A population-based study of aerococcal bacteraemia in the MALDI-TOF MS-era

Characteristics of urinary tract infections in children with positive urine culture for Aerococcusurinae

Urinary tract infections caused by Aerococcus urinae have rarely been reported in children, and the clinical characteristics remain unclear. We reviewed medical records of children whose urine cultures grew A. urinae (≥104 CFU/mL) at a tertiary children's hospital in Tokyo, Japan. We found 17 pediatric patients in a review of 22,769 urine cultures between June 2006 and May 2022. The median age of 17 patients was 10.7 years (IQR 8-13 years), and males represented 76.5 % of the patients. Sixteen patients (94.1 %) had underlying urological conditions (neurogenic bladder, vesicoureteral reflux, urethral stenosis, bladder exstrophy, or urinary catheterization). The chief symptoms were fever (35.3 %), malodorous urine (23.5 %), nausea (11.8 %), and back pain (5.9 %). Ten patients were asymptomatic. Pyelonephritis was diagnosed in five male patients. All of them had underlying abnormal conditions of the bladder, and two had malodorous urine. All patients had favorable outcomes after 10-14 days of ampicillin/amoxicillin-based antimicrobial therapy.

Acute Pyelonephritis with Bacteremia in an 89-Year-Old Woman Caused by Two Slow-Growing Bacteria: Aerococcus urinae and Actinotignum schaalii

Aerococcus urinae is an aerobic Gram-positive coccus that grows as tiny alpha-hemolytic colonies. Actinotignum schaalii is a slow-growing facultative anaerobic Gram-positive rod. These bacteria are part of the urogenital microbiota of healthy patients, but can also be involved in urinary tract infections (UTIs), particularly in elderly men and young children. Because A. urinae and A. schaalii are fastidious and are difficult to identify with phenotypic methods, they are underestimated causes of UTIs. Their growth is slow and requires a blood-enriched medium incubated under an anaerobic or 5% CO2 atmosphere for 48 h and from 24 to 48 h for A. schaalii and A. urinae, respectively. Furthermore, accurate identification is only possible using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) or molecular-based methods. In rare cases, these bacteria can be responsible for invasive infections. We describe, here, an unusual case of bacteremic UTI caused by both A. schaalii and A. urinae in an 89-year-old woman. She presented with dyspnea, and bacteriuria was noted. This challenging clinical and microbiological diagnosis was made in our laboratory by Gram staining urine with a leucocyte count >50/μL and/or a bacterial count >14/μL urinary culture on a blood agar plate. After 10 days of antimicrobial treatment consisting of 2 g amoxicillin PO t.i.d., the patient was discharged with a complete clinical and biological recovery. A. schaalii and A. urinae are probably still underestimated causes of UTIs. Microbiologists could consider the presence of these two bacteria using appropriate culture and identification methods in cases where a positive direct examination of urine reveals small Gram-positive rods or cocci, where undocumented UTIs are present in elderly patients, but also where a urinary dipstick is negative for nitrites and is associated with leukocyturia.

Susceptibility of Aerococcus urinae and Aerococcus sanguinicola to Standard Antibiotics and to Nitroxoline

Aerococcus urinae and Aerococcus sanguinicola have been increasingly recognized as causative agents of urinary tract infection (UTI) during the last decade. Nitroxoline achieves high urinary concentrations after oral administration and is recommended in uncomplicated UTI in Germany, but its activity against Aerococcus spp. is unknown. The aim of this study was to assess the in vitro susceptibility of clinical Aerococcus species isolates to standard antibiotics and to nitroxoline. Between December 2016 and June 2018, 166 A. urinae and 18 A. sanguinicola isolates were recovered from urine specimens sent to the microbiology laboratory of the University Hospital of Cologne, Germany. Susceptibility to standard antimicrobials was analyzed by disk diffusion (DD) according to EUCAST methodology, nitroxoline was tested by DD and agar dilution. Susceptibility of Aerococcus spp. to benzylpenicillin, ampicillin, meropenem, rifampicin, nitrofurantoin, and vancomycin was 100% and resistance was documented only against ciprofloxacin (20 of 184; 10.9%). MICs of nitroxoline in A. urinae isolates were low (MIC50/90 1/2 mg/L) while significantly higher MICs were observed in A. sanguinicola (MIC50/90 64/128 mg/L). If the EUCAST nitroxoline breakpoint for E. coli and uncomplicated UTI was applied (16 mg/L), 97.6% of A. urinae isolates would be interpreted as susceptible while all A. sanguinicola isolates would be considered resistant. Nitroxoline demonstrated high activity against clinical A. urinae isolates, but low activity against A. sanguinicola. Nitroxoline is an approved antimicrobial for UTI and could be an alternative oral drug to treat A. urinae urinary tract infection, yet clinical studies are needed to demonstrate this potential in vivo. IMPORTANCE A. urinae and A. sanguinicola have been increasingly recognized as causative agents in urinary tract infections. Currently, there are few data available on the activity of different antibiotics against these species and no data on nitroxoline. We demonstrate that clinical isolates in Germany are highly susceptible to ampicillin, while resistance to ciprofloxacin was common (10.9%). Additionally, we show that nitroxoline is highly active against A. urinae, but not against A. sanguinicola, which based on the presented data, should be considered intrinsically resistant. The presented data will help to improve the therapy of urinary tract infections by Aerococcus species.

