Antimicrobial Susceptibilities of Abiotrophia defectiva, Granulicatella adiacens, and Granulicatella elegans

Epidemiology, clinical characteristics, and outcome of infective endocarditis due to Abiotrophia and Granulicatella in a Tertiary Hospital in China, 2015-2023: a retrospective study

BACKGROUND

Abiotrophia (ABI) and Granulicatella (GRA) are rare causative pathogens in infective endocarditis (IE). This study aims to describe the epidemiology, clinical characteristics, and outcome of ABI/GRA-IE. The main features of ABI/GRA-IE were compared with Viridans group streptococci (VGS) IE.

METHODS

From January 2015 to December 2023, a total of 1531 definite IE in Zhongshan Hospital, Fudan University, Shanghai, China were retrospectively enrolled in this study. Clinical and laboratory data were collected.

RESULTS

Forty-five ABI/GRA-IE cases were identified, representing 2.9% of all IE cases in Zhongshan Hospital between 2015 and 2023, compared to 20.1% of VGS-IE. ABI and GRA IE shared similar clinical characteristics. Congenital valvulopathy was reported in 21 (46.7%) ABI/GRA-IE and 85 (28.8%) VGS-IE (P = 0.025). Pulmonary valve was more frequently affected in ABI/GRA-IE (6 [13.3%]) than VGS-IE (7 [2.4%]) (P = 0.002). Congestive heart failure was observed in 30 (66.7%) ABI/GRA-IE and 103 (34.9%) VGS-IE (P < 0.001). Systemic embolization excluding central nervous system (CNS) occurred in 13 (28.9%) ABI/GRA-IE and 39 (13.2%) VGS-IE (P = 0.012). In-hospital mortality was reported as 4.4% in ABI/GRA-IE and 3.7% in VGS-IE (P = 0.854).

CONCLUSION

GRA/ABI-IE was approximately one-seventh as prevalent as VGS-IE. Congestive heart failure and systemic embolization (excluding CNS) were more frequent in GRA/ABI-IE compared to VGS-IE. Mortality of ABI/GRA-IE in this study was comparable to that of VGS-IE and lower than previously reported results.

When less is more: the art of communicating clinical microbiology results

The clinical microbiology laboratory is capable of identifying microorganisms in clinical specimens faster and more accurately than ever before. At face value, this should enable patient care providers to make better-informed decisions and target antimicrobial therapies to deliver individualized care. Ironically, more complete and specific reporting of microorganisms isolated from specimens may result in overtreatment based on the presence of a pathogen, even in the absence of clear signs of clinical infection. This conundrum calls into question the role of the laboratory in contributing to care through selective or "exception" reporting whereby some results are selectively withheld when there is a low probability that laboratory findings correlate with the clinical infection. In a recent article published in the Journal of Clinical Microbiology, Bloomfield et al. (J Clin Microbiol 62:e00342-24, 2024, https://doi.org/10.1128/jcm.00342-24) examine the impact and safety of an exception reporting strategy applied to wound swab specimens. Canonical pathogens associated with skin and soft tissue infections including S. aureus and beta-hemolytic streptococci are withheld from the laboratory report if certain patient criteria are met that would put them at low risk of adverse outcomes if untreated, or if treated with guideline-recommended empiric therapy. Their central finding was an approximately 50% reduction in post-laboratory report antibiotic initiation without adverse events or increased 30-day admission rate (indicative of infection-related complications, e.g., disseminated disease). While effectively achieving their goal, the premise of exception reporting and other modified reporting strategies raises questions about the potential risk of underreporting and how to ensure that the message is being interpreted, and acted upon, by care providers as was intended by the laboratory.

Huge, invasive, and destructive Abiotrophia defectiva endocarditis of the aortic valve and the aortic wall: a case report of an emergency but successful Ross-Konno operation in a child

Background

Abiotrophia defectiva forms Gram-positive cocci, is part of normal oropharyngeal and gastrointestinal flora, and is rarely involved in endocarditis in children population. Its special nutritional requirements and subacute clinical course may delay diagnosis and proper treatment, leading to life-threatening consequences.

Case summary

We report a rare case of huge and destructive A. defectiva infective endocarditis (IE) of the aortic valve and the aortic wall in a 3-year-old child, in follow-up after surgical valvuloplasty for congenital aortic stenosis. The child presented at our department with signs of left side hemiplegia. Transthoracic echocardiography showed severe aortic regurgitation due to large vegetation extending to the aortic wall up to the aortic arch. Blood cultures resulted positive for A. defectiva. He was initially treated conservatively with antibiotic therapy. Ten days after admission, because of clinical deterioration, he required intubation and an emergency Ross-Konno operation. Despite the critical conditions and highly risky surgery, the child recovered well and was discharged home 5 weeks after the operation.

Discussion

Abiotrophia defectiva IE is rare in children. Since 1995, only 16 cases of A. defectiva IE have been reported in children, including our case. This pathogen has a higher rate of complications when affecting children rather than adult population. Our case demonstrates that conservative strategy with antibiotics is rarely resolutive in the case of IE caused by A. defectiva. Whenever one or more indications for surgery are present, surgical intervention should always be taken into consideration, even if clinical conditions are prohibitive and surgery is at very high risk.

Catheter related atrial thrombus caused by Abiotrophia defectiva: A case series and review of literature

Catheter related atrial thrombus (CRAT) is a devastating complication associated with tunneled hemodialysis catheter. Abiotrophia defectiva is a rare fastidious pathogen implicated predominantly in culture negative infective endocarditis. Here we report three cases of CRAT in maintenance hemodialysis patients with variable clinical presentation caused by Abiotrophia defectiva. Video assisted thoracoscopic retrieval of atrial thrombus is a novel technique which is scarcely reported in medical literature for surgical management of large atrial thrombus. Our cases were managed by timely administration of antibiotics and anticoagulants followed by surgical retrieval of atrial thrombus with removal of tunneled dialysis catheter. This case series illustrates the importance of prompt diagnosis, appropriate anticoagulation with antibiotics, and mini-invasive surgical removal of atrial thrombus for the management of CRAT.

Arteriovenous Graft Infection Due to Granulicatella adiacens

Granulicatella adiacens is a gram-positive coccus that is normally found in the human oral cavity and gastrointestinal and urogenital tracts but can rarely cause infection. When it does cause infection, Granulicatella adiacens has been most associated with bacteremia and endovascular infection, but to our knowledge, there are no previously documented cases of arteriovenous graft (AVG) infection. We present a case of Granulicatella adiacens bacteremia with associated AVG infection.

An Aminoglycoside-Sparing Regimen with Double Beta-Lactam to Successfully Treat Granulicatella adiacens Prosthetic Aortic Valve Endocarditis-Time to Change Paradigm?

