Francesca Lee

Evaluation of the Nanosphere Verigene Gram-Positive Blood Culture Assay with the VersaTREK Blood Culture System and Assessment of Possible Impact on Selected Patients

ABSTRACT The Verigene Gram-positive blood culture (BC-GP) assay (Nanosphere, Northbrook, IL) is a molecular method for the rapid identification of Gram-positive organisms and resistance markers directly from blood culture bottles. A total of 148 VersaTREK REDOX 1 40-ml aerobic bottles demonstrating Gram-positive bacteria were tested. Results were compared with those from conventional biochemical and matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) identifications. We obtained isolates of methicillin-resistant Staphylococcus aureus (MRSA) (24), methicillin-susceptible Staphylococcus aureus (MSSA) (14), methicillin-resistant Staphylococcus epidermidis (MRSE) (17), methicillin-susceptible Staphylococcus epidermidis (MSSE) (9), other coagulase-negative staphylococci (19), Streptococcus salivarius (5), Streptococcus parasanguinis (2), Streptococcus sanguinis (1), Streptococcus cristatus (1), the Streptococcus bovis group (5), Streptococcus agalactiae (9), the Streptococcus anginosus group (1), Streptococcus pneumoniae (6), vancomycin-resistant Enterococcus faecium (VRE FCM) (16), vancomycin-susceptible Enterococcus faecalis (3), Aerococcus viridans (2), Bacillus (6), Corynebacterium (8), Lactobacillus (2), Micrococcus (2), Neisseria mucosa (1), Escherichia coli (3), Candida tropicalis (1), Propionibacterium (1), and Rothia (1). Overall agreement with the culture results was 95%. A total of 137 of 138 (99%) monomicrobial cultures were concordant. We tested 9 polymicrobial samples and found 33% agreement. A chart review of 31 patients with MRSA, MSSA, or VRE demonstrated that the Nanosphere BC-GP assay might have led to more appropriate antibiotic selection for these patients an average of 42 h earlier. Additionally, contact isolation could have been initiated an average of 37 h earlier for patients with MRSA or VRE. The BC-GP assay may have a positive impact on patient care, health care costs, and antibiotic stewardship.

Antimicrobial prophylaxis may not be the answer: Surgical site infections among patients receiving care per recommended guidelines

BACKGROUND It is believed that compliance with all 3 components of perioperative antimicrobial prophylaxis, ie, timing, choice, and duration, yields greater reduction in surgical site infections (SSI). METHODS An observational study was performed among patients in the surgical care improvement project at a tertiary public academic hospital in the United States. The rates of SSI among patients who received appropriate antimicrobial agent(s) per current guidelines were compared with patients who did not. Medical record review was performed to compare the clinical characteristics of patients with SSI (cases) and an equal number of patients without SSI (matched controls). RESULTS From January 2008 to June 2009, 762 patients underwent 763 eligible surgical procedures. Forty-seven (6.2%) developed SSI. The rate of SSI in patients who received appropriate antimicrobial prophylaxis per guidelines was not different from those who did not (42/611, 6.9% vs 5/152, 3.3%, respectively; P value = .13). Patients with SSI were more likely to have an elevated body mass index (median and interquartile range in cases: 28.7 [27.0-34.9] vs 25.0 [22.4-30.4] in controls; P value = .02) and more likely to have diabetes (36% vs 9%, respectively; odds ratio, 5.71; 95% confidence interval: 1.43-22.8; P value = .02). CONCLUSION Compliance with timing, choice, and duration of antimicrobial prophylaxis as a whole did not lead to lower SSI. Elevated body mass index and diabetes were associated with a higher rate of SSI.

Bacteremia and septic arthritis due to a nontoxigenic strain of Clostridium difficile in a patient with sickle cell disease

Abstract A 22-year-old female with sickle cell disease presented with fevers, bilateral knee pain, and lethargy. Laboratory data revealed a leukocytosis and lactic acidosis. Blood and synovial fluid cultures grew a non-toxin-producing strain of Clostridium difficile. This case highlights the fact that nontoxigenic Clostridium difficile can cause significant disease.

Metastatic “Burned Out” Seminoma Causing Neurological Paraneoplastic Syndrome—Not Quite “Burned Out”

A 44-year-old man presented with cerebellar ataxia and limbic encephalitis and was ultimately diagnosed with metastatic germ cell neoplasm resulting from a “burned out” primary testicular tumor. The patient had progressive ataxia, leading to a thorough investigation for infectious, autoimmune, metabolic, and malignant causes of acquired cerebellar ataxia that revealed no significant findings. Testicular sonography demonstrated a possible right testicular lesion that was not confirmed on radical inguinal orchiectomy. F18-FDG positron emission tomography/computerized tomography scan revealed a solitary retroperitoneal lesion, concerning for metastatic disease but not amenable to percutaneous biopsy. A robotic retroperitoneal lymph node dissection was performed and pathology revealed a CD117-positive metastatic seminoma leading to appropriate germ cell tumor-directed chemotherapy. After completing chemotherapy and during 1 year of follow-up, there has been a gradual improvement of the patient’s neurological manifestations.

Ceftolozane/tazobactam sensitivity patterns in Pseudomonas aeruginosa isolates recovered from sputum of cystic fibrosis patients

Ceftolozane/tazobactam is a combination intravenous antibiotic with potentially important activity against drug-resistant Gram-negative organisms. Ceftolozane/tazobactams in vitro activity was evaluated in 30 samples collected from 23 adult cystic fibrosis patients with extended and pan-resistant Pseudomonas aeruginosa in 2015. Testing results demonstrated that 30% of the isolates were susceptible,13% were intermediate, and 57% were resistant. This suggests that ceftolozane/tazobactam may be a useful antibiotic in carefully selected, multidrug-resistant Pseudomonas isolates.

Why Can't We Just Use PCR? The Role of Genotypic versus Phenotypic Testing for Antimicrobial Resistance Testing

Abstract There is a need for phenotypic susceptibility testing that is expeditious and that can be performed directly from clinical specimens. While rapid pathogen identification is important, it is the susceptibility result that is essential for antimicrobial optimization. The options for rapid susceptibility testing are limited, with the majority of commercial tests available offering genotypic resistance detection only. In this article, a laboratorian and a clinician discuss the benefits and limitations of genotypic and phenotypic susceptibility testing and provide examples of how results should be interpreted to maximize the clinical utility.

Diagnostics and laboratory role in outbreaks

Purpose of review The review describes the investigative benefits of traditional and novel molecular epidemiology techniques, while acknowledging the limitations faced by clinical laboratories seeking to implement these methods. Recent findings Pulse-field gel electrophoresis and other traditional techniques remain powerful tools in outbreak investigations and continue to be used by multiple groups. Newer techniques such as matrix-assisted laser desorption/ionization-time of flight mass-spectrometry and whole genome sequencing show great promise. However, there is a lack of standardization regarding definitions for genetic relatedness, nor are there established criteria for accuracy and reproducibility. There are also challenges regarding availability of trained bioinformatics staff, and concerns regarding reimbursement. Summary There are many tools available for molecular epidemiologic investigation. Epidemiologists and clinical laboratorians should work together to determine which testing methods are best for each institution.