Infectious purpura fulminans associated with pneumococcal septicaemia in a patient with unacknowledged functional asplenia

Purpura fulminans (PF) is a life-threatening complication of septic shock that can occur due to disseminated infections with Streptococcus pneumoniae The spleen is an important organ in the immunisation process against encapsulated bacteria. Patients with asplenia, either functional or anatomical, are therefore at increased risk of developing serious infections and complications, such as PF, if infected with such bacteria.This case report presents a woman in her late 40s with unacknowledged functional asplenia who was admitted to the hospital with signs of an acute disseminated infection causing septic shock, signs of disseminated intravascular coagulation and infectious PF. A few days after admission, the blood cultures showed growth of S. pneumoniae With early sepsis treatment, the patient survived although with some complications. Clinical presentation, investigations, differential diagnosis, treatment and outcome are presented. Treatment and early recognition of PF are presented and discussed. Relevant recognition and preventative treatment strategies for patients with asplenia are also reviewed and discussed.This case demonstrates the importance of early recognition and treatment of PF in septic patients and the importance of preventive treatment strategies for patients with asplenia to avoid serious infections and complications.

Lemierre syndrome with pulmonary empyema caused by Prevotella intermedia

Lemierre syndrome is a rare disease that is most often caused by Fusobacterium necrophorum We present a case caused by Prevotella intermedia in a young, healthy man, complicated by multiple cavitary lung lesions, loculated pleural effusions requiring chest tube placement and trapezius abscess. Our case highlights (a) P. intermedia as a rare cause of Lemierre syndrome and (b) clinical response to appropriate antimicrobial therapy may be protracted.

Disseminated nocardiosis with persistent neurological disease

A man in his 80s with a history of sarcoidosis on chronic prednisone presented to the emergency department with several days of dyspnoea. A chest X-ray showed signs of pneumonia, and the patient was admitted. Blood and pleural fluid cultures grew Nocardia farcinica; therefore, the patient was started on treatment with trimethoprim-sulbactam and imipenem. Brain imaging showed evidence of dissemination of the infection to the central nervous system (CNS). The patient's admission was complicated by pleural effusions, acute kidney injury and pancytopenia, and therefore, his antibiotic regimen was ultimately transitioned from trimethoprim-sulfamethoxazole (TMP-SMX), meropenem and linezolid to imipenem and tedizolid. The patient received imipenem and tedizolid for the remainder of the admission. A repeat MRI of the brain was performed after 6 weeks of this dual antibiotic therapy, which unfortunately revealed persistent CNS disease. His regimen was then broadened to TMP-SMX, linezolid and imipenem. Despite these measures, however, the patient ultimately passed away from the infection.

Achromobacter pneumonia in a patient with advanced COPD, a diagnostic challenge

Bacterial pneumonia causes significant morbidity and mortality especially in elderly and immunocompromised hosts. Achromobacter xylosoxidans denitrificans pneumonia is very rarely reported. However, the reported cases have been in patients who are either immunocompromised or have bronchiectasis. We hereby present a unique case of Achromobacter xylosoxidans denitrificans pneumonia in an immunocompetent patient with advanced chronic obstructive pulmonary disease (COPD). Our patient is a Caucasian male admitted with shortness of breath, fever and cough. Chest X-ray demonstrated right-sided infiltrates and he was treated with intravenous ceftriaxone and azithromycin. He was discharged home on oral amoxicillin-clavulanate 875-125 mg two times per day for a total of 7 days. Patient returned to emergency room after 5 weeks with persistent symptoms and chest X-ray revealed persistent right-sided infiltrate and sputum culture showed Achromobacter xylosoxidans denitrificans. The patient was started on oral levofloxacin 750 mg one time per day for 2 weeks with resolution of symptoms.

Invasive group A streptococcal disease

We report on two children who had presented in a poor clinical state after an initial bout of cough, sore throat and fever for a few days. Both of them had multisystemic involvement with fluid-refractory septic shock requiring ionotropic support, intubation and care in the paediatric intensive care unit. Recent significant rise in scarlet fever has led to a significant increase in the number of invasive group A streptococcal infections with increased mortality in paediatric patients. Both of them had co-infection with influenza, which could have led to an increased risk of invasive group A streptococcal (iGAS) infection. After prompt treatment, including early initiation of antibiotics, they both recovered well. To our knowledge, there are no reported cases of iGAS infection from the UK in any medical journal though the fatal cases have been reported to the health statistics department by various National Health Service trusts individually.

