Anginosus Group Research Articles

Streptococcus Constellatus Empyema Presenting With Undulant Fever Pattern- A Case Report and Literature Review

Streptococcus anginosus group (SAG), or milleri group streptococci (MGS), is an uncommon group of bacteria that has been increasingly affecting the adult population. It is an interesting organism in that it is intensely pyogenic when pathogenic-much in the same character as Staphylococcus aureus. SAG includes three species: Streptococcus anginosus, Streptococcus intermedius, and <em>Streptococcus constellatus</em>. Members of the SAG are usually part of the indigenous oral, gastrointestinal, and genitourinary flora; however, with mucosal disturbance they can become pathogenic leading to infections.

Evaluation of amoxicillin, metronidazole and gentamicin dosage regimens for use in antibiotic prophylaxis in colorectal surgery.

To evaluate amoxicillin, metronidazole and gentamicin dosage regimens for antibiotic prophylaxis in colorectal surgery. The study was conducted in 20 patients undergoing colorectal surgery. Patients received one or two doses of amoxicillin 1000 mg, metronidazole 500 mg and gentamicin 3 mg/kg ideal body weight, banded by height. Antibiotic concentrations were measured up to 7 h post dose. Population pharmacokinetic (PopPK) analysis with NONMEM followed by Monte Carlo simulation of different dosage regimens was used to estimate the PTA for potential organisms associated with surgical site infections (SSIs). A median of 5 (range 3-6) concentrations were available per patient. CL and V of all antibiotics were related to weight; gentamicin CL was also related to CLCR. The administered doses maintained the desired PTA up to 8 h for the Streptococcus anginosus group but not for enterococci, Bacteroides fragilis group, MSSA, and Escherichia coli. An additional 500 mg amoxicillin every 4 h was sufficient to achieve the PTA for most relevant organisms but 2 hourly dosing was required for patients at risk of infective endocarditis. A metronidazole dose of 1000 mg was required for patients >85 kg. In patients with CLCR >50 mL/min, 5 mg/kg gentamicin (with an additional 2.5 mg/kg in prolonged surgery at 6 h) maintained PTA targets for >10 h. PopPK analysis with Monte Carlo simulation identified prophylactic antibiotic regimens that would maintain the PTA for organisms associated with SSIs during short- and long-duration colorectal surgery.

Association between obligatory anaerobes and empyema caused by Streptococcus anginosus group bacteria.

Co-infections of Streptococcus anginosus group (SAG) bacteria and obligate anaerobes are observed in patients with empyema; however, their epidemiology and pathology remain unknown. A retrospective study was performed with 44 patients who underwent pleural effusion microbiota evaluation between January 2006 and March 2018, using the clone library method for detecting empyema caused by SAG bacteria. Based on culture analysis of pleural effusion, 12 patients were diagnosed with empyema caused by SAG bacteria. Obligate anaerobe phylotypes were detected in eight patients (66.7%) using the clone library method, whereas anaerobic culture analysis detected anaerobes in only two patients (16.7%). No significant difference was observed between the clinical features of SAG-mediated empyema with and without anaerobes using the clone library method, except for chest computed tomographic data. Co-infection of SAG bacteria and obligate anaerobes may be underestimated if conventional culture methods are used. SAG-mediated empyema with and without anaerobes may present different radiological features; therefore, further studies are required.

Brain abscess of odontogenic origin in patients with malignant tumors: A report of two cases

Background: Oral infection and dental manipulations can lead to the development of brain abscesses, a rare but potentially life-threatening condition. Herein, we report patients undergoing cancer treatment who developed brain abscesses of odontogenic origin at our hospital.Case Description: Two patients developed brain abscesses during cancer treatment. Both underwent neurosurgical aspiration, and the causative microorganism was identified as Streptococcus intermedius of the Streptococcus anginosus group, which is a part of the normal bacterial flora in the oral cavity. There was clinical and radiographic evidence of dental infection in one of the patients diagnosed with a brain abscess of odontogenic origin. No infectious foci were found in the other patient during hospitalization for the abscess. However, the patient had undergone extraction of an infected tooth approximately 3 months before admission for the abscess, suggesting origination from an oral infection or dental manipulation. The patients’ cancers rapidly worsened because cancer treatment in both patients was interrupted for several months to treat the brain abscess.Conclusion: Oral infections can cause severe infections, such as brain abscesses, particularly during the treatment of malignant tumors. Improving the oral environment or treating oral infections before initiating treatment for malignant tumors is highly recommended. In addition, the possibility of odontogenic origin should always be considered as a potential etiology of brain abscesses.

