Interaction between bacteria and cholesterol crystals: Implications for endocarditis and atherosclerosis.

BACKGROUND: The interaction between pathogenic bacteria and cholesterol crystals (CCs) has not been investigated. However, CCs are found extensively in atherosclerotic plaques and sclerotic cardiac valves. Interactions between pathogenic bacteria and CCs could provide insights into destabilization of atherosclerotic plaques and bacterial adhesion to cardiac valves. METHODS: Staphylococcus aureus and Pseudomonas aeruginosa were used to assess in vitro bacterial adhesion to CCs and proliferation in the presence of CCs compared to plastic microspheres and glass shards as controls. Ex vivo studies evaluated bacterial adhesion to atherosclerotic rabbit arteries compared to normal arteries and human atherosclerotic carotid plaques compared to normal carotid arteries. Scanning electron microscopy (SEM) was used to visualize bacterial adhesion to CCs and confocal microscopy was used to detect cholesterol binding to bacteria grown in the presence or absence of CCs. RESULTS: In vitro, S. aureus and P. aeruginosa displayed significantly greater adhesion, 36% (p<0.0001) and 89% (p<0.0001), respectively, and growth upon exposure to CCs compared to microspheres or glass shards. Rabbit and human atherosclerotic arteries contained significantly greater bacterial burdens compared to controls (4× (p<0.0004); 3× (p<0.019), respectively. SEM demonstrated that bacteria adhered and appeared to degrade CCs. Consistent with this, confocal microscopy indicated increased cholesterol bound to the bacterial cells. CONCLUSIONS: This study is the first to demonstrate an interaction between bacteria and CCs showing that bacteria dissolve and bind to CCs. This interaction helps to elucidate adhesion of bacteria to sclerotic valves and atherosclerotic plaques that may contribute to endocarditis and plaque destabilization.

A Real-World Assessment of Clinical Outcomes and Safety of Eravacycline: A Novel Fluorocycline.

BACKGROUND: Eravacycline is a novel fluorocycline approved for treatment of intraabdominal infections, with a broad spectrum of activity against a range of pathogens including multidrug-resistant species, including ESBL- or KPC-producing isolates. It is approved for twice-daily dosing with no need for adjustment in renal dysfunction. In the concomitant administration with CYP 3A4-inducing drugs, eravacycline dosing should be modified. OBJECTIVE: To evaluate the efficacy and safety of eravacycline in a range of infections such as intraabdominal infections, pneumonia and diabetic foot infections in seriously ill patients. METHODS: A retrospective observational cohort study using electronic patient records of 50 consecutive patients administered eravacycline during inpatient acute care admission or as part of outpatient antibiotic therapy (OPAT). RESULTS: Therapy of 1.5 mg/kg q24h was initiated in the hospital in most patients, although some of the less sick were managed in the office or OPAT setting. All patients concluded their management outside of the hospital. Of the 50 patients, 47 (94%) achieved clinical resolution of their infection and 3 (6%) clinical failures occurred. Only three (6%) patients did not have comorbidities, three had a single comorbidity (6%), and the majority (88%) of patients had two or more comorbidities. Most common infections were intraabdominal (36%), pneumonia (18%), diabetic foot (12%), spontaneous bacterial peritonitis (8%) and empyema (8%). Almost half of infections had more than one pathogen isolated, and resistant isolates were frequent. The drug was well tolerated with only two reports of nausea, which did not result in treatment discontinuation, and in 30 days of post-eravacycline therapy only one case of Clostridiodes difficile. CONCLUSIONS: In this real-world setting, eravacycline demonstrated a similar high level of clinical efficacy as seen in clinical trials, 94%, in a variety of infections, including against multidrug-resistant bacteria, and was well tolerated.

Novel PCR-based methods enhance characterization of vaginal microbiota in a bacterial vaginosis patient before and after treatment.

Deep characterization, even by next-generation sequencing, of the vaginal microbiota in healthy women or posttreatment bacterial vaginosis patients is limited by the dominance of lactobacilli. To improve detection, we offer two approaches: quantitative PCR (qPCR) using phylogenetic branch-inclusive primers and sequencing of broad-spectrum amplicons generated with oligomers that block amplification of lactobacilli.

Pharmacokinetics and monte carlo simulations of doripenem in patients with febrile neutropenia.