Rapidly progressive empyema in the setting of vaping in an otherwise healthy patient

Vaping is defined as inhaling and exhaling vapour that is a product of heating a liquid or wax-like material. Electronic cigarettes (e-cigarettes) have become a popular method of smoking in the last decade and are advertised as an alternative to conventional smoking. Since the increase in e-cigarette use, various lung injury patterns have started to appear among users. Recent studies have shown an increased susceptibility to respiratory tract infections among e-cigarette/vaping product users. We present a case of pneumonia caused by Pseudomonas fluorescens complicated by rapidly developing empyema in an otherwise healthy patient.

Pulmonary nocardiosis following nodular bronchiectatic Mycobacterium avium complex pulmonary disease in an immunocompetent patient

A woman in her 70s with a history of nodular bronchiectatic Mycobacterium avium complex pulmonary disease (MAC-PD) presented with an exacerbated productive cough and worsening findings on chest imaging. Although repeated sputum culture tests were negative for acid-fast bacilli and only revealed normal respiratory flora, a bronchoscopy identified Nocardia sp. Consequently, she was diagnosed with pulmonary nocardiosis and was successfully treated with levofloxacin. It is known that pulmonary nocardiosis can manifest in immunocompetent individuals with bronchiectasis. For cases of refractory nodular bronchiectatic MAC-PD, it is vital to consider bronchoscopy to identify potential co-infections, such as Nocardia.

Pyopericardium presenting as pericardial tamponade in a patient with common variable immunodeficiency disorder

A male patient in his 20s with a medical history of common variable immunodeficiency disorder, non-compliant with therapy, presented to the emergency department with respiratory distress and severe hypoxaemia. Chest radiography demonstrated extensive bilateral infiltrates and an increased cardiothoracic ratio. Streptococcus pneumoniae urine antigen test was positive. ECG demonstrated diffuse ST-segment elevation. An arterial line was placed and demonstrated pulsus paradoxus. Transthoracic echocardiography revealed an extensive pericardial effusion, with echocardiographic signs of cardiac tamponade. Emergency subxiphoid pericardiocentesis was performed with an initial drainage of 750 mL of purulent fluid consistent with pyopericardium. Immediate haemodynamic improvement was observed. The patient required a second pericardiocentesis for drainage of a relapsing pericardial effusion. The course was complicated by effusive-constrictive pericarditis requiring anterior interphrenic pericardiectomy. Treatment with intravenous immunoglobulin and antibiotics led to a complete recovery.

Delftia acidovorans sepsis in a neonate with nosocomial pneumonia

A term neonate weighing 2900 g was referred in the first week of life with complaints of abdominal distension since birth. New onset respiratory distress was noted 36 hours prior to referral. Baby required non-invasive respiratory support and intravenous antibiotics as chest X-ray was suggestive of pneumonia. Ultrasound abdomen confirmed low ano-rectal malformation treated with cut-back anoplasty. Blood culture on admission grew a rare organism Delftia acidovorans The antibiotics were tailored as per the sensitivity pattern and continued for a duration of 14 days. Respiratory distress gradually resolved by day 10 of admission. The baby developed pneumonia after 36 hours of stay in the referring hospital; most probably indicating a hospital acquired source of this pathogen. To the best of our knowledge, this is the second reported neonatal case of D. acidovorans sepsis.

Simultaneous diagnosis of allergic bronchopulmonary aspergillosis and Mycobacterium avium complex lung disease

Allergic bronchopulmonary aspergillosis (ABPA) and Mycobacterium avium complex lung disease (MAC-LD) often coexist because bronchiectasis, caused by ABPA or MAC, might be an important predisposing factor for both conditions. Here, we describe a man with asthma symptoms who had centrilobular small nodules and mucoid impaction on chest CT. We diagnosed the patient with simultaneous ABPA and MAC-LD on the basis of bronchoscopy findings. Itraconazole monotherapy led to substantial clinical improvement, avoiding the adverse effects of systemic corticosteroids. Sputum culture conversion of MAC was achieved after switching from itraconazole monotherapy to combination therapy comprising clarithromycin, rifampicin and ethambutol. ABPA recurred but was controlled by reinitiation of itraconazole. Overall, corticosteroid management was avoided for 38 months. Itraconazole monotherapy may be selected as initial treatment for ABPA with chronic infection, including MAC.

