Staphylococcus prettenkoferi – biochemical properties, methods of species identification and clinical significance

Staphylococcus pettenkoferi was first isolated from blood culture a 25-years-old patient with fever of unknown etiology. Based on the literature analysis, it was found that it is an opportunistic microorganism. It causes blood stream infections and was an causative agent of osteomyelitis. Staphylococcus pettenkoferi is a component of the human microbiome, was found in a hospital environment and was also isolated from animals and their surroundings.

Bacterial and fungal profile, drug resistance pattern and associated factors of isolates recovered from blood samples of patients referred to Ethiopian Public Health Institute: cross-sectional study

Background Blood stream infections are serious infections that usually induce prolongation of hospital stay, morbidity and mortality in several countries including Ethiopia. The aim of this study was to determine bacterial and fungal profile, their drug resistance patterns, and risk factors associated with blood stream infections. Methods A cross sectional study design was conducted from February 23 to June 23, 2020 at Ethiopian public health. A structured questionnaire was used to collect data on socio-demographic factors and clinical conditions. Blood specimens were analyzed using standard microbiological techniques. Antimicrobial susceptibility tests were performed using Kirby–Bauer disc diffusion technique and Vitek compact 2. Simple and multiple logistic regressions were used to assess the potential risk factors. Results A total of 175 pathogens isolated from 346 blood specimens. Of these, 60% Gram-negative bacteria, 30.86% Gram-positive bacteria and 9.14% fungal isolates were identified. Burkholderia cepacia and Coagulase negative staphylococcus were the predominant pathogen among Gram-negative and Gram-positive bacteria respectively. Among fungus, Candida krusei (56.25%) was the most predominant isolate. The highest proportions of antibacterial resistance were observed among 3rd generation cephalosporin and penicillin. Most fungal isolates expressed resistance to fluconazole. Sex (P = 0.007), age (P < 0.001) and use of invasive medical devices (P = 0.003) were identified as risk factors for bacterial blood stream infections. Conclusion The study showed high prevalence of blood stream infection was due to B. cepacia and non-C. albicans spp. This finding alarming ongoing investigation of blood stream infection is important for recognizing future potential preventive strategies including environmental hygiene and management of comorbid medical diseases to reduce the problem.

The Impact of Tocilizumab Treatment for Cytokine Release Syndrome on the Incidence of Blood Stream Infections after Peripheral Blood Haploidentical Hematopoietic Cell Transplantation

Introduction: Cytokine release syndrome (CRS) is a potentially fatal systemic inflammatory response that can occur in patients undergoing haploidentical hematopoietic cell transplantation (haplo-HCT). IL-6 inhibitors, such as tocilizumab, are effective therapy in moderate to severe cases. Several studies have shown there to be a significant increase in infections with the use of tocilizumab in patients with rheumatoid arthritis, where it is given on a long term basis unlike in the post-haplo-HCT setting, where tocilizumab is rarely given for more than a few days. Severe CRS has been associated with increased infection risk in prior studies. However, the effect of anti-IL-6 therapy on infection risk has not been well established in the early haplo-HCT setting. In this study, we examined the effect of tocilizumab for treatment of CRS on the incidence of blood stream infections (BSIs) in the early post peripheral blood haplo-HCT setting. Patients and Methods: We performed a retrospective analysis of 235 patients who underwent T cell-replete peripheral blood haplo-HCTs from 2013 to 2020, stratified on CRS grade (graded by Lee criteria) and tocilizumab administration, for incidence of BSI. Positive blood cultures during days +2 to +28 post-haplo-HCT were included. Patients with positive blood cultures during the immediate peri-transplant period (days -5 to +1) were excluded as infection preceded CRS and tocilizumab administration. Patients who had positive blood cultures within 48 hours of CRS diagnosis were excluded as sepsis cannot be distinguished from CRS. Results: The overall incidence of bloodstream infection was 17% with 41 out of the total 235 patients having positive blood cultures. Patients with mild CRS had lower incidence of infection than patients with severe CRS (OR 0.31, 95% CI 0.13-0.74, p=0.0086). In the tocilizumab group, 31% (15/49) of patients had positive blood cultures compared with 14% (26/186) in the non-tocilizumab group (OR 1.61, 95% CI 0.30-8.60, p=0.58). However, after controlling for CRS grade, tocilizumab administration was not associated with higher rates of BSIs for any grade of CRS. Conclusions: Severe CRS after haplo-HCT is associated with higher risk of early BSI. However, tocilizumab therapy does not further increase risk of BSI in the early post-haplo-HCT setting. These data suggest that tocilizumab, a potentially life saving therapy, can be given without increasing risk of blood stream infections after haplo-HCT. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

