Antimicrob Agents Research Articles

Chloroquine or Hydroxychloroquine for COVID-19: Is Cardiotoxicity a Concern?

Chloroquine or Hydroxychloroquine for COVID-19: Is Cardiotoxicity a Concern?

COVID-19 in kidney transplant recipients.

There is minimal information on coronavirus disease 2019 (COVID‐19) in immunocompromised individuals. We have studied 10 patients treated at 12 adult care hospitals. Ten kidney transplant recipients tested positive for severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) by polymerase chain reaction, and 9 were admitted. The median age was 57 (interquartile range [IQR] 47‐67), 60% were male, 40% Caucasian, and 30% Black/African American. Median time from transplant to COVID‐19 testing was 2822 days (IQR 1272‐4592). The most common symptom was fever, followed by cough, myalgia, chills, and fatigue. The most common chest X‐ray and computed tomography abnormality was multifocal patchy opacities. Three patients had no abnormal findings. Leukopenia was seen in 20% of patients, and allograft function was stable in 50% of patients. Nine patients were on tacrolimus and a mycophenolic antimetabolite, and 70% were on prednisone. Hospitalized patients had their antimetabolite agent stopped. All hospitalized patients received hydroxychloroquine and azithromycin. Three patients died (30%), and 5 (50%) developed acute kidney injury. Kidney transplant recipients infected with COVID‐19 should be monitored closely in the setting of lowered immunosuppression. Most individuals required hospitalization and presenting symptoms were similar to those of nontransplant individuals.

Ruptured Popliteal Artery Aneurysm Complicated with Acute Respiratory Distress Syndrome Secondary to SARS-CoV-2 Infection

We herein report a rare case of the ruptured popliteal artery aneurysm in an 89-year-old man, whose recovery after surgical treatment was complicated with acute respiratory distress syndrome secondary to confirmed infection with SARS-CoV-2. Presenting symptoms, patient's comorbidities, and postoperative course complicated with cardiac and respiratory failure leading to adverse outcome are discussed in this case report.

Chloroquine-induced torsades de pointes in a patient with coronavirus disease 2019

Chloroquine-induced torsades de pointes in a patient with coronavirus disease 2019

Efforts to Reduce the Impact of Coronavirus Disease 2019 Outbreak on Radiation Oncology in Taiwan

Efforts to Reduce the Impact of Coronavirus Disease 2019 Outbreak on Radiation Oncology in Taiwan

Characterisation of Staphylococcus capitis Bloodstream isolates from south-east Queensland neonatal units

Aim: Characterise Staphylococcus capitis blood culture isolates from neonatal intensive care units (NICUs) including assessment of glycopeptide susceptibility, genomic assessment of resistance genes and virulence factors and phylogenetic analysis to assess for presence of nosocomial transmission and to assess if related to internationally distributed multi-resistant NRCS-A clone.1 Methods: 312 episodes of late onset sepsis in 2 south-east Queensland (SEQ) NICUs were assessed for eligibility over 10 years, 64 with S. capitis bacteraemia. 24 stored bloodstream isolates from NICUs across 2 SEQ centres were compared with 25 contemporaneously matched adult isolates and were evaluated for glycopeptide susceptibility. These methods included broth microdilution (performed at UQCCR, Herston), macro E tests, and vancomycin screening agar at Central Laboratory Pathology Queensland, and were complemented by whole genome sequencing performed with Illumina NextSeq. Results: 2 separate clusters were identified in NICU isolates suggesting local transmission (hospital 1, 10/14 within 6 SNPs; hospital 2, 8/10 within 8 SNPs). 22 isolates have same SCCmec type as NRCS-A, 21/24 appear to contain composite cassette. Growth on the VAN 4 screening agar indicative of reduced susceptibility and/or heteroresistance was present for 17/24 (71%) NICU/SCN isolates, compared with only two adult isolates. Other modalities of glycopeptide testing did not identify this trait, suggesting reduced sensitivity of these methods for S. capitis. Reference1.Carter GP, Ussher JE, Da Silva AG, et al. Genomic analysis of multi-resistant Staphylococcus capitis associated with neonatal sepsis. Antimicrob Agents Chemother 2018; 62: e00898–18.

Nephrotoxicity of Antimicrobials and Antibiotics.

Medication-induced nephrotoxicity remains one of the most common causes of acute kidney injury (AKI) among hospitalized patients. Within the extensive group of medications associated with AKI, antibiotics and other antimicrobials are well recognized triggers of structural and functional renal impairment. Clinical manifestations range from mild forms of tubular injury to significant deterioration of kidney function requiring acute renal replacement therapy. Several mechanisms are described, although the most frequent are acute interstitial nephritis, acute tubular necrosis, intratubular crystal deposition, and proximal/distal tubulopathy with electrolyte wasting abnormalities. General risk factors for antimicrobial-induced AKI include pre-existing chronic kidney disease, and concomitant use of medication with nephrotoxic potential. Prevention and early recognition of AKI represent the standard approach to mitigate AKI and avoid morbidity.