Fatal infective endocarditis caused by Aerococcus sanguinicola: a case report and literature review

Aerococcus sanguinicola is a bacterium that can cause urinary tract infections and on rare occasions infective endocarditis (IE). The prognosis of IE caused by aerococci is generally favourable despite that the patients are typically old and have multiple comorbidities. Here we report a case of A. sanguinicola native valve aortic IE in a 68-year-old man with an underlying urinary tract condition. The infection led to severe aortic valve insufficiency and rapid death before the patient could be subjected to surgery. This demonstrates that IE caused by A. sanguinicola can be severe and cause valve destruction. In addition to the case report, we provide a review of the current literature on A. sanguinicola IE.

Get the Species Right: Aerococcus viridans is Likely not Responsible

How to cite this article: Rasmussen M, Sunnerhagen T. Get the Species Right: Aerococcus viridans is Likely not Responsible. Indian J Crit Care Med 2022;26(10):1158.

Clinical and microbiological characterization of Aerococcus urinae bacteraemias at Helsinki metropolitan area, Finland

Our objective was to assess the incidence of bacteraemic Aerococcus urinae cases at Helsinki metropolitan area, Finland, from a 6-year study period (2013 to 2018) and to further characterize available cases. The study evaluates the outcome of commonly used cefuroxime treatment and determinate a set of A. urinae in vitro antimicrobial susceptibilities for benzylpenicillin, cefuroxime, and ceftriaxone. Clinical records of A. urinae bacteraemic patients were reviewed retrospectively. Antimicrobial susceptibility testing was performed by disk diffusion, gradient test, and broth microdilution for 139–141 clinical A. urinae isolates. Clinical data of 72/77 patients were combined with the in vitro susceptibilities. We found an increasing number of bacteraemic A. urinae cases within 6-year study period (p = 0.01). The patients were mainly elderly males, and all suffered from underlying conditions. A total of 27.3% of cases (21/77) showed polymicrobial blood cultures. Thirty-day mortality was 22.1%. Cefuroxime was the initial empiric antimicrobial agent given for 66/76 of the patients and treatment outcome was favorable for 20/22 patients who received cefuroxime at least up to day 5. All isolates were susceptible to benzylpenicillin and cefuroxime interpreted by EUCAST breakpoints for Aerococci and PK-PD breakpoints, respectively. MIC determinations gave variable results for ceftriaxone, 2.1–2.9% of the isolates were resistant. To conclude, it seems that the number of bacteraemic Aerococcus urinae cases is increasing at Helsinki metropolitan area, Finland, reflecting the growing blood culture sampling. Clinical A. urinae isolates were susceptible to cefuroxime in vitro. Treatment data indicate that empirical cefuroxime started for possibly urinary tract -derived community-acquired bacteraemia covers A. urinae.

Aerococcus urinae: A Rare Cause of Endocarditis Presenting With Acute Stroke

Aerococcus urinae is a rare organism infrequently isolated from cultures. Mostly known to cause urinary tract infection, it can cause bacteremia leading to severe urosepsis and infective endocarditis. Embolization is frequently reported with Aerococcus urinae endocarditis (AUE); hence, the presentation is highly variable. Sequelae such as various central nervous system manifestations, sepsis, valvular regurgitation with heart failure and even coronary artery involvement have been reported. We report a case of a 58-year-old man with AUE of the aortic valve, severe aortic regurgitation and embolic stroke as a result of embolization from AUE and ultimately required aortic valve replacement. Our case highlights this rare cause of endocarditis and offers insight into the variability of patient presentation and risk factors to consider.

A mouse model displays host and bacterial strain differences in Aerococcus urinae urinary tract infection

In recent years, the clinical significance of Aerococcus urinae has been increasingly recognized. A. urinae has been implicated in cases of urinary tract infection (UTI; acute cystitis and pyelonephritis) in both male and female patients, ranging from children to older adults. Aerococcus urinae can also be invasive, causing urosepsis, endocarditis, and musculoskeletal infections. Mechanisms of pathogenesis in A. urinae infections are poorly understood, largely due to the lack of an animal model system. In response to this gap, we developed a model of A. urinae urinary tract infection in mice. We compared A. urinae UTI in female C3H/HeN and C57BL/6 mice and compared four clinical isolates of A. urinae isolated from patients with UTI, urgency urinary incontinence, and overactive bladder. Our data demonstrate that host genetic background modulates A. urinae UTI. Female C57BL/6 female mice rapidly cleared the infection. Female C3H/HeN mice, which have inherent vesicoureteral reflux that flushes urine from the bladder up into the kidneys, were susceptible to prolonged bacteriuria. This result is consistent with the fact that A. urinae infections most frequently occur in patients with underlying urinary tract abnormalities or disorders that make them susceptible to bacterial infection. Unlike uropathogens such as E. coli, which cause infection and inflammation both of the bladder and kidneys in C3H/HeN mice, A. urinae displayed tropism for the kidney, persisting in kidney tissue even after clearance of bacteria from the bladder. Aerococcus urinae strains from different genetic clades displayed varying propensities to cause persistent kidney infection. Aerococcus urinae infected kidneys displayed histological inflammation, neutrophil recruitment and increased pro-inflammatory cytokines. These results set the stage for future research that interrogates host-pathogen interactions between A. urinae and the urinary tract.

