Patel, Robin

ABSTRACTIntraluminal infection of central venous catheters, used for long‐term treatment, can result in central line‐associated bloodstream infection (CLABSI). These infections can be challenging to prevent and treat due to formation of biofilms within catheter lumens, which shield bacteria from the human immune response and conventional antimicrobial therapies. Preventing bacterial colonization of catheter hubs is a strategy to prevent CLABSI. To address this, we developed a nonantibiotic, animal‐ready electrochemical catheter hub (e‐catheter hub), operated by a wearable, battery‐powered micropotentiostat (MP), that internally generates tunable hypochlorous acid (HOCl) for preventing intraluminal infection. The design evaluated three different electrode materials—titanium, platinum, and gold—for HOCl generation and biocidal activity, using working and counter electrodes of the same materials and a silver/silver chloride‐plated wire as a quasi‐reference electrode. e‐catheter hubs operated by MPs at 1.5 VAg/AgCl for 3 h generated HOCl, reducing Acinetobacter baumannii ATCC‐17978 below the detection limit (average reduction of 4.40 ± 0.05 log10 CFU/mL). The efficacy of e‐catheter hubs operated by MPs in generating HOCl and achieving biocidal activity is comparable to that of a commercial potentiostat. This study represents the first step in developing a localized, nonantibiotic strategy to mitigate CLABSI risk.

ABSTRACT Although lung transplant recipients who develop Ureaplasma- associated hyperammonemia syndrome are treated with Ureaplasma -targeted antibiotics, optimal therapy is incompletely defined, and typically not based on real-time antimicrobial susceptibility testing results. This study compared levofloxacin, azithromycin, and doxycycline prevention and treatment of Ureaplasma urealyticum (UU) and Ureaplasma parvum (UP) infections in an immunosuppressed murine lung infection model. For prophylaxis, mice received antibiotics before infection with UP-FS (susceptible to all study antibiotics), UP-AzmR (azithromycin-resistant), UP-LevR (levofloxacin-resistant), or UU-DoxR (doxycycline-resistant), with lung bacterial loads (color changing units [CCUs]) measured 18 hours following infection. For UP-FS, doxycycline was most active (Δ4.84 log 10 CCU/g; P = 0.0006), followed by levofloxacin (Δ2.45 log 10 CCU/g; P = 0.018), with azithromycin yielding a nonsignificant CCU reduction. Doxycycline (Δ1.9 log 10 CCU/g; P = 0.0025) and levofloxacin (Δ1.3 log 10 CCU/g; P = 0.004) showed activity against UP-AzmR. Only doxycycline showed activity against UP-LevR (Δ2.28 log 10 CCU/g; P = 0.0002), and only azithromycin showed activity against UU-DoxR (Δ0.67 log 10 CCU/g; P = 0.0175). For treatment, antibiotics were administered 24 hours following infection; doxycycline significantly reduced bacterial loads of all study isolates, except UU-DoxR. In addition, azithromycin was active against UP-LevR (Δ1.21 log 10 CCU/g reduction; P = 0.0003). In summary, except for doxycycline-resistant UU, doxycycline was active in preventing and treating Ureaplasma lung infection in immunosuppressed mice.

A novel Corynebacterium species, strain BD556T, isolated from blood, was identified at Mayo Clinic, Rochester, MN, USA. After failing definitive identification using MALDI-ToF MS and partial 16S rRNA gene sequencing, BD556T was characterized using a polyphasic approach, including phenotypic, biochemical and whole-genome sequencing methods. BD556T was a Gram-positive rod with clubbed ends, facultatively anaerobic, catalase-positive, oxidase-negative and non-motile. Colonies were white, opaque and non-haemolytic with halo-like edges. BD556T grew at 35 °C in room air, with CO2 and under anaerobic conditions. BD556T grew well in 0 and 6% NaCl and weakly in 10% NaCl. The genome size was 2 349 779 bp with a G+C content of 60.39%. Phylogenetic analysis using 16S rRNA gene sequence analysis, average nucleotide identity and digital DNA–DNA hybridization between the genome of BD556T and the closest type strains from the Type Strain Genome Server database yielded separation values well beyond those required for species delineation. Chemotaxonomic analyses of BD556T revealed ribose, arabinose and galactose as whole-cell sugars and an A1γ meso-diaminopimelic acid-direct peptidoglycan type. The major cellular fatty acids were C15 : 0 (21.0%), C16 : 0 (14.8%), C17 : 1 ω9c (26.2%), C17 : 0 (13.3%) and C18 : 1 ω9c (18.3%). Polar lipids included diphosphatidylglycerol, phosphatidylglycerol and unidentified glycolipids and phospholipids. BD556T also contained mycolic acids (32–36 carbons) typical of corynebacteria. The respiratory quinones were dominated by MK-8(H2) (71.2%) and MK-9(H2) (25.9%), with smaller amounts of MK-7(H2) and MK-10(H2). The results presented support the tenet that BD556T (=TSD 427T=NCTC 15078T) is a novel species for which the name Corynebacterium mayonis sp. nov. is proposed.