COVID-19 Outbreak: How to Use Current Knowledge to better Treat Positive Patients

COVID-19 Outbreak: How to Use Current Knowledge to better Treat Positive Patients

Using the IDEOM Workflow for LCMS-Based Metabolomics Studies of Drug Mechanisms.

Rapid advancements in metabolomics technologies have allowed for application of liquid chromatography mass spectrometry (LCMS)-based metabolomics to investigate a wide range of biological questions. In addition to an important role in studies of cellular biochemistry and biomarker discovery, an exciting application of metabolomics is the elucidation of mechanisms of drug action (Creek et al., Antimicrob Agents Chemother 60:6650-6663, 2016; Allman et al., Antimicrob Agents Chemother 60:6635-6649, 2016). Although it is a very useful technique, challenges in raw data processing, extracting useful information out of large noisy datasets, and identifying metabolites with confidence, have meant that metabolomics is still perceived as a highly specialized technology. As a result, metabolomics has not yet achieved the anticipated extent of uptake in laboratories around the world as genomics or transcriptomics. With a view to bring metabolomics within reach of a nonspecialist scientist, here we describe a routine workflow with IDEOM, which is a graphical user interface within Microsoft Excel, which almost all researchers are familiar with. IDEOM consists of custom built algorithms that allow LCMS data processing, automatic noise filtering and identification of metabolite features (Creek et al., Bioinformatics 28:1048-1049, 2012). Its automated interface incorporates advanced LCMS data processing tools, mzMatch and XCMS, and requires R for complete functionality. IDEOM is freely available for all researchers and this chapter will focus on describing the IDEOM workflow for the nonspecialist researcher in the context of studies designed to elucidate mechanisms of drug action.

A validated LC-MSMS method for the simultaneous quantification of meropenem and vaborbactam in human plasma and renal replacement therapy effluent and its application to a pharmacokinetic study.

A simple method for the simultaneous quantification of meropenem and the recently approved β-lactamase inhibitor, vaborbactam, in human plasma and renal replacement therapy effluent (RRTE) was developed and validated. This antibiotic combination protects a primary β-lactam, meropenem, with a new β-lactamase inhibitor, and expands the limited options for treatment of multidrug-resistant Gram-negative infections. Meropenem, vaborbactam, and the internal standards [2H6]-meropenem and sulbactam in plasma and RRTE were processed using acetonitrile followed by a chromatographic separation on a Poroshell HPH-C18 column with a gradient elution of the mobile phases and monitored using mass spectrometry detection. The calibration range was 0.05 to 100μgmL-1 for both meropenem and vaborbactam. The intra-day and inter-day precision and accuracy were less than 15% for both meropenem and vaborbactam and the recovery from plasma was 96% for both meropenem and vaborbactam and the recovery from RRTE was 93% and 103% for meropenem and vaborbactam, respectively. This methodology was successfully applied to an ex vivo characterisation study of the effects of renal replacement therapy modalities on the pharmacokinetics of meropenem and vaborbactam (Antimicrob Agents Chemother 62(10), 2018). Graphical abstract.

1579. Multidrug-Resistant Candida auris Isolates From New York Hospitals and Healthcare Facilities Are Susceptible to Antifungal Combinations

