Quantifying the impact of gut microbiota on inflammation and hypertensive organ damage

Aims: Hypertension (HTN) can lead to heart and kidney damage. The gut microbiota has been linked to HTN, although it is difficult to estimate its significance due to the variety of other features known to influence HTN. Methods and Results: In the present study, we used germ-free (GF) and colonized (COL) littermate mice to quantify the impact of microbial colonization on organ damage in HTN. Four-week-old male GF C57BL/6J littermates were randomized to remain GF or receive microbial colonization. HTN was induced by subcutaneous infusion with angiotensin (Ang) II (1.44mg/kg/d) and 1% NaCl in the drinking water; sham-treated mice served as control. Renal damage was exacerbated in GF mice, whereas cardiac damage was more comparable between COL and GF, suggesting that the kidney is more sensitive to microbial influence. Multivariate analysis revealed a larger effect of HTN in GF mice. Serum metabolomics demonstrated that the colonization status influences circulating metabolites relevant to HTN. Importantly, GF mice were deficient in anti-inflammatory fecal short-chain fatty acids (SCFA). Flow cytometry showed that the microbiome has an impact on the induction of anti-hypertensive myeloid-derived suppressor cells and pro-inflammatory Th17 cells in HTN. In vitro inducibility of Th17 cells was significantly higher for cells isolated from GF than conventionally raised mice. Conclusion: Microbial colonization status of mice had potent effects on their phenotypic response to a hypertensive stimulus, and the kidney is a highly microbiota-susceptible target organ in HTN. The magnitude of the pathogenic response in GF mice underscores the role of the microbiome in mediating inflammation in HTN.

Prevalence and antimicrobial resistance of Staphylococcus species isolated from cats and dogs

Background: Methicillin-resistant staphylococci (MRS) are an emerging global problem with serious public health concern.Aims: This study investigated the prevalence and antimicrobial susceptibility of commensal Staphylococcus species isolated from healthy and clinical cats and dogs.Methods: Nasal swab samples were collected from animals and processed using selective and semi-selective mediums. Presumptive isolates were subjected to biochemical testing and analyzed using the Phoenix automated identification and susceptibility testing system. PCRs protocols were used to screen for mecA and pvl genes.Results: In total, 151 pets (103 cats and 48 dogs) were enrolled, of which 14 dogs (29%) and 24 cats (23%) were colonized with various Staphylococcus species mainly originated from healthy animals. A total of 38 staphylococci isolates were collected and distributed between 24 coagulase-negative and 14 coagulase-positive staphylococci. Only 13 staphylococci strains were identified as MRS, out of which only five isolates expressed that the mecA gene exclusively originated from healthy pets.Conclusion: This is the first study reporting the prevalence and colonization status of staphylococci species and MRS strains isolated from cats and dogs in Libya. The study reports important information of medical and clinical importance on antimicrobial and multidrug resistance of different staphylococci strains, particularly the coagulase negative species.

Long-Term Outcomes of Bronchial Artery Embolization for Patients with Non-Mycobacterial Non-Fungal Infection Bronchiectasis

<b><i>Background:</i></b> There is no study on the predictive factors of recurrent haemoptysis after bronchial artery embolization (BAE) with the long-term outcomes in patients with bronchiectasis (BE). <b><i>Objectives:</i></b> To evaluate the long-term outcomes of BAE in BE patients without accompanying refractory active infection of mycobacteriosis and aspergillosis with analysis for the predictive factors of recurrent haemoptysis. <b><i>Methods:</i></b> Data of 106 patients with BE who underwent BAE using coils between January 2011 and December 2018 were retrospectively reviewed. The cumulative haemoptysis control rate was estimated using Kaplan-Meier methods with log-rank tests to analyze differences in recurrence-free rate between groups based on technical success and failure, bacterial colonization status, number of BE lesions, and vessels embolized to bronchial arteries (BAs) or BAs + non-bronchial systemic arteries (NBSAs). <b><i>Results:</i></b> Bacterial colonization was detected in approximately 60% of patients. Computed tomography showed bronchiectatic lesions with 2.9 ± 1.4 lobes. In the first series of BAE, embolization was performed in the BAs alone and BAs + NBSAs in 65.1 and 34.9% of patients, respectively, with 2.4 ± 1.4 embolized vessels in total. The median follow-up period was 1,000 (7–2,790) days. The cumulative haemoptysis control rates were 91.3, 84.2, 81.5, and 78.9% at 1, 2, 3, and 5 years, respectively. The haemoptysis control rates were higher in the technical success group than in the technical failure group (<i>p</i> = 0.029). <b><i>Conclusions:</i></b> High haemoptysis control rates for long-term periods were obtained by embolization for all visualized abnormal arteries, regardless of the colonization status, number of bronchiectatic lobes, and target vessels, irrespective of NBSAs.

