Aerococcus christensenii native aortic valve subacute bacterial endocarditis (SBE) presenting as culture negative endocarditis (CNE) mimicking marantic endocarditis

A Patient’s Six-Month Journey From Low Sodium to Blue Toes to Stroke: Non-infective Thrombotic Endocarditis Due to Non-small Cell Lung Cancer

We report a patient's journey with a four-year history of hypertension (HTN) and hyperlipidemia (HLD), stable on beta-blocker and statin, monitored every six months by alternating visits between her cardiologist and primary care physician (PCP) in North Carolina (NC). Six months before relocating to New York (NY) she had been informed about incidental severe hyponatremia during her last outpatient visit, the need for repletion with sodium chloride tablets, and the critical importance of prompt follow-up to rule out malignancy by starting with a chest X-ray. She opted not to follow instructions, continued cigarettes, and decided to spend the summer season with her son in NY. Six months after being told of her low sodium, she presented to our NY hospital with an acute, painful right foot blue toe syndrome. During the ischemic right foot evaluation, she was discovered to have adenocarcinoma of the right lung (stage 4) and a normal transthoracic echocardiogram (TTE). Heparin was initiated and thromboembolectomy with an endovascular bovine patch to revascularize the foot was successful, and post-procedure apixaban was started.

Hyponatremia was attributed to the syndrome of inappropriate antidiuretic hormone release (SIADH) secondary to non-small cell lung cancer (NSCLC). The serum sodium was stabilized, and the patient was discharged with a plan for outpatient follow-up with the cardiologist and oncologist within two weeks for hypertension, hyperlipidemia, hyponatremia, and management of stage 4 NSCLC. During her cardiology follow-up, 10 days after discharge, complaints of mild dyspnea on exertion (DOE) prompted an ECG (electrocardiogram) that revealed new T wave inversions in leads V3-6, and the patient was readmitted for non-ST elevation myocardial infarction (NSTEMI) evaluation. On day one of the readmission troponins were negative with normal ejection fraction (EF) on TTE and an acute 2 g/dl hemoglobin (Hb) drop with melena. This led to discontinuation of anticoagulation, initiation of intravenous (IV) pantoprazole, and endoscopy (EGD) which revealed gastritis. On the third day, she developed sudden expressive aphasia. Computed tomography (CT) of the head did not show any bleed but same-day magnetic resonance imaging (MRI) demonstrated multiple evolving acute infarcts. Transesophageal echocardiogram (TEE) demonstrated two large, mobile masses on the mitral valve consistent with vegetative endocarditis. Cultures for bacteria, fungi, and evaluation for organisms associated with culture-negative acute bacterial endocarditis/subacute bacterial endocarditis were unrevealing, thus confirming malignancy-associated non-infectious thrombotic endocarditis or non-bacterial thrombotic endocarditis (NBTE).

Gastrointestinal (GI) bleeding ceased, and the patient initially started on a heparin drip and transitioned to enoxaparin as lifelong anticoagulation for malignancy-associated NBTE. She recovered neurologically and was given pembrolizumab. At her recent 15-month visit she continued to have no residual neurological impairments, however, new positron emission tomography (PET) detected metastasis to the liver, lung, and adrenals which prompted evaluation for hospice care. We, therefore, emphasize the need for timely diagnosis of NBTE and prompt initiation of anticoagulation in suitable patients to prevent complications such as in our patient. Additionally, hyponatremia secondary to SIADH in NSCLC is a poor prognostic indicator of overall survival. 

Engineering a Next-Generation Glycoconjugate-Like Streptococcus pneumoniae Vaccine

We detail the development of a next-generation Streptococcus pneumoniae liposomal encapsulation of polysaccharides (LEPS) vaccine, with design characteristics geared toward best-in-class efficacy. The first generation LEPS vaccine, which contained 20 encapsulated pneumococcal capsular polysaccharides (CPSs) and two surface-displayed virulence-associated proteins (GlpO and PncO), enabling prophylactic potency against 70+ serotypes of Streptococcus pneumoniae (the causative agent of pneumococcal disease), was rationally redesigned for advanced clinical readiness and best-in-class coverage. In doing so, the virulent-specific GlpO protein antigen was removed from the final formulation due to off-target immunogenicity toward bacterial species within the human microbiome, while directed protection was maintained by increasing the dose of PncO from 17 to 68 μg. LEPS formulation parameters also readily facilitated an increase in CPS valency (to a total of 24) and systematic variation in protein-liposome attachment mechanisms in anticipation of clinical translation. An additional safety assessment study demonstrated that LEPS does not exhibit appreciable toxicological effects even when administered at ten times the effective dose. In summary, this new design offers the broadest, safest, and most-complete protection while maintaining desirable glycoconjugate-like features, positioning the LEPS vaccine platform for clinical success and a global health impact.

Clinical Characteristics and Laboratory Identification of Aerococcus Infections: An Australian Tertiary Centre Perspective

Aerococci uncommonly cause urinary tract (UTI) and bloodstream infections (BSI). The clinical characteristics and laboratory identification rates of Aerococcus in the Australian context are unknown. A retrospective observational cohort study of patients with positive Aerococcus cultures between 2010 and 2015 was performed. Patients were analysed according to predefined “asymptomatic bacteriuria,” “UTI,” and “BSI” groups. Forty-seven [40 (85%) for urine and 7 (15%) for blood] isolates were identified [38% male, median age of 79 (IQR 62–85) years], with corresponding identification rates of 24.2/100,000/year for urine (0.02%) and 7.3/100,000/year for blood cultures (0.007%). Since the use of matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF MS) identification rate in urine has increased from 14.7/100,000/year to 32/100,000/year (p = 0.02). For urine isolates, 14 (35%) met the definition for UTI whilst 26 (65%) were “asymptomatic bacteriuria.” Underlying urological abnormalities, catheterisation, and polymicrobial growth were common. Seventy percent of bacteriuria was treated regardless of colonisation or active infection status. Symptomatic patients were more likely to receive treatment (OR 7.2, 95% CI 1.4–35.3). In patients with BSI, 1 (14.2%) had endocarditis and 1 (14.2%) died. The majority of isolates were susceptible to penicillin (11/12 tested, 92%).

Aerococcus christensenii as Part of Severe Polymicrobial Chorioamnionitis in a Pregnant Woman

Chorioamnionitis is a potentially life threatening infection of the fetal membranes, commonly caused by ascending bacteria from the vagina and cervix. In our case, a healthy nullipara with a term pregnancy presented clinical signs of infection after induced labour with an intracervical balloon. Thick green and foul smelling amniotic fluid was observed and culture showed massive growth of Aerococcus christensenii, a facultative anaerob species found in the human vagina, previously only rarely alleged to cause invasive infection. Additional testing with 16S rRNA gene analysis also identified the presence of Gemella asaccharolytica, Snethia sanguinegens, Parvimonas micra and Streptobacillus moniliformis. The patient was treated with cefuroxime and metronidazole and recovered quickly. The newborn showed no signs of infection. This case points at the possible role of these pathogens in female genital tract infections. The case also underlines the importance of the combination of culture and culture independent diagnostic approaches to reveal possible polymicrobial natures of selected infections, in this case chorioamnionitis.