Background Candida auris outbreak continues unabated in New York with the current case counts exceeding 300 patients. We used a modification of standard CLSI broth microdilution method (BMD) if two-drug combinations are efficacious against C. auris isolates with high-resistance to fluconazole (FZ, MIC50 >256 mg/L), and variable resistance to other broad-spectrum antifungal drugs.MethodsBMD plates were custom-designed and quality controlled by TREK Diagnostic System. The combination tests of 15 drug-resistant C. auris involved microtiter wells with the initial 144 two-drug combinations and their two-fold dilutions (1/2–1/32) to get 864 two-drug combinations finally. We utilized MIC100 endpoints for the drug combination readings as reported earlier for the intra- and inter-laboratory agreements obtained against Candida species and Aspergillus fumigatus (Antimicrob Agents Chemother. 2015. 59:1759–1766). We also tested minimum fungicidal concentrations (MFC).ResultsWe tested all possible 864 two-drug antifungal combinations for nine antifungal drugs in use to yield 12,960 MIC100 readings, and MFC readings for 15 C. auris isolates. Flucytosine (FLC) at 2.0 mg/L potentiated most successful combinations with other drugs. Micafungin (MFG), Anidulafungin (AFG), Caspofungin (CAS) at individual concentrations of 0.25 mg/L combined well with FLC (2.0 mg/L) to yield MIC100 for 14, 13, and 12 of 15 C. auris isolates tested, respectively. MFG/FLC combination was also fungicidal for 4 of 15 isolates. AMB / FLC (0.25/1.0 mg/L) yielded MIC100 for 13 isolates and MFC for three test isolates. Posaconazole (POS), and Isavuconazole (ISA) and Voriconazole (VRC) also combined well with FLC (0.25/2.0 mg/L) to yield MIC100 for 12, 13, and 13 isolates, respectively. POS/FLC combination was fungicidal for three isolates.ConclusionWe identified seven two drug-combinations of antifungals efficacious against drug-resistant C. auris strains. The modified BMD combination susceptibility testing could be used by the clinical laboratories to assist providers with the selection of optimal treatment for C. auris candidemia. Disclosures All authors: No reported disclosures.

1576. Delaying the Start of Maintenance Vancomycin After a Loading Dose to Avoid a High 0–24h AUC

BackgroundVancomycin dosing guidelines recommend loading doses (LDs) (25–30 mg/kg TBW), and a maintenance regimen, usually started after a time period equal to the dosing interval. Studies of vancomycin exposure and nephrotoxicity conclude that a 0 to 24-hour area under the serum concentration–time curve (0–24AUC) > 677 mg-hour/L results in a 3- to 4-fold increased risk of nephrotoxicity (Zasowski EJ, Antimicrob Agents Chemother 2018). For vancomycin LDs we compare the calculated LD and the maintenance dose, and delay initiation of the maintenance regimen when the LD exceeds the daily maintenance dose by > 50%. This study assessed the pharmacokinetic outcomes from this technique.MethodsWe retrospectively reviewed 68 consecutive adult patients receiving therapeutic doses of vancomycin. Patient age, sex, height, weight, serum creatinine, and indication were used to calculate the daily dose/intervals for a steady-state 24-hr AUC of 400 or 600 mg-hour/L. The total 0–24AUC was calculated by adding the 0–24 AUC from a 25 mg/kg LD (max: 3 gm) to the 0–24AUC(s) for maintenance dose(s) within the first 24 hours. We compared the total 0-24AUC when the first maintenance dose was timed for the next dosing interval (“scheduled”) to that when the maintenance dose was delayed according to our protocol (“delayed”). We tested the proportion of patients who would be exposed to a vancomycin 0-24AUC > 677 mg-hour/L.Results16/68 patients were diagnosed with SSTI (goal 24 hr AUC: 400 mg-hour/L) and 52/68 with sepsis, bacteremia/endocarditis, or pneumonia (24 hr AUC: 600 mg-hour/L). Median daily maintenance dose was 1750 mg (range: 875–4,000 mg). For patients with a goal AUC of 400, the 0-24AUC was > 677 mg-hour/L in one patient using the “scheduled” process and in none of the patients using the “delayed” protocol. However, for patients with a goal AUC of 600, the 0-24AUC was > 677 mg-hour/L in 22/52 patients via the “scheduled” process vs. 4/52 patients via the “delayed” protocol.ConclusionFor patients with severe gram-positive bacterial infections requiring aggressive dosing of vancomycin, delaying the start of maintenance dosing following a large LD is an effective way to ensure attainment of goal therapeutic AUC within the first 24 hr without placing the patient at increased risk for nephrotoxicity.Disclosures All authors: No reported disclosures.