887. Implementation of a Surgical Site Infection (SSI) Prevention Bundle: Patient Compliance and Experience

Background An evidence-based preoperative bundle including chlorhexidine gluconate (CHG) bathing, screening for S. aureus nasal carriage and decolonizing carriers with mupirocin was the standard of care for patients having total joint arthroplasty (TJA) at a VA medical center. We aimed to assess patient compliance with mupirocin and CHG, and characterize patient perceptions of barriers and facilitators to compliance. Compliance with CHG Bathing & Mupirocin By Methicillin-resistant S. aureus (MRSA) or Methicillin-susceptible S. aureus (MSSA) Colonization Status Methods The bundle for S. aureus colonized patients having TJA included nasal mupirocin ointment twice daily and daily CHG bathing for 5 days before surgery. The bundle for non-carriers included CHG bathing the day before and the morning of surgery. From 7/2018-10/2019, inpatients completed a 31-item survey following their TJA. Results 73 patients completed the survey (~29% of the TJA population). 17 patients (23%) carried S. aureus & 56 patients (77%) were non-carriers. Patients reported high compliance with home use of CHG for the full number of days directed (88% when prescribed for 2 days; 71% when prescribed for 5 days; overall 85% used as prescribed; Figure). 7 (10%) patients reported CHG side effects, including burning or itchy/dry skin. 99% of patients reported willingness to use the CHG before a future surgery. Compliance with home use of mupirocin was lower (53% used as prescribed). Reported side effects included stinging, itching or dryness (N=2, 12%), unpleasant taste (N=2, 12%) & runny or stuffy nose (N=3, 18%). 100% of patients reported willingness to use mupirocin before a future surgery. Barriers to patient compliance with the bundle included forgetfulness and difficulty bathing daily. Facilitators to patient compliance included high facility compliance with S. aureus screening (100% patients reported), patient education regarding CHG and mupirocin use (95% patients recalled), and access to prescribed medications (100% patients received). Most patients (93%) reported no financial burden for mupirocin and 95% of patients reported no financial burden for CHG. Conclusion Patients reported high willingness to use the prevention bundle, yet mupirocin compliance was sub-optimal. Replacing patient-applied home mupirocin with nurse-applied day-of-surgery decolonization should be assessed in order to facilitate increased compliance. Disclosures All Authors: No reported disclosures

Potential Impact of CDC’s Enhanced Barrier Precautions Recommendations on Veterans’ Affairs Long-Term Care Facilities

Background: We previously showed that ~25% of Veterans’ Affairs (VA) long-term care facility (LTCF) residents had 1 or more indwelling medical devices. Of these devices, 36% were indwelling urinary catheters, 18% were percutaneous gastrostomy tubes, 12% were peripherally inserted central catheters, 8% were suprapubic urinary catheters, and 6% were peripheral intravenous catheters. Approximately 11% of those with an indwelling device developed an LTCF-acquired infection, compared to 3.5% of those without a device. Methicillin-resistant Staphylococcus aureus (MRSA) is a targeted multidrug-resistant organism (MDRO) in all VA LTCFs nationwide. All admissions to VA LTCFs are screened for MRSA carriage upon admission and, since 2013, those that screen positive (~21%) are placed in VA enhanced barrier precautions (EBPs). VA EBPs require that all healthcare workers entering a resident’s bedroom don gowns and gloves for specific activities likely to be associated with contamination of the worker’s hands and clothes. With proper hand hygiene and clean clothing, the colonized resident is encouraged to leave their bedroom and participate fully in all LTCF activities. In July 2019, the US Centers for Disease Control and Prevention (CDC) recommended the use of EBPs for all residents in LTCFs with a wound or device regardless of their colonization status if a resident is identified within the facility with novel or targeted MDROs including panresistant organisms, carbapenemase-producing gram-negative bacteria, and Candida auris. Methods: We assessed the potential impact of this recommendation on VA LTCFs by asking our 133 LTCFs to do a 1-day point-prevalence survey. Results: In total, 63 sites (47%) responded. On the survey day, there were 4,777 residents in the participating facilities, of whom 891 (18.7%) were under EBPs or contact precautions (CPs) for MRSA or other MDROs. Moreover, 963 (20.2%) residents (not already in EBP or CP) had a wound or an indwelling device such as central venous catheter, urinary catheter, feeding tube, tracheostomy or were on a ventilator (if >1 device, resident counted only once). If newly published CDC recommendations were implemented for novel or targeted MDRO precautions in VA LTCFs nationwide, 1,854 residents (38.8%) in VA LTCFs would be placed under EBPs or CPs. Conclusions: In VA LTCFs, adopting the CDC recommendation to place all patients with wounds or indwelling devices under EBPs regardless of colonization status would increase the percentage of residents on transmission-based precautions to ~40% (nearly doubling those in an isolation precaution status).Funding: NoneDisclosures: None

