Seven-year review of bacteremia caused by Streptococcus milleri and other viridans streptococci

Streptococcal Infections in Marine Mammals

Marine mammals are sentinels for the marine ecosystem and threatened by numerous factors including infectious diseases. One of the most frequently isolated bacteria are beta-hemolytic streptococci. However, knowledge on ecology and epidemiology of streptococcal species in marine mammals is very limited. This review summarizes published reports on streptococcal species, which have been detected in marine mammals. Furthermore, we discuss streptococcal transmission between and adaptation to their marine mammalian hosts. We conclude that streptococci colonize and/or infect marine mammals very frequently, but in many cases, streptococci isolated from marine mammals have not been further identified. How these bacteria disseminate and adapt to their specific niches can only be speculated due to the lack of respective research. Considering the relevance of pathogenic streptococci for marine mammals as part of the marine ecosystem, it seems that they have been neglected and should receive scientific interest in the future.

Pyogenic Liver Abscess and Sepsis Caused by Streptococcus constellatus in the Immunocompetent Host

Streptococcus constellatus is a member of Streptococcus milleri group which is a subgroup of Viridans streptococci, first described by Guthof in 1956 after being isolated from dental abscesses. S. constellatus, a gram positive, non-sporing, non-motile, catalase negative cocci, is the normal flora of the oropharyngeal, gastrointestinal and urogenital tract. It is not a commonly encountered pathogen but has a propensity to form abscesses and cause bacteremia in the immunocompromised patient. Here, we report a 78-year-old man with sepsis due to Streptococcus constellatus liver abscess. The patient had a history of hypertension, stroke, benign prostatic hyperplasia, vascular dementia and myocardial infarction status post coronary artery bypass grafting. There has been no particular link between any of these conditions to S. constellatus. However, immunocompromised status predisposes to fulminant infection and formation of abscesses. The patient was febrile with a temperature of 99.1°F, blood pressure of 143/73 mmHg and the heart rate (HR) of 98. Labs revealed a leukocytosis of 16.90 K/uL, hemoglobin 11.8 g/dL, hematocrit 35.8%, total bilirubin 1.7 mg/dL, direct bilirubin 1.0 mg/dL, aspartate aminotransferase (AST) 44 IU/L, alanine aminotransferase (ALT) 28 IU/L, alkaline phosphatase (ALKP) 176 IU/L and lactate dehydrogenase (LDH) was 290 IU/L. He was started on intravenous Maxipime and Unasyn which was switched to Rocephin and Clindamycin based on the Infectious disease recommendations. Metronidazole was also started and the serologies were sent for Entamoeba histolytica. Computerized tomography (CT) scan showed an abscess in the right lobe of the liver which was finally drained using an interventional radiology (IR)-guided approach. The cultures from the fluid and blood yielded S. constellatus and thus Metronidazole was discontinued. The patient improved after a few days and the drainage catheter was pulled out and the patient discharged in stable condition.

HANDOC: A Handy Score to Determine the Need for Echocardiography in Non-β-Hemolytic Streptococcal Bacteremia

Background

Non-β-hemolytic streptococci (NBHS) can cause infective endocarditis (IE). Echocardiography is used to diagnose IE, but it is not known which patients with NBHS bacteremia should undergo echocardiography.

Method

Medical records of patients with NBHS bacteremia in southern Sweden from 2012 to 2014 were studied retrospectively. The patients were divided into 2 cohorts. In the first, correlations between the reported data and IE were studied. These variables were used to construct the HANDOC score, which was then validated in the second cohort.

Results

Three hundred thirty-nine patients with NBHS bacteremia were included in the first cohort, of whom 26 fulfilled the criteria for IE. Several factors differed significantly between the patients with IE and those without. Among these variables, the presence of Heart murmur or valve disease; Aetiology with the groups of Streptococcus mutans, Streptococcus bovis, Streptococcus sanguinis, or Streptococcus anginosus; Number of positive blood cultures ≥2; Duration of symptoms of 7 days or more; Only 1 species growing in blood cultures; and Community-acquired infection were chosen to form the HANDOC score. With a cutoff between 2 and 3 points, HANDOC had a sensitivity of 100% and specificity of 73% in the first cohort. When tested in the validation cohort (n = 399), the sensitivity was 100% and the specificity 76%.

