the gram - negative coccobacillus pasteurella multocida is normally found in the oral cavity of dogs and cats . it is a recognised cause of wound infection as a result of bites , licking or scratching . bacteraemia and endocarditis are uncommon complications and , from literature reviews , are found to be associated with prior animal trauma , a second source of infection ( e.g. cellulitis ) and high mortality rates . we herein report a case in which a pet owner developed p. multocida endocarditis and was subsequently treated via opat ( outpatient parenteral antimicrobial therapy ) service with an excellent clinical outcome . species identification of p. multocida was performed using traditional microbiological methods and confirmed with 16s rrna sequencing and matrix - assisted laser desorption / ionization time - of - flight mass spectrometry ( maldi - tof ) . a 38-year - old man was admitted to our hospital with a 2 days history of fever , malaise and cellulitis around a mitrofanoff abdominal catheter . multiple comorbidities included marfan syndrome ( with metallic aortic valve inserted sixteen years before ) and congenital urological abnormalities that led to the mitrofanoff appendicovesicostomy and a recent renal transplant , five years and six months before admission respectively . he was on steroids and tacrolimus as immunosuppressive therapy . on presentation , the patient was febrile , hypotensive and tachycardic , had a normal leukocyte count ( 5.0910/l ) but raised creactive protein ( crp ) 45 mg / l with mild anaemia ( hb of 10.1 g / dl from a baseline of 14.6 g / dl ) and renal impairment ( creatinine 163 umol / l and urea 8.1 mmol / l ) . the cellulitis around the mitrofanoff abdominal catheter was noted and a swab was taken for culture . his chest x - ray did not show any relevant consolidation and abdominal ultrasound noted two small abdominal collections that had already been noted post - transplant and had since decreased in size . the patient was documented to be penicillin allergic ( previous skin rash ) , so was initiated on ertapenem iv 1 gr / od . the cellulitis improved and the patient was clinically well within 48 hours of commencing antibiotics . the blood culture set ( aerobic and anaerobic bottles ) taken on admission was positive with p. multocida but the abdominal swab grew only mixed anaerobes . urine culture was negative and all subsequent blood cultures taken after starting ertapenem were negative after 5 days of incubation . transesophageal ( tee ) echocardiography revealed the presence of a vegetation ( 0.57 0.2 cm ) above the atrium of the right coronary artery . a previous transthoracic echocardiogram ( tte ) , around one month prior to admission , was reported as negative . therefore , the patient was treated following our local protocol for infective endocarditis : he was switched to ceftriaxone iv 2 gr / od , a picc line was inserted in the right arm and he was discharged under the opat ( outpatient parenteral antimicrobial therapy ) service to complete six weeks iv antibiotics as an outpatient . on follow - up , two repeat ttes showed clear aortic valve . we reviewed all the previous reported cases of p. multocida endocarditis in the literature through pubmed and cross - references search . to our knowledge this is the twenty - first reported case of endocarditis but the first to be reported in a penicillin allergic patient . as with previous cases , the diagnosis of infective endocarditis was made according to duke criteria : one major criterion ( evidence of endocardial involvement ) and three minor criteria ( predisposing heart condition , fever and microbiological evidence with positive blood culture ) . laboratory isolation and identification of p. multocida was performed using standard microbiological techniques : api-20ne , api-20e ( biomerieux ) and the phoenix automated system ( bd ) . interestingly , both api profiles reported a low confidence value for identification as p. multocida to the species level ( cv 53% ) and the phoenix assay only identified the isolate to genus level as pasteurella spp . thus , confirmation of species identification was performed using 16s rrna sequencing and maldi - tof protein profiling : 16s rrna sequence was performed using pcr parameters detailed in maskell na et al . ( 2006 ) and we obtained a 584bp fragment sharing 99% sequence homology to that of p. multocida sub species septica . maldi - tof profiling was performed using a bruker daltonics microflex platform with recommended -cyano-4-hydroxycinnamic acid matrix under pre - defined conditions as specified by bruker . the maldi - tof mass spectra for the clinical isolate was analysed against maldi - tof mass spectra for 3,438 species of bacteria located in the bruker daltonics flexanalysis 3.0 database . the clinical isolate was identified as p. multocida with a confidence value of 2.321 indicating highly probable species identification , with no differential bacterial species being reported . sensitivities were as follow ( eucast breakpoints ) : penicillin mic ( mg / l ) was 0.19 , ciprofloxacin 0.016 , doxycycline 0.5 , co - trimoxazole 0.032 , ertapenem 0.016 and ceftriaxone < 0.016 , all being susceptible . of note the accuracy of previous reports in the literature has been questioned as their standard microbiological description was incomplete and pasteurella species may be misidentified as haemophilus spp . they both belong to the pasteurellaceae family and based on the genomic sequence it appears they diverged approximately 270 million years ago . are gram - negative coccobacilli generally present in the oral cavity of cats and dogs . to date twenty - one species have been identified and the species p. multocida can be further divided into three different subspecies ( subspecies multocida , septicum and gallicida ) . the spectrum of infections varies from skin and soft tissue to central nervous system infections . ten out of twenty - one ( 47.6% ) endocarditis cases described in the literature had close contact with animals detailed in the clinical history . our patient did not have a clear history of bites or scratches but he did have two cats at home and close contact with dogs at his sister 's house . in fact , of the cases of p. multocida endocarditis reviewed , two out of twenty - one ( 9.5% ) had cirrhosis as underlying condition . penicillin still remains the best antimicrobial agent for the treatment of virtually all forms of pasteurella infection . a fluoroquinolone , doxycycline , or co - trimoxazole should be considered for skin and soft tissue infections as an alternative for patients with intolerance to -lactams . there are no clear guidelines about the treatment of p. multocida endocarditis in penicillin - allergic patients . the patient was known to be penicillin allergic ( previous rash ) and ciprofloxacin and doxycycline were contraindicated as causing interaction with his anticoagulant treatment . we decided then to switch to ceftriaxone as this antibiotic is already vastly used in the treatment of endocarditis caused by other gram - negative organisms and is more cost effective . aminoglycosides have moderate to poor in vitro activity against pasteurella and probably should not be used , particularly given the paucity of clinical experience . finally , our patient improved within 48 hours of commencing antimicrobial therapy and surgical intervention was unnecessary . from the literature , only three other cases have been successfully treated with solely antibiotics and valve replacement was mandatory in seventeen out of twenty - one ( 81% ) of cases described . clinicians may face various challenges , from achieving the correct species identification to chosing treatment regimens in penicillin - allergic patients . in our case new diagnostic techniques such as 16s rrna sequencing and maldi - tof were demonstrated to be invaluable tools for species confirmation . we propose that maldi - tof is a rapid , accurate method for the identification of p. multocida from bacterial cultures and can significantly reduce the time to diagnosis of p. multocida bacteraemia . furthermore we have shown that cephalosporins and carbapenems are probably good substitutes for penicillin in case of allergy .
pasteurella multocida is a rare cause of infective endocarditis with only a few cases described . 
 this report involves a 38-year - old penicillin - allergic patient in an immunocompromised state with several co - morbidities . 
 two molecular microbiological techniques , 16s rrna sequencing and matrix - assisted laser desorption / ionization time - of - flight mass spectrometry were used to confirm the species identification as p. multocida . 
 previous reports in the literature are also reviewed .