(1) Background: Granulicatella adiacens is a former nutritionally variant streptococci (NVS). NVS infective endocarditis (IE) is generally characterized by a higher rate of morbidity and mortality, partially due to difficulties in choosing the most adequate microbiological culture method and the most effective treatment strategy, and partially due to higher rates of complications, such as heart failure, peripheral septic embolism, and peri-valvular abscess, as well as a higher rate of valve replacement. Depending on the affected valve (native valve endocarditisNVE, or prosthetic valve endocarditisPVE), the American Heart Association (AHA) 2015 treatment guidelines (GLs) suggest penicillin G, ampicillin, or ceftriaxone plus gentamicin (2 weeks for NVE and up to 6 weeks for PVE), while vancomycin alone may be a reasonable alternative in patients who are intolerant of β-lactam therapy. The European Society of Cardiology (ESC) 2023 GLs recommend treating NVE with penicillin G, ceftriaxone, or vancomycin for 6 weeks, suggesting combined with an aminoglycoside (AG) for at least the first 2 weeks only for PVE; likewise, the same recommendations for IE due to Enterococcus faecalis. (2) Methods: Starting from the case of a 51-year-old man with G. adiacens aortic bio-prosthesis IE who was successfully treated with aortic valve replacement combined with double beta-lactams, an AG-sparing regimen, we performed microbiology tests in order to validate this potential treatment change. (3) Results: As for E. faecalis IE, we found that the combination of ampicillin plus cephalosporines (like ceftriaxone or ceftobiprole) showed a synergistic effect in vitro, probably due to wider binding to penicillin-binding proteins (PBPs), thus contributing to enhanced bacterial killing and good clinical outcome, as well as avoiding the risk of nephrotoxicity due to AG association therapy. (4) Conclusions: Further studies are required to confirm this hypothesis, but double beta-lactams and an adequate sourcecontrol could be a choice in treating G. adiacens IE.

A Perilous Combination: Streptococcus Coinfection with Human Plague-Report of Two Cases and Review of the Literature, 1937-2022

Background: Plague in humans and animals is caused by Yersinia pestis, a zoonotic gram-negative bacterium endemic in certain regions of Asia, Africa, and the United States. Coinfection with both Y. pestis and Streptococci species has been anecdotally reported in humans and associated with severe and rapidly fatal disease. Methods: This report presents two cases of patients who died following Y. pestis and Streptococcus coinfection. Additional cases of previously published Y. pestis-Streptococcus coinfection were identified and reviewed using a search of electronic databases. Results: The first case patient developed cough and dyspnea following 4 days of fever, malaise, and back pain and died before receiving medical care. Postmortem blood cultures were positive for Y. pestis, Streptococcus pyogenes, and Streptococcus dysgalactiae. The second case patient was hospitalized with fever, vomiting, diarrhea, and dyspnea and died of sepsis and respiratory failure on the day of admission. Y. pestis and Streptococcus pneumoniae were isolated from blood cultures drawn on admission. Seven additional cases of Y. pestis and Streptococcus coinfection were identified, dating between 1948 and 2009. These patients were healthy overall before their illness, with ages ranging from 9 to 60 years. The majority of patients had primary bubonic plague with associated pneumonia or septicemia. None of the patients who died received timely antimicrobial therapy directed against gram-negative pathogens. In every case but one, an occupational or environmental risk factor for plague was later identified. Conclusion: Y. pestis infection begins with a pre-inflammatory phase, during which Y. pestis and other pathogens can rapidly proliferate. Streptococci, which are frequently asymptomatic colonizers, may become invasive in this environment, leading to coinfection. The challenges of diagnosing Y. pestis in the context of coinfection may delay effective treatment. This case series and literature review illustrate the importance of clinicians remaining alert to environmental and occupational exposures in patients presenting with an infectious syndrome, especially in those who have an unexpectedly severe clinical presentation.

Liver abscess due to Granulicatella adiacens in an immunocompetent patient: Case report

Pyogenic liver abscesses due to Granulicatella adiacens are infections associated with high mortality, mainly in immunocompromised patients. The main microorganisms associated with liver abscesses are Klebsiella pneumoniae, and Escherichia coli, though it may also be polymicrobial. However, case reports describing liver infection by Granulicatella adiacens are scarce. We present the case of an immunocompetent adult patient who presented 15 days of evolution consisting of quantified fever peaks associated with asthenia, adynamia, chills, jaundice and coluria. The initial clinical examination revealed a generalized icteric tint without abdominal pain, and blood pressure with a tendency to hypotension. Biliopancreatic confluent neoplasia, secondary cholangitis and sepsis of biliary origin were suspected, initiating fluid resuscitation and antibiotic therapy; blood cultures and complementary diagnostic studies were taken. Hepatobiliary ultrasound with evidence of an abscess of 73 x 62 mm in segment IV; the bile duct and pancreas were within normal limits. To better characterize the lesion evidenced in the liver, a contrast-enhanced computed tomography of the abdomen was performed. The patient completed antibiotic management with ciprofloxacin, vancomycin, and metronidazole in good condition and was successfully discharged. This is the first pyogenic liver abscess reported caused by Granulicatella adiacens in an immunocompetent patient, in whom early microbiological diagnosis in conjunction with targeted antibiotic treatment and percutaneous drainage of the lesion was decisive in the clinical outcome.

Disseminated Streptococcus gallinaceus infection. A new breed of zoonotic Streptococcus

Streptococcus gallinaceus is a new species of Streptococcus that was first isolated in 2004 in chickens. Infections in humans are associated with chicken exposure. There are very few case reports of human infections with this organism and none with disseminated infection. We report a case of Streptococcus gallinaceus bacteremia complicated by aortic valve endocarditis and lumbar osteomyelitis and paraspinal abscess in a patient with chicken exposure. The patient presented with progressive lower back pain and malaise. Blood culture was positive for Streptococcus gallinaceus. Magnetic resonance imaging (MRI) of the spine showed L2-L3 osteomyelitis with a compression fracture and paraspinal abscess. Transthoracic echocardiography revealed severe aortic insufficiency, 1-cm aortic valve echo density suspected to be a vegetation, and perforation of the right coronary cusp. He subsequently underwent anaortic valve repair. Pathology confirmed acute endocarditis with associated vegetations and granulation tissues. He was successfully treated with a six-week course of ceftriaxone.

Draft Genome Sequence of Granulicatella sp. Strain S8, Isolated from a Marine Fish, Seriola quinqueradiata

In this study, Granulicatella sp. strain S8 was isolated from the gut of a marine fish, Seriola quinqueradiata, and the draft genome was sequenced. Various genes responsible for pathogenesis, metabolite biosynthesis, defense, and lactic acid production were predicted. The genome sequence of this facultative anaerobe provides insights into its distinctive features.