Conclusions

HANDOC can be used in to identify patients with NBHS bacteremia who have a risk of IE so low that echocardiography can be omitted; therefore, its implementation might reduce the use of echocardiography.

External validation of the HANDOC score - high sensitivity to identify patients with non-beta-haemolytic streptococcal endocarditis

Background: Invasive infections with non-beta-haemolytic streptococci (NBHS) is quite common and presents the clinicians with difficulties regarding which patients are at risk for infective endocarditis (IE). The HANDOC score was developed to identify patients with NBHS bacteraemia who are at low risk of IE. This study was conducted to validate HANDOC in an external cohort.Methods: Patients with NBHS in blood cultures between March and September 2016 in a Danish centre were included as part of an on-going study. Patient characteristics were collected to classify bacteria according to Dukés criteria and the components of the HANDOC score were collected retrospectively from the patients' medical records.Results: 68 patients were included in the cohort, of which 16 fulfilled Dukés criteria for IE. All patients with IE (16 of 16) had a HANDOC score above the predefined cut-off. Cases of IE were found in patients with. Streptococcus mitis, Streptococcus bovis, Streptococcus mutans, Streptococcus anginosus, and Streptococcus sanguinis group streptococci. The HANDOC score thus had a sensitivity of 100% and a specificity of 62% in this cohort.Conclusions: HANDOC has a sensitivity of 100% and a relatively high specificity (62%) also in a prospectively enrolled cohort of patients from another country than its origin. This indicates that HANDOC can be implemented in clinical practice to identify patients with a low risk of IE in whom echocardiography can be omitted.

Cerebellar abscesses, infective endocarditis and bacteraemia due to a rare pathogen: Streptococcus constellatus

Intracranial infections may result from contiguity, such as mastoiditis or acute otitis media, or from haematogenous dissemination from an infectious source. Streptococcus constellatus, a coccus from the normal genital, oral and gastrointestinal flora, has a tendency to form abscesses, but not to cause infective endocarditis (IE). Also, S. constellatus is an extremely rare causative agent of brain abscess. We report the case of a woman with a colorectal tumour who presented with IE and cerebellar abscesses due to a S. constellatus bacteraemia.

[Streptococcus milleri: An unusual cause of skull extensive osteomyelitis in an immunocompetent patient]

INTRODUCTION

Streptococcus milleri (Streptococcus anginosus, intermedius and constellatus) are commensal organisms, which can become pathogenic and cause infection with frequent abscess formation, local or metastatic extension. Osteomyelitis of the skull has been rarely reported in this type of infection.

CASE REPORT

Skull osteomyelitis due to Streptococcus milleri is reported in a 61-year-old immunocompetent man without any medical history, occurring 10 months after a head injury without any wound or complication at initial presentation. A progressive right parieto-occipital headache with worsening and increased acute phase reactants evoked a giant cell arteritis. After few days of corticosteroid therapy (0.5 mg/kg/day), diagnosis of subcutaneous abscess associated to an extensive osteomyelitis of the skull due to Streptococcus milleri was diagnosed. The outcome was favorable after drainage of one liter of pus, irrigation, debridement and antibiotherapy by amoxicillin for 8 weeks.

CONCLUSION

It is necessary to discuss the differential diagnosis of giant cell arteritis particularly when symptoms are unusual. Even a short-term corticosteroid therapy may dramatically exacerbate an undetected infection.

Thalamic abscess caused by a rare pathogen: streptococcus constellatus

Streptococcus constellatus is a microorganism that lives commensally in the oropharyngeal region, urogenital region, and intestinal tract. However, it can cause infection in patients with certain predisposing factors. Rarely, this microorganism can cause a brain abscess. Thalamic localization of brain abscesses is much rarer than abscesses in other locations of the brain. Brain abscess caused by streptococcus constellatus are very rarely been reported in the literature. We present a rare case of a left-sided thalamic abscess caused by streptococcus constellatus in a 25-year-old male patient who was injured by shrapnel pieces in the head and who was malnourished. The patient was successfully treated by stereotactic aspiration and antibiotherapy.

Intra-Abdominal Abscess and Primary Peritonitis Caused by Streptococcus anginosus

Introduction

The Streptococcus anginosus group of bacteria are low-virulence bacteria existing as commensals in the oral flora and gastrointestinal tracts of humans. S. anginosus may spread to the blood in individuals with poor oral hygiene in cases of oral infections, such as gingivitis and tooth abscesses, that develop following the loss of mucosal unity. This may lead to infections in the whole body, primarily as brain and liver abscesses.