A RARE CASE OF CORYNEBACTERIUM STRIATUM NATIVE VALVE ENDOCARDITIS

SESSION TITLE: Wednesday Medical Student/Resident Case Report Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/23/2019 09:45 AM - 10:45 AM INTRODUCTION: Corynebacterium diphtheroids species are aerobic, Gram-positive bacilli often considered as part of normal skin flora and mucous membranes. Though frequently isolated in cultures, they are often assumed to be skin contaminants. Nonetheless, over the last decade they are reported to cause life threatening diseases including bacteremia and endocarditis. They cause 4-9% of prosthetic vale endocarditis but are only responsible for 0.2 to 0.4% of native valve endocarditis (NVE)(1). CASE PRESENTATION: 54 years old female with past medical history significant for hypertension, hyperlipidemia, mild intermittent asthma, anemia, seizure disorder, transient ischemic attack, cerebrovascular accident without any residual deficit, atrial fibrillation on coumadin, schizophrenia, chronic back pain, cocaine use, recent colitis presented with complains of intermittent fever, chills for few weeks and mechanical fall one day prior to presentation. She was recently treated for colitis at outside hospital (OH) and was discharged on oral co-amoxiclav. She reported that she had bacteremia. Vitals: temp 101.5F, Blood pressure (BP) 102/67mmhg. Physical examination: irregular heart rate, wheezing, positive cervical and lumbar paraspinal tenderness. Labs: normocytic anemia with hemoglobin of 10.4, platelet count of 115 x 109/L, sub-therapeutic international normalized ratio (INR) of 1.11 and cervical spine X-ray suggestive of disc space narrowing at C5-C6. Cefepime 1gm IVSS q8h and vancomycin 1gm IVSS q12h were started. Hospital course was complicated by hypotension with BP of 80s-90s systolic/50’s to 60’s diastolic, non-responsive to intravenous fluids and drop in oxygen saturation to 80’s due to development of pulmonary edema. Blood cultures were positive for gram positive rods. Medical records from OH revealed blood cultures positive for gram positive rods. Antibiotic was changed to ampicillin to cover possible listeria monocytogenes (blood cultures positive for gram positive rods). Transthoracic echocardiogram (TTE) was suggestive of aortic valve vegetation with severe regurgitation (See Figure 1). She was considered candidate for aortic valve replacement and transferred to cardiothoracic surgery. She successfully underwent aortic valve replacement. Final results of blood cultures grew “Corynebacterium Striatum (C. Striatum)”. DISCUSSION: This case highlights a patient with native valve endocarditis secondary to C. Striatum and its management. C. striatum is being recently recognized as a nosocomial opportunistic pathogen (2,3) and can rarely cause NVE. CONCLUSIONS: We stress that clinicians should be vigilant and consider Corynebacterium species as potential culprits while managing patients with bacteremia due to gram positive bacilli and should be cautious while labelling them as skin contaminants. Reference #1: Belmares J, Detterline S, Pak JB, Parada JP. Corynebacterium endocarditis species-specific risk factors and outcomes. BMC Infect Dis. 2007;7:4. Reference #2: Lee JY, Lee SH, Kim WH. Three-valve Endocarditis Caused by Corynebacterium striatum. Korean Circ J. 2018;48(9):861-2. Reference #3: McMullen AR, Anderson N, Wallace MA, Shupe A, Burnham CA. When Good Bugs Go Bad: Epidemiology and Antimicrobial Resistance Profiles of Corynebacterium striatum, an Emerging Multidrug-Resistant, Opportunistic Pathogen. Antimicrob Agents Chemother. 2017;61(11). DISCLOSURES: No relevant relationships by Moses Bachan, source=Web Response No relevant relationships by Zinobia Khan, source=Web Response No relevant relationships by Dileep Kumar, source=Web Response