Pangenome analysis and virulence profiling of Streptococcus intermedius

BackgroundStreptococcus intermedius, a member of the S. anginosus group, is a commensal bacterium present in the normal microbiota of human mucosal surfaces of the oral, gastrointestinal, and urogenital tracts. However, it has been associated with various infections such as liver and brain abscesses, bacteremia, osteo-articular infections, and endocarditis. Since 2005, high throughput genome sequencing methods enabled understanding the genetic landscape and diversity of bacteria as well as their pathogenic role. Here, in order to determine whether specific virulence genes could be related to specific clinical manifestations, we compared the genomes from 27 S. intermedius strains isolated from patients with various types of infections, including 13 that were sequenced in our institute and 14 available in GenBank.ResultsWe estimated the theoretical pangenome size to be of 4,020 genes, including 1,355 core genes, 1,054 strain-specific genes and 1,611 accessory genes shared by 2 or more strains. The pangenome analysis demonstrated that the genomic diversity of S. intermedius represents an “open” pangenome model. We identified a core virulome of 70 genes and 78 unique virulence markers. The phylogenetic clusters based upon core-genome sequences and SNPs were independent from disease types and sample sources. However, using Principal Component analysis based on presence/ absence of virulence genes, we identified the sda histidine kinase, adhesion protein LAP and capsular polysaccharide biosynthesis protein cps4E as being associated to brain abscess or broncho-pulmonary infection. In contrast, liver and abdominal abscess were associated to presence of the fibronectin binding protein fbp54 and capsular polysaccharide biosynthesis protein cap8D and cpsB.ConclusionsBased on the virulence gene content of 27 S. intermedius strains causing various diseases, we identified putative disease-specific genetic profiles discriminating those causing brain abscess or broncho-pulmonary infection from those causing liver and abdominal abscess. These results provide an insight into S. intermedius pathogenesis and highlights putative targets in a diagnostic perspective.

Clinical Microbiology Perspective of Empyema caused by Streptococcus constellatus in Malignancy Patient: A Case Report

Introduction: Streptococcus constellatus (SC) is commensal bacteria and belongs to Streptococcus anginosus group (SAG). However, SC causes infections especially in patient with underlying diseases. SC empyema is a clinical case that is described in very few studies, especially in Indonesia.Case: A 45-year-old man was admitted to emergency department in Dr. Soetomo General Hospital Surabaya with respiratory insufficiency on November 11th 2020 after 3 months of non-productive cough and a week of weakness. He was diagnosed with empyema on right hemithorax and received chest tube insertion. SC was isolated from pleural fluid sample after first day of culture on Bactec BD bottle. GeneXpert result of pleural fluid was negative for Mycobacterium tuberculosis (MTB). He completed 10 days of intravenous ampicillin-sulbactam and metronidazole. The CT scan reported solid mass of 4.7x7.4x7.8 cm in posterolateral segment of inferior lobe right lung, right pleural effusion, with adenocarcinoma as biopsy result.Discussion: SC is a normal commensal in respiratory tract, however with the presence of a certain factor such as immunocompromised, colonized SAG directly induces an infection after entering normal sterile sites in the body including pleural fluid.Conclusion: Although infection caused by SC is a rare case, it still should be considered in clinical diagnosis and treatment of related infections, particularly in patients with comorbidities. The prognosis was good with appropriate antibiotics and chest tube insertion.