Case Presentation

A 32-year-old male patient presented with complaints of nausea, vomiting, and diffuse abdominal pain. Diffuse abdominal tenderness and rebound tenderness were detected particularly in the epigastrium and right upper quadrant. Laboratory assessment revealed a leukocyte count of 20,500/mm³. Free fluid around the liver and heterogeneous areas of abscess formation in the right lateral gallbladder were revealed on abdominal computed tomography. Diffuse adhesions between the bowel and seropurulent free liquid in the abdomen were detected on surgical exploration, and a sample was taken for cultures. The patient was discharged without complications on the sixth postoperative day and his antibiotic course was completed with 4 weeks of oral treatment. We reviewed the literature for similar cases of disseminated pyogenic infections caused by the S. anginosus group.

Conclusions

It should be kept in mind that the oral flora bacterium S. anginosus may cause transient bacteremia and deep-seated organ abscesses in immunodeficient patients with poor oral hygiene. Such patients with intra-abdominal abscesses should be treated with antibiotics and surgery.

Bloodstream infections caused by Streptococcus anginosus group bacteria: A retrospective analysis of 78 cases at a Japanese tertiary hospital

OBJECTIVES

To investigate the characteristics of Streptococcus anginosus group (SAG) bacteremia in recent years, we conducted a retrospective cohort study and compared its findings with the data from previous studies.

METHODS

All patients with positive blood cultures from May 2005 to September 2014 in a tertiary care center with 925 beds were included.

RESULTS

There were 78 cases of SAG bacteremia (51 cases men; median age, 68 years) during the study period. The most common comorbidities were solid tumors in 32.1% of the patients. The most common infection source was hepatobiliary in one-third of all cases. Other infection sites included the following: intra-abdominal (12.8%), thoracic (10.3%), musculoskeletal (9%), urinary tract (7.7%), soft tissues (7.7%), and cervicofacial (6.4%). Susceptibility to penicillin, clindamycin and erythromycin were 100% (78/78), 95% (70/74) and 85% (39/46), respectively. Surgery along with systemic antibiotic treatment was administered in 53% of the cases. In-hospital mortality was 14.1%.

CONCLUSION

The clinical sources of the SAG bacteria were diverse, and hepatobiliary infection was the most common source of infection. In more than half of the patients, surgical treatment was performed. Susceptibility to penicillin was 100%, but susceptibility to erythromycin was lower than that reported in previous studies.

Clinical and microbiological outcomes in patients with Streptococcus anginosus group bacteraemia identified through use of a rapid microarray assay

Limited data exist evaluating outcomes in patients with serious Streptococcus anginosus group infections, particularly bacteraemia. A retrospective, single-centre cohort study was conducted to characterize potential risk factors along with clinical and microbiological outcomes in patients with S. anginosus group bacteraemia (SAGB). Adult inpatients with SAGB identified using the Verigene Gram-positive blood culture assay between March 2013 and April 2014 were included. Patients aged ≤ 18 or >89 years, those with SAGB identified at an outside facility and those who were incarcerated were excluded. Differences between groups were explored using a Wilcoxon rank-sum test, χ2 test, Student's t-test or Fisher's exact test as appropriate and a two-tailed P value of ≤ 0.05 was considered statistically significant. The 34 patients who met the inclusion criteria were 57 ± 14 (mean ± SD) years old and had a median Charlson co-morbidity index of 4 [interquartile range (IQR) 1-6] and 10 (29%) were immunosuppressed at baseline. Almost half (47%) had received antibiotics in the previous 90 days. Twelve (35%) patients had gastrointestinal malignancies and the commonest source of bacteraemia was the gastrointestinal tract (53%). The primary species responsible for SAGB was S. anginosus (68%), and overall susceptibility to penicillin was 91%. Patients were most often treated with a β-lactam/β-lactamase inhibitor combination (36%) for a duration of 8 (IQR 4-13) days. Length of stay (LOS) and infection-related LOS were 10 (IQR 5-17) and 9 (IQR 4-12) days, respectively. Twenty [59%] patients achieved a clinical cure, while 29 (85%) achieved a microbiological cure. Four (12%) patients died and one patient was readmitted within 30  days. In the largest cohort of patients with SAGB to date, gastrointestinal malignancies may have been an important risk factor for SAGB, while rapid identification via a microarray assay likely contributed to improved disease recognition and timely pharmacological and non-pharmacological therapy.