MASSIVE LUNG ABSCESS DUE TO STREPTOCOCCUS INTERMIDIUS IN AN IMMUNOCOMPETENT PATIENT

SESSION TITLE: Monday Fellow Case Report Posters SESSION TYPE: Fellow Case Report Posters PRESENTED ON: 10/21/2019 02:30 PM - 03:15 PM INTRODUCTION: Streptococcus intermidius (SI) is a gram positive bacterium which is a part of the oral, respiratory, urogenital as well as gastrointestinal flora. We present a case of a massive lung abscess with severe acute respiratory distress syndrome (ARDS) requiring veno-venous extracorporeal membrane oxygenation (V-v ECMO) in an immunocompetent patient. CASE PRESENTATION: A 54-year-old male patient with past history of diabetes mellitus presented with shortness of breath and fever. The patient was found to have tachycardia, tachypnea and low blood pressure. A Chest radiograph showed a large dense appearing mass like lesion in the right lung (Figure 1)and a CT scan was performed. The scan showed a 14 cm lung abscess with dense necrotic material (Figure 2&3). The patient decompensated and required emergent intubation with a bedside drainage of the lung abscess and placement of a chest tube. Cultures on the aspirated material grew Streptococcus Intermidius. The patient was started on antibiotics Cefepime and Metronidazole. The patient developed severe ARDS and required the V-v ECMO. The V-v ECMO was explanted after 6 days. Over the course of his stay, the chest tube continued to drain purulent material with a continued air leak. The patient underwent a right lung decortication by a video assisted thoracoscopic surgery (VATS). Due to the prolonged intubation and a likelihood of failure of weaning a tracheostomy was performed. The patient was discharged to a rehabilitation facility with a month long course of Cefepime and Metronidazole. On a 12 month follow up the patient was doing well and the tracheostomy had been successfully decanulated. DISCUSSION: Streptococcus intermidius is a gram positive bacterium that belongs to the Streptococcus Millieri group (SMG). Streptococcus intermidius is usually associated with infections of the head, neck and respiratory tract and have a tendency to cause abscesses (1). Infections with SI a commoner in individuals with uncontrolled or undiagnosed diabetes, malignancy or intravenous drug use. Individuals with poor oral hygiene and dental caries are also at risk for getting SI infections (2). Multiple sites for infections are reported in literature including brain, lung, liver and head /neck region abscesses. A multiplex polymerase chain reaction (PCR) may aid in early detection of SI, while cultures can take over a week to grow. A study of the antibiotic sensitivities of SMG showed excellent susceptibility to Penicillin, Ampicillin and Ceftriaxone (3). However, penetration of the drugs into the abscess and necrotic material remains poor and surgical drainage and decortication is usually required. CONCLUSIONS: Streptococcus Intermidius is an important cause of empyema, early diagnosis and treatment is imperative to limit significant morbidity and mortality. Reference #1: Reddy S, Singh K, Hughes S. Liver Abscesses Caused by Streptococcus intermedius in an Immunocompromised Patient. Cureus. 2018;10(1):e2107. Published 2018 Jan 24. https://doi.org/10.7759/cureus.2107 Reference #2: Ramhmdani S, Bydon A. Streptococcus intermedius: an unusual cause of spinal epidural abscess. J Spine Surg. 2017;3(2):243-249. Reference #3: Tracy M, Wanahita A, Shuhatovich Y, Goldsmith EA, Clarridge JE, Musher DM. Antibiotic susceptibilities of genetically characterized Streptococcus milleri group strains. Antimicrob Agents Chemother. 2001;45(5):1511-4. DISCLOSURES: No relevant relationships by Yizhak Kupfer, source=Web Response No relevant relationships by Ravikaran Patti, source=Web Response No relevant relationships by Vignesh Ponnusamy, source=Web Response No relevant relationships by Chanaka Seneviratne, source=Web Response No relevant relationships by Ankur Sinha, source=Web Response No relevant relationships by Parita Soni, source=Web Response No relevant relationships by Taek Sang Yoon, source=Web Response

Establishing the Genotyping Method for NAT2 Polymorphism in Vietnamese Tuberculoma Patients