The corruption of innate immunity by Streptococcus anginosus group

Abstract Streptococcus anginosus group (SAG), formerly known as Streptococcus milleri, consists of three distinct streptococcal species: Streptococcus anginosus, Streptococcus constellatus, and Streptococcus intermedius. SAG was considered as commensal bacteria of colon, oral cavity and vagina. Recent observation reported those bacteria as potent pathogens found in brain or liver abscess. Mechanism of SAG pathogenesis is still unknown, despite the strong set of clinical data. In our study, we determined the virulence of different SAG clinical isolates by examining the activity of hemolysins, DNAses and proteases. By using Dictyostelium discoideum as model for screening SAG virulence we selected a few high and low virulence strains out of 41 SAG isolates. Finally, we established and characterized the infection process of selected SAG strains by wax worm Galleria mellonella. Therefore, we aimed to characterize how those bacteria can interact with human innate immunity. In our experiments, using both human serum and whole blood we demonstrated, that these bacteria are resistant to killing by non-specific mechanisms of the immune response. Our studies have demonstrated that SAG have numerous virulence factors which differ among examined strains, and which allow bacteria to effectively colonize the human body and avoid elimination by the immune system. Supported by National Science Centre, Poland 2018/29/B/NZ6/00624

Streptococcus anginosus group infection as a predictor for the progression of descending necrotizing mediastinitis

The prognosis of descending necrotizing mediastinitis (DNM), especially that extending inferiorly to the carina, remains poor. The identification of additional prognostic factors may improve the prognosis. We retrospectively analyzed six patients who underwent thoracic surgery for DNM extending to the anterior and posterior mediastinum inferior to the carina (Endo classification type IIB) from 2014 to 2020. We reviewed their characteristics, clinical course, causative bacteria, and treatment to investigate their prognostic factors. The median patient age was 62 years. Five patients were men and one patient was a woman. The causative disease in three of the patients was pharyngolaryngeal, and for the others, it was an odontogenic infection. Five patients had sepsis and four had disseminated intravascular coagulation (DIC) at surgery. Four patients had polymicrobial infections of aerobic and anaerobic bacteria, all of whom showed gas bubbles on a chest computed tomography scan and detection of Streptococcus anginosus group (SAG). All patients underwent cervicotomy, tracheostomy, and mediastinal drainage and debridement via a transthoracic approach. Three patients underwent additional surgery or drainage because an additional abscess appeared postoperatively. The median duration of hospitalization was 58 days and the mixed infections, including SAG, were all detected in the three cases of long-term hospitalization. No disease-associated death was observed during the follow-up period of 18 months. Mixed infection, including SAG, may be a predictor for DNM aggravation and spread. Gas bubbles on a chest computed tomography scan suggest polymicrobial aerobic and anaerobic infections including SAG, which require broad-spectrum antibiotic therapy and aggressive drainage and surgery.

Pleural fluid investigations for pleural infections

: Over 1.5 million patients are admitted to hospital with pneumonia in the United States each year. Up to 50% of them can develop a parapneumonic effusion which is associated with higher mortality. The incidence of pleural infection continues to rise, particularly in the elderly and those with comorbidities. Parapneumonic effusions cover a spectrum of presentations from a free-flowing ‘simple parapneumonic effusion’ to a septated ‘complicated parapneumonic effusion’ (CPE) (usually from bacterial pleural invasion) and ‘empyema’ (presence of pleural pus). Pleural infection is defined as either CPE or empyema, and usually requires evacuation of the infected fluid. Laboratory investigations play an essential part of the diagnosis and management of pleural infection. A parapneumonic effusion is typically a neutrophil-rich exudate. Presence of bacteria from culture of the fluid defines pleural infection but conventional culture methods have a low yield. Surrogate pleural fluid markers are often employed to confirm a CPE, including low pleural fluid pH (<7.2) or glucose (<3.3 mmol/L) and elevated lactate dehydrogenase (LDH). Measurement of pleural fluid triglyceride and chylomicrons (for chylothorax) and cholesterol (for pseudochylothorax) may be needed to separate lipid pleural effusions from empyema. Tuberculous pleural effusions usually result from a hypersensitivity pleuritis and are lymphocyte predominant with elevated pleural fluid adenosine deaminase (ADA) and interferon gamma levels. Culture yield of mycobacteria is typically low. Caseating granulomas on pleural tissue biopsy is often considered diagnostic. Common organisms for community-acquired pleural infection include Streptococcus pneumoniae, Streptococcus anginosus group bacteria and Staphylococcus aureus. Hospital-acquired pleural infections have higher mortality and are often polymicrobial which can include S. aureus, Enterobacteriaceae and anaerobes. Antibiotics and evacuation of the infected fluid, usually by chest tube drainage, remain the mainstay of treatment. Intrapleural fibrinolytic and deoxyribonuclease therapy, or occasionally surgical drainage, may be required.