Characterization of high-level daptomycin resistance in Viridans group Streptococci developed upon in vitro exposure to daptomycin

Viridans group streptococci (VGS) are part of the normal flora that may cause bacteremia, often leading to endocarditis. We evaluated daptomycin against four clinical strains of VGS (MICs = 1 or 2 μg/ml) using an in vitro-simulated endocardial vegetation model, a simulated bacteremia model, and kill curves. Daptomycin exposure was simulated at 6 mg/kg of body weight and 8 mg/kg every 24 h for endocardial and bacteremia models. Total drug concentrations were used for analyses containing protein (albumin and pooled human serum), and free (unbound) drug concentrations (93% protein bound) were used for analyses not containing protein. Daptomycin MICs in the presence of protein were significantly higher than those in the absence of protein. Despite MICs below or at the susceptible breakpoint, all daptomycin regimens demonstrated limited kill in both pharmacodynamic models. A reduction of approximately 1 to 2 log10 CFU was seen for all isolates and dosages except daptomycin at 6 mg/kg, which achieved a reduction of 2.7 log10 CFU/g against one strain (Streptococcus gordonii 1649) in the endocardial model. Activity was similar in both pharmacodynamic models in the presence or absence of protein. Similar activity was noted in the kill curves over all multiples of the MIC. Regrowth by 24 h was seen even at 8× MIC. Postexposure daptomycin MICs for both pharmacodynamic models increased to >256 μg/ml for all isolates by 24 and 72 h. Despite susceptibility to daptomycin by standard MIC methods, these VGS developed high-level daptomycin resistance (HLDR) after a short duration following drug exposure not attributed to modification or inactivation of daptomycin. Further evaluation is warranted to determine the mechanism of resistance and clinical implications.

An unusual case of Streptococcus anginosus group pyomyositis diagnosed using direct 16S ribosomal DNA sequencing

Bacteria belonging to the Streptococcus anginosus group (Streptococcus intermedius, Streptococcus constellatus and Streptococcus anginosus) are capable of causing serious pyogenic infections, with a tendency for abscess formation. The present article reports a case of S anginosus group pyomyositis in a 47-year-old man. The pathogen was recovered from one of two blood cultures obtained from the patient, but speciation was initially not performed because the organism was considered to be a contaminant (viridans streptococci group). The diagnosis was ultimately confirmed using 16S ribosomal DNA sequencing of purulent fluid obtained from a muscle abscess aspirate. The present case serves to emphasize that finding even a single positive blood culture of an organism belonging to the S anginosus group should prompt careful evaluation of the patient for a pyogenic focus of infection. It also highlights the potential utility of 16S ribosomal DNA amplification and sequencing in direct pathogen detection from aspirated fluid in cases of pyomyositis in which antimicrobial therapy was initiated before specimen collection.

Mitral and aortic valve endocarditis caused by a rare pathogen: Streptococcus constellatus

Streptococcus constellatus endocarditis is associated with systemic embolism and frequently with a poor prognosis. We describe the first case reported in the literature of infective endocarditis by penicillin-resistant S. constellatus causing both mitral and aortic valve regurgitation, treated successfully with double-valve replacement.

Gastrointestinal stromal tumor complicated by Streptococcus milleri bacteremia and liver abscess

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. Often discovered incidentally, GISTs can present with nonspecific abdominal symptoms or more overt symptoms of bleeding, obstruction, or perforation. Despite a myriad of clinical presentations, bacteremia associated with a GIST has not been described. In this report, we present an unusual clinical case that illustrates how GISTs can become infected, and demonstrate the importance of Streptococcus milleri bacteremia as an indicator of possible underlying gastrointestinal neoplasm.

Streptococcus constellatus bacteremia causing septic shock following tooth extraction: a case report

Introduction

Organisms of the Streptococcus milleri group consists of Streptococcusintermedius, Streptococcus constellatus, and Streptococcus anginosus. Though they are commonly associated with abscesses, bacteremia with subsequent septic shock and mortality is infrequent.