Congenital myopathy presenting as recurrent pneumonia with lung collapse and pulmonary artery hypertension

A boy presented with cough, breathlessness for 1 month, fever for 1 week with similar previous episodes without hospitalisation. He had generalised muscle wasting, acute chronic malnutrition and required immediate ventilation. Provisional diagnosis of recurrent pneumonia with failure to thrive was made. As serial chest X-rays showed recurrent lung collapse, congenital lung anomalies were ruled out. 2D-echocardiography showed pulmonary arterial hypertension. Workup for congenital immunodeficiency and cystic fibrosis was negative. There was no improvement in muscle mass despite total parenteral nutrition. He was noticed to have myopathic facies. History was reviewed when the mother reported reduced fetal movements in this pregnancy. The patient had low voice amplitude. Creatine kinase levels were normal. Muscle biopsy followed by whole exome sequencing identified frameshift duplication NM_020451.3(SELENON):c.249_250dupGG (p.Asp84Glyfs*17), thus, confirming diagnosis of SEPN1-related congenital myopathy (CM) with fibre-type disproportion. Respiratory system involvement was distracter, emphasising consideration of CM while evaluating persistent lung collapse with muscle wasting.

Unravelling the mystery of a rare infection: a challenging case of pulmonary sequestration with Mycobacterium avium complex and the importance of a thorough microbiological investigation

Pulmonary sequestration is a rare congenital condition. It is a dysplastic lung tissue with a separate systemic blood supply and without a bronchial tree connection. The emergence of a superimposed infection can lead to its diagnosis, such as Staphylococcus aureus, Pseudomonas aeruginosa, Nocardia asteroids and Aspergillus sp pneumonia. Mycobacterium avium complex (MAC) superimposed disease is exceedingly rare. We report a case of a man in his third decade without known medical disorders presenting with a persistent cough. After an extensive microbiological workup, an MAC infection was diagnosed. An elevated carbohydrate antigen 19-9 (CA 19-9) was also noted. He was treated with antimycobacterial therapy and lobectomy resulting in clinical improvement and CA19-9 normalisation. This case illustrates the value of comprehensive microbiological investigations in patients with chronic respiratory symptoms and imaging findings that are not typical of bacterial pneumonia. Clinical studies remain needed to investigate the utility of CA 19-9 in a scoring system to guide MAC therapy.

Isolated pulmonary hydatid cyst

Echinococcosis is primarily a disease of developing nations with poor medical infrastructure, where cohabitation with domesticated animals is common. These conditions, in conjunction with the inherent chronicity of the disease, lead to low rates of diagnosis and high morbidity. Robust surveillance is not readily available in communities with the highest disease burden.WHO classifications assist in diagnostic and treatment endeavours especially in countries where this disease is not commonly encountered. However, the understanding of the pathophysiology of echinococcosis and optimal treatment are still lacking in certain patient populations.We present the case of a female from Central Asia with an isolated pulmonary hydatid cyst. She was diagnosed several months after she had an uncomplicated pregnancy and gave birth to a healthy baby girl. Due to a delay in surgical intervention, our patient received a prolonged course of treatment which resulted in a significant reduction in the size of the cyst. Given her improvement, we questioned the current guidelines set by the WHO regarding surgical resection of pulmonary hydatid cysts, compared with an extended course with albendazole in patients with an unusual and protracted course of the disease. Furthermore, we discuss the possible role of pregnancy in exacerbating symptoms of underlying pulmonary hydatid disease.

Mycoplasma hominis necrotising pneumonia in an immunocompetent adult male

Mycoplasma hominis, a common coloniser of the urogenital tract, is a rare cause of respiratory infections in an immunocompetent patient. M. hominis lacks a cell wall and can be difficult to identify with standard culture methods posing difficulties in diagnosis and treatment. We describe a case of M. hominis pneumonia in an immunocompetent man in his early 40s without any risk factors presenting with a cavitary lesion who developed empyema and necrotising pneumonia requiring surgical debridement. Identification of M. hominis and subsequent modification of antibiotic therapy led to favourable outcome. M. hominis should be considered in the differential diagnosis of patients with treatment resistant pneumonia especially in patients with trauma, intracranial injury, lung transplant or if immunocompromised. While M. Hominis is naturally resistant to all antibiotics that target cell wall synthesis, we recommend levofloxacin or other fluoroquinolone to most effectively treat with doxycycline as a potential alternative.