Summary:Aerococcus urinae clinical isolates are genetically diverse and display differential capacity to cause UTI in a mouse model. Infection was rapidly cleared from the bladder, but persisted and caused inflammation in the kidney.

Soul of the Jukskei River: The Extent of Bacterial Contamination in the Jukskei River in Gauteng Province, South Africa

River water quality is an important health issue as the water is utilised for drinking, domestic and agricultural use in developing countries. This study aimed to investigate the effect water from a major city has on the water quality of the Jukskei River that daylights in Johannesburg, South Africa. The river water samples were analysed for physio-chemical properties, microbiology, antibiotic resistance of bacterial isolates, genetic markers, and potentially toxic metals. Data analysis revealed increased electrical conductivity, total dissolved solids, and turbidity since 2010. Total Coliform and Escherichia coli detected were above the South African water quality guidelines for domestic, recreational, and irrigation purposes. Additionally, sodium, zinc, nickel, lithium, and lead exceeded the guidelines in domestic, recreational, and irrigation water. Pathogenic strains of E. coli (aEPEC, EHEC, EIEC, and EAEC) were isolated from the water. Various other potentially pathogenic organisms that have been implicated as causes of gastro-intestinal, and a wide range of other diseases, were also detected and demonstrated multiple levels of resistance to antibiotics tested. The results show that the river water is a potential health threat to downstream users. These results will feed into the environmental management action plan for Water for the Future (NGO group).

Background of patients with Aerococcus spp. detected in blood cultures, and drug sensitivity of Aerococcus spp

This study aimed to review the clinical characteristics of patients with Aerococcus spp. detected by blood culture, and drug susceptibility of Aerococcus spp. All cases of Aerococcus spp. determined using blood culture between June 2013 and May 2020 in a single institution were included; patient information (age, sex, comorbidities, outcome, diagnosis, antimicrobial agents) was analyzed. The cohort comprised 25 patients (18 [72%] men and 7 [28%] women; median age, 84.5 [range, 75-87] years). Thirteen (52%) patients had urinary tract infections(UTI) caused by Aerococcus spp. All patients had a favorable prognosis, except 1 who died owing to infective endocarditis. Drug susceptibility testing showed that most isolates were susceptible to β-lactams except 1. However, 24 (96%) cases were resistant to trimethoprim-sulfamethoxazole and 10 (40%) to quinolones. Aerococcus spp. are important causative agents of bacteremia and UTI. The increasing reports of Aerococcus spp. infections could lead to better treatment schemes and facilitate diagnosis.

Validation of a Gradient Diffusion Method (Etest) for Testing of Antimicrobial Susceptibility of Aerococcus urinae to Fluoroquinolones

Aerococcus urinae is a urinary pathogen with well-described resistance to fluoroquinolones. This study aimed to validate the gradient diffusion (GD) method (Etest) on cation-adjusted Mueller-Hinton agar with 5% sheep blood for testing the susceptibilities of Aerococcus urinae to the antimicrobial agents ciprofloxacin and levofloxacin and to compare the Etest to the broth microdilution (BMD) method from CLSI document M45-A3. Agar dilution (AD), as recommended by EUCAST, was used as an alternative reference method to arbitrate discrepancies or address technical issues. Aerococcus urinae isolates from urinary specimens were prospectively collected between June 2016 and December 2017 from six hospitals in Quebec, Canada, and identifications were confirmed using Vitek MS with the IVD 3.0 database. Of the 207 isolates tested using BMD, 37 (17.9%) showed trailing and 19 (9.2%) showed insufficient growth; these were tested using AD. Also, 38 isolates (18.4%) for ciprofloxacin and 13 isolates (6.3%) for levofloxacin showed a lack of essential or categorical agreement between the Etest and BMD and were also tested by AD. By use of a combined reference method (BMD or AD), the susceptibility rates of Aerococcus urinae were 82.6% and 81.6% for ciprofloxacin and levofloxacin, respectively. Categorical agreement between GD and the combined reference methods was 95.2% for ciprofloxacin and 97.1% for levofloxacin, with no very major error identified. Major and minor error rates were 0.6% and 4.3% for ciprofloxacin and 1.2% and 1.9% for levofloxacin. Overall, antimicrobial susceptibility testing (AST) using the Etest on sheep blood agar showed good agreement with the reference methods and can be considered by clinical laboratories wishing to perform AST on Aerococcus urinae isolates.

Management and treatment of Aerococcus bacteremia and endocarditis

OBJECTIVES

We describe our multicenter experience on diagnosis and management of Aerococcus bacteremia including the susceptibility profile of Aerococcus species and a suggested algorithm for clinicians.

METHODS

Retrospective study of all patients with positive blood cultures for Aerococcus species from January 2005 to July 2020 in our institution with clinical data and susceptibility profile. Data were collected from both electronic health record and clinical microbiology laboratory database.

RESULTS

There were 219 unique isolates with only the susceptibility profiles available, while 81 patients had clinical information available. Forty-nine of those cases were deemed as true bloodstream infection and the rest were of unclear clinical significance. Cases of endocarditis (n = 7) were high-grade, monomicrobial bacteremia caused by Aerococcus urinae. Patients with endocarditis were younger (66 vs 80 p < 0.05). The risk for endocarditis was higher if duration of symptoms was longer than 7 days (OR 105, 95% CI: 5-2271), or if there were septic emboli (OR 71, 95% CI: 3-1612). A DENOVA score cutoff of ≥ 3 was 100% sensitive and 89% specific in detecting endocarditis. The 30-day and 3-month all-cause mortality for bacteremia was 17% and 24%, respectively. Six out of seven patients with endocarditis survived.