The microbiome affects liver sphingolipids and plasma fatty acids in a murine model of the Western diet based on soybean oil

Studies in mice using germfree animals as controls for microbial colonization have shown that the gut microbiome mediates diet-induced obesity. Such studies use diets rich in saturated fat, however, Western diets in the USA are enriched in soybean oil, composed of unsaturated fatty acids (FAs), either linoleic or oleic acid. Here we addressed whether the microbiome is a variable in fat metabolism in mice on a soybean oil diet. We used conventionally-raised, low-germ, and germfree mice fed for 10 weeks diets either high (HF) or low (LF) in high-linoleic-acid soybean oil as the sole source of fat. All mice, including germfree, gained relative fat weight and consumed more calories on the HF versus LF soybean oil diet. Plasma fatty acid levels were generally dependent on diet, with microbial colonization status affecting iso-C18:0, C20:3n-6, C14:0, and C15:0 levels. Colonization status, but not diet, impacted levels of liver sphingolipids including ceramides, sphingomyelins, and sphinganine. Our results confirm that absorbed fatty acids are mainly a reflection of the diet, and show that microbial colonization influences liver sphingolipid pools.

Abstract P027: Hypertensive Cardiorenal Damage Is Aggravated In Axenic Mice

Introduction: The gut microbiota is suspected to play a role in hypertension and hypertensive end organ damage. In the present study, we used germ-free mice to demonstrate that microbial colonization modulates the response to a hypertensive stimulus. Methods: Four-week-old male germ-free C57BL6/J littermates were randomized to remain germ-free (GF) or to receive microbiota transfer from SPF donor mice to achieve full colonization status (COL). At 12 weeks, Angiotensin (Ang) II was infused s.c. for 14 days (1.44mg/kg/d, osmotic minipumps) and 1% NaCl added to the drinking water; sham-treated mice served as control. After 14 days of AngII we assessed inflammation and organ damage. Results: Fecal bacterial load in COL mice was similar to SPF donor mice (qPCR). Shotgun metagenomic sequencing of fecal samples revealed hypertension-induced alterations in microbiome composition confirming previous reports. Serum metabolome analysis ( Biocrates MxP Quant 500) confirmed the absence of microbiota-dependent metabolites in GF. Interestingly, microbiota-dependent metabolites relevant for cardiovascular risk (TMAO, indoxyl sulfate) were elevated in hypertensive COL mice compared to sham-treated. Hypertensive kidney damage was aggravated in GF mice. However, marker genes for tubular damage ( Lcn2 ), inflammation ( Ccl2 ), and fibrosis ( Col1a3 ) showed a stronger increase in GF mice (fold changes [fc] COL vs. GF: 7.5 vs 11.0, 1.2 vs 3.3, 1.3 vs 2.2, respectively). Albuminuria (fc 2 vs 25) and histology for kidney fibrosis (fc 1.1 vs 1.4) confirmed the aggravated kidney damage in GF mice. Similarly, we observed an aggravated cardiac damage in GF mice. Flow cytometry of splenic lymphocytes showed that the adaptive immune response to AngII + 1% NaCl, as evidenced by Th17 (fc 1.4 vs 2) and CD8+ central memory cells, was intensified in GF mice. In vitro , naïve T cells isolated from GF mice more readily polarized into Th17 (26 ± 5%) compared to T cells from SPF mice (19 ± 1%). Conclusion: The bacterial colonization status has potent effects on the phenotypic response to a hypertensive stimulus, evident to varying degrees in hearts and kidneys. The inflammatory response and the end organ damage in GF compared to COL mice demonstrates the importance of the gut microbiota in hypertension.