The metabolism of Isoniazid, one of the first-line antituberculosis drugs for TB treatment and prophylaxis, depends on the acetyltransferase 2 acetylation (NAT2) phenotype. Different phenotypes of NAT2 will lead to differences in drug concentration and the risk of uncontrolled side effects, such as hepatitis, peripheral neuropathy, gastrointestinal disorders (nausea, vomiting, and stomach pain). These risks are related to the presence of mutant NAT2 alleles such as NAT2*5 (c.341T> C), *6 (c.590G> A) and *7 (c.857G> A), that reduce the N- acetyltransferase activity. Therefore, the genotyping method for NAT2 polymorphism using RFLP and Sanger sequencing was established. The method was successfully applied to determine the polymorphism of 84 TB patients. This study provides a better tool for analyzing NAT2 gene to assist clinicians in treating isoniazid.
 Keywords
 Enzyme NAT2, isoniazid, single nucleotide polymorphism, RFLP, Sanger sequencing.
 References
 [1] U.A. Boelsterli, K.K. Lee, Mechanisms of isoniazid-induced idiosyncratic liver injury: emerging role of mitochondrial stress, J. Gastroenterol. Hepatol. 29 (2014) 678–687.[2] A. Zabost, S. Brzezinska, M. Kozinska, M. Blachnio, J. Jagodzinski, Z. Zwolska, E. Augustynowicz-Kopec, Correlation of N-acetyltransferase 2 genotype with isoniazid acetylation in Polish tuberculosis patients, Biomed Res Int. 2013 (2013) 1-5.[3] M. Kinzig-Schippers, D. Tomalik-Scharte, A. Jetter, B. Scheidel, V. Jakob, M. Rodamer, I. Cascorbi, O. Doroshyenko, F. Sorgel, U. Fuhr, Should we use N-acetyltransferase type 2 genotyping to personalize isoniazid doses? Antimicrob Agents Chemother. 49 (2005) 1733-8[4] K. Walker, G. Ginsberg, D. Hattis, D.O. Johns, K.Z. Guyton, B. Sonawane, Genetic polymorphism in N-Acetyltransferase (NAT): Population distribution of NAT1 and NAT2 activity, J Toxicol Environ Health B Crit Rev. 12 (2009) 440-472. [5] G. Ramachandran, S. Swaminathan, Role of pharmacogenomics in the treatment of tuberculosis: a review, Pharmgenomics Pers Med. 5 (2012) 89-98.[6] J. Azuma, M. Ohno, R. Kubota, S. Yokota, T. Nagai, K. Tsuyuguchi, Y. Okuda, T. Takashima, S. Kamimura, Y. Fujio, I. Kawase, Pharmacogenetics-based tuberculosis therapy research group, NAT2 genotype guided regimen reduces isoniazid-induced liver injury and early treatment failure in the 6-month four-drug standard treatment of tuberculosis: a randomized controlled trial for pharmacogenetics-based therapy, Eur J Clin Pharmacol. 69 (2013) 1091-1101.[7] P.S. Adole, P.S. Kharbanda, S. Sharma, N-acetyltransferase 2 (NAT2) gene polymorphism as a predisposing factor for phenytoin intoxication in tuberculous meningitis or tuberculoma patients having seizures - A pilot study, Indian J Med Res. 143 (2016) 581-590.[8] WHO Scientific Group on Pharmacogenetics and World Health Organization, Pharmacogenetics: report of a WHO scientific group,World Health Organization Technical Report Series. (1973)[9] T.D. Da Silva, A.V. Felipe, J.M. De Lima, C.T. Oshima, N.M. Forones, N-Acetyltransferase 2 genetic polymorphisms and risk of colorectal cancer, World J Gastroenterol. 17 (2011) 760-765. [10] E.Y. Lau, J.S. Felton, F.C. Lightstone, Insights into the o-acetylation reaction of hydroxylated heterocyclic amines by human arylamine N-acetyltransferases: a computational study, Chem Res Toxicol. 19 (2006) 182-1190.[11] Ensembl - EBI, http://asia.ensembl.org/Homo_sapiens/Variation/Population?db=core;r=8:18399844-18400844;v=rs1801280;vdb=variation;vf=1243314,2019 (Ensembl release 96 - April 2019).[12] I.B. Kuznetsov, M. McDuffie, R. Moslehi, A web server for inferring the human N-acetyltransferase-2 (NAT2) enzymatic phenotype from NAT2 genotype, Bioinformatics. 25 (2009) 1185-1186. [13] P. Wang, K. Pradhan, X.B. Zhong, X. Ma, Isoniazid metabolism and hepatotoxicity, Acta Pharm Sin B. 6 (2016) 384-392.[14] M. Ohno, I. Yamaguchi, I. Yamamoto, T. Fukuda, S. Yokota, Slow N-acetyltransferase 2 genotype affects the incidence of isoniazid and rifampicin-induced hepatotoxicity, Int J Tuberc Lung Dis. 4 (2000) 256-261. [15] G.M. Lower, T. Nilsson, C.E. Nelson, H. Wolf, T.E. Gamsky, G.T. Bryan, N-acetyltransferase phenotype and risk in urinary bladder cancer: approaches in molecular epidemiology. Preliminary results in Sweden and Denmark, Int J Epidemiol. 36 (2007) 11-18.
 
 

Early discharge criteria in patients with acute bacterial skin and skin structure infections in a large tertiary-care teaching hospital in Florence, Italy

The study is aimed at retrospectively estimating the percentage of inpatients with severe acute bacterial skin and skin structure infections (ABSSSI) who met the early discharged (ED) criteria adapted from Nathwani et al. (Int J Antimicrob Agents. 2016 Aug;48(2):127-36) and to calculate the number of hospitalization days that could be potentially saved. A retrospective study was conducted in a tertiary care hospital in Florence, Italy. We included all patients admitted for cellulitis and post-surgical infections from 2014 to 2017. Demographic and clinical data were obtained from electronic medical records. We a priori defined the following as a risk factor for non-adherence (RFNA): active or on methadone intravenous drug users, homeless, migrants without health care assistance, and patients who need a caregiver to take prescribed medications. One hundred sixty-two subjects were enrolled. Of them, 94 (58.0%) were male, and 113 (69.7%) had cellulitis/erysipelas. A microbiological isolate was obtained in 51 patients (31.4%); Staphylococcus aureus was the most frequent (47%). Eighty-four (51.8%) were ED suitable, with 258 (49.0%) patient days potentially saved. Among the 78 not ED suitable patients, the most common reason for prolonged length of stay (LOS) was having at least one RFNA (34.6%). Fourteen (18.0%) had one RFNA. Half of the patients admitted in our hospital met the ED criteria with a sparing close to 50% in terms of hospitalization days. Unstable social and personal factors were the most frequent causes for prolonged LOS. In this selected subset of patients, more recent and easier to administer treatments, including long-acting agents, could be proposed.

