia in the case-control analysis. Similarly, Seybold et al (23) reported that crude in-hospital mortality was lower for MRSA USA300 than other MRSA strains in patients with bloodstream infections, including 17% with pulmonary infections.…”

Section: Discussionmentioning

confidence: 93%

Analysis of Pathogen and Host Factors Related to Clinical Outcomes in Patients with Hospital-Acquired Pneumonia Due to Methicillin-Resistant Staphylococcus aureus

et al. 2012

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dMethicillin-resistant Staphylococcus aureus (MRSA) is a major cause of nosocomial pneumonia. To characterize pathogen-derived and host-related factors in intensive care unit (ICU) patients with MRSA pneumonia, we evaluated the Improving Medicine through Pathway Assessment of Critical Therapy in Hospital-Acquired Pneumonia (IMPACT-HAP) database. We performed multivariate regression analyses of 28-day mortality and clinical response using univariate analysis variables at a P level of <0.25. In isolates from 251 patients, the most common molecular characteristics were USA100 (55.0%) and USA300 (23.9%), SCCmec types II (64.1%) and IV (33.1%), and agr I (36.7%) and II (61.8%). Panton-Valentine leukocidin (PVL) was present in 21.9%, and vancomycin heteroresistance was present in 15.9%. Mortality occurred in 37.1% of patients; factors in the univariate analysis were age, APACHE II score, AIDS, cardiac disease, vascular disease, diabetes, SCCmec type II, PVL negativity, and higher vancomycin MIC (all P values were <0.05). In multivariate analysis, independent predictors were APACHE II score (odds ratio [OR], 1.090; 95% confidence interval [CI], 1.041 to 1.141; P < 0.001) and age (OR, 1.024; 95% CI, 1.003 to 1.046; P ‫؍‬ 0.02). Clinical failure occurred in 36.8% of 201 evaluable patients; the only independent predictor was APACHE II score (OR, 1.082; 95% CI, 1.031 to 1.136; P ‫؍‬ 0.002). In summary, APACHE II score (mortality, clinical failure) and age (mortality) were the only independent predictors, which is consistent with severity of illness in ICU patients with MRSA pneumonia. Interestingly, our univariate findings suggest that both pathogen and host factors influence outcomes. As the epidemiology of MRSA pneumonia continues to evolve, both pathogen-and host-related factors should be considered when describing epidemiological trends and outcomes of therapeutic interventions. Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of hospital-acquired pneumonia (HAP), ventilatorassociated pneumonia (VAP), and health care-associated pneumonia (HCAP) (26). These infections are associated with significant morbidity, mortality, and cost burdens (3,20,25).While previous studies have attempted to identify risk factors for morbidity and mortality in patients with MRSA infections, they have typically focused on either the pathogen or the host. For example, severity of underlying illness, septic shock, age, comorbidities, and other selected host-related factors appear to be independent predictors of poor outcomes (5-7, 10, 14). MRSA features associated with poor prognosis in a variety of infection types include increases in vancomycin MIC, vancomycin heteroresistance, presence of Panton-Valentine leukocidin (PVL), agr group I, individual genes, and persistent colonization (1, 9, 11, 27). Because the outcomes of MRSA pneumonia are probably due to a combination of factors, studies are needed to evaluate the combined roles of MRSA-derived and host-related factors in a large sample of patients with HAP, VAP, or HCAP ...

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Section: Discussionmentioning

confidence: 93%

Analysis of Pathogen and Host Factors Related to Clinical Outcomes in Patients with Hospital-Acquired Pneumonia Due to Methicillin-Resistant Staphylococcus aureus

et al. 2012

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“…In a study carried by Ameer Abbas et al [22], in the Indian hospital, it was found that of 201 isolates of S. aureus, 142 (28.6%) HA-MRSA and 58 (11.6%) CA-MRSA.…”

Section: Discussionmentioning

confidence: 97%

Typing of Methicillin-Resistant Staphylococcus aureus Isolate from Healthcare Workers in Larestan, Iran