Case presentation

We report a case of a 27-year-old Chinese man who presented with Streptococcus constellatus bacteremia following an incomplete tooth extraction resulting in septic shock.

Conclusion

Bacteremia from the Streptococcus milleri group is infrequent but must trigger the search for an underlying abscess. Knowledge of each member's predilection for different clinical presentations can aid in determining the location of the underlying source of infection.

Streptococcus intermedius causing infective endocarditis and abscesses: a report of three cases and review of the literature

Background

Streptococcus intermedius is a member of the Streptococcus anginosus group. Clinical disease with S. intermedius is characterized by abscess formation and rarely endocarditis. Identification of Streptococcus intermedius is difficult, leading to the development of molecular methods to more accurately identify and characterize this organism.

Case presentation

Over a period of 6 months we encountered three cases of invasive Streptococcus intermedius infection presenting as hepatic abscesses, brain abscess, and endocarditis. We confirmed our microbiologic diagnosis through 16S sequencing and found a common virulence gene in each case.

Conclusion

Our report illustrates three different clinical manifestations due to Streptococcus intermedius infection that can be encountered in healthy individuals in a community hospital setting. To our knowledge, this is the first case of Streptococcus intermedius endocarditis confirmed by 16S sequencing analysis. The use of molecular methods may allow a better understanding of the epidemiology and pathogenesis of this organism.

A polymicrobial perspective of pulmonary infections exposes an enigmatic pathogen in cystic fibrosis patients

Lung disease is the leading cause of morbidity and mortality in cystic fibrosis (CF) patients. A modest number of bacterial pathogens have been correlated with pulmonary function decline; however, microbiological and molecular evidence suggests that CF airway infection is polymicrobial. To obtain a more complete assessment of the microbial community composition and dynamics, we undertook a longitudinal study by using culture-independent and microbiological approaches. In the process, we demonstrated that within complex and dynamic communities, the Streptococcus milleri group (SMG) can establish chronic pulmonary infections and at the onset of 39% of acute pulmonary exacerbations, SMG is the numerically dominant pathogen. We report the comprehensive polymicrobial community dynamics of a CF lung infection in a clinically relevant context. If a given organism, such as Pseudomonas aeruginosa, becomes resistant to antibiotic therapy, an alternative treatment avenue may mediate the desired clinical response by effectively managing the composition of the microbial community.

Group milleri streptococci: significant pathogens in solid organ recipients

Group milleri streptococci (GMS) comprise a heterogeneous group of streptococci including the species intermedius, constellatus and anginosus. They may cause chronic intra-abdominal and intrathoracic abscesses, which are difficult to treat. This is a retrospective analysis including 45 transplant recipients in whom GMS were isolated. The epidemiology, clinical significance and the impact on the outcome in all transplant patients with infections caused by GMS during a 4-year period (2001-2004) was evaluated. The 45 solid organ recipients (88 isolates) included 34 liver-, four kidney/pancreas-, one kidney-, two small bowel-, three combined liver/kidney- and one combined kidney/small bowel transplant recipient. In 42 cases GMS caused intra-abdominal infection, in two cases pleural empyema and in one case soft tissue infection. Only a single isolate of GMS was cultured from blood. In 54 of the 88 specimens (61%), which grew GMS, other pathogens were also isolated. GMS frequently caused recurrent cholangitis (n = 17) associated with anastomotic and nonanastomotic biliary strictures. These cases were managed by repeated stenting or surgical intervention and prolonged antibiotic therapy. No patient died directly related to GMS infection and all except one case responded to combined surgical/antibiotic treatment. One pancreas graft was lost because of erosion haemorrhage associated with an abscess. GMS were susceptible to penicillin G, carbapenems and clindamycin, whereas cephalosporins and quinolones showed intermediate activity or resistance in some cases, and GMS in general were found resistant to aminoglycosides. GMS may cause serious infections in transplant recipients which are difficult to treat. Their prevalence in transplant surgical site infections thus far may have been underestimated.