Abiotrophia defectiva meningitis following ventriculoperitoneal shunt repair: Case report and literature review

Introduction

Abiotrophia defectiva is an uncommon and potentially severe cause of bacterial meningitis that can be seen in the setting of neurosurgical procedures. We describe here a case of A. defectiva meningitis in a patient with VP shunt revision.

Case report

The patient is a 59-year-old female with VP shunt placed several years prior in the setting of normal pressure hydrocephalus. She underwent successful shunt repair following worsening gait abnormalities. On post-operative day 8 she was brought to the emergency room with fevers, photophobia and altered mentation. CSF cultures returned positive for A. defectiva and she was treated with intravenous vancomycin. Due to the presence of retained hardware she was discharged on chronic suppressive therapy with oral amoxicillin.

Conclusion

This case illustrates A. defectiva as a cause of bacterial meningitis following neurosurgical intervention. It is important to consider this fastidious organism and tailor antimicrobial therapy appropriately to prevent significant morbidity and mortality. As was the case with our patient, suppressive therapy may be warranted in setting of retained hardware.

Abiotrophia defectiva Endocarditis: A Rare Cause with Aggressive Systemic Embolisation and Need of Valve Replacement

Infective endocarditis (IE) is a well-described infectious disease, one with increased morbidity and mortality being the third or fourth most common life-threatening infection syndrome. Abiotrophia defectiva is a non-motile, catalase negative, gram-positive coccus in a chain, which can be isolated from the oral cavity, intestinal, and genitourinary tracts. IE due to this agent is rare and associated with heart valve destruction, congestive heart failure, and high embolisation rates, these being the major mortality causes. We present a case of IE due to this agent, complicated with a stroke, and splenic and renal infarction, with the need for aortic valve replacement. This article highlights the gaps of knowledge left by the rarity of this disease, which range from its diagnosis to its treatment, and what we need to mitigate such gaps, supported with a case description of a successful treatment of this infection.

LEARNING POINTS

Infective endocarditis due to Abiotrophia defectiva has usually an indolent course, but the embolisation potential is very high.The major causes of mortality with this species are congestive heart failure due to valve destruction and the presence of multiple emboli.Surgical intervention rates are high with Abiotrophia defectiva, reaching 50% of cases.

Impact of different oral treatments on the composition of the supragingival plaque microbiome

Background

Dental plaque consists of a diverse microbial community embedded in a complex structure of exopolysaccharides. Dental biofilms form a natural barrier against pathogens but lead to oral diseases in a dysbiotic state.

Objective

Using a metaproteome approach combined with a standard plaque-regrowth study, this pilot study examined the impact of different concentrations of lactoperoxidase (LPO) on early plaque formation, and active biological processes.

Design

Sixteen orally healthy subjects received four local treatments as a randomized single-blind study based on a cross-over design. Two lozenges containing components of the LPO-system in different concentrations were compared to a placebo and Listerine®. The newly formed dental plaque was analyzed by mass spectrometry (nLC-MS/MS). 

Results

On average 1,916 metaproteins per sample were identified, which could be assigned to 116 genera and 1,316 protein functions. Listerine® reduced the number of metaproteins and their relative abundance, confirming the plaque inhibiting effect. The LPO-lozenges triggered mainly higher metaprotein abundances of early and secondary colonizers as well as bacteria associated with dental health but also periodontitis. Functional information indicated plaque biofilm growth.

Conclusion

In conclusion, the mechanisms on plaque biofilm formation of Listerine® and the LPO-system containing lozenges are different. In contrast to Listerine®, the lozenges led to a higher bacterial diversity.

Antibiotic Resistance of Selected Bacteria after Treatment of the Supragingival Biofilm with Subinhibitory Chlorhexidine Concentrations

Due to increasing rates of antibiotic resistance and very few novel developments of antibiotics, it is crucial to understand the mechanisms of resistance development. The aim of the present study was to investigate the adaptation of oral bacteria to the frequently used oral antiseptic chlorhexidine digluconate (CHX) and potential cross-adaptation to antibiotics after repeated exposure of supragingival plaque samples to subinhibitory concentrations of CHX. Plaque samples from six healthy donors were passaged for 10 days in subinhibitory concentrations of CHX, while passaging of plaque samples without CHX served as control. The surviving bacteria were cultured on agar plates and identified with Matrix-assisted Laser Desorption/Ionization-Time of Flight-Mass spectrometry (MALDI-TOF). Subsequently, the minimum inhibitory concentrations (MIC) of these isolates toward CHX were determined using a broth-microdilution method, and phenotypic antibiotic resistance was evaluated using the epsilometertest. Furthermore, biofilm-forming capacities were determined. Repeated exposure of supragingival plaque samples to subinhibitory concentrations of CHX led to the selection of oral bacteria with 2-fold up to 4-fold increased MICs toward CHX. Furthermore, these isolates showed up to 12-fold increased MICs towards some antibiotics such as erythromycin and clindamycin. Conversely, biofilm-forming capacity was decreased. In summary, this study shows that oral bacteria are able to adapt to CHX, while also decreasing their susceptibility to antibiotics.

Clinical characteristics and outcome of infective endocarditis due to Abiotrophia and Granulicatella compared to Viridans group streptococci

OBJECTIVE

To describe the clinical characteristics and outcome of Abiotrophia and Granulicatella infective endocarditis and compare them with Viridans group streptococci infective endocarditis.

METHODS

All patients in the International Collaboration on Endocarditis (ICE) - prospective cohort study (PCS) and the ICE-PLUS cohort were included (n=8112). Data from patients with definitive or possible IE due to Abiotrophia species, Granulicatella species and Viridans group streptococci was analyzed. A propensity score (PS) analysis comparing the ABI/GRA-IE and VGS-IE groups according to a 1:2 ratio was performed.

RESULTS

Forty-eight (0.64%) cases of ABI/GRA-IE and 1,292 (17.2%) VGS-IE were included in the analysis. The median age of patients with ABI/GRA-IE was lower than VGS-IE (48.1 years vs. 57.9 years; p=0.001). Clinical features and the rate of in-hospital surgery was similar between ABI/GRA-IE and VGS-IE (52.1% vs. 45.4%; p=0.366). Unadjusted in-hospital death was lower in ABI/GRA-IE than VGS-IE (2.1% vs. 8.8%; p=0.003), and cumulative six-month mortality was lower in ABI/GRA-IE than VGS-IE (2.1% vs. 11.9%; p<0.001). After PS analysis, in-hospital mortality was similar in both groups, but six-month mortality was lower in the ABI/GRA IE group (2.1% vs. 10.4%; p=0.029).