CONCLUSIONS

Antibiotic regimen for aerococcal bloodstream infections and endocarditis should be guided by species identification and antimicrobial susceptibility testing. DENOVA scoring system's performance in this study is more congruent to other studies. Hence, it can be used as an adjunctive tool in assessing the need for echocardiogram to rule out endocarditis. In our experience, two and four weeks of treatment for bloodstream infections and endocarditis, respectively, had good outcomes.

Aerococcus urinae Isolated from Women with Lower Urinary Tract Symptoms: In Vitro Aggregation and Genome Analysis

Aerococcus urinae is increasingly recognized as a potentially significant urinary tract bacterium. A. urinae has been isolated from urine collected from both males and females with a wide range of clinical conditions, including urinary tract infection (UTI), urgency urinary incontinence (UUI), and overactive bladder (OAB). A. urinae is of particular clinical concern because it is highly resistant to many antibiotics and, when undiagnosed, can cause invasive and life-threatening bacteremia, sepsis, or soft tissue infections. Previous genomic characterization studies have examined A. urinae strains isolated from patients experiencing UTI episodes. Here, we analyzed the genomes of A. urinae strains isolated as part of the urinary microbiome from patients with UUI or OAB. Furthermore, we report that certain A. urinae strains exhibit aggregative in vitro phenotypes, including flocking, which can be modified by various growth medium conditions. Finally, we performed in-depth genomic comparisons to identify pathways that distinguish flocking and nonflocking strains.IMPORTANCE Aerococcus urinae is a urinary bacterium of emerging clinical interest. Here, we explored the ability of 24 strains of A. urinae isolated from women with lower urinary tract symptoms to display aggregation phenotypes in vitro We sequenced and analyzed the genomes of these A. urinae strains. We performed functional genomic analyses to determine whether the in vitro hyperflocking aggregation phenotype displayed by certain A. urinae strains was related to the presence or absence of certain pathways. Our findings demonstrate that A. urinae strains have different propensities to display aggregative properties in vitro and suggest a potential association between phylogeny and flocking.

Subacute Aerococcus urinae Infective Endocarditis With Mycotic Aneurysms in a Pediatric Patient: Case Report and Literature Review

Aerococcus urinae has been found to cause urinary tract infection in elderly patients and has been reported as a rare cause of infective endocarditis associated with significant morbidity and death in adults. However, information regarding its occurrence in children is lacking. We report here the case of a pediatric patient with subacute A urinae infective endocarditis with mycotic aneurysms.

Risk for Endocarditis in Bacteremia With Streptococcus-Like Bacteria: A Retrospective Population-Based Cohort Study

Background

Many genera and species of Streptococcus-like bacteria (SLB) can cause infective endocarditis (IE), but little is known about the epidemiology of and the risk factors for IE in SLB-bacteremia. The aim of the study was to analyze this in a cohort of patients with SLB-bacteremia, focusing on Abiotrophia, Aerococcus, Gemella, and Granulicatella. We also evaluated whether published scoring systems generated for other Gram-positive bacteria known to cause IE (HANDOC for streptococci and NOVA and DENOVA for enterococci) could be used in SLB bacteremia to decide whether transesophageal echocardiography (TEE) could be omitted.

Methods

Positive blood cultures with SLB were retrieved from population-based registries in Sweden (3.2 million inhabitants), from January 2012 to December 2017. Clinical data were collected from medical records. Risk factors for IE were analyzed and the performances of the scoring systems were calculated.

Results

The incidence of bacteremia with the 4 SLB genera was 30 episodes/1 000 000 population per year, of which Aerococcus contributed with 18. Among 568 episodes of bacteremia, 32 cases of IE were identified (5.6%). Infective endocarditis was most common in bacteremia with Abiotrophia (4 of 19) followed by Granulicatella (9 of 124), Gemella (6 of 87), and Aerococcus (13 of 338). NOVA had 100% sensitivity to identify IE but a low specificity (15%). For HANDOC and DENOVA, the sensitivities were 97% and 91%, respectively, whereas specificities were 85% and 90%, respectively, and numbers needed to screen were 3.6 and 2.8, respectively.

Conclusions

Bacteremia with these SLB is relatively rare, and the decision whether TEE should be performed or not could be based on either HANDOC or DENOVA.

Mitral Valve Endocarditis with Perforation from a Urinary Source: An Unusual Case and Literature Review

Aerococcus urinae (AU) is a rare pathogen, identified as gram-positive, catalase-negative coccus that grows in pairs and clusters which has been reported to mainly cause urinary tract infections (UTI), especially in elderly males. Treatment for this microorganism is usually with beta-lactams although cultures with antibiotic susceptibility testing are imperative. We present a case of AU endocarditis initially treated with IV antibiotics; nevertheless, the patient required emergent mitral valve replacement due to severe mitral insufficiency and perforation. We also present an analysis with high-yield points summarizing epidemiology, risk factors, microbiology, clinical features, diagnostic workup, and management of AU in general and AU endocarditis. Finally, we post a literature review of relevant cases and the impact of different variables associated with it.