BACKGROUND: Doripenem is a group 2 carbapenem with enhanced in vitro activity against gram-negative bacteria including Pseudomonas aeruginosa. There is a paucity of pharmacokinetic/pharmacodynamic data on doripenem in patients with febrile neutropenia. OBJECTIVE: To conduct a pharmacokinetic evaluation of 2 doses of doripenem in patients with febrile neutropenia and provide probability estimates of attaining effective drug exposure against common gram-negative pathogens. METHODS: We obtained multiple blood samples from 12 adults with febrile neutropenia who were receiving either 500 mg or 1000 mg of intravenous doripenem over 4 hours every 8 hours. Following at least 2 doses, serum concentrations were measured in each subject at 1, 4, 6, and 8 hours after initiation of a dose by a validated high-performance liquid chromatography assay. The derived pharmacokinetic parameters from these serum levels were used to perform a 5000-patient Monte Carlo simulation against bacteria with minimal inhibitory concentrations (MICs) of 0.008-64 mg/L to determine probability estimates of the time in which unbound drug concentrations remain above the MIC (fT(>MIC)). RESULTS: The mean pharmacokinetic parameters in these patients were a volume of distribution of 43.9 L, an elimination rate constant of 0.37 h(-1), a total clearance of 14.4 L/h, and an area under the concentration-time curve of 57.6 mg•h/L. An optimal probability of target attainment (40% fT(>MIC)) of 90% was obtained against bacteria with MICs ≤2 mg/L and ≤4 mg/L with 500-mg and 1000-mg doses, respectively. Adverse events associated with doripenem were not observed. CONCLUSIONS: The findings from this analysis of doripenem suggest that higher doses, as well as prolonged infusions, may be necessary to optimally treat selected gram-negative bacteria (eg, P. aeruginosa) in patients with febrile neutropenia.

High-throughput identification and quantification of Candida species using high resolution derivative melt analysis of panfungal amplicons.

Fungal infections pose unique challenges to molecular diagnostics; fungal molecular diagnostics consequently lags behind bacterial and viral counterparts. Nevertheless, fungal infections are often life-threatening, and early detection and identification of species is crucial to successful intervention. A high throughput PCR-based method is needed that is independent of culture, is sensitive to the level of one fungal cell per milliliter of blood or other tissue types, and is capable of detecting species and resistance mutations. We introduce the use of high resolution melt analysis, in combination with more sensitive, inclusive, and appropriately positioned panfungal primers, to address these needs. PCR-based amplification of the variable internal transcribed regions of the rDNA genes generates an amplicon whose sequence melts with a shape that is characteristic and therefore diagnostic of the species. Simple analysis of the differences between test and reference melt curves generates a single number that calls the species. Early indications suggest that high resolution melt analysis can distinguish all eight major species of Candida of clinical significance without interference from excess human DNA. Candida species, including mixed and novel species, can be identified directly in vaginal samples. This tool can potentially detect, count, and identify fungi in hundreds of samples per day without further manipulation, costs, or delays, offering a major step forward in fungal molecular diagnostics.

Decreased diversity of the fecal Microbiome in recurrent Clostridium difficile-associated diarrhea.

Antibiotic-associated diarrhea due to Clostridium difficile (CDAD) is thought to reflect colonization of a disrupted microbial community by the pathogen. We profiled the fecal microbiota of patients with CDAD (both initial and recurrent episodes) by culture-independent phylogenetic analysis of 16S rRNA-encoding gene sequences. Compared with those from control subjects and patients with an initial episode, the fecal communities in patients with recurrent CDAD were highly variable in bacterial composition and were characterized by markedly decreased diversity. Preservation and restoration of the microbial diversity could represent novel strategies for prevention and treatment of recurrent CDAD, which is often recalcitrant to existing therapies.

Bacterial vaginosis: culture- and PCR-based characterizations of a complex polymicrobial disease's pathobiology.

Bacterial vaginosis (BV) is an enigmatic polymicrobial disease, and its evolution and pathobiology will not be solved by traditional culture-based methods. Characterization of the vaginal microbiota by polymerase chain reaction-based methods holds great promise. Molecular studies have identified species not detected by culture, but they also have missed some species identified by culture. These studies allow classification of both normal and BV patients based on distinct microbiologic profiles, which may prove important in accessing risk of BV, response to treatment, and risk of complications. More studies using new generations of primers and standardized methods are needed, and data must be analyzed after grouping patients according to microbiologic profiles.