Jess F. Peterson

Spectra MRSA, a New Chromogenic Agar Medium To Screen for Methicillin-Resistant Staphylococcus aureus

ABSTRACT A novel chromogenic medium, Spectra MRSA (Remel, Lenexa, KS), was designed to detect methicillin-resistant Staphylococcus aureus (MRSA) rapidly and more efficiently than traditional media (i.e., tryptic soy agar with 5% sheep blood [SBA] and mannitol salt agar [MSA]). A multicenter study (including four clinical trial sites and the Medical College of Wisconsin [MCW] Milwaukee, WI) compared the performance characteristics of Spectra MRSA to those of the traditional media for the detection of MRSA. For this study, 767 nasal swab specimens from the multicenter study (traditional medium used, SBA) and 667 nasal swab specimens from MCW (traditional medium used, MSA) were plated on each test medium and examined after 24 and 48 h of incubation. At 24 h, the sensitivity and the specificity of each medium were as follows: in the multicenter study, 95.4% and 99.7%, respectively, for Spectra MRSA and 93.6% and 100%, respectively, for SBA; at MCW, 95.2% and 99.5%, respectively, for Spectra MRSA and 88.7% and 94.0%, respectively, for MSA. The positive predictive values of each medium at 24 h were as follows: in the multicenter study, 98.1% for Spectra MRSA and 100% for SBA; at MCW, 95.2% for Spectra MRSA and 60.4% for MSA. In our evaluation, we found that Spectra MRSA was able to rapidly identify and differentiate methicillin-resistant S. aureus from methicillin-susceptible S. aureus on the basis of the utilization of chromogens that result in denim blue colonies, thus eliminating the need for biochemical analysis and antimicrobial susceptibility testing. Extending the incubation beyond 24 h did not significantly improve the recovery of MRSA and resulted in decreased specificity.

Evaluation of Spectra VRE, a New Chromogenic Agar Medium Designed To Screen for Vancomycin-Resistant Enterococcus faecalis and Enterococcus faecium

ABSTRACT Spectra VRE (Remel, Lenexa, KS) is a chromogenic medium designed to recover and differentiate vancomycin-resistant Enterococcus faecium and Enterococcus faecalis (VRE). This medium was compared to bile esculin azide agar (BEAV) and was 98.2% sensitive and 99.3% specific compared to BEAV, which was 87.6% sensitive and 87.1% specific at 24 h.

Evaluation of a Microarray-Based Genotyping Assay for the Rapid Detection of Cytochrome P450 2C19 * 2 and * 3 Polymorphisms From Whole Blood Using Nanoparticle Probes

Numerous drugs such as clopidogrel have been developed to reduce coagulation or inhibit platelet function. The hepatic cytochrome P450 (CYP) pathway is involved in the conversion of clopidogrel to its active metabolite. A recent black-box warning was included in the clopidogrel package insert indicating a significant clinical link between specific CYP2C19 genetic variants and poor metabolism of clopidogrel. Of these variants, *2 and *3 are the most common and are associated with complete loss of enzyme activity. In patients who are carriers of a CYP2C19 *2 or *3 allele, the conversion of clopidogrel to its active metabolite may be reduced, which can lead to ischemic events and negative consequence for the patient. We examined the ability of the Verigene CLO assay (Nanosphere, Northbrook, IL) to identify CYP2C19 *2 and *3 polymorphisms in 1,286 unique whole blood samples. The Verigene CLO assay accurately identified homozygous and heterozygous *2 and *3 phenotypes with a specificity of 100% and a final call rate of 99.7%. The assay is fully automated and can produce a result in approximately 3.5 hours.

Alternative Use for Spectra MRSA Chromogenic Agar in Detection of Methicillin-Resistant Staphylococcus aureus from Positive Blood Cultures

ABSTRACT Spectra MRSA agar (Remel, Lenexa, KS), a novel chromogenic medium originally developed to detect methicillin-resistant Staphylococcus aureus (MRSA) from nasal swabs, was evaluated in this multicenter study for the detection of MRSA from positive blood cultures exhibiting Gram-positive cocci upon initial Gram staining.

Circulating Breast Carcinoma Cells Mimicking Therapy-Related Acute Myeloid Leukemia: A Potential Cytogenetic and Flow Cytometry Pitfall.