CONCLUSIONS

Patients with ABI/GRA-IE were younger, had similar clinical features and rates of surgery and better prognosis than VGS-IE.

Clinical features and antimicrobial susceptibility of oral bacteria isolated from the blood cultures of patients with infective endocarditis

Background/purpose

The epidemiology of infective endocarditis (IE) is under constant change due to the aging society and increases in antimicrobial-resistant pathogens. However, IE remains severe. This study aimed to review the current clinical characteristics of IE and the antimicrobial susceptibility of oral bacteria (OB) isolated from blood cultures to implement appropriate antimicrobial prophylaxis.

Materials and methods

We retrospectively investigated the clinical features of 180 patients with IE in whom OB and pathogens except OB (eOB) were identified as causative microorganisms via blood cultures. The susceptibility of the OB group to eight antibiotics was examined by broth microdilution.

Results

Among causative microorganisms, the isolation rate of staphylococci was slightly higher than that of OB; however, the difference was not significant (36.7% vs. 33.8%, p = 0.3203). The number of patients with underlying cardiac disease was significantly higher in the OB group than in the eOB group (53.7% vs. 34.1%, p = 0.0113). Only one ampicillin-resistant OB was detected (2.0%). OBs were significantly less susceptible to clarithromycin and azithromycin than to ampicillin (98.0% vs. 66.7% and 98.0% vs. 60.0%, p = 0.0003 and p = 0.0003, respectively). Moreover, OBs were significantly less susceptible to clarithromycin and azithromycin than to clindamycin (66.7% vs. 88.2% and 60.0% vs. 88.2%, p = 0.0301 and p = 0.0217, respectively).

Conclusion

OBs were susceptible to ampicillin. However, the susceptibility of OBs to clarithromycin and azithromycin was significantly lower than that to ampicillin and clindamycin. These results are important and should help decisions regarding guide antimicrobial prophylaxis.

Abiotrophia Defectiva as a Rare Cause of Mitral Valve Infective Endocarditis With Mesenteric Arterial Branch Pseudoaneurysm, Splenic Infarction, and Renal Infarction: A Case Report

Introduction

Abiotrophia defectiva (A. defectiva) is a rare species leading to infective endocarditis (IE) with a poor prognosis. We describe a previously healthy patient with mitral valve infective endocarditis caused by A. defectiva.

Case report

A young man was admitted with intermittent fever. Echocardiography confirmed vegetation on the mitral valve with evidence of valve perforation and severe mitral regurgitation. Three sets of blood cultures became positive for A. defectiva. As he presented with manifestations of mesenteric arterial branch pseudoaneurysm, splenic and renal infarction, mitral valve replacement, and embolization of superior mesenteric aneurysm were operated during 8 weeks' targeted antibiotic therapy.

Conclusion

This case study emphasizes the importance of considering A. defectiva as a rare but important cause of IE and of performing blood culture to make its accurate diagnosis and timely anti-infective treatment. Early surgical management and active prevention of complications have been associated with a favorable prognosis.

Abiotrophia Causing Prosthetic Joint Septic Arthritis

A 71-year-old Caucasian male with a past medical history of Charcot-Marie-Tooth disease type 2 presented to our rural hospital for left knee pain, swelling, and difficulty walking. The patient had prior bilateral total knee replacements with a subsequent left knee revision due to infection. Joint aspiration was culture-positive and 16S recombinant DNA (rDNA) sequence positive for Abiotrophia defectiva. The patient underwent a left total knee extraction with a temporary antibiotic spacer insertion. On discharge, the patient received an initial six weeks of ceftriaxone 2g IV. At the outpatient six-week follow-up, the patient was cleared of the Abiotrophia infection. However, later complications and a subsequent Enterobacter cloacae infection arose.

Case Report: Report of Infective Endocarditis Caused by Abiotrophia defectiva and Literature Review

OBJECTIVE

To report the clinical features of the first child with infective endocarditis (IE) caused by Abiotrophia defectiva in mainland China and to raise awareness of the disease.

METHODS

The clinical data of a child with IE caused by A. defectiva admitted to Xi'an Children's Hospital in July 2021 were collected, and the relevant literature was reviewed.

RESULTS

The child was a female, 8 years old, admitted with fever for 4 days and right-sided limb weakness for 3 days. The illness started with suppurative tonsillitis, followed by headache, fatigue, right-sided mouth, slurred speech, right limb weakness, and unstable holding. Transthoracic echocardiography showed that the mitral valve vegetation was formed and vegetation could also be seen at the entrance of the pulmonary vein at the posterior wall of the left atrium. Cranial contrast-enhanced MRI + magnetic resonance angiography showed multiple intracranial pseudoaneurysm formation and pontine infarction. After A. defectiva was detected by metagenomic next-generation sequencing (mNGS) in cerebrospinal fluid and blood detected, the infection was controlled by anti-infective treatment with meropenem and vancomycin. On the 36th day after admission, due to severe headache and slurred speech, the head CT showed hemorrhage of right parietal pseudoaneurysm and cerebral sickle hernia, and right temporo-occipital hematoma evacuation, cerebrovascular malformation resection, and cranial decompression were performed immediately. After the surgery, her speech ability gradually recovered, the muscle strength of her left upper limb was about grade III, while the muscle strength of the rest of the limbs was normal. After a total of 60 days of hospitalization, her family requested to be discharged.

CONCLUSION

This pediatric patient is the first case of childhood IE caused by A. defectiva in mainland China, and the first time in the world that A. defectiva was detected by mNGS in patients with IE.

A Rare Case of Granulicatella adiacens Vertebral Osteomyelitis

Vertebral osteomyelitis caused by Granulicatella adiacens is rarely described. We report a 45-year-old immunocompetent male with back pain caused by G. adiacens osteomyelitis. This case is remarkable due to the absence of endocarditis. A clinician should therefore consider G. adiacens osteomyelitis even in the absence of concurrent hematogenous spread.

Aortic Valve Replacement and Penicillin Desensitization in a Patient with Abiotrophia defectiva Aortic Valve Endocarditis

Abiotrophia defectiva is an uncommon and insidious yet destructive cause of infective endocarditis preferentially treated with penicillin/gentamicin and often requiring surgical treatment. A 60-year-old man with penicillin anaphylaxis history presented with fevers and a nonspecific constellation of symptoms. He was ultimately diagnosed with bicuspid aortic valve infective endocarditis based on blood cultures growing A.defectiva and echocardiographic evidence of bicuspid aortic valve, severe valvular regurgitation, and 5 × 7 mm vegetation. Aortic valve replacement and culture yielded penicillin-sensitive A.defectiva. After successful penicillin desensitization, antibiotic therapy was switched from vancomycin/gentamicin to benzylpenicillin. This is the first published case of penicillin desensitization in a patient with A.defectiva-associated infection. Penicillin desensitization, optimal antibiotic therapy, prompt aortic valve replacement, and close collaboration between cardiology and various other specialties were essential in achieving a positive outcome.