Rare and unexpected cause for retropharyngeal abscess in an immunocompetent man: metastatic community-acquired methicillin-resistant Staphylococcus aureus infection

Staphylococcus aureus causes clinical diseases ranging from mild skin infections to devastating conditions such as septic shock, endocarditis and osteomyelitis. S. aureus is a common cause of community-acquired bacteraemia. Prolonged bacteraemia may cause metastatic infection, manifesting as endocarditis, osteomyelitis and abscesses. A man in his 20s presented with a short-duration of fever and odynophagia. CT of the neck suggested a retropharyngeal abscess. Retropharyngeal abscesses are typically polymicrobial and caused by resident oral cavity flora. In the hospital, he developed shortness of breath and hypoxia. CT of the chest showed peripheral, subpleural nodular opacities raising suspicion for septic pulmonary emboli. Blood cultures demonstrated the growth of methicillin-resistant S. aureus The patient completely recovered with antibiotic therapy alone. This is a unique and rare presentation case of metastatic S. aureus bacteraemia, manifesting as a retropharyngeal abscess without any evidence of infective endocarditis on transoesophageal echocardiography.

Diffuse cryptococcal pneumonia in multicentric Castleman's disease with elevated serum IgG4

A woman in her 60s with suspected multicentric Castleman's disease, who was receiving treatment with oral prednisolone, presented to our hospital with mild cough and malaise. Chest CT showed diffuse infiltrative and granular shadows, indicating exacerbation of lung lesions caused by steroid-resistant multicentric Castleman's disease. A video-assisted thoracoscopic lung and mediastinal lymph node biopsy was performed. The biopsy revealed mediastinal lymph node tissue consistent with multicentric Castleman's disease, as well as presence of Cryptococcus neoformans in the alveolar space. C. neoformans infection in immunocompromised individuals may present with diffuse lung lesions and should be noted as a mimicker of acute exacerbation of Castleman's disease.

Type 2 hyper-IgM syndrome with a rare variant of AICDA gene mutation in a young woman

We report the case of a woman in her early 20s with a history of recurrent infection, atopic dermatitis, filariasis and bilateral purulent ear discharge since childhood with tonsillar enlargement on examination. She was started on supportive care and evaluated for primary immunodeficiency disease. Blood investigations revealed increased IgM levels with reduced IgG, IgA and IgE levels. Radiological imaging of the chest revealed bilateral bronchiectasis. Otoscopic examination showed features suggestive of chronic suppurative otitis media. Next-generation sequencing identified homozygous single base pair deletion in exon 2 of the activation-induced cytidine deaminase gene. Thus, a diagnosis of hyper-IgM syndrome type 2 was confirmed. The patient was started on monthly intravenous immunoglobulin replacement therapy and is currently symptomatically better, and she remains under regular follow-up.

Pneumocystis jirovecii pneumonia in a patient treated with trastuzumab-deruxtecan

Trastuzumab-deruxtecan (T-DXd) is a novel antibody drug conjugate that has improved treatment outcomes in patients with ERBB2-positive cancer, including locally advanced or metastatic gastric and gastro-oesophageal junction adenocarcinoma. One of the reported side effects of this medication is drug-induced pneumonitis. We present in this case report, a diagnostic dilemma of a patient presenting with clinical and radiographical features of drug-induced pneumonitis but was found to have pneumocystis jirovecii pneumonia (PJP). Our case is the first of PJP in a patient treated with T-DXd, highlighting the increasing incidence of this opportunistic infection in patients with solid malignancy. It also highlights the clinical and radiographical similarities between the PJP and drug-induced pneumonitis.