Perigenital necrotizing soft tissue infection caused by Aerococcus urinae

Aerococcus urinae can cause severe invasive infections emanating from the urinary tract especially in older males with comorbidities. Here we describe a case of an 80 year-old man with multiple comorbidities presenting with a peri-penile abscess and signs of severe infection. Upon incision A. urinae was isolated in pure culture and the infection was cured by a combination of drainage and antimicrobials. This case demonstrates the potential of A. urinae to cause severe soft tissue infections in predisposed individuals.

Identification of two abundant Aerococcus urinae cell wall-anchored proteins

Aerococcus urinae is an emerging pathogen that causes urinary tract infections, bacteremia and infective endocarditis. The mechanisms through which A. urinae cause infection are largely unknown. The aims of this study were to describe the surface proteome of A. urinae and to analyse A. urinae genomes in search for genes encoding surface proteins. Two proteins, denoted Aerococcal surface protein (Asp) 1 and 2, were through the use of mass spectrometry based proteomics found to quantitatively dominate the aerococcal surface. The presence of these proteins on the surface was also shown using ELISA with serum from rabbits immunized with the recombinant Asp. These proteins had a signal sequence in the amino-terminal end and a cell wall-sorting region in the carboxy-terminal end, which contained an LPATG-motif, a hydrophobic domain and a positively charged tail. Twenty-three additional A. urinae genomes were sequenced using Illumina HiSeq technology. Six different variants of asp genes were found (denoted asp1-6). All isolates had either one or two of these asp-genes located in a conserved locus, designated Locus encoding Aerococcal Surface Proteins (LASP). The 25 genomes had in median 13 genes encoding LPXTG-proteins (range 6-24). For other Gram-positive bacteria, cell wall-anchored surface proteins with an LPXTG-motif play a key role for virulence. Thus, it will be of great interest to explore the function of the Asp proteins of A. urinae to establish a better understanding of the molecular mechanisms by which A. urinae cause disease.

Treatment considerations for potential uropathogens detected by precision microbiological testing

PURPOSE

The clinical and microbiological data for urinary tract infections (UTIs) for 6 organisms detected by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) at community health systems were examined.

SUMMARY

The use of precision microbiological diagnostic testing such as MALDI-TOF and real-time quantitative polymerase chain reaction has increased the ability to detect a wider spectrum of organisms. This has raised questions of the clinical relevance of infrequently encountered organisms, especially when cultured from urine. This article reviews clinical and microbiological data for UTIs for 6 organisms detected by MALDI-TOF at community health systems (Actinotignum schaalii, Chryseobacterium indologenes, Aerococcus urinae, Aerococcus sanguinicola, Corynebacterium riegelii, and Corynebacterium urealyticum). Since little information currently exists, most of the data associating the aforementioned organisms with UTIs were derived from case reports. Although these organisms are more readily identified using precision microbiological diagnostic testing methods, infection should not be assumed based on culture results alone since asymptomatic bacteriuria has been reported. Similar to more common urinary pathogens, clinical correlation is essential. To facilitate treatment, we provide a table of empirical options likely to achieve clinical success based on in vivo and in vitro data. If available, pathogen-specific susceptibility data should be used to direct therapy.

CONCLUSION

Clinical and microbiological data and potential treatment options were presented for 6 traditionally underrecognized organisms that are increasingly being found from urinary specimens. The treatment recommendations should be interpreted cautiously as they were devised through the use of very limited data.

A rare case of Aerococcus urinae infective endocarditis in an atypically young male: case report and review of the literature

BACKGROUND

Aerococcus urinae is a gram-positive, alpha-hemolytic coccus bacterium primarily implicated in less than 1 % of all symptomatic urinary tract infections. Risk factors for disease include male gender, advanced age, and comorbid genitourinary tract pathology. Infections beyond the genitourinary tract are rare, though spondylodiscitis, perineal abscesses, lymphadenitis, bacteremia, meningitis, and endocarditis have been reported. Less than fifty cases of A. urinae infective endocarditis (IE) have been described in the literature. The rare occurrence of A. urinae in human infections and resultant lack of randomized controlled trials have resulted in a significant degree of clinical uncertainty in the management of A. urinae IE.

CASE PRESENTATION

We present an unusual case of a forty-three year-old male with A. urinae infective endocarditis (IE) who was successfully treated with mitral valve replacement and six weeks of penicillin/gentamicin therapy. In addition, we include a comprehensive review of all reported cases of IE due to A. urinae with specific attention to therapeutic regimens and treatment durations.

CONCLUSION

Recent advances in diagnostic technology have led to an increase in the frequency A. urinae is diagnosed. Reviewing cases of Aerococcus urinae infections, their clinical courses and subsequent management can assist future healthcare providers and their patients.

Aerococcus urinae as the Causative Agent in Infective Endocarditis of the Aortic Valve in a Pediatric Patient

Aerococcus species were first described in 1953. They have been previously described as the causative agent of urinary tract infections in the elderly but rarely the causative agent for severe infections. However, there are very few cases reported in the pediatric population. To our knowledge, we report the first case of an adolescent with infective endocarditis caused by Aerococcus urinae.