Clinical Features and Outcomes of Streptococcus anginosus Group Infective Endocarditis: A Multicenter Matched Cohort Study.

BackgroundAlthough Streptococcus anginosus group (SAG) endocarditis is considered a severe disease associated with abscess formation and embolic events, there is limited evidence to support this assumption.MethodsWe performed a retrospective analysis of prospectively collected data from consecutive patients with definite SAG endocarditis in 28 centers in Spain and Italy. A comparison between cases due to SAG endocarditis and viridans group streptococci (VGS) or Streptococcus gallolyticus group (SGG) was performed in a 1:2 matched analysis.ResultsOf 5336 consecutive cases of definite endocarditis, 72 (1.4%) were due to SAG and matched with 144 cases due to VGS/SGG. SAG endocarditis was community acquired in 64 (88.9%) cases and affected aortic native valve in 29 (40.3%). When comparing SAG and VGS/SGG endocarditis, no significant differences were found in septic shock (8.3% vs 3.5%, P = .116); valve disorder, including perforation (22.2% vs 18.1%, P = .584), pseudoaneurysm (16.7% vs 8.3%, P = .108), or prosthesis dehiscence (1.4% vs 6.3%, P = .170); paravalvular complications, including abscess (25% vs 18.8%, P = .264) and intracardiac fistula (5.6% vs 3.5%, P = .485); heart failure (34.7% vs 38.9%, P = .655); or embolic events (41.7% vs 32.6%, P = .248). Indications for surgery (70.8% vs 70.8%; P = 1) and mortality (13.9% vs 16.7%; P = .741) were similar between groups.ConclusionsSAG endocarditis is an infrequent but serious condition that presents a prognosis similar to that of VGS/SGG.

#39: Streptococcus anginosus Group Infections in Children: A Retrospective Cohort Study, 2015–2019

Abstract Background Infections attributed to the Streptococcus anginosus group (SAG), which includes Streptococcus anginosus, Streptococcus constellatus, and Streptococcus intermedius, have varying clinical presentations. SAG infections are difficult to identify initially, and members of the group may require different management strategies. Methods A retrospective review of SAG-positive cultures from January 2015, to September 2019, was conducted to describe the demographic, clinical, and laboratory features including the site of infection, antibiotic susceptibility, management, and clinical outcome. Results We identified 561 patients [median age 11.3, interquartile range (IQR) 7.1–14.9 years, male:female ratio 3:2, non-Hispanic–non-Latino 454 (81%), White 279 (49%)]. Thirty-nine (7%) had at least one underlying condition. Of these, inflammatory bowel disease 15 (39%), diabetes 7 (18%), immunodeficiency 5 (13%). SAG was found in exudate, fluid, or aspirate (537/561, 96%), blood (11/561, 2%), and tissue (11/561, 2%) samples; 388 (69%) were polymicrobial infections. The most common site of infection was intra-abdominal (175, 31%), followed by neck/odontogenic (114. 20%) and genitourinary tract (66, 12%). The median length of stay was 6 days (IQR 3–10 days) and was statistically significantly longer for patients with blood, central nervous system, and pulmonary infections compared with soft tissue and upper respiratory tract infections (P &amp;lt; 0.001). Beta-lactams were the most commonly used antibiotics (38%), followed by clindamycin (30 %) (see Figure for antibiotic susceptibility results) and 33 (56%) patients received combination therapy. We did not observe any SAG attributed to mortality. Conclusions In our retrospective cohort, SAG infections were more commonly identified in males, were associated with abscess formation, and presented as polymicrobial infections. Children with underlying comorbidities are more likely to present with systemic SAG infections. SAG-associated infections can be variable in presentation site and severity and should be considered as pathogens when managing patients.