Abstract Background Methicillin-resistant Staphylococcus aureus (MRSA) is a common cause of orthopedic implant-associated infection, where S. aureus can survive intracellularly and form biofilms. Vancomycin has poor activity against staphyloccoccal biofilms. Although rifampin is effective against staphylococcoal biofilms and has intracellular activity, resistance may develop when it is used as a single agent. Contezolid is a novel oxazolidinone with reported activity against S. aureus in vitro and in vivo in both murine systemic and thigh infection models. Here, we assessed the in vivo activity of contezolid, with and without rifampin, in a rat model of foreign body osteomyelitis. Figure 1. Quantities of MRSA IDRL-6169 recovered from A. tibia B. K-wire. Circles represent values from individual animals; horizontal lines represent mean values. Compared to no treatment: *p=0.0186 **p<0.0002 Methods The left tibia of 60 male Wister rats were inoculated with arachidonic acid (sclerosing agent) and 106 cfu MRSA IDRL-6169 and a K-wire implanted. After four weeks, rats received either no treatment, contezolid (50 mg/kg orally, every 12 h), rifampin (10 mg/kg intraperitoneally every 12 h), rifampin plus contezolid, or vancomycin (75 mg/kg intraperitoneally, every 12 h) plus rifampin for 21 days. Following treatment, tibiae were harvested and cyropulverized. Tibiae and K-wires were cultured separately, and results reported as log10 cfu/gram of bone or K-wire (limit of detect 0.1 log10), respectively. Wilcoxon rank-sum test and false discovery rates were performed and p< 0.05 considered significant. Results Results are shown in Figure 1. MRSA was recovered from tibiae and K-wires of all untreated animals, at means of 5.1 log10 cfu/bone and 3.0 log10 cfu/K-wire, respectively. There was a 1.0 log10 cfu/g mean reduction in MRSA recovered from the tibiae of contezolid-treated rats compared to untreated rats (p=0.0186), and a 0.2 log10 reduction on K-wires. No MRSA was recovered from the tibiae or K-wires in animals receiving rifampin, whether alone or in combination with contezolid or vancomycin. Conclusion Contezolid was active against MRSA in a rat model of foreign body osteomyelitis, reducing bacterial loads in bone, albeit not on K-wires, unless co-administered with rifampin. Disclosures Robin Patel, MD, a patent on Bordetella pertussis/parapertussis PCR issued, a patent on a device/method for sonication with royalties paid by Samsung to Mayo Clinic, a: See above|MicuRx Pharmaceuticals and BIOFIRE: Grant/Research Support|PhAST, Day Zero Diagnostics, Abbott Laboratories, Sysmex, DEEPULL DIAGNOSTICS, S.L., Netflix, Oxford Nanopore Technologies and CARB-X: Advisor/Consultant|Up-to-Date and the Infectious Diseases Board Review Course.: Honoraria