Population-based surveillance of invasive pyogenic streptococcal infection in a large Canadian region

Pyogenic streptococci are a major cause of invasive infection. This study presents the results of a population-based laboratory surveillance for invasive pyogenic streptococcal infections among residents of the Calgary Health Region (population 1 million) between 1 July 1999 and 30 June 2004. The overall annual incidence rate was 18.65/100,000 population, with isolates belonging to the Streptococcus milleri group forming the most important aetiology (incidence of 8.65/100,000 population). Invasive infection with groups A, B, G and C streptococci occurred at annual rates of 4.27, 3.13, 1.83 and 0.41/100,000 population, respectively. There was a close relationship between increasing age and development of an invasive pyogenic streptococcal infection, and the incidence of infection was higher among males than among females. Differences in the seasonal occurrence and focus of infection occurred between the different groups.

In vitro activity of sitafloxacin compared with several fluoroquinolones against Streptococcus anginosus and Streptococcus constellatus

The in vitro activities of sitafloxacin and seven other fluoroquinolones a (ciprofloxacin, tosufloxacin, sparfloxacin, levofloxacin, T-3811ME, moxifloxacin and trovafloxacin) were examined by the microdilution method against 79 clinically isolated 'Streptococcus milleri' group (SMG) microorganisms. No statistically significant differences were found between the minimum inhibitory concentrations (MIC(50) and MIC(90)) against Streptococcus anginosus and Streptococcus constellatus. Sitafloxacin was the most active agent of the eight fluoroquinolones tested against SMG, with a MIC(90) of 0.06 microg/mL, which was 8 times more active than ciprofloxacin and 16 times more active than levofloxacin. Although none of the SMG strains showed high resistance to any of the fluoroquinolones tested, three agents (trovafloxacin, sitafloxacin and T-3811ME) had low MICs against 23 SMG strains against which levofloxacin had a MIC> 1 microg/mL. In conclusion, several fluoroquinolones have low MICs against SMG, but sitafloxacin has the lowest.

Empyema of lung associated with Streptococcus milleri infection

Empyema of the lung is a very serious illness which must be detected quickly and treated aggressively. We report an unusual case of empyema of the lung associated with a boating accident while the patient was fishing in a sea loch off the west coast of Scotland.

Prospective study of Streptococcus milleri hepatic abscess

Thirty-seven cases of microbiologically demonstrated pyogenic hepatic abscess were observed in a prospective study over a seven-year period. Biliary disease was the most common source of liver abscess (42%). Streptococcus milleri was the most common cause of hepatic abscess, accounting for 51% of the cases. Hepatic abscess is due to Streptococcus milleri clinically distinct from other forms of pyogenic liver abscess due to its torpid nature and the longer duration of its symptoms [42 vs. 11 days]. Occult hepatic abscess should be suspected if the blood culture is positive for Streptococcus milleri, since 28% of bacteremia cases due to Streptococcus milleri stem from hepatic abscesses. It is important to distinguish Streptococcus milleri from other members of the viridans streptococci group, which are frequently isolated as contaminants, but only exceptionally cause hepatic abscess. Unlike other pyogenic hepatic abscesses, those caused by Streptococcus milleri are frequently monomicrobial (79%). In the present study, empirical therapy of pyogenic hepatic abscess always included a drug that is effective against Streptococcus milleri.

Antimicrobial susceptibility of viridans group streptococci

A total of 68 viridans group streptococci, including 31 Streptococcus sanguis, 12 S. mitis, 3 S. salivarius, and 8 S. milleri from blood, and an additional 14 S. milleri from abscesses and normally sterile sites, were tested against penicillin, amoxicillin, cefazolin, ceftriaxone, meropenem, clindamycin, quinupristin/dalfopristin, rifampin, levofloxacin, ofloxacin, vancomycin, and gentamicin with the microdilution method. The susceptibility rates for S. sanguis were: penicillin, 74%; amoxicillin, 84%; ceftriaxone, 94%; clindamycin, 87%, and vancomycin, 100%. The susceptibility rates for S. mitis were: penicillin, 42%; amoxicillin, 67%; ceftriaxone, 58%; clindamycin, 100%; and vancomycin, 100%. The susceptibility rates for S. milleri were: penicillin, 100%, amoxicillin. 100%; ceftriaxone, 100%, clindamycin, 100%; and vancomycin, 100%. Two of the three isolates of S. salivarius were susceptible to penicillin, amoxicillin, and ceftriaxone; all were susceptible to clindamycin and vancomycin. Levofloxacin, quinupristin/dalfopristin, and rifampin were highly active against all isolates.