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 ß-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.

A novel plasmid from Aerococcus urinaeequi of porcine origin co-harboring the tetracycline resistance genes tet(58) and tet(61).

Tetracyclines are the broad-spectrum agents used in veterinary medicine and food animal production. Known mechanisms of tetracycline resistance include ribosome protection, active efflux and enzymatic inactivation. However, the presence of two different tet genes conferring different resistance mechanisms on the same plasmid has rarely been reported. In this study, we identified the tandem tetracycline resistance genes tet(61)-tet(58) on the novel plasmid pT4303. These tet genes were identified for the first time in Aerococcus urinaeequi. Reduced susceptibility to doxycycline was observed in S. aureus RN4220 harboring tet(61) when an extra tet(58) was expressed. Plasmid pT4303 was electrotransformed into S. aureus RN4220, E. faecalis JH2-2, S. suis BAA and E. coli DH5α and conferred tetracycline resistance (MIC ≥ 16) in both Gram-positive and Gram-negative bacteria, assuming that it might serve as a vehicle for the dissemination of the tetracycline resistance genes tet(61) and tet(58).

Characteristics of Aerococcus viridans isolated from porcine fetuses in Korean farms.

Swine abortion caused by viruses as well as bacteria has caused many economic losses in domestic farms over the years; however, bacterial abortion has not yet been studied in Korea. Several bacterial species were isolated from aborted fetuses (n = 103) for which the cause of death was not viral abortion. Among them, we focused on Aerococcus viridans, which had the highest positive rate within three provinces (Gangwon, Jeonnam and Gyeongnam). A total of 16 isolates were identified as A. viridans by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), and 13 were characterized by both antibiotic resistance and 16S rRNA gene analysis. Based on antibiotic susceptibility testing result, eight antimicrobials could not effectively eliminate the present isolation (more than 40% of isolates can resist these antibiotics), while all except two strains were susceptible to trimethoprim/sulfamethoxazole. Molecular analysis indicated genetic variation among these strains. This study is the first report detecting A. viridans from aborted fetuses in Korean domestic farms.

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.IMPORTANCEAerococcus 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.

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.

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.

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.

An initially unidentified case of urinary tract infection due to Aerococcus urinae.

Aerococcus urinae is a microorganism responsible for urinary tract and blood stream infections which are rarely reported in clinical practice. However, it has been proposed that the infrequency of such reports may be partially due to difficulties related to pathogen identification. We present here a case of an elderly male patient with urinary tract infection where A. urinae was initially not identified by a private microbiology laboratory. Our report highlights the need to consider A. urinae as a causative agent of urinary tract infections because if not identified and properly treated it may lead to endocarditis or septicemia.

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 ß-lactam allergy or renal insufficiency.

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

The purpose of this study was to determine the incidence of aerococcal bacteraemia in the MALDI-TOF MS-era, to describe the clinical presentation and to determine the MIC values of aerococci for ten antibiotics. Aerococci in blood cultures were identified through searches in the laboratory database for the years 2012-2014. MALDI-TOF MS, sequencing of the 16S rRNA gene and a PYR test were used for species identification. Patients' medical charts were systematically reviewed. Etests were used to determine MIC values. Seventy-seven patients were identified (Aerococcus urinae n = 49, Aerococcus viridans n = 14, Aerococcus sanguinicola n = 13 and Aerococcus christensenii n = 1) corresponding to incidences of 14 cases per 1,000,000 inhabitants per year (A. urinae) and 3.5 cases per 1,000,000 inhabitants per year (A. sanguinicola and A.viridans). A. urinae was in pure culture in 61 %, A. sanguinicola in 46 % and A. viridans in 36 % of the cases. The A. urinae and A. sanguinicola patients were old and many had urinary tract disorders, and a majority had a suspected urinary tract focus of the bacteraemia. Eighty percent of the A. urinae patients were men. Five A. urinae patients were diagnosed with infective endocarditis. Six patients died within 30 days. Most isolates had low MICs to penicillins and carbapenems. MALDI-TOF MS has led to an increased identification of aerococcal bacteremia. A. urinae remains the most common Aerococcus in blood cultures and in aerococcal IE.

Molecular and antibiotic susceptibility characterization of Aerococcus viridans isolated from porcine urinary infection.

