Molecular Epidemiology of Methicillin-Resistant Staphylococcus aureus Isolates from Patients Newly Identified as Nasal Carriers

Weir, Sharada; Fram, Julia; Berg, Gretchen; Kabbani, Dima; Strymish, Judith; Tang, Melody; Fitzsimmons, Dianne; Brecher, Stephen M.

doi:10.1128/jcm.01143-12

Cited by 6 publications

(6 citation statements)

References 24 publications

(24 reference statements)

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“…Several studies demonstrated that patients are frequently recolonized after treatment (9,21), and they also associated the use of mupirocin with increased rates of resistance (7). In our facility, the baseline level of mupirocin resistance in isolates from patients who had received mupirocin therapy was low (9%), which was comparable to reports from other VA hospitals (19). Of the patients in our study who were recolonized after mupirocin therapy, 30% were recolonized with a different strain.…”

Section: Discussionsupporting

confidence: 80%

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In Vitro Activity of Retapamulin and Antimicrobial Susceptibility Patterns in a Longitudinal Collection of Methicillin-Resistant Staphylococcus aureus Isolates from a Veterans Affairs Medical Center

Harrington

Black

Clarridge

2016

Antimicrob Agents Chemother

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bMupirocin is a topical antimicrobial used to decolonize patients who carry methicillin-resistant Staphylococcus aureus (MRSA), and the topical agent retapamulin may be a potential alternative therapy. The goal of this study was to determine the in vitro activity of retapamulin as well as a panel of 15 antimicrobial agents, including mupirocin, for 403 MRSA isolates collected longitudinally from a naive population at the Veterans Affairs Puget Sound Health Care System. The MICs for retapamulin had a unimodal distribution, ranging from 0.008 to 0.5 g/ml. One isolate had an MIC of >16 g/ml, was also resistant to clindamycin and erythromycin, and was recovered from the nares of a patient undergoing hemodialysis. Twenty-four isolates (6%) and 11 isolates (3%) demonstrated low-level resistance (MICs of 8 to 64 g/ml) and high-level resistance (MICs of >512 g/ml), respectively, to mupirocin. Isolates were recovered from 10 patients both before and after mupirocin therapy. Of those, isolates from 2 patients demonstrated MIC changes postmupirocin therapy; in both cases, however, strain typing demonstrated that the preand postmupirocin strains were different. A total of 386 isolates (96%) had vancomycin MICs of <1.0 g/ml; 340 isolates (84%) were resistant to levofloxacin, 18 isolates (4.5%) were resistant to trimethoprim-sulfamethoxazole, and 135 isolates (33%) had elevated MICs of 4 g/ml for linezolid. The baseline levels of resistance were low for mupirocin (9%) and even lower for retapamulin (0.25%) Although the use of mupirocin is currently the standard therapy for decolonization practices, the activity of retapamulin warrants its consideration as an alternative therapy in MRSA decolonization regimens.

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Section: Discussionsupporting

confidence: 80%

“…Isolates from the outpatient group, nares conversion isolates, and isolates classified as strain types USA100 and USA300 demonstrated significant differences from the overall rates. Although USA300 remains a predominant strain type in the United States, the distribution of strain types varies among VA hospitals (18,19).…”

Section: Discussionmentioning

confidence: 99%

In Vitro Activity of Retapamulin and Antimicrobial Susceptibility Patterns in a Longitudinal Collection of Methicillin-Resistant Staphylococcus aureus Isolates from a Veterans Affairs Medical Center

Harrington

Black

Clarridge

2016

Antimicrob Agents Chemother

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“…Patients who have a positive carriage pattern on the initial hospitalization continue to carry MRSA either always or intermittently over long periods of time [13]. The benefit of repeated MRSA screening in these patients is unclear, since most will not have the consistently negative result over 3 consecutive tests in the absence of antibiotic exposure that would be required to move the patient out of the “MRSA-colonized” category.…”

Section: Discussionmentioning

confidence: 99%

“…We also did not account for MSSA colonization or differences in virulence among nasal MRSA isolates that could have impacted infection risk. Our recent molecular evaluation of nasal MRSA and MSSA among newly colonized veterans identified a low prevalence of USA300 and Panton-Valentine Leukocidin (PVL) genes and no association between USA300 MRSA carriage and subsequent infection risk [13].…”

Section: Discussionmentioning

confidence: 99%

MRSA Nasal Carriage Patterns and the Subsequent Risk of Conversion between Patterns, Infection, and Death