Circulating tumor cells are rare in peripheral blood smears. We report the case of a patient with circulating breast carcinoma cells resembling circulating myeloid blasts and provide a brief review of the literature. Peripheral blood smears and a bone marrow aspirate were examined morphologically and by flow cytometry and fluorescence in situ hybridization (FISH). Bone marrow histology in conjunction with immunohistochemical stains was also evaluated. A population of atypical cells with blast-like morphology was present in the peripheral blood. Flow cytometry showed a 9% population of CD45 dim positive, CD13 partial positive, and CD15 variably positive cells. Peripheral blood FISH analysis revealed deletion 7q, gain of 8q, and deletions 16q and 17q in 32.5% to 36% of 200 interphase cells analyzed. The bone marrow biopsy showed cohesive groups of cytokeratin AE1/AE3 positive cells. Our report demonstrates that circulating carcinoma cells can mimic a high-grade myeloid neoplasm morphologically and by flow cytometry and FISH analysis.

Concomitant 11p15.4‐p15.5 duplication and terminal 22q13.33 deletion in a patient with features of Beckwith–Wiedemann syndrome

Concomitant 11p15.4-p15.5 Duplication and Terminal 22q13.33 Deletion in a Patient with Features of Beckwith–Wiedemann Syndrome Jess F. Peterson,* David P. Bick, Gabrielle C. Geddes, Julie McCarrier, John W. Grignon Jr, Brett Chirempes, Ulrich Broeckel, Fatima Abidi, Richard C. Rogers, Luigi Boccuto, Barbara DuPont, and Peter vanTuinen Department of Pathology, Medical College of Wisconsin, Milwaukee, Wisconsin Wisconsin Diagnostic Laboratories, Milwaukee, Wisconsin Department of Pediatrics, Section of Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin Advanced Genomics Laboratory, Children’s Hospital of Wisconsin, Milwaukee, Wisconsin Department of Pediatrics, Section of Genomic Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin Greenwood Genetic Center, Greenwood, South Carolina

Elucidating discrepant results in a prenatal diagnosis of 48,XXY,+18 (Edwards and Klinefelter syndromes)

Keywords: Edwards syndrome; Klinefelter syndrome; 48,XXY,+18; 47,XY,+18; mosaicism; non-invasive prenatal testing (NIPT); chorionic villus sampling (CVS)

Leukemic phase and CSF involvement of diffuse large B-cell lymphoma with a complex karyotype including a TP53 deletion

Diffuse large B‐cell lymphoma in rare instances can present initially in a leukemic phase and mimic other lymphoid diseases. In such cases, advanced diagnostic testing including immunophenotyping, FISH analysis, and karyotyping can help determine the accurate diagnosis which is key in the management of the disease.

Inheritance of a Balanced t(12;20)(q24.33;p12.2) and Unbalanced der(13)t(7;13)(p21.3;q33.2) from a Maternally Derived Double Balanced Translocation Carrier

We report a 4-month-old male proband with a history of prominent forehead, hypertelorism, ear abnormalities, micrognathia, hypospadias, and multiple cardiac abnormalities. Initial microarray analysis detected a concurrent 7p21.3-p22.3 duplication and 13q33.2-q34 deletion indicating an unbalanced rearrangement. However, subsequent conventional cytogenetic studies only revealed what appeared to be a balanced t(12;20)(q24.33;p12.2). Fluorescence in situ hybridization (FISH) using chromosome-specific subtelomere probes confirmed the presence of an unbalanced der(13)t(7;13)(p21.3;q33.2) and balanced t(12;20)(q24.33;p12.2), both of maternal origin. In addition to our unique clinical findings, this case highlights the benefits and limitations of both conventional cytogenetic studies and microarray analysis and how FISH complements each methodology.

A Rare Combination of Functional Disomy Xp, Deletion Xq13.2-q28 Spanning the XIST Gene, and Duplication 3q25.33-q29 in a Female with der(X)t(X;3)(q13.2;q25.33)

We report a 19-year-old female patient with a history of short stature, primary ovarian insufficiency, sensorineural hearing loss, sacral teratoma, neurogenic bladder, and intellectual disability with underlying mosaicism for der(X)t(X;3)(q13.2;q25.33), a ring X chromosome, and monosomy X. Derivative X chromosomes from unbalanced X-autosomal translocations are preferentially silenced by the XIST gene (Xq13.2) located within the X-inactivation center. The unbalanced X-autosomal translocation in our case resulted in loss of the XIST gene thus precluding the inactivation of the derivative X chromosome. As a result, clinical features of functional disomy Xp, Turners syndrome, and duplication 3q syndrome were observed. Importantly, indications of the derivative X chromosome were revealed by microarray analysis following an initial diagnosis of Turners syndrome made by conventional cytogenetic studies approximately 18 months earlier. This case demonstrates the importance of utilizing microarray analysis as a first-line test in patients with clinical features beyond the scope of a well-defined genetic syndrome.