a.defectiva was originally known as a member of the nutritionally variant streptococci ( nvs ) .
the nvs were first described by frenkle and hirsch as new types of viridans streptococci based on certain phenotypic characteristics .
two genera have been proposed based on 16s rrna which are : abiotrophia and granulicatella .
a.defectiva is part of the normal flora of the oral cavity , the urogenital and the intestinal tracts .
this bacterium has been associated with various serious infections including bacteremia , endocarditis , brain abscess , septic arthritis and total knee arthroplasty infections [ 69 ] . in this report
, we describe a patient with ie caused by a. defectiva in an attempt to increase awareness about this organism and to highlight the difficulties encountered in the diagnosis and in the treatment .
a 35 years old saudi male was diagnosed to have rheumatic heart disease in the year 1991 .
in late february 2005 , he was admitted to prince sultan cardiac center through the emergency department as he presented with intermittent fever for six months , left ankle joint pain and swelling for 5 days , significant weight loss and fatigue .
the patient had been non - compliant with the monthly penicillin prophylaxis for the last seven years and he repeatedly refused av replacement . physical examination on
admission revealed : a pulse rate of 105/minute , temperature of 36.9oc and blood pressure of 133/48 mmhg .
he had finger clubbing , left ankle swelling , splenomegaly , displacement of apex beat and a high pitched early diastolic murmur heard maximally over the third and fourth left intercostals spaces .
laboratory investigations were as follows : wbc 8 x 109/l , haemoglobin : 8.1 g / dl , platelets : 305x109/l , esr : 73 and crp : 101mg / l . tee revealed highly mobile vegetation ( 2.9 x 0.6 mm ) attached to the ventricular surface of the non - coronary cusp of the rheumatic av with no aortic root abscess .
the left ventricle ( lv ) was severely dilated with abnormal systolic function and the lv ejection fraction was 40% .
blood cultures were processed in the bactec 9240 blood culture system ( beckton dickinson ) .
the organism grew well on chocolate agar but poorly on 5% blood agar after 48 hour incubation .
satellitism was found after a single cross - streak of staphylococcus aureus was placed on the blood agar plate .
the bacterium was identified as a. defectiva with > 95% confidence by api 20 strep system after 24 hour incubation .
antimicrobial susceptibility was determined by the e - test for penicillin and the disc diffusion method on mueller- hinton agar with 5% sheep blood for the other antibiotics .
results were interpreted according to the clinical laboratory standard institute ( clsi ) criteria for a - hemolytic streptococci other than streptococcus pneumoniae .
the organism was found to be susceptible to penicillin , cefuroxime , ceftriaxone , erythromycin , imipenem , vancomycin , chloramphenicol and rifampicin but resistant to gentamicin .
high level resistance to gentamicin was not seen in this isolate ( gentamicin mic was < 500 g / ml ) .
vancomycin mic was < 1 g / ml . the patient was initially treated with vancomycin and gentamicin until the blood culture isolate was identified after which vancomycin was replaced by intravenous penicillin g 24 million units per day and gentamicin was continued intravenously at a dose of 1 mg / kg every eight hour .
few days later , surgery was performed as the clinical condition of the patient deteriorated and as the repeated echocardiogram showed persistently large vegetations and progressive av desrtuction . at surgery a large vegetation was seen on the ventricular side of the av leaflet , the av annulus was enlarged and the aortic non - coronary cusp was found to be perforated .
the damaged av was excised and a carbomedics size 2.7 mm mechanical valve was implanted .
the histologic examination demonstrated large vegetations with dense fibrin and platelet aggregates in addition to few leucocytes and bacterial colonies i.e. the infiltrate was suggestive of ie .
cultures of the av and follow up blood cultures were all negative . the antibiotics were continued for one month and the patient was discharged home in march 2005 .
however , some studies have estimated that this organism is responsible for 5 - 6% of all cases of ie [ 1 , 11 ] .
endocarditis caused by a.defectiva carries greater morbidity and mortality than endocarditis caused by other streptococci .
it is characterized by the occurrence of certain complications such as congestive heart failure , embolization and an increased rate of surgical interventions [ 13 , 16 ] .
these infections usually respond poorly to antibiotics and several studies have reported bacteriologic failure rates of up to 40% with relapse rates of up to 17% despite the treatment with antibiotics that were effective in vitro .
multiple factors contribute to the increased virulence of abiotrophia species such as the production of an exopolysaccharide , the long generation time which can have an impact on the in vivo tolerance ; and the persistence as a result of the development of cell - wall deficient bacteria promoted by the treatment with -lactam antibiotics [ 2 , 17 , 18 ] .
it grows more slowly than other streptococci , thus cultivation and identification are often difficult [ 1 , 2 ] .
molecular techniques were used to improve the detection and facilitate the identification of a.defectiva . the use of 16s rrna genepolymerase chain reaction amplification followed by restriction fragment length polymorphism ( pcr - rflp )
was shown to be a rapid and a more accurate method for the identification of a.defectiva .
abiotrophia is less susceptible in- vitro to penicillin than other streptococci and several studies have shown that the prevalence of beta - lactam and macrolide resistance is high .
also , resistance to the extended  spectrum cephalosporins and the new fluoroquinolones have been reported [ 20 , 21 ] .
however , high level of resistance to the aminoglycosides , as encountered with enterococci , has not been reported with a.defectiva .
the in - vitro antimicrobial susceptibility testing of abiotrophia has not been standardized yet and the results of in - vitro susceptibility testing do not correlate well with the clinical outcome in patients treated for endocarditis .
therefore it is recommended that patients with endocarditis should be treated with a long - term combination therapy e.g. penicillin and gentamicin for 4 - 6 weeks . even with this regimen , the rates of bacteriologic failure and relapse are still high therefore careful follow up of these cases is mandatory [ 14 , 16 ] .
the portal of entry in most reported cases of endocarditis is via the oral cavity .
the dental extraction in our patient served as a risk factor for the development of ie in the previously damaged av leading to progressive valvular destruction and perforation .
the lack of prophylactic antibiotic prior to the procedure had contributed significantly to the disease process .
endocarditis caused by a.defectiva has been reported to result in heart failure by destroying heart valves . in our patient ,
replacement of the av was carried out due to the extensive valvular damage and the large vegetation size with the potential of embolization .
he was treated with a combination regimen of penicillin and gentamicin for 4 weeks . a multi - disciplinary approach from cardiology , cardiac surgery , intensive care , microbiology and infectious diseases departments contributed to the favorable outcome .
 a 35-year  old man with pre - existing rheumatic heart disease and aortic regurgitation ( ar ) presented with intermittent fever , ankle swelling and clinical evidence of endocarditis . 
 transoesophageal echocardiogram ( tee ) revealed vegetations and destruction of the aortic valve ( av ) . 
 blood cultures grew a gram positive coccobacillus which was phenotypically identified as abiotrophia defectvia ( a.defectiva ) . 
 a diagnosis of infective endocarditis ( ie ) due to a.defectiva was made . 
 treatment , with penicillin and gentamicin , was administered for 4 weeks . 
 mechanical valve replacement was required few days after starting the antibiotic therapy . 
 the patient had a favorable outcome on follow up . 
 although a.defectiva is an uncommon cause of endocarditis , early and correct identification of this pathogen is important to improve the outcome and the prognosis of patients with ie due to this organism . 
Introduction
Case Report
Discussion
Conclusion