Aerococcus viridans has been reported as a human and animal pathogen causing urinary tract infection, arthritis, pneumonia, meningitis and endocarditis. Routinely, A. viridans is not surveyed in clinical diagnosis laboratories and commonly is misidentified as other bacteria. There is no concrete data on the prevalence and impact of the pathogen to both human and animal health. In the present study, we report the isolation and molecular and antibiotic susceptibility characterization of A. viridans strains from porcine urinary infections. A total of 22 isolates were identified as A. viridans by MALDI-TOF MS and confirmed by 16S rRNA gene sequencing. Isolates were genotyped by single enzyme amplified fragments length polymorphism (SE-AFLP) that resulted in 19 clusters of which 81.2% were composed by single isolates. The high genetic heterogeneity corroborates previous studies and appears to be a particularity of A. viridans. The minimal inhibitory concentration (MIC) values also presented variability especially for ceftiofur, fluoroquinolones and aminoglycosides. The high MICs of aminoglycosides, tetracyclines and macrolides seen among the A. viridans corroborate previous reports and the widespread veterinary usage of these antibiotics demand attention for the implication of A. viridans infection to both human and animal health.

Clinical and microbiological features of infective endocarditis caused by aerococci.

PURPOSE: To define the clinical presentation of aerococcal infective endocarditis (IE) and the prevalence of synergy between penicillin and gentamicin on aerococcal isolates. METHODS: Cases of aerococcal IE between 2002 and 2014 were identified in the Swedish Registry of Infective Endocarditis (SRIE). MALDI-TOF MS was used to confirm species determination. The medical records were analysed and compared to cases reported to the SRIE caused by other pathogens. RESULTS: Sixteen cases of aerococcal IE, fourteen with Aerococcus urinae and two with Aerococcus sanguinicola, were confirmed. Etest-based methods and time-kill experiments suggested synergy between penicillin and gentamicin towards seven of fifteen isolates. The patients with aerococcal IE were significantly older than those with streptococci or Staphylococcus aureus IE. Most of the patients had underlying urinary tract diseases or symptoms suggesting a urinary tract focus of the infection. Seven patients with aerococcal IE presented with severe sepsis but ICU treatment was needed only in one patient and there was no fatality. Valve exchange surgery was needed in four patients and embolization was seen in three patients. CONCLUSIONS: This report is the largest on aerococcal IE and suggests that the prognosis is relatively favourable despite the fact that the patients are old and have significant comorbidities.

Identification and Antimicrobial Resistance of Bacteria Isolated from Probiotic Products Used in Shrimp Culture.

Probiotics are increasingly used in aquaculture to control diseases and improve feed digestion and pond water quality; however, little is known about the antimicrobial resistance properties of such probiotic bacteria and to what extent they may contribute to the development of bacterial resistance in aquaculture ponds. Concerns have been raised that the declared information on probiotic product labels are incorrect and information on bacterial composition are often missing. We therefore evaluated seven probiotics commonly used in Vietnamese shrimp culture for their bacterial species content, phenotypic antimicrobial resistance and associated transferable resistance genes. The bacterial species was established by 16S rRNA sequence analysis of 125 representative bacterial isolates. MIC testing was done for a range of antimicrobials and whole genome sequencing of six multiple antimicrobial resistant Bacillus spp. used to identify resistance genes and genetic elements associated with horizontal gene transfer. Thirteen bacterial species declared on the probiotic products could not be identified and 11 non-declared Bacillus spp. were identified. Although our culture-based isolation and identification may have missed a few bacterial species present in the tested products this would represent minor bias, but future studies may apply culture independent identification methods like pyro sequencing. Only 6/60 isolates were resistant to more than four antimicrobials and whole genome sequencing showed that they contained macrolide (ermD), tetracycline (tetL), phenicol (fexA) and trimethoprim (dfrD, dfrG and dfrK) resistance genes, but not known structures associated with horizontal gene transfer. Probiotic bacterial strains used in Vietnamese shrimp culture seem to contribute with very limited types and numbers of resistance genes compared to the naturally occurring bacterial species in aquaculture environments. Approval procedures of probiotic products must be strengthened through scientific-based efficacy trials and product labels should allow identification of individual bacterial strains and inform the farmer on specific purpose, dosage and correct application measures.

Characterization of Aerococcus viridans isolated from milk samples from cows with mastitis and manure samples.