Desarrollo de un medio simple para el aislamiento selectivo de bacterias del grupo Streptococcus anginosus

Bacteria of the Streptococcus anginosus group (SAG) have recently been recognized as contributors of bronchopulmonary disease in cystic fibrosis (CF). Routine detection and quantification are limited by current CF microbiology protocols. The development of the CHROMagar™ StrepB chromogenic medium modified by the addition of plasma, nalidixic acid, colistin and sulfadiazine to make it selective for SAG bacteria is described. This medium could be used as a diagnostic tool to detect SAG in respiratory samples from patients suffering from chronic lung disease.

Role of Streptococcus intermedius phosphoglucosamine mutase in bacterial growth, cell morphology, and resistance to polymorphonuclear leukocyte killing

ObjectivesStreptococcus intermedius is a member of the anginosus group of streptococci, an oral commensal bacterium found in infected root canals, and the causative agent of deep-seated abscesses. This organism has slow clearance when phagocytosed within neutrophils. Here, we investigated the role of its phosphoglucosamine mutase (GlmM), an enzyme associated with peptidoglycan synthesis, in bacterial growth, cell morphology, and resistance to polymorphonuclear leukocyte killing. MethodsThe glmM-deletion (ΔglmM) mutant and the plasmid-borne complementation (ΔglmM/glmM) strain of S. intermedius were generated. The wild type, the ΔglmM mutant, and the ΔglmM/glmM strain were phagocytosed with human polymorphonuclear leukocytes (PMNs), and bacterial viability in PMNs was determined by LIVE/DEAD staining. Additionally, bacterial growth and cell morphology were also compared. ResultsThe survival rate of the ΔglmM mutant was significant lower than that of the wild type. Although the difference in the survival rate of the ΔglmM/glmM strain compared to that of the wild type or the ΔglmM mutant was not significant, the rate appeared to be restored to the middle level. Compared to the wild type and the ΔglmM/glmM strain, the ΔglmM mutant showed reduced growth potential, a significant increase in the number of bacterial chains, and heterogeneous bacteria. ConclusionsGlmM is one of the factors responsible for the stable resistance of S. intermedius to clearance by PMNs.

Microbiology of parapharyngeal abscesses in adults: in search of the significant pathogens

We aimed to describe the microbiology of parapharyngeal abscess (PPA) and point out the likely pathogens using the following principles to suggest pathogenic significance: (1) frequent recovery, (2) abundant growth, (3) growth in relative abundance to other microorganisms, (4) percentage of the isolates recovered in both absolute and relative abundance, (5) more frequent recovery in PPA pus compared with tonsillar surface and tissue. Comprehensive bacterial cultures were performed on specimens obtained from adult patients (n = 60) with surgically verified PPA, who were prospectively enrolled at five Danish ear-nose-throat departments. The prevalent isolates (in PPA pus) were unspecified anaerobes (73%), non-hemolytic streptococci (67%), Streptococcus anginosus group (SAG) (40%), Corynebacterium spp. (25%), Neisseria spp. (23%), Fusobacterium spp. (22%), Fusobacterium necrophorum (17%), Prevotella spp. (12%), and Streptococcus pyogenes (10%). The bacteria most frequently isolated in heavy (maximum) growth were unspecified anaerobes (60%), SAG (40%), F. necrophorum (23%), and Prevotella spp. (17%). The predominant microorganisms (those found in highest relative abundance) were unspecified anaerobes (53%), SAG (28%), non-hemolytic streptococci (25%), F. necrophorum (15%), S. pyogenes (10%), and Prevotella spp. (10%). Four potential pathogens were found in both heavy growth and highest relative abundance in at least 50% of cases: F. necrophorum, Prevotella spp., SAG, and S. pyogenes. SAG, Prevotella spp., F. necrophorum, S. pyogenes, and Bacteroides spp. were recovered with the same or higher frequency from PPA pus compared with tonsillar tissue and surface. Our findings suggest that SAG, F. necrophorum, Prevotella, and S. pyogenes are significant pathogens in PPA development.