Abstract Background Intestinal colonization with carbapenem-resistant organisms (CRO) may be considered to inform empiric antibiotic selection for symptomatic infection. However, it is unclear how often gut colonizing CRE isolates are related to bloodstream isolates in hospitalized patients with bacteremia, especially in areas with high CRO prevalence. Minimum spanning tree of isolate relatedness Isolates and corresponding patient number (P1-P6) and rectal (R) or blood (B) specimen are noted within circles and allelic differences are numerated on linking lines between the circles. Group 1 and 3 isolates are possibly related to each other. Created with BioRender.com. Methods Patients with paired K. pneumoniae carbapenemase (KPC)-producing K. pneumoniae isolates cultured from surveillance rectal specimens and clinically collected blood specimens collected within 1-8 days of each other between 2019-2023 were identified at 3 Greek hospitals. Isolates were frozen and shipped to a reference laboratory in the U.S for whole genome sequencing (WGS) using Illumina MiSeq. Assembly and core genome multilocus sequence typing (cgMLST) analysis were performed with Ridom SeqSphere+ software. Isolate relatedness was based on the total number of allelic differences between each isolate: < 15, related; 16-50, possibly related; ≥ 51, unrelated. Results One hundred eight paired isolates were identified from 54 unique patients; 6 pairs and 12 total isolates underwent cgMLST. In 5 of 6 pairs (83%), the rectal isolate was collected prior to the bloodstream isolate. Rectal and bloodstream isolates were related to one another in 5 of 6 (83%) pairs and were unrelated in 1 pair. Two pairs collected from 2 distinct patients admitted to the same intensive care unit (patients 2 and 3, Figure) were possibly related (16-50 allelic differences) to each other. Conclusion In this pilot evaluation conducted in a setting of high CRO prevalence, KPC-producing K. pneumoniae isolated from paired rectal and blood specimens from individual patients were often related to each other, suggesting that intestinal colonization by this organism could inform empiric antibiotic treatment for bacteremia. Two patients from the same hospital unit had isolates that were possibly related, suggesting within hospital transmission. WGS is a powerful tool that can inform clinical and infection control practices. WGS of the remaining K. pneumoniae pairs and additional Acinetobacter baumannii pairs is ongoing. Disclosures Robin Patel, MD, I already disclosed so please pull from disclosure for other abstracts: Advisor/Consultant|I already disclosed so please pull from disclosure for other abstracts: Grant/Research Support|I already disclosed so please pull from disclosure for other abstracts: Honoraria

Abstract Background Phage therapy is being evaluated to treat bacterial infections. Host-related factors that might abrogate phage efficacy remain incompletely characterized. Phage aggregation has been hypothesized to protect phages in harsh environments. Herein, effects of immunized rabbit sera on phage aggregation were assessed. Methods Three New Zealand rabbits were immunized weekly for 3 weeks by intramuscular injection of phage K. Serum samples were collected weekly at times 0, 7, 14, 21 and 28. Development of an antibody response was confirmed by ELISA. Phage K was exposed to immunized serum with or without heat-inactivated host bacterium (Staphylococcus aureus ATCC 19685) as follows. 45 µl of phage K (1010±1 plaque forming units/mL [pfu/ml]) was mixed with 5 µl immunized serum diluted 1:1000 with or without heat-inactivated bacterial host in phosphate buffered saline (PBS). After incubation, exposed phage was visualized using transmission electron microscopy (TEM, JEOL) at 80kV. Results Phage K immunization elicited a strong IgG response. Exposure to immunized serum led to a decrease in viable phage over time, abrogated by adding heat-inactivated bacteria (Fig 1). TEM imaging showed phage clustering with exposure to immunized serum (Fig 2A); clusters appeared disorganized with concomitant exposure to heat-inactivated host bacteria (Fig 2B). Exposure of phage to heat-inactivated bacteria without serum yielded evenly distributed phage, with minimal clustering (Fig 2C). Conclusion Phage K exposure elicited a neutralizing immune response associated with decreased phage survival in immunized serum, prolonged by adding heat-inactivated host bacteria. TEM imaging showed phage K clustering in different ways depending on the microenvironment encountered. Biological relevance and mechanistic underpinnings of these phenomena need further characterization. Disclosures Robin Patel, MD, a patent on Bordetella pertussis/parapertussis PCR issued, a patent on a device/method for sonication with royalties paid by Samsung to Mayo Clinic, a: See above|MicuRx Pharmaceuticals and BIOFIRE: Grant/Research Support|PhAST, Day Zero Diagnostics, Abbott Laboratories, Sysmex, DEEPULL DIAGNOSTICS, S.L., Netflix, Oxford Nanopore Technologies and CARB-X: Advisor/Consultant|Up-to-Date and the Infectious Diseases Board Review Course.: Honoraria