Case of clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) due to Legionella pneumonia

Clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) is a clinicoradiologic syndrome diagnosed by temporary hyperintense lesion in the area, including the splenium of the corpus callosum, on diffusion-weighted imaging and neuropsychiatric symptoms that recover without sequelae. MERS is rare in adults, especially elderly people. We herein report a man in his 60s diagnosed with MERS caused by Legionella pneumonia. He completely recovered with only the administration of levofloxacin and azithromycin despite the risk factors of an advanced age, medical history of untreated hypertension, bilateral spontaneous pneumothoraxes, smoking and drinking habits and pulmonary emphysema. To our knowledge, this is the oldest case of MERS due to Legionella pneumonia and extremely old among total MERS cases. Our research revealed that Legionella species are the most common pathogens of adult-onset MERS, while viruses are the main causative factors in children. This case helps clarify the features of MERS in high-risk adults.

Recurrent pneumonia post atrial fibrillation ablation: do not forget to look for pulmonary vein stenosis

A man in his 50s presented with persistent chest pain, haemoptysis, cough and dyspnoea 5 months after undergoing catheter ablation for atrial fibrillation (AF). Several chest CT scans suggested pneumonia. Despite adequate treatment for recurrent pneumonia, symptoms persisted. While reviewing the initial chest CT, a partial venous infarction of the left lower lobe associated with severe left inferior pulmonary vein stenosis (PVS) was diagnosed. Stenting of the left inferior pulmonary vein with a vascular bare metal stent was performed, guided by fluoroscopy and transoesophageal echocardiography. Dual antiplatelet therapy (aspirin/clopidogrel) was introduced for 3 months, followed by long-term aspirin monotherapy. The treatment resulted in relief of his symptoms and the resolution of pulmonary opacities on chest CT. Despite low frequency, AF ablation remains the most common cause of acquired PVS. As highlighted in this case, symptoms are not specific and include recurrent pulmonary infection with delayed management.

Asymptomatic pulmonary cryptococcosis presenting with mixed lesions of infiltrative and nodular shadow in an immunocompromised patient

Pulmonary cryptococcosis (PC) is a rare fungal lung infection that usually occurs in immunocompromised hosts. We report a rare case of PC with asymptomatic and mixed lesions of infiltrative and nodular shadows. A woman in her 50s with a 7-year history of methotrexate treatment for rheumatoid arthritis (RA) presented with abnormal chest shadows on annual examination. Chest CT revealed two tiny nodules and two infiltrative shadows in the right lower lobe of the lung. We suspected lung cancer, cryptogenic organising pneumonia or RA-interstitial lung disease. However, transbronchial lung biopsy and positivity for serum cryptococcal antigen confirmed the diagnosis of PC. We initiated treatment with fluconazole, which drastically reduced the chest shadows without any adverse events. Since PC can present with several pulmonary shadows, it should be considered as a differential diagnosis of any pulmonary lesion.

Coexistence of pan-hypogammaglobulinaemia and primary ciliary dyskinesia

A patient, an adolescent male, presented to us with complaints of recurrent respiratory tract infections since childhood. Differentials considered were cystic fibrosis (CF), bronchial asthma with allergic bronchopulmonary aspergillosis (ABPA), primary ciliary dyskinesia (PCD) and primary immunodeficiency disorders. Sweat chloride test, total IgE and Aspergillus fumigatus specific serum IgE and IgG levels were normal ruling out CF and ABPA. Nasal nitric oxide (NO) screening test showed reduced NO levels, and high-speed video microscopy of nasal scrapings showed stiff beating cilia with reduced ciliary beat frequency confirming the diagnosis of PCD. Immunodeficiency workup showed reduced serum IgG, IgA and IgM, when repeated on two separate occasions when the patient was not harbouring any active infection, suggestive of pan-hypogammaglobulinaemia. Thus, a diagnosis of coexistent PCD and pan-hypogammaglobulinaemia was made. Detection of immunodeficiency disorders is important in patients with PCD as they may benefit from immunoglobulin replacement.

Hypermucoviscous Klebsiella pneumoniae invasive syndrome in a patient with diabetes without liver abscess

Klebsiella pneumoniae is part of the human gastrointestinal microbiota. It is also a well-known cause of community and nosocomial infections, involving mainly the lung and urinary tract. An invasive syndrome with liver abscess due to a new hypervirulent strain of K. pneumoniae was recently described. Several cases have been reported, mainly in Asia. Here, we show a case of a patient with an extrahepatic involvement affecting the lung and prostate.