Preoperative undernutrition predicts postoperative complications of acute empyema.

IntroductionSurgery for acute empyema is associated with postoperative complications and relapse. Establishing a predictor for postoperative complications may improve prognosis.ObjectivesTo demonstrate undernutrition as a predictor of complications after surgery for acute empyema.MethodsWe retrospectively analyzed 52 consecutive patients who underwent surgery for acute empyema from 2004 to 2019 and validated the correlation of undernutrition with serum albumin level, patient characteristics, hospital stay, and postoperative complications.ResultsThe median preoperative serum albumin level was 2.4 g/dL (range: 1.1‐3.4). The levels in all patients were lower than the standard value (3.5 g/dL). Patients were divided into two groups based on the median serum albumin levels: the low serum albumin level group (group L, n = 28) and the high serum albumin level group (group H, n = 24). Group L patients were significantly older (64.5 vs 52.9 years, P = .002), had lower median body mass index (21.0 vs 24.2, P = .008), and significantly had Streptococcus anginosus group as the causative bacteria (50% vs 21%, P = .044). Their hospitalization duration was significantly longer (28.1 vs 14.8 days, P < .001), and postoperative complications were significant or tended to be more frequent (all incidence; 11 (39%) vs 2 (8%), P = .012, respiratory‐related; 7 (25%) vs 1 (4%), P = .056) in group L. Further analyses revealed that other undernutrition indicators also correlated with postoperative complications.ConclusionsPreoperative serum albumin level is a valid predictor of complications after surgery for acute empyema. Preoperative nutrition management for empyema patients may reduce the occurrence of postoperative complications.

Toward understanding the signals of bacteriocin production by Streptococcus spp. and their importance in current applications.

Microorganisms have developed quorum sensing (QS) systems to detect small signaling molecules that help to control access to additional nutrients and space in highly competitive polymicrobial niches. Many bacterial processes are QS-regulated; two examples are the highly related traits of the natural genetic competence state and the production of antimicrobial peptides such as bacteriocins. The Streptococcus genus is widely studied for its competence and for its ability to produce bacteriocins, as these antimicrobial peptides have significant potential in the treatment of infections caused by multiple-resistant pathogens, a severe public health issue. The transduction of a two-component system controls competence in streptococci: (1) ComD/E, which controls the competence in the Mitis and Anginosus groups, and (2) ComR/S, which performs the same function in the Bovis, Mutans, Salivarius, and Pyogenic groups. The cell-to-cell communication required for bacteriocin production in the Streptococcus groups is controlled mainly by a paralog of the ComD/E system. The relationships between pheromone signals and induction pathways are related to the bacteriocin production systems. In this review, we discuss the recent advances in the understanding of signaling and the induction of bacteriocin biosynthesis by QS regulation in streptococci. This information could aid in the design of better methods for the development and production of these antimicrobial peptides. It could also contribute to the analysis and emerging applications of bacteriocins in terms of their safety, quality, and human health benefits.