Urinary tract infection by aerococcus sanguinicola. An emerging opportunistic pathogen

Elderly patients with underlying urological disease have a greater risk of urinary tract infections due to uncommon pathogens. The disease caused by Aerococcus has been underestimated, but mass spectrometry could be a simple method for identifying this pathogen. In this study, we report 2 cases of urinary tract infection by Aerococcus sanguinicola. A descriptive clinical-microbiological study was conducted on the presence of A. sanguinicola causing urinary tract infections. The presence of A. sanguinicola occurred in elderly patients with previous urological disease and a significant count in urine obtained through bladder catheterisation. Correct identification was achieved through mass spectrometry, and the clinical outcome of administering amoxicillin and cefuroxime was satisfactory. In this study, we also report the pathogenic capacity of A. sanguinicola. When there is a significant number of alpha-haemolytic microorganisms in the urine cultures, A. sanguinicola should be ruled out before reporting a result as urogenital microbiota.

A Case of Pacemaker Endocarditis Caused by Aerococcus urinae

Background

Aerococcus urinae has lately been acknowledged as a cause of infective endocarditis (IE) especially in older males with underlying urinary tract disorders. In this population, cardiac implanted electronical devices (CIED) are not uncommon, but despite the capacity of A. urinae to form biofilm in vitro, no cases of aerococcal CIED infections have been reported to date.

Case Presentation

An 84-year-old male with pacemaker was admitted with dysuria one month after a transurethral procedure for urinary bladder cancer. A. urinae was isolated from urine and blood. Transesophageal echocardiography (TEE) was without signs of vegetation on valves or pacing cables. The patient was treated with a twelve-day course of β-lactam antibiotics. Forty days after the initial admission, the patient was readmitted due to malaise, general pain of the joints, chills, and renewed blood cultures grew A. urinae. TEE demonstrated a 10 × 5 mm vegetation on either the tricuspid valve or one of the pacing cables. The pacemaker system was completely removed and demonstrated macroscopic signs of infection. A temporary system was implanted, and after 14 days of penicillin G treatment, a new system permanent system was implanted. Total treatment time was 40 days. Recovery was uneventful.

Conclusion

This report demonstrates that A. urinae can cause CIED infection. In patients with A. urinae bacteremia and a CIED, this risk must be considered, especially if bacteremia reoccurs.

Case Report: A rare case of prosthetic valve infective endocarditis caused by Aerococcus urinae

Infective endocarditis (IE) is a serious and life-threatening cardiac condition, most commonly caused by staphylococci, Streptococcus viridans, and enterococci. However, in special settings, IE can be caused by rare organisms. Here we present a case of IE caused by Aerococcus urinae in a 75-year-old man with a bioprosthetic aortic valve.  Aerococcusurinae is a gram-positive, catalase-negative microorganism and is usually an isolate of complicated urinary tract infections in the elderly male population.  Improvements in diagnostic testing including use of matrix-assisted laser desorption ionization– a time of flight mass spectrometry (MALDI-TOF MS) have played an important role in recognition of Aerococcus urinae.

A prospective observational treatment study of aerococcal urinary tract infection

OBJECTIVES

Aerococcus urinae and Aerococcus sanguinicola cause urinary tract infections (UTIs) and antibiotic treatment recommendations are solely based on in vitro findings and limited clinical experience. Our objective was to investigate the effectiveness of different treatment strategies in aerococcal UTI through a prospective observational study.

METHODS

Urine samples with aerococci were identified and patients were enrolled. The aerococci were subjected to Etests. Information on clinical symptoms, and the treatment given, was collected. Patients were interviewed after the conclusion of treatment to assess clinical cure and a control urine culture assessed the microbiological cure.

RESULTS

Of 31,629 urine samples, 144 grew aerococci and fulfilled the inclusion criteria. 91 patients gave consent and the 72 patients with UTI were assessed for treatment outcome. 53 patients had A. urinae UTI, while 19 had A. sanguinicola UTI. Nitrofurantoin was most commonly prescribed, achieving clinical and microbiological success in 71/76% of cases of A. urinae UTI, and 42/50% of cases of A. sanguinicola UTI. Pivmecillinam achieved success in patients with A. urinae cystitis and ciprofloxacin in patients with pyelonephritis.

CONCLUSIONS

Our results support that nitrofurantoin is a valid option for the treatment of cystitis caused by A. urinae.

Aerococcus urinae and Aerococcus sanguinicola: Susceptibility Testing of 120 Isolates to Six Antimicrobial Agents Using Disk Diffusion (EUCAST), Etest, and Broth Microdilution Techniques

BACKGROUND

Aerococcus urinae and Aerococcus sanguinicola are relatively newcomers and emerging organisms in clinical and microbiological practice. Both species have worldwide been associated with urinary tract infections. More rarely cases of bacteremia/septicemia and infective endocarditis have been reported. Treatment options are therefore important. Just recently, European recommendations on susceptibility testing and interpretive criteria have been released.

OBJECTIVE

In this investigation 120 A. urinae and A. sanguinicola isolates were tested for susceptibility to six antimicrobial agents: Penicillin, cefotaxime, meropenem, vancomycin, linezolid, and rifampicin.

METHODS

Three susceptibility testing methods were used; disk diffusion according to The European Committee on Antimicrobial Susceptibility Testing (EUCAST) standardized disk diffusion methodology and MIC determination with Etest and broth microdilution (BMD). All testing was performed with EUCAST media for fastidious organisms.