Development of high level daptomycin resistance (HLDR) in Abiotrophia and Granulicatella spp isolates from patients with infective endocarditis (IE)

Abiotrophia and Granulicatella species are fastidious organisms, representing around 1%-3% of infective endocarditis (IE). Little is known about the optimal antibiotic treatment of these species, and daptomycin has been suggested as a therapeutic option. We describe the antimicrobial profile in Abiotrophia and Granulicatella IE isolates, investigate high-level daptomycin resistance (HLDR) development and evaluate daptomycin activity in combination therapy. In vitro studies with 16 IE strains (6 A. defectiva, 9 G. adiacens and 1 G. elegans) were performed using microdilution to determine minimal inhibitory concentration (MIC) and time-kill methodology to evaluate combination therapy. Daptomycin non-susceptibility (DNS; MIC≥ 2 mg/L) and HLDR (MIC≥256 mg/L) were based on existing Clinical and Laboratory Standards (CLSI) breakpoints for viridans streptococci. All isolates were susceptible to vancomycin: G. adiacens was more susceptible to penicillin and ampicillin than A. defectiva (22% vs. 0%, and 67% vs. 33%) but less susceptible to ceftriaxone and daptomycin (56% vs. 83%, and 11% vs. 50%). HLDR developed in both A. defectiva (33%) and G. adiacens (78%) after 24h exposure to daptomycin. Combination therapy did not prevent the development of daptomycin resistance with ampicillin (2/3 strains), gentamicin (2/3 strains), ceftriaxone (2/3 strains) or ceftaroline (2/3 strains). Once developed, HLDR was stable for a prolonged time (>3 weeks) in G. adiacens, whereas in A. defectiva the HLDR it reversed to baseline MIC at day 10. This study is first to demonstrate rapid HLDR development in Abiotrophia and Granulicatella species in vitro. Resistance was stable, and most combination therapies did not prevent it.

Infective endocarditis by a rare and fastidious agent: Abiotrophia defectiva

Abiotrophia defectiva is a nutritional variant streptococcus, with affinity for endovascular structures that cannot be cultured on non-supplemented media, leading to a delay in diagnosis. This case describes a 36-year-old woman with a previously known bicuspid aortic valve that presented with asthenia, myalgias and anorexia with 2-month onset. On admission, we documented fever and a systolic murmur. Transthoracic echocardiography revealed an oscillating mass attached to the aortic valve. The patient was admitted with a possible diagnosis of infective endocarditis. Later, blood cultures were positive for A. defectiva Due to severe aortic regurgitation and congestive heart failure, she underwent surgical aortic valve replacement. After 6 weeks of antimicrobial therapy, the patient experienced full recovery. Despite of its rarity, A. defectiva endocarditis is associated with significant morbidity with mortality and physicians must have a high level of suspicion to ensure a prompt diagnosis and provide the appropriate treatment.

Assessment of the spoilage microbiota in minced free-range chicken meat during storage at 4 C in retail modified atmosphere packages

This study assessed the evolution of spoilage microbiota in association with the changes in pH and concentrations of lactic and acetic acids in retail oxygen-free modified atmosphere (30:70 CO₂/N₂) packages (MAP) of minced free-range chicken meat during storage at 4 °C for 10 days. MAP retarded growth of spoilage lactic acid bacteria (LAB) below 6.5 log cfu/g and fully suppressed growth of pseudomonads, enterobacteria, enterococci, staphylococci and yeasts. Two distinct Latilactobacillus sakei strain biotypes were predominant and Leuconostoc carnosum, Carnobacterium divergens, Latilactobacillus fuchuensis and Weissella koreensis were subdominant at spoilage. The chicken meat pH ranged from 5.8 to 6.1. l-lactate (832 mg/100 g on day-0) decreased slightly on day-7. d-lactate remained constantly below 20 mg/100 g, whereas acetate (0-59 mg/100 g) increased 5-fold on day-7. All MAP samples developed off-odors on day-7 and a strong 'blown-pack' sulfur-type of spoilage on day-10. However, neither the predominant Lb. sakei nor other LAB or gram-negative isolates formed H₂S in vitro, except for C. divergens.

Microbial population shift and metabolic characterization of silver diamine fluoride treatment failure on dental caries

The objective of this pilot study was to describe the microbial profiles present in the plaque and saliva of children who continued to develop new carious lesions following treatment with silver diamine fluoride ("nonresponders") compared to caries active, caries-free, and children immediately receiving SDF treatment for untreated caries in order to identify potential microbial differences that may relate to a re-incidence of caries. Saliva and plaque samples from infected and contralateral sites were obtained from twenty children who were either caries free, had active carious lesions, were caries active and received SDF treatment immediately before sampling, or had previously received SDF treatment and developed new caries. In total, 8,057,899 Illumina-generated sequence reads from 60 samples were obtained. Reads were processed using the Quantitative Insights Into Microbial Ecology pipeline. Group differences were assessed using Analysis of Variance Models and Tukey Honest Significant Differences. To identify significant taxa between treatment groups, Linear discriminant analysis Effect Size (LefSe) and Analysis of Differential Abundance Taking Sample Variation Into Account were used. Differential abundant analysis indicated that members of the Lachnospiraceae family were significantly enriched in non-responders and the genus Tannerella and species Granulicatella adiances were also highly abundant in this group. LefSe analysis between non-responders and SDF-treated groups revealed that genera Leptotrichia and Granulicatella were enriched in non-responders. We observed the highest abundance of phosphotransferase system and lowest abundance of lipopolysaccharide synthesis in non-responders. The microbiome in dental biofilms is responsible for initiation and progression of dental caries. SDF has been shown to be effective in arresting the progression carious lesions, in part due to its antimicrobial properties. Findings suggest that the differential abundance of select microbiota and specific pathway functioning in individuals that present with recurrent decay after SDF treatment may contribute to a potential failure of silver diamine fluoride to arrest dental caries. However, the short duration of sample collection following SDF application and the small sample size emphasize the need for further data and additional analysis.

Repurposing of Tamoxifen Against the Oral Bacteria

Objectives

Tamoxifen (TAM), which is used for treating breast cancer, has exhibited another important function as an antimicrobial agent. The objective of this study is to investigate the antibacterial action of TAM against the bacteria present in the human oral cavity.