Ebadi

Ashrafi²

2018

Journal of Microbiology and Infectious Diseases

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Objective: The aim of this study was to determine the antimicrobial susceptibility and cassette chromosome typing in Methicillin-Resistant Staphylococcus aureus (MRSA) isolated from healthcare workers. Methods:Two hundred thirty nasal swabs were collected from healthcare workers of three hospitals in Larestan, Iran. Antibiotic susceptibility was determined by disk diffusion method according to CLSI guideline. The minimum Inhibitory concentration (MIC) of vancomycin and screening test with methicillin were measured by E-test and agar screen plate procedures. Cefoxitin disc diffusion test was performed. MRSA isolates were selected and investigated for mecA gene and SCCmec typing by multiplex-PCR, then five methods were compared. Results:In total, 37 S. aureus were isolated, 28 were defined as MRSA. Frequency of SCCmec types were as nine SCCmec I, eight SCCmec IV, five SCCmec II, four SCCmec V and two SCCmec III. In this study, 75% of isolates were CA-MRSA, 25% were HA-MRSA. Evaluation of antibiotic resistance showed the greatest resistance to penicillin and the lowest resistance was observed to vancomycin and by E-test method 28.5% of isolates were intermediate resistance to vancomycin. However, screening test detected 92.8% resistance with oxacillin and 28 of isolates were resistant with Cefoxitin disc diffusion. For these 28 isolates mecA was positive. Conclusion:As a result, in our S. aureus isolates methicillin resistance was75.7%. The most frequent type was SCCmec I. Our result showed high rates of antibiotic resistance specially to methicillin in the S. aureus isolated hospitals that is a serious warning to the treatment of infection caused by this bacterium. J Microbiol Infect Dis 2018; 8(1):1-7

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“…Despite this deadly status, broad diversity exists among strains within this species. Some strains are present as asymptomatic colonizers of the human nose (2), others cause skin and soft tissue infections, and some can cause life-threatening and severe disease (3). One strain, known as USA300, has replaced other strains of S. aureus to become the predominant cause of methicillin-resistant S. aureus (MRSA) infections in the United States (4), and its prevalence is increasing rapidly worldwide (5).…”

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confidence: 99%

Comparative genome-scale modelling of Staphylococcus aureus strains identifies strain-specific metabolic capabilities linked to pathogenicity

Bosi

Monk

Aziz

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

224

196

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Staphylococcus aureus is a preeminent bacterial pathogen capable of colonizing diverse ecological niches within its human host. We describe here the pangenome of S. aureus based on analysis of genome sequences from 64 strains of S. aureus spanning a range of ecological niches, host types, and antibiotic resistance profiles. Based on this set, S. aureus is expected to have an open pangenome composed of 7,411 genes and a core genome composed of 1,441 genes. Metabolism was highly conserved in this core genome; however, differences were identified in amino acid and nucleotide biosynthesis pathways between the strains. Genome-scale models (GEMs) of metabolism were constructed for the 64 strains of S. aureus. These GEMs enabled a systems approach to characterizing the core metabolic and panmetabolic capabilities of the S. aureus species. All models were predicted to be auxotrophic for the vitamins niacin (vitamin B3) and thiamin (vitamin B1), whereas strain-specific auxotrophies were predicted for riboflavin (vitamin B2), guanosine, leucine, methionine, and cysteine, among others. GEMs were used to systematically analyze growth capabilities in more than 300 different growth-supporting environments. The results identified metabolic capabilities linked to pathogenic traits and virulence acquisitions. Such traits can be used to differentiate strains responsible for mild vs. severe infections and preference for hosts (e.g., animals vs. humans). Genome-scale analysis of multiple strains of a species can thus be used to identify metabolic determinants of virulence and increase our understanding of why certain strains of this deadly pathogen have spread rapidly throughout the world.systems biology | mathematical modeling | pathogenicity | core genome | pangenome

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Predictors of Clinical Virulence in Community-Onset Methicillin-Resistant Staphylococcus aureus Infections: The Importance of USA300 and Pneumonia

Abstract: Our findings suggest that USA300 infections are negatively associated with severe clinical courses, suggesting less virulence than other MRSA strains, except in the setting of pneumonia with septic pulmonary emboli.

Cited by 38 publications

References 48 publications

Analysis of Pathogen and Host Factors Related to Clinical Outcomes in Patients with Hospital-Acquired Pneumonia Due to Methicillin-Resistant Staphylococcus aureus

Analysis of Pathogen and Host Factors Related to Clinical Outcomes in Patients with Hospital-Acquired Pneumonia Due to Methicillin-Resistant Staphylococcus aureus

Typing of Methicillin-Resistant Staphylococcus aureus Isolate from Healthcare Workers in Larestan, Iran

Comparative genome-scale modelling of Staphylococcus aureus strains identifies strain-specific metabolic capabilities linked to pathogenicity

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