Evaluation of the Impact of Direct Plating, Broth Enrichment, and Specimen Source on Recovery and Diversity of Methicillin-Resistant Staphylococcus aureus Isolates among HIV-Infected Outpatients

McAllister, Sigrid K.; Albrecht, Valérie; Fosheim, Gregory E.; Lowery, H. Ken; Peters, Philip J.; Gorwitz, Rachel J.; Guest, J. L.; Hageman, Jeffery; Mindley, Rondeen; McDougal, Linda K.; Rimland, David; Limbago, Brandi

doi:10.1128/jcm.05323-11

Cited by 17 publications

(16 citation statements)

References 48 publications

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“…It should be noted that the study size limits the detection of small differences in sensitivity. The most striking finding of this study is that almost half of all MRSA isolates remained undetected when using direct culture only, an observation which confirms previous reports that broth enrichment is essential for detection of MRSA (1,(3)(4)(5).…”

supporting

confidence: 78%

Evaluation of Brilliance MRSA 2 Agar for Detection of Methicillin-Resistant Staphylococcus aureus in Clinical Samples

et al. 2013

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We compared 2 chromogenic media (Oxoid Brilliance MRSA 2 agar [Thermo Fisher Scientific] and MRSA-ID [bioMérieux]) for the detection of methicillin-resistant Staphylococcus aureus (MRSA) in 1,368 hospital samples. For both media, broth enrichment was essential to obtain satisfactory diagnostic performance. Although with direct cultures only, the diagnostic performance (particularly sensitivity) of Brilliance MRSA 2 agar appears better than that of MRSA-ID, no difference in sensitivity or specificity between the media was detected after inclusion of an enrichment step. R apid and accurate screening of patients for methicillin-resistant Staphylococcus aureus (MRSA) is essential to control MRSA in hospitals. Several chromogenic selective media have been developed to facilitate such screening. We previously compared the diagnostic performances of two of these media, Brilliance MRSA agar (Thermo Fisher Scientific) and MRSA-ID (bioMérieux, France), for the detection of MRSA in nose and throat samples taken from veterinarians and their household members (1). Although sensitivities were high and similar for both media, the specificity of the Brilliance MRSA agar (88.7%) was substantially less than that of MRSA-ID (98.5%). Since then, the manufacturer of the Brilliance MRSA agar has redeveloped the medium to improve its accuracy, particularly the specificity, which would reduce the number of confirmatory tests required. In the current study, we compared the performances of the new Brilliance MRSA 2 agar and MRSA-ID for the detection of MRSA.The study was conducted in the Laboratory for Microbiology and Infection Control in Amphia Hospital, Breda, The Netherlands. In this laboratory, the MRSA-ID medium was used for the routine screening for MRSA, and the Brilliance MRSA 2 agar was included as a comparator for this study. The composition of each chromogenic medium is proprietary. The selective mixture inhibits the growth of methicillin-sensitive staphylococci and most other bacteria and yeasts. Contrary to MRSA-ID medium, the performance of Brilliance MRSA 2 agar is not affected by light exposure, which is a practical advantage in its use. On Brilliance MRSA 2 agar, MRSA forms distinctive blue colonies, while such colonies on the MRSA-ID medium are green.Rectal, throat, and nose swabs were collected between December 2011 and July 2012 using the ESwab transport medium (Copan Diagnostics). ESwab containers were vortexed, and swabs were used to inoculate both MRSA-ID agar and Brilliance MRSA 2 agar plates and a Columbia agar plate with 5% sheep blood (SBA growth control). The order in which samples were inoculated on the 2 chromogenic media was alternated weekly. The fluid remaining from the ESwab container (500 to 1,000 l) was inoculated in Mueller-Hinton broth (6.5% NaCl) that was subcultured after 18 to 24 h of incubation at 36 to 37°C in normal atmosphere on both chromogenic media and on a Columbia agar plate with 5% sheep blood (SBA). The latter was included as a backup to detect the presence of MRSA strains that would r...

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confidence: 78%

Evaluation of Brilliance MRSA 2 Agar for Detection of Methicillin-Resistant Staphylococcus aureus in Clinical Samples

et al. 2013

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“…Swabs were incubated at 37°C for 24 hours in tryptic soy broth (Remel Inc.) and streaked a second time onto MSA. 18 Colonies from all MSA cultures resembling S. aureus were subsequently inoculated into tryptic soy agar (TSA) and transported to the University of Texas School of Public Health in Houston for additional testing. In Houston, cultures were regrown on MSA and then incubated at 37°C for 24 hours on blood agar, to assess hemolysis and test for coagulase activity (BactiStaph Latex 450; Remel Inc.), and on TSA, to test for catalase activity (Sigma, St. Louis, MO).…”

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confidence: 99%

Prevalence of Staphylococcus aureus Nasal Carriage in Human Immunodeficiency Virus–Infected and Uninfected Children in Botswana: Prevalence and Risk Factors