Materials and Methods

The bacteria present in the human oral cavity were isolated from healthy individuals. Different concentrations of TAM were tested against the isolated bacteria. Additionally, bactericidal and bacteriostatic effects of TAM were also determined.

Results

Out of 23 isolated bacteria, a greater number of Gram-positive bacteria were highly susceptible to the low concentrations of TAM than Gram-negative bacteria. Kytococcus sedentarius, which is Gram-positive bacterium, and Pseudomonas stutzeri, which is Gram-negative bacterium, needed a high minimum inhibitory concentration value of TAM (2.5 mg/mL) to be inhibited by TAM's bacteriostatic action. Resistance to TAM was also observed in three strains of Gram-positive and four strains of Gram-negative bacteria.

Conclusion

TAM has shown a potential antibacterial effect against the bacteria present in the oral cavity, especially against Gram-positive bacteria. This effect is mostly bacteriostatic. This study also found bacterial resistance toward TAM.

Nutritionally variant streptococci causing endophthalmitis associated with intravitreal anti-vascular endothelial growth factor injection

Purpose

To describe the clinical course and microbial properties of the first two reported cases of nutritionally variant Streptococci (Granulicatella adiacens and Abiotrophia defectiva) endophthalmitis following intravitreal anti-vascular endothelial growth factor injection (IVI).

Observations

A 74 year-old female developed Granulicatella adiacens endophthalmitis following IVI. The patient underwent a pars plana vitrectomy and visual acuity recovered to 20/30 in six weeks. Similarly, an 88 year-old male developed Abiotrophia defectiva endophthalmitis after IVI. After a pars plana vitrectomy, the visual acuity recovered to 20/60 at five weeks.

Conclusions and Importance

Endophthalmitis due to Streptococcus species has traditionally resulted in uniformly poor visual outcomes. However, nutritionally variant Streptococci, now reclassified as Granulicatella and Abiotrophia species, appear to have a less aggressive clinical course and better visual acuity outcomes. To the authors’ knowledge, these are the first reports of nutritionally variant Streptococci following IVI related endophthalmitis.

Atypical presentation of Abiotrophia defectiva infective endocarditis in an octogenarian

Blood cultures should be performed in non-specifically unwell older adults following nonspecific presentations. Prompt diagnosis and commencement of targeted antimicrobial therapy are essential in older patients with A. defectiva IE.

Prosthetic Joint Infection After Dental Work: Is the Correct Prophylaxis Being Prescribed? A Systematic Review

Background

Prosthetic joint infection (PJI) of total hip (THA) or total knee arthroplasty (TKA) after dental procedures is uncommon, and antibiotic prophylaxis remains controversial. For high-risk patients, the American Academy of Orthopedic Surgeons recommends amoxicillin prophylaxis. However, no systematic review of the literature of PJIs associated with dental procedures explores if amoxicillin is suitable for the reported organisms.

Methods

A librarian-assisted search of the major databases (PubMed, Medline, Embase, Scopus) identified 954 articles. Only case reports, case series, and reviews with patient level data were included. After exclusions, 79 articles were fully reviewed.

Results

Forty-four PJIs after dental procedures were identified, 22 in primary THA, 20 in primary TKA, one in revision THA, and one in a hip resurfacing procedure. Antibiotic prophylaxis was documented for 5 patients. The dental procedure was invasive in 35 (79.5%). Comorbidities were present in 17 patients (38.7%). The organisms reported were Streptococcus spp. in 44%, other aerobic gram-positives in 27%, anaerobic gram-positives in 18%, and gram-negative organisms in 11%. An estimated 46% of organisms may be resistant to amoxicillin. The outcomes of treatment were reported for 35 patients (79.5%). Twenty-seven patients (61.4%) had no clinical signs of PJI at the final follow-up visit.

Conclusions

Lower extremity PJI associated with dental procedures is often caused by organisms unlikely to be prevented with amoxicillin. Additional studies are warranted to determine the choice and efficacy of antibiotic prophylaxis to prevent dental-associated PJI in the highest risk patients. Insufficient data exist to recommend the optimal treatment for patients with PJI in THA and TKA associated with dental procedures.

Endoscopic discectomy and debridement for a patient with spondylodiscitis caused by Granulicatella adiacens following mitral valve repair: a case report

We present the case of 40-year-old female patient had severe low back pain after robotic mitral valve repair for chordae tendineae rupture of anterior mitral leaflet. Lumbar-spine magnetic resonance imaging and blood culture diagnosed with Granulicatella adiacens spondylodiscitis at L5-S1, which was successfully treated with percutaneous spine endoscopic debridement and prolonged antimicrobial treatment. Early isolation and treatment of pathogens may decrease the need for surgical intervention with rapid recovery and a shorter duration of hospitalization. We should be aware of the diagnosis of spondylodiscitis when a patient has low back pain with a previous cardiac or dental procedure history. Endoscopic discectomy with debridement is a minimally invasive, safe, direct visualization and effective approach for treatment of infectious spondylodiscitis and is beneficial for symptom relief.

Simultaneous bilateral revision total knee arthroplasty following Abiotrophia defectiva infection

A 65-year old man presented with 6-week history of bilateral knee pain and swelling, with difficulty mobilising. He had bilateral total knee arthroplasties in situ performed 5 years prior complicated by postoperative wound infection. Bilateral synovial fluid cultures were positive for Abiotrophia defectiva, and extensive investigations had not identified an extra-articular source of infection. Failing debridement antibiotic and implant retention procedure, the patient underwent a simultaneous bilateral 2-stage revision with articulated cement spacers impregnated with vancomycin and gentamycin. The patient received 6 weeks of intravenous antibiotics after each stage. A. defectiva is a nutritiously fastidious organism, posing a challenge for clinical laboratories to isolate and perform antimicrobial susceptibility testing, yet prosthetic joint infections caused by A. defectiva are scarce in literature and present atypically with subacute signs of chronic infection. This poses a diagnostic and therapeutic challenge, and two-stage revision is the only documented treatment that successfully eradicates the infection.

Abiotrophia defectiva liver abscess in a teenage boy after a supposedly mild blunt abdominal trauma: a case report

Background

A pyogenic liver abscess (PLA) represents a pus-filled cavity within the liver parenchyma caused by the invasion and multiplication of bacteria. The most common offender isolated from the PLA in children is Staphylococcus aureus. Abiotrophia defectiva is a Gram-positive pleomorphic bacterium, commonly found in the oral cavity, intestinal, and genitourinary mucosa as part of the normal microbiota. It has been proven to be an etiological factor in various infections, but rarely in cases of PLA. The case presented here is, to the best of our knowledge, the first pediatric case of PLA caused by A. defectiva.

