gemella morbillorum is a gram - positive , catalase - negative , facultatively anaerobic coccus that often behaves as commensal bacteria of the mucous membranes of oropharynx , gastrointestinal tract , and female genital tract .
however , in some rare cases , this bacterium has been implicated in serious invasive infections , especially endocarditis 1 .
possible predisposing factors for gemella morbillorum endocarditis include situations in which there is a lack of the gastrointestinal mucosal barrier integrity , as surgical manipulation of the oral cavity and gastrointestinal tract neoplasia 2,3 .
severe cases of gemella endocarditis have been reported , both cases requiring cardiac valve replacement and cases with fatal outcome 4 ; this fact underscores the potential virulence of this pathogen in the setting of infective endocarditis .
we present here a case of cardiogenic shock as a complication of acute mitral valve regurgitation following gemella morbillorum native valve endocarditis in a 72-year - old male .
a 72-year - old caucasian male with a history of hypertension , type-2 diabetes mellitus , peripheral arterial disease of the lower limbs , and previous coronary artery bypass graft surgery was admitted to a tertiary referral hospital in southern brazil with dry cough , fever , anorexia , loss of more than 10% of body weight , and dyspnea in the last 30  days . upon arrival to the emergency department ,
the patient was hypotensive ( blood pressure 78/53  mmhg ) , tachycardic ( heart rate 122  bpm ) , feverish ( axillary temperature 38.4c ) , with jugular turgor at 45 , with bibasilar pulmonary rales and with new systolic mitral regurgitation murmur ( murmur grade 4 ) .
the patient rapidly developed cardiorespiratory collapse requiring mechanical ventilation and continuous infusion of vasopressors ; he also presented oliguria ( urine output < 0.5  ml / kg / h ) and signs of poor peripheral perfusion ( cold extremities , cyanosis , and capillary refill time > 2  sec ) .
the initial chest x - ray showed signs of pulmonary congestion and cardiomegaly ( fig.1 ) .
the complete blood count demonstrated leukocytosis ( 12 920 white blood cells / mm ) and normocytic anemia ( hemoglobin level of 11.3  g / dl ) .
the erythrocyte sedimentation rate and the c - reactive protein plasma levels were elevated ( 91  mm / h and 6.8  mg / dl , respectively ) .
the transesophagic echocardiography at the bedside showed mitral valve thickening suggestive of infectious etiology and large flail of the anterior leaflet ; the mitral regurgitant jet intensity and area were consistent with severe insufficiency ( fig.2 ) .
the bedside lung ultrasound showed bilateral multiple b - lines in a diffuse pattern , which is also compatible with pulmonary edema .
a definitive diagnosis of mitral native valve endocarditis with cardiogenic shock due to severe acute mitral valve regurgitation was made .
the initial empirical antimicrobial therapy administered was ceftriaxone plus gentamicin ( initiated within 50  min after hospital arrival ) .
the hemodynamic instability was treated with norepinephrine ( doses up to 1.0  g / kg / min ) and intra - aortic balloon pump counterpulsation implant .
the patient was taken to emergency mitral valve replacement surgery ; his preoperative mortality risk according euroscore ii was 55.2% .
immediately after valve replacement surgery ( bioprosthetic mitral valve ) , there was progressive improvement in cardiogenic shock with gradual reduction of the vasopressor dose .
gemella morbillorum was isolated in two independent samples of blood cultures collected from distinct peripheral veins .
although there is no clinical and laboratory standards institute ( clsi ) standard method and interpretation of susceptibility testing for gemella , susceptibility testing was performed using the clsi method for viridans group streptococci on mueller - hinton agar supplemented with 5% sheep 's blood and incubated at 35c with 5% co2 for 24  h 5 ; the isolated bacteria was sensitive to penicillin , ceftriaxone , and vancomycin .
after results of antimicrobial susceptibility tests , the antibiotic regimen was de - escalonated to penicillin g plus gentamicin . during hospitalization ,
the patient became dependent on mechanical ventilation due to critical illness polyneuropathy and refractory pulmonary congestion ( including need for tracheostomy and continuous ultrafiltration in order to negative fluid balance ) .
in the twenty - seventh day of hospitalization , after a brief period of clinical improvement , the patient had a new episode of shock associated with pulmonary edema ; there was lung compliance worsening and need for mechanical ventilation with high pressures and high fraction of inspired oxygen .
the patient was taken to emergency surgery for valve replacement again ; however , he ended up dying during the procedure .
initial transesophageal echocardiography showing a mass adhered to the ventricular side of the mitral valve .
the present case report describes an unusual etiology of infective endocarditis with unfavorable clinical course despite appropriate treatment , gemella morbillorum .
although noninvasive infections were reported , the few described cases were generally associated with serious infections , such as endocarditis , bloodstream infections , and central nervous system infections 68 .
previously , gemella morbillorum was considered to be a viridans streptococcus due to its microbiological similarities with the genus streptococcus ; only in 1988 , based on its biomolecular and physiological characteristics , this bacterium was reclassified as part of a distinct genus , gemella 
 9 . however
, both the clinical course and the antimicrobial susceptibility patterns of infections associated with this organism seems to be similar to those seen with viridans streptococci 10 .
the ability of this bacterium to cause destruction of the cardiac valve tissue , contributes to rapid deterioration of patients with endocarditis culminating in cardiogenic shock  a very serious condition associated with high mortality rates in the context of infective endocarditis 11 .
septic shock is another reported complication of gemella morbillorum invasive infections associated with high mortality rates 12 .
the high virulence profile of gemella morbillorum is not well studied , but is hypothesized that this microorganism may share the same pathogenic mechanisms found in viridans streptococci bacteria , which are often associated with severe infections in both immunocompetent and immunocompromised patients 13,14 . in summary , our case report contributes to the limited literature regarding the characteristics of infections by gemella morbillorum and provides further evidence about the high virulence of this pathogen .
written informed consent was obtained from the patient for publication of this case report and any accompanying images .
a copy of the written consent is available for review from the editor - in - chief of this journal .
 key clinical messagegemella morbillorum is a rare cause of infective endocarditis . 
 consequently , little is known about the natural course of endocarditis secondary to this pathogen . 
 herein , we report a case of cardiogenic shock as a complication of acute mitral valve regurgitation following gemella morbillorum native valve endocarditis . 
Background
Case Report
Discussion
Consent
Conflict of Interest