Carbon-Electrode Dielectrophoresis to Identify Candida strains

Presented here is the use of 3D carbon microelectrodes in the separation of two different Candida strains using dielectrophoresis. The identification of Candida glabrata from Candida albicans has clinical relevance as front line antibiotics commonly used for Candida albicans, the most likely cause of candidiasis, are not effective to eradicate C. glabrata. Candidiasis occurs when a Candida species infiltrates the bloodstream. It is the most common bloodstream infection in the United States, and represents a significant challenge to the healthcare industry (1). While these yeast species are common inhabitants of the gastrointestinal tract and skin, they have the potential to cause infection in patients with compromised immune systems. These infections are problematic in hospitals, and have been estimated to have a mortality rate of up to 44% in some studies (2). Standard procedures following suspicion of candidiasis is the culturing of a sample for up to 1-2 days in agar followed by further testing to analyze spore formation before the species can be appropriately identified and treated (1). In the meantime, the patient is treated with a cocktail of antibiotics to target the most common pathogens. However, C. glabrata are resistant to commonly used antifungal drugs such as fluconazole (3). Hence, a rapid assay to detect the presence of Candida in a sample and further identifying the strain present can have a drastic impact on the treatment of candidiasis. This will enable timely treatment with the most suitable antibiotic, i.e. amphotericin B for C. glabrata, rather than treating the patient with a cocktail of antibiotics; an approach now leading to resistance in many Candida strains (3). Here we report the potential of dielectrophoresis to separate strains of Candida. Dielectrophoresis is an electrokinetic method that allows the dielectric properties of cells to be exploited for manipulation, isolation, and separation purposes. This is because targeted cells will display a specific response to a non-uniform electric field varying in frequency and magnitude (4). In our system, we implement the electric field gradient required for DEP using 3D carbon electrodes. When compared to traditional 2D electrodes, the use of 3D electrodes reduces the main distance from any cell flowing in the channel to the nearest electrode, thus resulting in better trapping throughput and efficiency (4). The use of carbon allows for a more robust device since carbon features a wider electrochemical stability than Au and Pt. Initial results show that different Candida strains feature a different DEP response at different frequencies (fig. 1). Using these methods of manipulation, our goal is to use this technique to devise a tool that uses the different response frequencies to separate the strains of Candida present in a sample. This could be useful in a clinical diagnostic setting for determining which strain is present to pinpoint certain interventions that are preferred for the different strains. Ongoing work is on determining the specific frequency at which one strain, and not the other, shows positive DEP as the basis of isolation. We will trap one strain on the electrode array while eluting the other one. This will allow for cell separation but also enrichment of the targeted species. Once enriched, the population concentration could be determined using optical or electrochemical means. Candidiasis affects thousands of people worldwide due to it’s resistant tendencies. A DEP-based assay to detect the cause of candidiasis will be an important tool in reducing its socioeconomic burden. Morrell M, Fraser VJ, Kollef MH. 2005. Delaying the empiric treatment of Candida bloodstream infection until positive blood culture results are obtained: a potential risk factor for hospital mortality. Antimicrob Agents Chemother 49:3640-3645. Almirante B, Rodriguez D, Park BJ, Cuenca-Estrella M, Planes AM, Almela M, Mensa J, Sanchez F, Ayats J, Gimenez M, Saballs P, Fridkin SK, Morgan J, Rodriguez-Tudela JL, Warnock DW, Pahissa A, Barcelona Candidemia Project Study Group. 2005. Epidemiology and predictors of mortality in cases of Candida bloodstream infection: results from population-based surveillance, Barcelona, Spain, from 2002 to 2003. J Clin Microbiol 43: 1829 –1835. https://doi.org/10.1128/JCM.43.4.1829-1835.2005Fidel PL, Jr, Vazquez JA, Sobel JD. 1999. Candida glabrata: review of epidemiology, pathogenesis, and clinical disease with comparison to C. albicans. Clin Microbiol Rev 12:80 –96.Martinez-Duarte, R., Renaud, P., & Madou, M. J. (2011). A novel approach to dielectrophoresis using carbon electrodes. Electrophoresis. doi:10.1002/elps.201100059 Figure 1

Manipulation of the microbiota to eradicate multidrug-resistant Enterobacteriaceae from the human intestinal tract

Manipulation of the microbiota to eradicate multidrug-resistant Enterobacteriaceae from the human intestinal tract