RESULTS

Data obtained in this study were part of the background data for establishing EUCAST breakpoints. MIC values obtained by Etest and BMD were well correlated with disk diffusion results.

CONCLUSION

All isolates were found susceptible to all six antimicrobial agents: penicillin, cefotaxime, meropenem, vancomycin, linezolid, and rifampicin.

Genomic characterization, phylogenetic analysis, and identification of virulence factors in Aerococcus sanguinicola and Aerococcus urinae strains isolated from infection episodes

Aerococcus sanguinicola and Aerococcus urinae are emerging pathogens in clinical settings mostly being causative agents of urinary tract infections (UTIs), urogenic sepsis and more seldomly complicated infective endocarditis (IE). Limited knowledge exists concerning the pathogenicity of these two species. Eight clinical A. sanguinicola (isolated from 2009 to 2015) and 40 clinical A. urinae (isolated from 1984 to 2015) strains from episodes of UTIs, bacteremia, and IE were whole-genome sequenced (WGS) to analyze genomic diversity and characterization of virulence genes involved in the bacterial pathogenicity. A. sanguinicola genome sizes were 2.06-2.12 Mb with 47.4-47.6% GC-contents, and 1783-1905 genes were predicted whereof 1170 were core-genes. In case of A. urinae strains, the genome sizes were 1.93-2.44 Mb with 41.6-42.6% GC-contents, and 1708-2256 genes of which 907 were core-genes. Marked differences were observed within A. urinae strains with respect to the average genome sizes, number and sequence identity of core-genes, proteome conservations, phylogenetic analysis, and putative capsular polysaccharide (CPS) loci sequences. Strains of A. sanguinicola showed high degree of homology. Phylogenetic analyses showed the 40 A. urinae strains formed two clusters according to two time periods: 1984-2004 strains and 2010-2015 strains. Genes that were homologs to virulence genes associated with bacterial adhesion and antiphagocytosis were identified by aligning A. sanguinicola and A. urinae pan- and core-genes against Virulence Factors of Bacterial Pathogens (VFDB). Bacterial adherence associated gene homologs were present in genomes of A. sanguinicola (htpB, fbpA, lmb, and ilpA) and A. urinae (htpB, lap, lmb, fbp54, and ilpA). Fifteen and 11-16 CPS gene homologs were identified in genomes of A. sanguinicola and A. urinae strains, respectively. Analysis of these genes identified one type of putative CPS locus within all A. sanguinicola strains. In A. urinae genomes, five different CPS loci types were identified with variations in CPS locus sizes, genetic content, and structural organization. In conclusion, this is the first study dealing with WGS and comparative genomics of clinical A. sanguinicola and A. urinae strains from episodes of UTIs, bacteremia, and IE. Gene homologs associated with antiphagocytosis and bacterial adherence were identified and genetic variability was observed within A. urinae genomes. These findings contribute with important knowledge and basis for future molecular and experimental pathogenicity study of UTIs, bacteremia, and IE causing A. sanguinicola and A. urinae strains.

Clinical Characteristics and Laboratory Identification of Aerococcus Infections: An Australian Tertiary Centre Perspective

Aerococci uncommonly cause urinary tract (UTI) and bloodstream infections (BSI). The clinical characteristics and laboratory identification rates of Aerococcus in the Australian context are unknown. A retrospective observational cohort study of patients with positive Aerococcus cultures between 2010 and 2015 was performed. Patients were analysed according to predefined “asymptomatic bacteriuria,” “UTI,” and “BSI” groups. Forty-seven [40 (85%) for urine and 7 (15%) for blood] isolates were identified [38% male, median age of 79 (IQR 62–85) years], with corresponding identification rates of 24.2/100,000/year for urine (0.02%) and 7.3/100,000/year for blood cultures (0.007%). Since the use of matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF MS) identification rate in urine has increased from 14.7/100,000/year to 32/100,000/year (p = 0.02). For urine isolates, 14 (35%) met the definition for UTI whilst 26 (65%) were “asymptomatic bacteriuria.” Underlying urological abnormalities, catheterisation, and polymicrobial growth were common. Seventy percent of bacteriuria was treated regardless of colonisation or active infection status. Symptomatic patients were more likely to receive treatment (OR 7.2, 95% CI 1.4–35.3). In patients with BSI, 1 (14.2%) had endocarditis and 1 (14.2%) died. The majority of isolates were susceptible to penicillin (11/12 tested, 92%).

A rare case of aerococcus urinae infective endocarditis

Introduction:Aerococcus urinae is a rare cause of infective endocarditis. Aerococcus is a gram positive cocci that is easily misidentified as Staphylococci or Streptococci. The true incidence rate of this pathogen is likely underestimated. Recent advances in laboratory diagnostic methods with matrix-associated laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) have lead to increased recognition of this pathogen in the clinical microbiology lab, and awareness as a cause of infective endocarditis in the infectious disease community.

Case reports: Aerococcus usually affects males with underlying urinary tract conditions. Herein, we report a case of prosthetic aortic valve endocarditis caused by Aerococcus urinae.

Discussion: Our patient was considered high risk for cardiac surgery and was treated successfully with intravenous antibiotics alone for six weeks.

Conclusion: Infective endocarditis should be considered in all cases of Aerococcus bacteremia and appropriate diagnostic evaluations pursued.