Case presentation

A 13-year-old Caucasian boy presented with a two-day history of abdominal pain, fever up to 40 °C, and polyuria. Contrast-enhanced computed tomography (CT) scan revealed a single, multiloculated liver lesion, suggestive of a liver abscess. The boy had sustained a bicycle handlebar injury to his upper abdomen 3 weeks before the symptoms appeared and had been completely asymptomatic until 2 days before admission. He was successfully treated with antibiotic therapy and open surgical drainage. A. defectiva was isolated from the abscess material. Histopathology report described the lesion as a chronic PLA.

Conclusions

A. defectiva is a highly uncommon cause of liver abscess in children. In such cases, various predisposing factors should be considered, including antecedent blunt abdominal trauma.

In vitro antimicrobial activity against Abiotrophia defectiva and Granulicatella elegans biofilms

OBJECTIVES

To determine the efficacy of different antibiotics (alone or in combination) against Abiotrophia defectiva and Granulicatella elegans biofilms and to investigate the anti-biofilm activity of gentamicin alone versus blood culture isolates from both species.

METHODS

The activity of benzylpenicillin, clindamycin, daptomycin, fosfomycin, gentamicin, levofloxacin and rifampicin against 24-hour-old biofilms of A. defectiva and G. elegans was investigated in vitro by conventional microbiological methods and isothermal microcalorimetry.

RESULTS

For planktonic bacteria, the MIC values of tested antibiotics ranged from 0.016 to 64 mg/L, as determined by microcalorimetry. Higher antibiotic concentrations, ranging from 1 to >1024 mg/L, were needed to produce an effect on biofilm bacteria. Gentamicin was an exception as it was active at 1 mg/L against both planktonic and biofilm G. elegans. A synergistic effect was observed when daptomycin was combined with benzylpenicillin, gentamicin or rifampicin against A. defectiva biofilms and when gentamicin was combined with rifampicin or levofloxacin against G. elegans biofilms. A. defectiva clinical isolates displayed greater variability in gentamicin susceptibility as compared with G. elegans strains.

CONCLUSIONS

Antimicrobial susceptibility profiles vary widely between Abiotrophia and Granulicatella biofilms, and synergistic effects of the tested antibiotics were heterogeneous. The clinical relevance of these in vitro observations needs to be confirmed in experimental in vivo conditions and human trials, before guidelines for the treatment of A. defectiva and G. elegans infections are established. This study suggests the benefit of further clinical exploration of antibiotic combinations with anti-biofilm effect.

Abiotrophia defectiva as a cause of infective endocarditis with embolic complications in children

Abiotrophia defectiva is a rare pathogen of infective endocarditis (IE) but is frequently involved in embolic complication and valvular dysfunction. IE caused by A. defectiva in children is poorly studied. This study reports four cases of A. defectiva IE in children and reviews previously reported five pediatric cases of A. defectiva IE. Most of the patients presented with a subacute course, with prolonged fever or atypical symptoms. Eight patients had embolic complications at presentation. All nine children were treated with combination antimicrobial therapy and six of them received surgical intervention. All patients recovered well without relapse. A. defectiva should be considered in children with infective endocarditis, especially in those with atypical presentations. As complications are frequent and more than half of the patients need surgical treatment, prompt diagnosis along with appropriate treatment is necessary.

Granulicatella adiacens abscess: Two rare cases and review

Granulicatella adiacens is a nutritionally variant streptococcus species. These bacteria are rarely isolated in the laboratory due to their fastidious growth requirements. These have been mostly reported from bloodstream infections, infective endocarditis, infections of orbit, nasolacrimal duct and breast implants. Here, we are reporting two cases of subcutaneous abscesses caused by G. adiacens. In first case, it was isolated from abscess around elbow joint and second case was a suprapatellar abscess. We have also reviewed the published data concerning diagnosis and antimicrobial susceptibility pattern of Granulicatella infections and included some Indian cases.

Epidemiology, Clinical Features, and Outcome of Infective Endocarditis due to Abiotrophia Species and Granulicatella Species: Report of 76 Cases, 2000-2015

Background

Infective endocarditis (IE) caused by Abiotrophia (ABI) and Granulicatella (GRA) species is poorly studied. This work aims to describe and compare the main features of ABI and GRA IE.

Methods

We performed a retrospective study of 12 IE institutional cases of GRA or ABI and of 64 cases published in the literature (overall, 38 ABI and 38 GRA IE cases).

Results

ABI/GRA IE represented 1.51% of IE cases in our institution between 2000 and 2015, compared to 0.88% of HACEK (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella)-related IE and 16.62% of Viridans group streptococci (VGS) IE. Institutional ABI/GRA IE case characteristics were comparable to that of VGS, but periannular complications were more frequent (P = .008). Congenital heart disease was reported in 4 (10.5%) ABI and in 11 (28.9%) GRA cases (P = .04). Mitral valve was more frequently involved in ABI than in GRA (P < .001). Patient sex, prosthetic IE, aortic involvement, penicillin susceptibility, and surgical treatment were comparable between the genera. New-onset heart failure was the most frequent complication without genera differences (P = .21). Five (13.2%) ABI patients and 2 (5.3%) GRA patients died (P = .23). Factors associated with higher mortality were age (P = .02) and new-onset heart failure (P = .02). The genus (GRA vs ABI) was not associated with higher mortality (P = .23).

Conclusions

GRA/ABI IE was more prevalent than HACEK IE and approximately one-tenth as prevalent as VGS; periannular complications were more frequent. GRA and ABI genera IE presented similar clinical features and outcomes. Overall mortality was low, and related to age and development of heart failure.

Exploring the microbiota of upper respiratory tract during the development of pneumonia in a mouse model

The alteration of the microbial community in the upper respiratory tract (URT) can contribute to the colonization and invasion of respiratory pathogens. However, there are no studies regarding whether the characteristics of the URT microbiota can be affected by infections in lower respiratory tract (LRT). To elucidate the microbial profiles of the URT during pneumonia, the oral, nasal, and lung microbiota was evaluated at the early phase in a murine pneumonia model by direct intratracheal inoculation of Klebsiella pneumoniae. The meta 16S rRNA sequencing of bronchoalveolar lavage fluid after K. pneumoniae inoculation presented alterations in the beta diversity of the microbes, but not in the alpha diversity. At this point, a significant increase in microbial alpha diversity was observed in the oral cavity, but not in the nasal cavity. The significant increase was observed in the family Carnobacteriaceae and family Enterococcaceae. These results suggest that characterizing the microbial community of the respiratory tract may not just involve a simple downstream relationship from the URT to the LRT. The health status of the LRT may influence the oral microbiota. Thus, evaluation of the oral microbiota may contribute towards monitoring lung health; the oral microbiota may act as a diagnostic marker of pneumonia.

