Aggregatibacter aphrophilus in a patient with recurrent empyema: a case report

Brain abscess due to Aggregatibacter aphrophilus in association with atrial septal defect：Case report and literature review

BACKGROUND

Aggregatibacter aphrophilus（A. aphrophilus）is one of the organisms of the HACEK group. Previously reported cases of brain abscesses caused by A. aphrophilus infection have occurred in children with a basis for congenital heart disease, or in adults with a basis for dental disease. Rare cases of brain abscess caused by A. aphrophilus have been reported in adults with congenital heart disease or in patients without dental disease history. Herein we present a rare case of brain abscess caused by A. aphrophilus, who was in association with atrial septal defect for more than 20 years, and had no dental disease and did not develop infective endocarditis.

CASE PRESENTATION

A 51-year-old female was admitted due to progressively worsening headache and left limb weakness for more than 10 days. She denied the history of chronic diseases such as hypertension and diabetes, and no periodontal disease. While she had a history of atrial septal defect, a form of congenital heart disease with severe pulmonary hypertension for more than 20 years. After admission, echocardiographic illustrated congenital heart disease with severe pulmonary hypertension. CT and MRI showed brain abscess. Cerebrospinal fluid (CSF) results also confirmed the presence of intracranial infection. Empirical therapy with vancomycin 1.0 g i.v q12h and meropenem 2.0 g i.v q8h was initiated from the day of admission. On the fourth day after admission, brain abscess resection and decompressive craniectomy were performed, and the pus drained on operation were cultured and Gram-negative bacilli grew, which was identified as A.aphrophilus. Vancomycin was discontinued and meropenem was continued（2.0 g i.v q8h）for 5 weeks, followed by oral levofloxacin 0.5 qd for 4 weeks of out-patient antibiotics. The patient recovered fully within 9 weeks of treatment.

CONCLUSIONS

This is the first case of A. aphrophilus to cause brain abscess in adult with a history of congenital heart disease for more than 20 years, who had no dental disease and did not develop infective endocarditis. We also highlight the value of bacterial 16 S rDNA PCR amplification and sequencing in identifying bacteria in abscesses which are culture-negative, and prompt surgical treatment，choosing effective antibiotics and appropriate course of treatment will get better clinical effect.

A rare cause of culture negative bioprosthetic valve endocarditis: a case report of Aggregatibacter aphrophilus infection

Background

The prevalence of culture negative infective endocarditis (IEC) is reported as 2–7% though this figure may be as high as 70% in developing countries.¹ This higher rate will, at least in part, be due to reduced diagnostic facilities though some data suggests higher rates even when appropriate cultures were taken. The frequency is significantly elevated in patients who have already been exposed to antibiotics prior to blood cultures.^1,2 A rare cause of culture negative IEC is the HACEK group of organisms that are normal habitants of the oropharyngeal flora and account for 1–3% of native valve endocarditis.³Aggregatibacter aphrophilus (A. aphrophilus) is a member of the HACEK group of organisms.

Case summary

A 32-year-old gentleman with a previous bioprosthetic aortic valve presented with a 1-week history of diarrhoea, vomiting, malaise, and weight loss. He was awaiting redo surgery for stenosis of the bioprosthesis, which had been inserted aged 17 for aortic stenosis secondary to a bicuspid valve. The initial blood tests revealed liver and renal impairment with anaemia. A transoesophageal echocardiogram demonstrated a complex cavitating aortic root abscess, complicated by perforation into the right ventricle. He underwent emergency redo surgery requiring debridement of the aortic abscess, insertion of a mechanical aortic prosthesis (St Jude Medical, USA), annular reconstruction and graft replacement of the ascending aorta. Despite antibiotic therapy, he remained septic with negative blood and tissue cultures. Bacterial 16S rRNA gene sequencing confirmed A. aphrophilus infection, for which intravenous ceftriaxone was initiated. This was subsequently changed to ciprofloxacin due to neutropenia. The patient self-discharged from the hospital during the third week of antibiotic therapy. One week later, he was re-admitted with fever, night sweats, and dyspnoea. Transthoracic echocardiogram revealed a large recurrent aortic abscess cavity around the aortic annulus fistulating into the right heart chambers; this was confirmed by a computed tomography scan. There was dehiscence of the patch repair. Emergency redo aortic root replacement (25 mm mechanical valve conduit, ATS Medical, USA) and annular reconstruction was performed with venoarterial extracorporeal membrane oxygenation (VA-ECMO) support. VA-ECMO was weaned after 3 days. The patient completed a full course of intravenous meropenem and ciprofloxacin and made a good recovery.

Discussion

IEC with oropharyngeal HACEK organisms is rare and difficult to diagnose, due to negative blood culture results. The broad-range polymerase chain reaction and gene sequencing with comparison to the DNA database is useful in these circumstances. This case demonstrates the importance of the 16S rRNA gene sequencing for HACEK infection diagnosis and appropriate antibiotic treatment.