Microbiology of orbital cellulitis with subperiosteal abscess in children: Prevalence and characteristics of Streptococcus anginosus group infection

ABSTRACT Purpose To evaluate the predominant pathogens and clinical course in pediatric patients with orbital cellulitis (OC) complicated by subperiosteal abscess (SPA). Methods This is a single-center retrospective chart review evaluating pediatric patients with OC complicated by SPA treated at a tertiary care center in the Pacific Northwest. Data were analyzed for characteristics, rates of infection, and antibiotic resistance of the predominant pathogens in pediatric patients. Results Twenty-seven children were identified with OC complicated by SPA and bacterial cultures drawn. The average age (SD) of the patients was 9.2 years (4.8), median 9.6; 15 range 5 months to 17.2 years. Seventeen (63.0%) were male. Sinusitis was present in all patients. Streptococcus species were the most common pathogen accounting for 52% (17/33) of isolates. Streptococcus anginosus group (SAG) was the predominant species and were isolated in 10 out of 27 (37%) children in the study. Twenty-one (78%) patients required surgery for the treatment of SPA. Among surgically treated patients, females tended to be younger than males (p = .068). Pediatric patients with SAG infections required more surgery than children without this isolate, 100% and 65%, respectively (p = .030). Female patients tended to have SAG infections more often than males (p = .063). Conclusions Orbital infections caused by SAG require surgical management more often than those caused by other pathogens. Our results suggest a difference in pathogenic organisms in male and female patients with SPA. SAG is one of the most common pathogens isolated in orbital cellulitis complicated by SPA in children.

723. Epidemiology, Risk Factors, and Treatment Considerations for Pyogenic Liver Abscess (PLA) in the Calgary Health Zone (CHZ) Revisited: A Population-Based Study

BackgroundPLA is a significant cause of morbidity and mortality. However, its epidemiology and outcomes have not been recently evaluated in the CHZ. Understanding current trends will help guide management.MethodsIn this population-based study, we evaluated epidemiology, risk factors, and treatment of patients with PLA in the CHZ. CHZ residents aged ≥ 20 years diagnosed with PLA in 2015-2017 were included. Charts were reviewed for demographics and clinical outcomes. Multivariate logistic regression was used to determine factors associated with 30-day mortality. Findings were compared to a previous assessment of PLA in the CHZ from 1999-2003 (Kaplan et al., 2004).ResultsA total of 136 patients with PLA were identified, representing an annual incidence rate of 3.7 cases per 100,000 population. Compared to 1999-2003, incidence of PLA was increased (2.3 per 100,000; p< 0.01) but mortality was similar (1999-2003: 0.22 per 100,000 vs. 2015-2017: 0.26 per 100,000; p=0.6). The most common culprit organisms were Streptococcus anginosus group (40%), Klebsiella species (25%), Escherichia coli (18%), and obligate anaerobes (16%). Pathogen prevalence was similar to the prior cohort. Compared to 1999-2003, antibiotic resistant organisms were more frequent (8% vs 1%, p=0.04). In our cohort, liver aspirations were less frequent (p=0.02) but aspirate culture was more often positive (p< 0.01). The median duration of intravenous antibiotic therapy was longer compared to previous (2015-2017: 23 days (IQR 9-38) vs. 1999-2003: 17 days (IQR 10-29); p=0.001). Similarly, the total duration of antibiotic therapy was longer (2015-2017: 42 days (IQR 25-65) vs. 1999-2003: 31 days (IQR 18-45); p< 0.001). Thirty-day mortality from admission was 7% and did not differ amongst cohorts. Risk factors are shown in Table-1.Table-1: Risk factors for 30-day mortality in PLA ConclusionIncidence of PLA in the CHZ is rising with more antimicrobial resistance. Diagnostic liver aspirations are less frequent. Antibiotic durations are longer with no reduction in mortality. Understanding changing trends is valuable in directing future care. Encouraging liver aspirations to obtain a microbiologic diagnosis, especially with increasing resistance, is crucial. Considering shorter antibiotic durations in light of stable mortality warrants further exploration.Disclosures All Authors: No reported disclosures

191. oral versus Intravenous Antibiotic Treatment in Skin and Soft Tissue Infections as a Consequence of Intravenous Drug Use: A Retrospective Study to Demonstrate Noninferiority