Abstract Background Chronic periprosthetic joint infection is commonly managed with two-stage exchange. Clinically, evaluation for persistent infection at the second stage of exchange may inform management. The aim of this study was to evaluate the yield of periprosthetic tissue and antimicrobial-containing cement spacer sonicate fluid cultures at the second stage of two-stage exchange surgeries. Methods Periprosthetic tissue and sonicate fluid cultures of hip and knee cement spacers removed at the second stage of two-stage exchange surgeries between January 2010 and December 2020 were studied. Two or more positive tissue cultures yielding the same organism were considered positive. For sonicate culture, ≥20 CFU/10 ml of sonicate fluid was considered positive. Persistent infection was defined by the presence of at least one of the following: intraoperative purulence, sinus tract, histopathology showing acute inflammation, or clinical signs of infection. Cement spacers were removed as part of spacer exchange if persistent infection was suspected or for insertion of a new implant if infection was not suspected. Results 172 cultures were evaluated, 69% from knees and 31% from hips. Median patient age was 64 years; 53% were men. 38/172 (22%) of cement spacers were removed as part of a spacer exchange and 134/172 (78%) for insertion of a new implant. Persistent infection was present in 49/172 (28%). 18/172 (10%) received antibiotics 2 weeks before culture, including 8/18 (44%) undergoing spacer exchange. For persistent infections, tissue and sonicate culture were positive in 11/49 and 5/49, respectively. In the 123 without persistent infection, no tissue or sonicate cultures were positive. When a new implant was placed, persistent infection was observed in 18/134 (13%), and tissue and sonicate cultures were positive in 4/18 and 1/18, respectively. When a new implant was placed (116) and no infection was found, all tissue and sonicate cultures were negative. After spacer exchange, persistent infection was present in 31/38 (81%), and tissue and sonicate cultures were positive in 8/31 and 3/31, respectively; in the 7 without infection, there were no positive cultures. Conclusion Sonication culture of cement spacers and periprosthetic tissue cultures have low sensitivities for persistent infection. Disclosures Matthew Abdel, MD, Stryker: Advisor/Consultant|Stryker: Royalties Nicholas Bedard, MD, Stryker: Advisor/Consultant Robin Patel, MD, a patent on Bordetella pertussis/parapertussis PCR issued, a patent on a device/method for sonication with royalties paid by Samsung to Mayo Clinic, a: See above|MicuRx Pharmaceuticals and BIOFIRE: Grant/Research Support|PhAST, Day Zero Diagnostics, Abbott Laboratories, Sysmex, DEEPULL DIAGNOSTICS, S.L., Netflix, Oxford Nanopore Technologies and CARB-X: Advisor/Consultant|Up-to-Date and the Infectious Diseases Board Review Course.: Honoraria

