Anaerobic Gram-positive Cocci Research Articles

Peptostreptococcus Mycotic Pseudo-Aneurysm

Mycotic pseudo-aneurysm is a rare and potentially fatal sequela of bacteraemia. The injury results in a localized, irreversible dilatation due to destruction of the blood vessel wall by infection, usually with an aerobic bacterium. Anaerobic bacteria are uncommon. We report an unusual case of a 72-year-old Caucasian man who presented with a rapidly progressive mycotic pseudoaneurysm of the right subclavian artery due to an anaerobic Gram-positive coccus Peptoniphilus asaccharolyticus. Despite optimal treatment, combining antibiotics and surgery, mycotic pseudo-aneurysm has a poor prognosis. When surgery is not possible, antibiotics alone with or without the placement of an endovascular stent have been proposed but in such cases, mortality is very significant. Despite the availability of non-invasive imaging techniques, a strong clinical suspicion is essential for early diagnosis of a mycotic aneurysm. Clinicians must be aware of these important aspects of management.

A Rare Case of Fournier’s Gangrene caused by <em>Helcococcus kunzii</em>

Fournier’s gangrene is an acute rapidly progressing form of necrotizing fasciitis involving the genitalia and perianal regions. Trauma and local infection are the most common risk factors especially in the setting of diabetes. It is usually a polymicrobial infection caused by skin flora of the genital area. The most commonly isolated aerobic microorganism are Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus, while Bacteroides fragilis is a common culprit from the anaerobic group. We report a patient with Fournier’s gangrene caused by Helcococcus kunzii; anaerobic gram-positive coccus not known to be associated with Fournier’s gangrene before.

The optimization and validation of the Biotyper MALDI-TOF MS database for the identification of Gram-positive anaerobic cocci

Gram-positive anaerobic cocci (GPAC) account for 24%–31% of the anaerobic bacteria isolated from human clinical specimens. At present, GPAC are under-represented in the Biotyper MALDI-TOF MS database. Profiles of new species have yet to be added. We present the optimization of the matrix-assisted laser desorption–ionization time-of-flight mass spectrometry (MALDI-TOF MS) database for the identification of GPAC. Main spectral profiles (MSPs) were created for 108 clinical GPAC isolates. Identity was confirmed using 16S rRNA gene sequencing. Species identification was considered to be reliable if the sequence similarity with its closest relative was ≥98.7%. The optimized database was validated using 140 clinical isolates. The 16S rRNA sequencing identity was compared with the MALDI-TOF MS result. MSPs were added from 17 species that were not yet represented in the MALDI-TOF MS database or were under-represented (fewer than five MSPs). This resulted in an increase from 53.6% (75/140) to 82.1% (115/140) of GPAC isolates that could be identified at the species level using MALDI-TOF MS. An improved log score was obtained for 51.4% (72/140) of the strains. For strains with a sequence similarity <98.7% with their closest relative (n = 5) or with an inconclusive sequence identity (n = 4), no identification was obtained by MALDI-TOF MS or in the latter case an identity with one of its relatives. For some species the MSP of the type strain was not part of the confined cluster of the corresponding clinical isolates. Also, not all species formed a homogeneous cluster. It emphasizes the necessity of adding sufficient MSPs of human clinical isolates.

Microbiology of Root Canal Infections.

Inflammatory reaction in the periapical tissues is induced by microbial infection in the root canal system. The aim of root canal treatment is to preserve healthy periapical tissues or to provide healing of them in restorable teeth, which have sufficient periodontal support. The amount of microbial cells in the root canal system and their virulence as well as host responses influence on the degree of periapical inflammation and symptoms. Microbial biofilm formation is typically seen on root canal walls but some microbial species are able to invade the dentine tubules to varying depth. In prolonged and complicated infections, or in case of risk of systemic spread of infection, root canal sampling for microbiological diagnostics is recommended. Anaerobic gram-negative rods are commonly isolated organisms in primary infections. In post-treatment disease, the microflora is dominated by facultatively anaerobic gram-positive cocci and rods such as Streptococcus, Enterococcus, Peptostreptococcus and Actinomyces species. Instrumentation, disinfection and interappointment medication in strict aseptic conditions are essential steps for eradication of microbial species from the infected root canal system. During past decades, Enterococcus faecalis and Candida albicans have been commonly associated organisms in treatment-resistant infections. Novel microbial detection methods are giving increasing knowledge about microbial species associated with endodontic infections and their roles in them.