BackgroundSkin and soft tissue infections (SSTIs) are among the most prevalent infectious complications of intravenous drug use (IVDU). Given its polymicrobial nature, studies focusing on SSTIs in the general population may not be generalizable this group. We completed a retrospective chart review to better characterize the safety and efficacy of oral versus intravenous (IV) antibiotics for the treatment SSTIs in IVDU.MethodsWe reviewed patients admitted with bacterial SSTIs and IVDU from January 01, 2012 to December 31, 2019 based on ICD-10 codes. SSTIs complicated by bacteremia, endocarditis, bone or joint involvement on index admission were excluded. Patients who received < 48 hours of IV antibiotics were considered oral therapy, otherwise they were considered IV therapy. Patient comorbidities, incision and drainage (I&D) status, substance use, microbiology and antimicrobial data were reviewed.ResultsOf 231 eligible patients, 84 received oral therapy. There was no statistical difference in patient characteristics between the two therapy groups. Streptococcus anginosus group were the most common organisms found (33%) followed by Staphylococcus aureus (31%). There was no statistical difference between rates of readmission (p=0.87), recurrent primary site infection (p=1.00), repeat debridement (p=0.08) or occurrence of deep-seated infections within 90 days of treatment completion. No morality was observed. The oral group had shorter length of stay (3 vs. 5 days, p < 0.001) and shorter total duration of antibiotics (10 vs. 13 days, p < 0.001). Overall, 90% of those with abscess underwent I&D, which did not differ between therapy groups. Time to I&D was shorter (0 vs. 1 day, p=0.005) in the oral group. Patients who did not receive and I&D were more likely to be readmitted within 90 days (p=0.025).ConclusionIn SSTIs related to IVDU, oral antibiotic therapy was noninferior to IV in terms of mortality, readmission, and deep-seated infection rates within 90 days of treatment completion and had a decreased length of stay and total treatment duration. A delay in I&D led to increased length of stay and lack of I&D increased readmission rate. Therefore, a prompt I&D may allow a safe and effective early transition to oral therapy in SSTIs related to IVDU.Disclosures All Authors: No reported disclosures

1563. Variations in the clinical spectrum of the Streptococcus anginosus group: a report of two rare presentations

BackgroundThe Streptococcus Anginosus Group (SAG) formerly Streptococcus Milleri Group is a subgroup of viridans streptococci including S. anginosus, intermedius, and constellatus. SAG are microaerophilic digestive tract commensals. They are associated with empyema and deep organ abscesses. We present 2 unusual cases: necrotizing fasciitis and aortic valve endocarditis with aortic root abscess, resulting in septic emboli causing renal infarction.MethodsReview of the literature and reported cases of SAG.ResultsCase1) 48 year-old-male with history of HTN, T2DM, presented with swelling and erythema of the right arm of 2-day evolution. Exam: tender, erythematous indurated right deltoid. Significant labs: WBC 25k/uL and lactate of 2.5. CT of the RUE showed an extensive fluid collection. Vancomycin, levofloxacin and clindamycin were initiated, surgical debridement revealed extensive necrotizing fasciitis Wound cultures grew S. constellatus. Required multiple debridement and prolonged course of penicillin G. Case 2) 53-year-old male with history of COPD, Prior Splenectomy for a large splenic infarct, heterozygous factor V Leiden mutation, HCV infection, cirrhosis, presented with right flank pain, hematuria over 5 days. Labs: WBC 16.8 k/uL, CT abdomen with contrast: right renal infarct. Heparin drip, Vancomycin and Ceftriaxone were initiated. Blood cultures grew S. anginosus. TEE revealed new aortic valve vegetations with severe aortic regurgitation. His condition deteriorated, requiring aortic valve surgery, found to have aortic root abscess requiring aortic root replacement.Necrotizing Fascitis - Soft Tissue Air Post-Surgical Debridement Right Renal Infarct ConclusionSAG infections infections are unique from other S viridans, causing severe deep organ abscesses requiring combined surgical and antibiotic therapy. Isolation in clinical specimens should alert the possibility of severe life threatening infections. Here we highlight 2 unusual manifestations of necrotizing fasciitis and aortic valve endocarditis with aortic root abscess and possible large septic renal embolism. One patient had a splenectomy. We are not sure if this contributed to a severe SAG infectionDisclosures All Authors: No reported disclosures