Mycoplasma pneumoniae-associated diffuse alveolar haemorrhage: an atypical presentation of a prevalent pathogen

A transgender man in his late teens presented with signs of multisystem disease, including hepatitis, mucositis and bone marrow suppression. He later developed dyspnoea, leucocytosis and bilateral pulmonary infiltrates on chest radiograph. He was treated for community-acquired pneumonia. After several days of treatment, he developed hypoxaemic respiratory failure due to bronchoscopy-confirmed diffuse alveolar haemorrhage (DAH). The differential diagnosis and workup were extensive, and he was ultimately treated with intravenous steroids and five sessions of plasmapheresis for a presumed autoimmune aetiology. Investigations were remarkable only for elevated IgM and IgG to Mycoplasma pneumoniae (MP). This case represents a rare presentation of multisystem disease secondary to MP in adults. Clinicians should consider Mycoplasma infection in cases of multisystem disease and observe for DAH even after initiation of appropriate therapy.

Acute fibrinous and organising pneumonia

Acute fibrinous and organising pneumonia (AFOP) is a rare histological pattern of interstitial lung disease. The authors describe a 60-year-old woman admitted to the hospital for sustained fever, presenting with an alveolar opacity on chest X-ray, with the presumed diagnosis of community-acquired pneumonia and the onset of antibiotics. Since serological results suggested that Legionella pneumophila was the infectious agent, she was discharged on levofloxacin. A week later, she was again admitted with fever. CT scan showed opacities with crescentic morphology and a central ground-glass area suggestive of cryptogenic organising pneumonia. Microbiological, serological and autoimmunity tests were negative. She underwent surgical lung biopsy that revealed inflammatory infiltrate, macrophage desquamation, fibroblasts proliferation and fibrin deposition in the alveolar spaces, consistent with AFOP. She started corticotherapy with good response. Disease relapsed after prednisolone discontinuation, 10 months later. Currently, the patient is on prednisolone 5 mg/day without clinical and radiological recurrence.

Rapid developing empyema by group F beta Streptococcus anginosus group

A 43-year-old male had progressive pleuritic left-sided chest tightness with shortness of breath. He had dental caries and tenderness on palpation of the left lateral chest. Complete blood count showed leucocytosis. CT scan of the chest with pulmonary emboli protocol showed multiple pulmonary nodules and nodular pleural thickening at left posterior lateral pleura. Forty-eight hours post CTPE scan, CT scan of the chest, abdomen and pelvis displayed right lower lobe consolidation and left-sided pleural effusion with superimposed compressive atelectasis. Ceftaroline intravenous was initiated, with CT-guided pigtail chest tube insertion. Pleural fluid later grew group F beta-haemolytic Streptococcus anginosus Patient improved significantly and was discharged 11 days later with intravenous ertapenem. Patients with group F beta-haemolytic streptococci should be managed aggressively with early and accurate diagnosis, antibiotics, drainage and possible surgery.

Novel variant of common variable immunodeficiency

A 57-year-old woman with frequent respiratory infections was initially diagnosed with IgG subclass deficiency based on low levels of IgG subclasses 2 and 3. Three years later, she progressed to having IgA deficiency as well. With a normal total IgG level, she does not meet criteria for common variable immunodeficiency (CVID). This may represent a variant of CVID. This also highlights the importance of immunoglobulin subclass estimation in patients where immunodeficiency is suspected clinically. She is being treated with rotational antibiotics the first 10 days of every month, monthly intravenous immunoglobulin (IVIG) infusion and osteopathic manipulation one to two times per month. On this regimen, although she has had several viral respiratory infections, she has avoided further hospitalisation for more than 1 year.

Aggregatibacter actinomycetemcomitans pneumonia with chest and abdominal wall involvement

A 54-year-old man presented with a productive cough, chest pain, fever and weight loss. Initial analysis revealed a palpable chest wall mass and consolidation in the left lower lobe and pleural abnormalities on imaging. At that point no infectious cause or malignancy was identified. Microbiological analysis of a needle biopsy from a newly developed abdominal wall mass revealed growth of Aggregatibacter actinomycetemcomitans The patient was successfully treated with antibiotic therapy for 1 year. Aggregatibacter actinomycetemcomitans is a Gram-negative coccobacillus and is part of the normal oral flora. It is capable of causing infections in humans including periodontitis, soft tissue abscesses and systemic invasive infections, most commonly endocarditis.