Abbreviations: AV: Aortic valve; IE: Infective endocarditis

A rare case of perineal abscess caused by aerococcus urinae

Aerococcus urinae, a previously misidentified pathogen, has become increasingly recognized to cause severe and even fatal infections. Aerococcus-related perineal abscess infections have not previously been reported in the literature. Most reported cases of infections caused by Aerococcus are urinary tract infections, bacteremia, and even rare cases of endocarditis. We report an unusual case of a perineal abscess caused by Aerococcus urinae.

Aerococcus Viridans: A Rare Pathogen Causing Urinary Tract Infection

Aerococci are Gram-positive cocci with colony morphology similar to viridans streptococci. Most often these isolates in clinical samples are misidentified and considered insignificant. However, with the use newer techniques like Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass-Spectrometry (MALDI-TOF MS), aerococci have been recognized as significant human pathogens capable of causing a diverse spectrum of infections. Among the different species of aerococci, Aerococcus urinae is the most common agent causing Urinary Tract Infection (UTI) followed by A. sanguinocola. Aerococcus viridans (A. viridans) have been reported rarely in urinary tract infections. The antimicrobial resistance in aerococci in terms of its intrinsic resistance and evolving resistance to penicillin and vancomycin has raised the concern for better understanding of this pathogen. We recently encountered two cases of nosocomial UTI caused by A. viridans which are being reported here.

Clinical and microbiological features of Actinotignum bacteremia: a retrospective observational study of 57 cases

The purpose of this study was to investigate the incidence, clinical presentation, and prognosis of Actinotignum bacteremia in southern Sweden. Actinotignum isolates in blood cultures were identified retrospectively between 1st January 2012 and 31st March 2016 through searches in the clinical microbiology laboratory database. The population covered by this laboratory is approximately 1.3 million. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used for species determination. Etests were used for minimum inhibitory concentration (MIC) determination. The patients’ medical charts were reviewed. Fifty-eight episodes in fifty-seven patients with Actinotignum bacteremia were identified (A. schaalii = 53, A. sanguinis = 1, A. urinale = 2, and Actinotignum species = 3), which corresponds to an incidence of 11 cases per million inhabitants. Fifty-one percent of the isolates were in pure culture. The MICs were low for β-lactam antibiotics, whereas high MICs were recorded for ciprofloxacin and trimethoprim. Patients had a median age of 82 years, 72% were male, and a majority had underlying urological conditions. Thirty-six of the patients were diagnosed with a focus from the urinary tract. Thirty-one patients developed severe sepsis and nine patients died during the hospital stay. Our study is the largest of Actinotignum bacteremia and demonstrates that it is a condition with a significant fatality that affects elderly persons with underlying conditions. β-Lactams represent a rational treatment option.

Aerococcus urinae, a rare cause of infective endocarditis

We present the case of an elderly male who was initially seen in our hospital for a urinary tract infection that was treated with oral ciprofloxacin. He was admitted 2 weeks later with altered mental status and fever, and was found to have bacteraemia with Aerococcus urinae Owing to altered mental status a brain MRI was performed which showed evidence of embolic stroke. Following this, a transesophageal echocardiogram showed severe mitral regurgitation and a vegetation >1 cm involving the mitral valve with associated destruction of posterior valve leaflets. The patient was started on antibiotics intravenous penicillin G and intravenous gentamicin for a total duration of 6 weeks. He underwent mitral valve replacement on day 4 of hospitalisation. The postoperative course was complicated by ventilator-dependent respiratory failure, requiring tracheostomy and eventual transfer to a skilled nursing facility. Unfortunately, he died after 2 weeks of stay at the facility.

Bactericidal activity of penicillin, ceftriaxone, gentamicin and daptomycin alone and in combination against Aerococcus urinae

Aerococcus urinae can cause severe infections (bacteraemia and endocarditis) that are associated with high mortality. However, data on the bactericidal and synergistic activity for clinically implemented antibiotics are scarce. Time-kill analyses were performed on two clinical isolates (AU1 and AU2) and the reference strain ATCC 700306 for penicillin (PG), ceftriaxone (CRO), gentamicin (GEN), daptomycin (DAP) and their combinations. AU1 and AU2 were CRO-resistant (MICs, 2 µg/mL) and ATCC 700306 was high-level GEN-resistant (MIC, 512 µg/mL), whereas all strains were PG- and DAP-susceptible (MICs, ≤0.125 and ≤1 µg/mL, respectively). CFU counts were determined at various time points from 0 to 48 h. All experiments were performed at 0.5×, 1×, 2× and 4× MIC. PG and CRO were not bactericidal for all strains, whereas DAP exhibited bactericidal activity at all concentrations for AU2 and ATCC 700306. The combination of PG or CRO with GEN was bactericidal for AU1 and AU2 at antibiotic concentrations ≥1× MIC. Bactericidal synergism was detected for PG or CRO combined with GEN in the two clinical isolates. PG plus CRO showed non-bactericidal synergism for ATCC 700306. DAP with GEN was synergistic at 1× MIC for AU1, whereas the killing activity of DAP was too pronounced to detect potential synergism in AU2. The combination of PG or CRO with GEN is synergistic and bactericidal. Moreover, these in vitro data suggest that DAP may represent a potential bactericidal treatment alternative against A. urinae. This finding could be important for the treatment of patients with a β-lactam allergy or renal insufficiency.