Native Valve Infective Endocarditis with Osteomyelitis and Brain Abscess Caused by Granulicatella adiacens with Literature Review

Granulicatella adiacens is a type of NVS (nutritionally variant streptococci) rarely causing infective endocarditis (IE). NVS are fastidious and unable to sustain growth on routine culture media due to lack of specific nutrients. Endocarditis caused by NVS due to their virulence is associated with higher treatment failures and mortality rates. New antimicrobial susceptibility patterns are indicative of a significant rise in penicillin resistance and susceptibility differences between NVS subspecies. Initial empirical therapy is essential as a delay in using the appropriate agent leads to poor results. We present a case of an immunocompetent young female with recent intravenous drug abuse resulting in native mitral valve endocarditis with ruptured chordae tendineae and septic embolization, causing brain abscess and lumbar spine osteomyelitis. She was transferred to a tertiary center where she underwent mitral valve replacement successfully and treated with six weeks of intravenous vancomycin and ertapenem. To our knowledge, ours is the first case report of G. adiacens endocarditis in an adult with brain abscess and osteomyelitis with an excellent response to antibiotic therapy. Based on our case report, literature review, and new antimicrobial susceptibility patterns, updates to treatment guidelines are suggested to improve the therapeutic outcomes.

Granulicatella adiacens and Abiotrophia defectiva Native Vertebral Osteomyelitis: Three Cases and Literature Review of Clinical Characteristics and Treatment Approach

Granulicatella adiacens and Abiotrophia defectiva are an increasingly recognized cause of osteoarticular infections. We describe two cases of G. adiacens and one case of A. defectiva native vertebral osteomyelitis (NVO) and review all published cases. Nine cases of G. adiacens NVO and two cases of A. defectiva NVO were previously described. Patients were usually middle-aged men, and classical risk factors for NVO were present in half of the cases. Concomitant bacteremia was reported in 78.6% of cases, and concurrent infective endocarditis occurred in 36.4% of this sub-group of patients. Many different antibiotic schemes were recorded, with median treatment duration of 6 weeks. In the most recent reports, glycopeptides represented the most frequent empirical therapy, possibly due to the increasing emergence of G. adiacens and A. defectiva penicillin-resistant strains. Stabilization surgery was rarely required (14.3% of cases), and clinical cure was generally achieved. In conclusion, Granulicatella spp. and Abiotrophia spp. NVO is rare but increasingly described. A total antibiotic course of six weeks seems to be appropriate for noncomplicated cases, and clinical outcome is generally favorable.

Trivalvular infective endocarditis secondary to Granulicatella adiacens and Peptostreptococcus spp

We present a case of a 42-year-old Caucasian man that came to our facility complaining of dyspnea and subjective fevers and was found to have infective endocarditis. His blood cultures initially grew Peptostreptococcus spp and he was started on penicillin and gentamicin. Repeat blood cultures, drawn 48 h later, became positive for Granulicatella adiacens. Vancomycin was added at this point, given reports of growing penicillin resistance of Granulicatella spp. Transthoracic echocardiogram showed multiple vegetations on the aortic, mitral and tricuspid valves. The patient’s final antibacterial regimen consisted of intravenous penicillin G 24 million units daily and vancomycin (goal trough of 15–20) for a total of 6 weeks. The first 2 weeks of his regimen also included gentamicin. The patient was not considered for valve replacement surgery given concern for continued use of illicit intravenous drugs. Peptostreptococcus species are anaerobic, non-spore forming, gram-positive cocci, thought to generally have a subacute clinical presentation. Granulicatella genus is nutritionally deficient bacteria which require a supplemented media in order to grow. Both of these bacteria are present in the mouth and gastrointestinal flora. The rate of infective endocarditis from anaerobic species has been reported up to 16%, which includes multiple species. While on nutritionally deficient bacteria are reported to be involved on infective endocarditis in the range of 3–8%. Antimicrobial resistance is on the rise for both of these species, which makes the appropriate choice of antimicrobials quite important.

Development of a periprosthetic joint infection by Abiotrophia defectiva years after total knee arthroplasty

A 74-year-old male presented with acute right knee pain and inability to ambulate. The patient had a total knee arthroplasty, previously complicated by a periprosthetic femur fracture requiring surgical fixation and subsequent methicillin-resistant Staphylococcus epidermidis periprosthetic joint infection treated via two-stage revision. Cultures from knee fluid aspiration were positive for Abiotrophia defectiva. Identification was confirmed using matrix-assisted laser desorption ionization–time of flight mass spectrometry. The patient underwent a two-stage revision. Between stages, the patient received intravenous ceftriaxone for six weeks with subsequent normalization of inflammatory markers. Diagnosis of periprosthetic joint infection with identification of the organism is important to guide appropriate treatment.

Chronic mandibular osteomyelitis caused by Granulicatella adiacens in an immunocompetent child

We report a pediatric case aged 10 years with Granulicatella adiacens-associated chronic mandibular osteomyelitis. The causative pathogen was uncertain because polymicrobial species were detected from the bacterial culture in bone marrow fluid. In contrast, G. adiacens was predominantly identified in the clone library analysis of the bacterial 16S rRNA gene sequence. Vancomycin to which G. adiacens was reported to be susceptible was not administrated sufficiently to this patient because of its adverse event, whereas linezolid and ciprofloxacin was alternatively effective for the treatment of chronic mandibular osteomyelitis.

Aortitis caused by Abiotrophia defectiva: Description of two cases

Abiotrophia defectiva is a well-known endocarditis pathogen, however it has never been described as a cause of primary aortitis. Here we describe the first published case of thoracic aortitis and an unusual case of aortic graft infection due to A. defectiva, which were both managed conservatively.

Cardiogenic and septic shock associated with aortic and mitral valve infective endocarditis caused by Abiotrophia Defectiva from a urinary tract infection

Abiotrophia defectiva, also known as nutritionally variant streptococcus, is part of the normal flora of the oral cavity and urogenital and intestinal tracts and is a rare cause of infective endocarditis. It is fastidious or difficult to culture and associated with high rates of septic embolization, treatment failure and mortality. We describe an unusual presentation of infective endocarditis with severe mitral valve regurgitation due to Abiotrophia defectiva in an immunocompetent patient. After a complicated hospital course, surgical replacement of both the mitral and aortic valves was performed. We suggest that this patient likely had subacute infective endocarditis before diagnosis and treatment of her urinary tract infection, and following treatment failure, she developed life-threatening infective endocarditis. This case report highlights that patients with Abiotrophia defectiva infections are at high risk for infective endocarditis and that the clinical progression from this infection can be slow, with difficulty isolating the pathogen, which can significantly impact patient outcome.