220. The Treatment of Enterococcus Blood Stream Infections in Patients Receiving Extracorporeal Membrane Oxygenation

Background Background: Extracorporeal membrane oxygenation (ECMO) is a growing modality of life support that is subject to a high rate of nosocomial infections. There is a paucity of data to guide treatment for infections on ECMO, which can lead to vastly different practice patterns at different centers. This case series describes the outcomes of patients with Enterococcus bacteremia at a single center. Methods A retrospective chart review was performed on all patients who received ECMO support at a tertiary academic medical center with ECMO capabilities between October 2012 and May 2020 with positive blood cultures for Enterococcus species. Results A total of 10 patients had Enterococcus bacteremia during the study period with E. faecalis (n=7, 70%) more commonly than E. faecium (n=3, 30%). Infections occurred more often in men (n=6, 60%) than women (n=4, 40%) with median age 36 (IQR: 31-42). Infections occured late in the hospitalization (median: 33 days (IQR: 26-59)) and after several weeks on the ECMO circuit (median: 24 days (22-52)). Infections were often polymicrobial (n=5, 50%). There were no cases of infective endocarditis. Infections were treated with 7-14 days of therapy with ampicillin being the most common antibiotic prescribed (n=5, 50%). Four (40%) patients were decannulated before completion of therapy. No patients had cannulas removed due to bacteremia. There were no cases of recurrence. Mortality was 20% in this cohort. Clinical Characteristics of Patients with Enterococcus Bacteremia Conclusion Enterococcus is a common cause of blood stream infections in patients with prolonged courses on ECMO circuit. In this cohort of patients, Enterococcus did not cause any metastatic infections and was generally treated with 7-14 days of antibiotics without recurrence, despite many patients remaining on ECMO for extended periods after clearance. As ECMO use continues to expand, there will need to be more data on treatment outcomes of infections to establish best practices. Disclosures All Authors: No reported disclosures

1224. In vitro Activities of Ceftaroline and Comparator Agents against Gram-positive Bacterial Pathogens Causing Blood Stream Infections in a Global Population: ATLAS Surveillance Program 2012-2019

Background Typical gram-positive organisms causing bloodstream infections (BSI) include Staphylococcus aureus (methicillin-susceptible [MSSA] and -nonsusceptible [MRSA]), coagulase negative staphylococci, Streptococcus pneumoniae and beta hemolytic streptococci. The parenteral cephem ceftaroline fosamil is approved for treatment of patients with community-acquired bacterial pneumonia caused by S. pneumoniae (including cases with concurrent bacteremia), MSSA, Haemophilus influenzae, and some species of Enterobacterales. Limited data have been published on the in vitro activity of ceftaroline against recent gram-positive clinical isolates known to be frequent bacterial causes of blood stream infections. Methods Standard CLSI broth microdilution MIC determinations (M07) were performed with ceftaroline and comparator agents. MICs were interpreted using 2021 CLSI MIC breakpoints. Clinically relevant, non-duplicate, isolates cultured from blood by clinical laboratories in 2012-2019 were tested by the ATLAS (Antimicrobial Testing Leadership and Surveillance) program central laboratory (IHMA, Inc., Schaumburg, IL, USA). In total, 21,967 non-duplicate isolates of S. aureus, S. epidermidis, S. pneumoniae and beta hemolytic streptococci from BSI collected between 2012 and 2019 were tested. Isolates came from (n/%): Asia/South Pacific (2,970/13.5%), Europe (13,691/62.3%), Latin America (2,824/12.9%), MidEast/Africa (1,498/6.8%), and North America (Canada only) (984/4.5%). Results Ceftaroline and comparator agent activities are summarized in the following table. Results Table Conclusion Greater than 99% of S. pneumoniae, beta-hemolytic streptococci and MSSA isolates included in a 2012-2019 collection of gram-positive blood stream pathogens were susceptible to ceftaroline. 90.8% of MRSA were susceptible, and 9.1% isolates categorized as susceptible-dose dependent (MIC, 2-4 µg/mL); four isolates (two from Thailand and one each from China and S. Korea) were resistant to ceftaroline (MIC &gt;4 µg/mL). The ceftaroline MIC90 for S. epidermidis was 0.5 µg/mL, with 97.7% of MICs ≤1 µg/mL. Ceftaroline continues to demonstrate potent in vitro activity against clinically relevant pathogens associated with BSI. Disclosures Meredith Hackel, PhD MPH, IHMA (Employee)Pfizer, Inc. (Independent Contractor) Gregory Stone, PhD, AztraZeneca (Shareholder, Former Employee)Pfizer, Inc. (Employee) Daniel F. Sahm, PhD, IHMA (Employee)Pfizer, Inc. (Independent Contractor)