Abstract Background Wound biofilm infections impact ∼2% of the United States and at-risk individuals often have underlying morbidities such as diabetes. Antibiotics and topical approaches like debridement or silver dressings have had limited success, underscoring a need for strategies that efficiently target pathogens in wound beds. Methods We developed a hydrogen peroxide (H2O2) generating electrochemical bandage (e-bandage) composed of carbon fabric electrodes separated by cotton fabric with an Ag/AgCl reference electrode (RE) placed between cotton fabric layers. The e-bandage is controlled by a wearable micropotentiostat (MP); H2O2 is generated by O2 + 2H++ 2e- → H2O2. O2 is dissolved on a primary working electrode with negative polarity compared to the RE while a positively polarized secondary counter electrode generates H+ and e-. The H2O2 e-bandage/MP device has in vitro activity against mono- and dual-species bacterial and fungal biofilms. We showed that the H2O2 e-bandage decreased the burden of methicillin-resistant Staphylococcus aureus and/or Pseudomonas aeruginosa with difficult-to-treat resistance in a murine wound infection model. Given this, we initiated a H2O2 e-bandage safety assessment on healthy human skin. Here, testing of a non-polarized, circular (2 cm diameter) device pre-loaded with biocompatible hydrogel containing 0.9% NaCl is reported. Sterilized e-bandages assessed in a shelf-life study retained activity for two weeks. Adults with intact forearm skin were then recruited to the Clinical Research Trials Unit at the Mayo Clinic. Consented individuals had a non-polarized e-bandage covered by Tegaderm placed on their forearm. A MP enclosed in a biocompatible case was connected to the e-bandage and secured using skin tape. One day later, the device was removed and a follow-up phone call made six days later to assess for adverse effects. Results Three volunteers wearing a non-polarized H2O2 e-bandage experienced no discomfort, irritation, allergic reaction, or skin discoloration after device removal and seven days post device placement. Conclusion These preliminary studies combined with the previously performed murine bacterial biofilms work support further studies of this novel device for treating wound infections caused by antimicrobial resistant pathogens. Disclosures Robin Patel, MD, a patent on Bordetella pertussis/parapertussis PCR issued, a patent on a device/method for sonication with royalties paid by Samsung to Mayo Clinic, a: See above|MicuRx Pharmaceuticals and BIOFIRE: Grant/Research Support|PhAST, Day Zero Diagnostics, Abbott Laboratories, Sysmex, DEEPULL DIAGNOSTICS, S.L., Netflix, Oxford Nanopore Technologies and CARB-X: Advisor/Consultant|Up-to-Date and the Infectious Diseases Board Review Course.: Honoraria

Abstract Background 16S ribosomal RNA (rRNA) gene PCR and sequencing may serve as an adjunctive diagnostic tool in complex infections, identifying bacteria in patients on antibiotics whose cultures may be negative. Data on the optimal clinical settings for utilizing this type of testing are limited. This study reviews a single center's 16S rRNA PCR/sequencing experience in children to identify clinical syndromes and optimize specimen choice for higher yield, leading to testing of appropriate patients. Methods A retrospective study was performed at Mayo Clinic, Rochester involving children aged 0 to 18 years whose normally sterile tissue or fluid samples underwent 16S rRNA gene PCR/sequencing. The assay involved an up-front real-time PCR assay, reported as negative or submitted to Sanger or next-generation sequencing depending on Ct values. Data was collected on patient characteristics and results of 16S rRNA gene PCR/sequencing and conventional tests. Impact on clinical decision-making was assessed as to whether the advanced molecular diagnostic changed antimicrobial therapy. Results A total of 162 tests were performed on 124 patients, including 47% females (58/124) with a median age of 9.6 (range, 2.2-15.0) years. Overall, 33/162 (20%) of tests were positive in 24/124 (19%) patients. 58% of positive tests (19/33) were from samples with negative bacterial cultures. Cerebrospinal fluid was the most common specimen tested (n=38; 31%). Positive results were more likely from fluid compared to tissue samples (OR [95% CI]: 3.1 [1.3, 7.1], p=.007; OR [95% CI]: 0.3 [0.1, 0.8], p=.007, respectively). Testing was positive in 5/10 (50%) pleural fluids tested, a higher positivity rate than any other specimen type (OR [95% CI]: 5 [1.3, 19.0], p=.011). No significant changes in antibiotics were made within 24 hours of reporting positive 16S rRNA gene PCR/sequencing results. Conclusion This study highlights the importance of selecting appropriate sample types for 16S rRNA gene PCR/sequencing in pediatric patients. The assay is most likely to yield positive results in children with pleural effusion and in other fluid samples such as subdural and synovial fluid. Further implementation science research is needed to achieve impact on clinical practice. Disclosures Robin Patel, MD, a patent on Bordetella pertussis/parapertussis PCR issued, a patent on a device/method for sonication with royalties paid by Samsung to Mayo Clinic, a: See above|MicuRx Pharmaceuticals and BIOFIRE: Grant/Research Support|PhAST, Day Zero Diagnostics, Abbott Laboratories, Sysmex, DEEPULL DIAGNOSTICS, S.L., Netflix, Oxford Nanopore Technologies and CARB-X: Advisor/Consultant|Up-to-Date and the Infectious Diseases Board Review Course.: Honoraria