Martinello

Young²,

Strymish

et al. 2013

PLoS ONE

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BackgroundPatterns of methicillin-resistant S. aureus (MRSA) nasal carriage over time and across the continuum of care settings are poorly characterized. Knowledge of prevalence rates and outcomes associated with MRSA nasal carriage patterns could help direct infection prevention strategies. The VA integrated health-care system and active surveillance program provides an opportunity to delineate nasal carriage patterns and associated outcomes of death, infection, and conversion in carriage.Methods/FindingsWe conducted a retrospective cohort study including all patients admitted to 5 acute care VA hospitals between 2008–2010 who had nasal MRSA PCR testing within 48 hours of admission and repeat testing within 30 days. The PCR results were used to define a baseline nasal carriage pattern of never, intermittently, or always colonized at 30 days from admission. Follow-up was up to two years and included acute, long-term, and outpatient care visits. Among 18,038 patients, 91.1%, 4.4%, and 4.6% were never, intermittently, or always colonized at the 30-day baseline. Compared to non-colonized patients, those who were persistently colonized had an increased risk of death (HR 2.58; 95% CI 2.18;3.05) and MRSA infection (HR 10.89; 95% CI 8.6;13.7). Being in the non-colonized group at 30 days had a predictive value of 87% for being non-colonized at 1 year. Conversion to MRSA colonized at 6 months occurred in 11.8% of initially non-colonized patients. Age >70 years, long-term care, antibiotic exposure, and diabetes identified >95% of converters.ConclusionsThe vast majority of patients are not nasally colonized with MRSA at 30 days from acute hospital admission. Conversion from non-carriage is infrequent and can be risk-stratified. A positive carriage pattern is strongly associated with infection and death. Active surveillance programs in the year following carriage pattern designation could be tailored to focus on non-colonized patients who are at high risk for conversion, reducing universal screening burden.

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“…These includes Acinetobacter baumannii ATCC19606, Escherichia coli ATCC29522, Staphylococcus aureus ATCC29523, Staphylococcus epidermidis ATCC12228 (as representatives of Gram-positive and Gram-negative bacteria), and two antibiotic-resistant strains of methicillin-resistant S . aureus (MRSA) BBA1680, USA300 and BBA1683, USA400 [ 31 , 32 ]. E .…”

Section: Methodsmentioning

confidence: 99%

Involvement of multiple stressors induced by non-thermal plasma-charged aerosols during inactivation of airborne bacteria

et al. 2017

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A lab-scale, tunable, single-filament, point-to-point nonthermal dieletric-barrier discharge (DBD) plasma device was built to study the mechanisms of inactivation of aerosolized bacterial pathogens. The system inactivates airborne antibiotic-resistant pathogens efficiently. Nebulization mediated pre-optimized (4 log and 7 log) bacterial loads were challenged to plasma-charged aerosols, and lethal and sublethal doses determined using colony assay, and cell viability assay; and the loss of membrane potential and cellular respiration were determined using cell membrane potential assay and XTT assay. Using the strategies of Escherichia coli wildtype, over-expression mutant, deletion mutants, and peroxide and heat stress scavenging, we analyzed activation of intracellular reactive oxygen species (ROS) and heat shock protein (hsp) chaperons. Superoxide dismutase deletion mutants (ΔsodA, ΔsodB, ΔsodAΔsodB) and catalase mutants ΔkatG and ΔkatEΔkatG did not show significant difference from wildtype strain, and ΔkatE and ΔahpC was found significantly more susceptible to cell death than wildtype. The oxyR regulon was found to mediate plasma-charged aerosol-induced oxidative stress in bacteria. Hsp deficient E. coli (ΔhtpG, ΔgroEL, ΔclpX, ΔgrpE) showed complete inactivation of cells at ambient temperature, and the treatment at cold temperature (4°C) significantly protected hsp deletion mutants and wildtype cells, and indicate a direct involvement of hsp in plasma-charged aerosol mediated E. coli cell death.

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Molecular Epidemiology of Methicillin-Resistant Staphylococcus aureus Isolates from Patients Newly Identified as Nasal Carriers

Cited by 6 publications

References 24 publications

In Vitro Activity of Retapamulin and Antimicrobial Susceptibility Patterns in a Longitudinal Collection of Methicillin-Resistant Staphylococcus aureus Isolates from a Veterans Affairs Medical Center

In Vitro Activity of Retapamulin and Antimicrobial Susceptibility Patterns in a Longitudinal Collection of Methicillin-Resistant Staphylococcus aureus Isolates from a Veterans Affairs Medical Center

MRSA Nasal Carriage Patterns and the Subsequent Risk of Conversion between Patterns, Infection, and Death

Involvement of multiple stressors induced by non-thermal plasma-charged aerosols during inactivation of airborne bacteria

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