Thirty-eight Aerococcus viridans isolates were obtained from milk from 478 cows with clinical mastitis in a farm during the periods between November 2011 and February 2012, and between December 2012 and March 2013. Additional isolates were obtained from processed manure (a mixture of composted manure, straw and hydrated lime) and bedding materials. The processed manure was later used to cover the floor of the stalls in barns as bedding materials. The temperatures recorded in the composted and processed manure were not as high as those generally observed during satisfactory composting. To reveal the association of A. viridans in manure-related products with intramammary infection in cows, isolates were characterized by their DNA fragment patterns as determined by pulsed-field gel electrophoresis (PFGE) and antimicrobial susceptibility testing. Isolates obtained from milk, processed manure and bedding materials had identical DNA fragment patterns. Antimicrobial susceptibilities were determined for 29 isolates from milk, processed manure and bedding materials. Of these, 26 (89.7%) were resistant to clindamycin, whereas virtually all the isolates were susceptible to 12 other antimicrobials including cefalosporins that have been used to treat bovine mastitis in Japan. In vitro, three A. viridans isolates from milk and an isolate from processed manure survived for 3 hr in Good's buffer (pH 9) at high temperature (50°C). The results suggest that the processed manure and bedding materials in this farm were possible sources of A. viridans that caused infection in the cows with mastitis.

Molecular and Phenotypic Characterization of Aerococcus viridans Associated with Subclinical Bovine Mastitis.

Aerococcus viridans is a wide spread bacterium in the environment and clinically this organism is associated with different diseases in animals and humans. However, the geno- and phenotypic characterization of A. viridans associated with bovine mastitis has not yet been reported. The objectives of this study were to investigate the genetic and phenotypic diversity of A. viridans isolates using three different molecular methods including 16S rRNA gene sequencing, pulsed-field gel electrophoresis and random amplified polymorphic DNA (RAPD) along with biochemical tests, including antimicrobial susceptibility test. In total, 60 A. viridans strains were cultured from dairy herds presenting with subclinical mastitis. The results of biochemical tests revealed that most of the isolates (75.0%) were accurately identified by API Rapid 20 Strep system and the majority of A. viridans strains (96.7%) were found to be catalase negative, while two (3.3%) isolates were weakly positive. All isolates were resistant to trimethoprim-sulfamethoxazole, followed by streptomycin (96.7%), tetracycline (65.0%) and clindamycin (56.7%) by minimum inhibition concentration-determining broth microdilution technique. As compared to the sequence of 16S rRNA gene, both PFGE and RAPD showed their capacities to discriminate the intra-species diversity of A. viridans. Furthermore, most of the isolates obtained from the same herd or region belonged to the same major RAPD group, which indicated that RAPD is an appropriate assay for tracking the origins of isolates and epidemiological studies of A. viridans. This is a novel approach to use three molecular techniques and to compare their efficiency regarding the genetic diversity of A. viridans. The data suggest that A. viridans associated with subclinical mastitis has a considerable phenotypic and genotypic diversity.

Epidemiology and antibiotic susceptibility of aerococci in urinary cultures.

In this study, we present population-based data regarding the prevalence of aerococci in clinical urinary samples. During a 3-month period, all aerococcal isolates from urinary samples from 2 clinical microbiology laboratories were collected. We identified 64 Aerococcus urinae isolates and 40 Aerococcus sanguinicola isolates, which correlates with an incidence of 33 cases of aerococcal bacteriuria per 100,000 inhabitants per year. The median age was 83years for all patients with aerococcal bacteriuria, which was significantly higher than for patients with Escherichia coli or Enterococcus faecalis bacteriuria. Sex was almost equally distributed between men and women with aerococcal bacteriuria, whereas females dominated in E. coli bacteriuria. The aerococcal isolates displayed low MICs for ampicillin, cefalotin, mecillinam, and nitrofurantoin. Most A. sanguinicola isolates were resistant to ciprofloxacin, whereas most A. urinae isolates had low MICs. Clinical studies are needed to establish clinical breakpoints and optimal treatment.

In vitro activity of clinically implemented ß-lactams against Aerococcus urinae: presence of non-susceptible isolates in Switzerland.

We analyzed the in vitro susceptibility to several ?-lactams and vancomycin of 80 Aerococcus urinae isolates collected during 2011-2012 in Switzerland. MICs were determined by Etest (bioMérieux) on Müller-Hinton agar with 5% sheep blood and interpreted according to the CLSI and EUCAST criteria set for viridans streptococci. MIC50/90 for penicillin, amoxicillin, ceftriaxone and vancomycin were 0.016/0.064 mg/l, 0.032/0.064 mg/l, 0.125/0.5 mg/l and 0.38/0.5 mg/l, respectively. Three (3.8%) isolates were resistant to ceftriaxone regardless of the criteria used (MICs ?2 mg/l); one of them was also non-susceptible to penicillin (MIC of 0.25 mg/l) according to CLSI. ß-lactam resistance in A. urinae is a concern and suggests that more studies are needed to determine the molecular mechanisms of such resistance.