An unusual case of multiple hepatic and pulmonary abscesses caused by Aggregatibacter aphrophilus in a young man: a case report

Background

Aggregatibacter aphrophilus, formerly known as Haemophilus aphrophilus, belongs to the HACEK organisms, a group of pathogens classically associated with infectious endocarditis. A. aphrophilus is a rarely found pathogen, though abscess formation in various organs has been described, typically due to spread from an infected heart valve. Here we describe the unusual case of multiple hepatic abscesses caused by A. aphrophilus.

Case presentation

A 33-year-old Caucasian man presented at our hospital with fever and malaise, elevated inflammatory markers, and liver enzymes. Imaging was compatible with multiple liver and pulmonary abscesses, without evidence of endocarditis. Cultures of blood and liver abscess material remained without growth. Polymerase chain reaction finally revealed Aggregatibacter aphrophilus in the liver tissue. The patient recovered fully within 6 weeks of doxycycline treatment.

Conclusions

There are only a few case descriptions of liver abscesses caused by A. aphrophilus. As a ubiquitous organism in the gastrointestinal tract, A. aphrophilus may reach the liver via the portal venous system, as well as through hematogenous spread from the oropharynx. HACEK organisms are notoriously difficult to grow on culture, which highlights the diagnostic importance of eubacterial PCR.

Isolation of Aggregatibacter aphrophilus from bronchoalveolar lavage in a paediatric patient presenting with haemoptysis

We report a rare case of non–cystic fibrosis bronchiectasis accompanied by protracted infection with Aggregatibacter aphrophilus in a 12-year-old boy with haemoptysis.

Aggregatibacter aphrophilus ventriculitis following C1-C2 transarticular screw fixation

OBJECTIVE

Central nervous system (CNS) infections after cervical spine surgery are a rare but serious complication and may be caused by uncommon pathogens. We report the case of a 57-year-old male who developed slowly progressive mental confusion with headaches, increased daytime sleepiness and mild gait disturbance within the last 3 weeks. Six weeks prior to admission to our department, he underwent an atlantoaxial fusion by C1-C2 transarticular screw fixation for rheumatoid arthritis related C1-C2 multidirectional instability.

METHODS

We analyzed clinical and neuroradiological findings.

RESULTS

The findings were consistent with communicating hydrocephalus secondary to ventriculitis and the left C1-C2 screw was found to be misplaced with perforation of the dura. The situation was interpreted as implant related surgical site infection of the cerebrospinal fluid followed by ventriculitis and hydrocephalus. Bacterial broad range 16S rRNA gene PCR from the cerebrospinal fluid (CSF) followed by sequencing identified Aggregatibacter aphrophilus as the causative agent, while conventional cultures remained negative due to its fastidious growth. The patient was successfully treated with a lumbar drain and intravenous ceftriaxone.

CONCLUSIONS

To our knowledge, this is the first report of Aggregatibacter aphrophilus ventriculitis following C1-C2 transarticular screw fixation.

A Case of Aggregatibacter aphrophilus Multiple Abscess

We report a case of brain and lung abscesses caused by Agreggatibacter aphrophilus in a 43-YEAR-OLD man with past history of splenectomy and drug addiction, in the absence of endocarditis. Microbiological samples remain negatives and diagnosis was made by 16S rDNA PCR performance on abscess fluid for this coccobacillus that belongs to the HACEK group. The patient’s clinical symptoms resolved within 6 weeks of treatment with cefotaxim.

Microbial community profiling of human saliva using shotgun metagenomic sequencing

Human saliva is clinically informative of both oral and general health. Since next generation shotgun sequencing (NGS) is now widely used to identify and quantify bacteria, we investigated the bacterial flora of saliva microbiomes of two healthy volunteers and five datasets from the Human Microbiome Project, along with a control dataset containing short NGS reads from bacterial species representative of the bacterial flora of human saliva. GENIUS, a system designed to identify and quantify bacterial species using unassembled short NGS reads was used to identify the bacterial species comprising the microbiomes of the saliva samples and datasets. Results, achieved within minutes and at greater than 90% accuracy, showed more than 175 bacterial species comprised the bacterial flora of human saliva, including bacteria known to be commensal human flora but also Haemophilus influenzae, Neisseria meningitidis, Streptococcus pneumoniae, and Gamma proteobacteria. Basic Local Alignment Search Tool (BLASTn) analysis in parallel, reported ca. five times more species than those actually comprising the in silico sample. Both GENIUSand BLAST analyses of saliva samples identified major genera comprising the bacterial flora of saliva, but GENIUS provided a more precise description of species composition, identifying to strain in most cases and delivered results at least 10,000 times faster. Therefore, GENIUS offers a facile and accurate system for identification and quantification of bacterial species and/or strains in metagenomic samples.