Reid

Fischer

Mannathoko

et al. 2017

The American Society of Tropical Medicine and Hygiene

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Abstract. Staphylococcus aureus is an important cause of morbidity and mortality in children in sub-Saharan Africa (SSA). A major risk factor for staphylococcal infection is S. aureus colonization of the anterior nares. We sought to define risk factors for S. aureus carriage and characterize antimicrobial resistance patterns in children in Botswana. A cross-sectional study was conducted at two clinical sites in southern Botswana. Patients under 18 years of age underwent two nasal swabs and brief interviews, 4 weeks apart. Standard microbiological techniques were used. For persistent carriers, S. aureus was isolated from swabs at both time points, and for intermittent carriers, S. aureus was isolated from only one swab. Poisson regression with robust variance estimator was used to compare prevalence of carriage and the resistance phenotypes. Among 56 enrollees, prevalence of S. aureus colonization was 55% (N = 31), of whom 42% (N = 13) were persistent carriers. Of human immunodeficiency virus-infected children, 64% (N = 9) were carriers. Risk factors for nasal carriage included a history of tuberculosis (prevalence ratio [PR] = 1.60; 95% confidence interval [CI] = 1.02, 2.51; P = 0.040) and closer proximity to health care (PR = 0.89; 95% CI = 0.80, 0.99; P = 0.048). Prior pneumonia was more common among persistent rather than intermittent carriers (PR = 2.64; 95% CI = 1.64, 4.23; P < 0.001). Methicillin-resistant S. aureus (MRSA) prevalence was 13%. Of isolates tested, 16% were resistant to three or more drugs (N = 7/44). In summary, children in southern Botswana are frequently colonized with S. aureus. Antibiotic resistance, especially MRSA, is also widespread. Antibiotic recommendations for treatment of staphylococcal infections in SSA should take cognizance of these resistance patterns.

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“…One possible explanation for this observation is that CA-MRSA strains might preferentially colonize at nonnasal body sites. The throat and groin have been implicated as important sites of S. aureus and MRSA colonization among certain patient populations (8,9), and other studies have suggested that colonization patterns of CA-MRSA strains may be distinct from those of health care-associated MRSA strains (10,11). The epidemiology of community-associated S. aureus colonization and its role in subsequent infection are not well characterized in the United States.…”

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confidence: 99%

Staphylococcus aureus Colonization and Strain Type at Various Body Sites among Patients with a Closed Abscess and Uninfected Controls at U.S. Emergency Departments

et al. 2015

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d Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is a prevalent cause of skin and soft tissue infections (SSTI), but the association between CA-MRSA colonization and infection remains uncertain. We studied the carriage frequency at several body sites and the diversity of S. aureus strains from patients with and without SSTI. Specimens from the nares, throat, rectum, and groin of case subjects with a closed skin abscess (i.e., without drainage) and matched control subjects without a skin infection (n ‫؍‬ 147 each) presenting to 10 U.S. emergency departments were cultured using broth enrichment; wound specimens were cultured from abscess cases. Methicillin resistance testing and spa typing were performed for all S. aureus isolates. S. aureus was found in 85/147 (57.8%) of abscesses; 49 isolates were MRSA, and 36 were methicillin-susceptible S. aureus (MSSA). MRSA colonization was more common among cases (59/147; 40.1%) than among controls (27/147; 18.4%) overall (P < 0.001) and at each body site; no differences were observed for MSSA. S. aureus-infected subjects were usually (75/85) colonized with the infecting strain; among MRSA-infected subjects, this was most common in the groin. The CC8 lineage accounted for most of both infecting and colonizing isolates, although more than 16 distinct strains were identified. Nearly all MRSA infections were inferred to be USA300. There was more diversity among colonizing than infecting isolates and among those isolated from controls versus cases. CC8 S. aureus is a common colonizer of persons with and without skin infections. Detection of S. aureus colonization, and especially MRSA, may be enhanced by extranasal site culture. Staphylococcus aureus frequently causes invasive and life-threatening infections. While historically common in patients with significant health care exposure, community-associated methicillin-resistant S. aureus (CA-MRSA) has emerged as an important cause of disease (1). CA-MRSA is the most common cause of skin and soft tissue infections (SSTI) among people presenting to emergency departments (EDs) in much of the United States, most of which are caused by a single MRSA strain, pulsed-field type USA300 (2). S. aureus colonization with methicillin-susceptible S. aureus (MSSA) is common in the general population, especially in the anterior nares (3). Studies of MRSA pathogenesis in health care settings have demonstrated that nasal colonization typically precedes and is a risk factor for infection (4); therefore, prevention strategies in health care often involve decolonization, especially before invasive surgical procedures (5).Despite the increasing prevalence of CA-MRSA infections, nasal colonization with MRSA has been infrequently detected during CA-MRSA outbreaks or in nationally representative prevalence surveys (6, 7). One possible explanation for this observation is that CA-MRSA strains might preferentially colonize at nonnasal body sites. The throat and groin have been implicated as important sites of S. aureus and MRSA c...

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Evaluation of the Impact of Direct Plating, Broth Enrichment, and Specimen Source on Recovery and Diversity of Methicillin-Resistant Staphylococcus aureus Isolates among HIV-Infected Outpatients

Cited by 17 publications

References 48 publications

Evaluation of Brilliance MRSA 2 Agar for Detection of Methicillin-Resistant Staphylococcus aureus in Clinical Samples

Evaluation of Brilliance MRSA 2 Agar for Detection of Methicillin-Resistant Staphylococcus aureus in Clinical Samples

Prevalence of Staphylococcus aureus Nasal Carriage in Human Immunodeficiency Virus–Infected and Uninfected Children in Botswana: Prevalence and Risk Factors

Staphylococcus aureus Colonization and Strain Type at Various Body Sites among Patients with a Closed Abscess and Uninfected Controls at U.S. Emergency Departments

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