Effect of Azadirachtin on Bacterial Biofilm Formation

Due to the overuse of currently available antibiotics, bacteria are rapidly evolving resistance to modern medical treatments. Because of this fact, it is important to find alternative antimicrobic agents for which bacteria have not yet developed resistance. To compound this problem, it has been identified that bacteria living in biofilms (as aggregates protected by extracellular polymeric matrix) can be up to 1000 times more antibiotic‐resistant than their planktonic counterparts. The NIH has reported that up to 80% of chronic and 65% of all human infections are biofilm‐associated. One major therapeutic alternative to modern antibiotics is phytochemicals (plant‐derived compounds). A phytochemical of interest, azadirachtin, is derived from the neem tree (Azadirachta indica) which has been historically used in the Indian subcontinent as an herbal remedy for many ailments including those caused by parasites and bacteria. A significant source of infection in hospitals is Staphylococcus aureus which is known for emerging antimicrobic resistance and tendency to form biofilms. The purpose of my project was to identify if azadirachtin inhibits biofilm formation. In order to determine the effects of azadirachtin on biofilm, a microplate biofilm quantitative assay was performed. S. aureus that were methicillin resistant (MRSA, 4 different strains) or susceptible (MSSA, 3 different strains) were assessed. Bacteria were first inoculated into tryptic soy broth (TSB) and incubated (37°C, overnight). Afterwards, bacteria were standardized to a spectrophotometric A590 of 0.1–0.2 growth. Once standardized, the bacteria were transferred to 96‐well microplates with/without azadirachtin (0–0.8 mM) and incubated (37°C, 20 h). Following incubation, bacteria were killed with glutaraldehyde and microplates were washed (three times with dH2O). Subsequently, crystal violet (0.1% aqueous) was added to stain the biofilm. Excess dye was removed by washing (three times with dH2O) and stained biofilm was solubilized (8% acetic acid). Solubilized biofilm was quantitated by A590 readings. Results indicated that azadirachtin had no significant (p<0.05) effect on mean biofilm amounts for MRSA and MSSA biofilm formation. As azadirachtin appears to elicit no anti‐biofilm effect on the Gram positive S. aureus, our next step will be to ascertain its effect on Gram negative Pseudomonas aeruginosa biofilm.Support or Funding InformationFinancial support for VK was received from the DeNardo Education and Research Foundation.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

1066. Adjuvant β-Lactam Therapy Combined with Vancomycin for Methicillin-Resistant Staphylococcus aureus (MRSA) Bacteremia: Does β-Lactam class Matter?

BackgroundVancomycin (VAN) combined with a β-lactam (COMBO) expedites MRSA bacteremia clearance compared with VAN alone. However, the impact of COMBO on persistent MRSA bacteremia (PB) using a contemporary definition of ≥5 days is unknown. There is also no consensus on which β-lactam (BL) should be combined with VAN. We sought to assess PB rates among adults who received COMBO or VAN and the impact of BL class on PB.MethodsThis was an analysis of pooled data from two published studies of adults with MRSA bacteremia (Dilworth et al., Antimicrob Agents Chemother. 2014;58(1):102–109; Casapao et al., Pharmacotherapy. 2017;37(11):1347–1356). All patients received intravenous VAN for ≥72 hours. COMBO patients received an intravenous BL for ≥48 hours with VAN, started within 24 hours of VAN. The remaining patients comprised the VAN group. The primary outcome was PB (≥5 days). The impact of BL class on PB was assessed. Acute kidney injury (AKI, serum creatinine increase from baseline by 0.5 mg/dL or 50%) was examined as a secondary outcome. Demographics were compared between groups. Multivariable logistic regression models compared PB between COMBO and VAN.ResultsIn total, 156 patients were included (VAN = 66; COMBO = 90). The groups were similar except COMBO patients were more likely to have a pulmonary bacteremia source (12.2% vs. 1.5%, P = 0.014) and a higher median (IQR) vancomycin serum level (mg/L, 17.8 (13.9, 23.6) vs. 15.7 (11.3, 20.6); P = 0.039). PB was less common in COMBO (26.7% vs. 43.9%, P = 0.027). In a multivariable model COMBO was inversely associated with PB (adjusted odds ratio [aOR], 95% confidence intervals [CI], 0.48, 0.24–0.95). AKI was more common in COMBO (18.9% vs. 7.6%, P = 0.062). PB and AKI rates by BL class are shown in the table below, with VAN listed for reference.Variable, n (%)Carbapenem, n = 8Cephalosporin, n = 25Penicillin, n = 56 P-valueVAN, n = 66PB0 (0)8 (32)15 (26.8)0.19129 (43.9)AKI1 (12.5)4 (16)12 (21.4)0.7495 (7.6)ConclusionCOMBO reduced the likelihood of PB but had a higher AKI rate. There were no significant differences in PB by BL class. Clinically, COMBO may reduce PB rates and prevent overuse of salvage antibiotic therapy. BL choice for COMBO warrants further investigation.Disclosures All authors: No reported disclosures.