Surgical Site Infections in Pediatric Spine Surgery: Comparative Microbiology of Patients with Idiopathic and Nonidiopathic Etiologies of Spine Deformity.

Surgical site infections (SSIs) are a concern in pediatric spine surgery with unusually high rates for a clean surgery and especially for patients with deformity of nonidiopathic etiology. Microbiologic differences between etiologies of spine deformities have been poorly investigated. We reviewed all cases of SSI in spinal surgery between 2007 and 2011. Characteristics of cases and of bacteria according to the etiology of the spine disease were investigated. Of 496 surgeries, we identified 51 SSIs (10.3%) in 49 patients. Staphylococcus aureus was the most frequent pathogen whatever the etiology (n = 31, 61% of infection cases). The second most frequent pathogens vary according to the etiology of the spine deformity. It was Gram-negative bacilli (GNB) in nonidiopathic cases (n = 19, 45% of cases) and anaerobe in idiopathic cases (n = 8, 38% of cases), particularly Gram-positive anaerobic cocci (n = 5, 24% of cases). Infection rate was 6.8% in cases with idiopathic spine disease (n = 21) and 15.9% in cases with nonidiopathic spine disease (n = 30). Nonidiopathic cases were more frequently male with lower weight. American Society of Anesthesiologists score was more often greater than 2, they had more frequently sacral implants and postoperative intensive care unit stay. GNB were significantly associated with a nonidiopathic etiology, low weight, younger age and sacral fusion. SSIs were polymicrobial in 31% of cases with a mean of 1.4 species per infection cases. S. aureus is the first cause of SSI in pediatric spine surgery. However, Gram-positive anaerobic cocci should be taken into account in idiopathic patients and GNB in nonidiopathic patients when considering antibiotic prophylaxis and curative treatment.

Pylephlebitis Due to Parvimonas micra

Parvimonas micra is an anaerobic Gram-positive coccus that is part of the normal flora of the mouth and the gastrointestinal tract. It can cause a broad range of invasive infections in humans, including intra-abdominal abscesses and bacteremia. It previously belonged to the genus Peptostreptococcus until anaerobic Gram-positive cocci have undergone extensive reclassification after the development of newer molecular techniques. Considering their various clinical manifestations related to their virulence, it is paramount for clinicians to recognize the characteristics of the major anaerobic Gram-positive cocci and their associated clinical importance. We herein report a case of bacteremia due to P. micra in a 62-year-old man who developed cholecystitis complicated by pylephlebitis. We then review other cases of P. micra–associated infections reported in the literature to discuss its pathogenic potentials and clinical manifestations.

Gemella Prosthetic Aortic Valve Endocarditis Treated Successfully with Vancomycin and Gentamicin

Gemella are facultatively anaerobic Gram-positive cocci found in the oral cavity. Endocarditis from this organism is rare. We describe a case of late onset aorticprosthetic valve endocarditis with Gemella after dental surgery that was successfully medically managed with vancomycin and gentamicin.

First case of infectious endocarditis caused by Parvimonas micra

P. micra is an anaerobic Gram-positive cocci, and a known commensal organism of the human oral cavity and gastrointestinal tract. Although it has been classically described in association with endodontic disease and peritonsillar infection, recent reports have highlighted the role of P. micra as the primary pathogen in the setting of invasive infections. In its most recent taxonomic classification, P. micra has never been reported causing infectious endocarditis in humans. Here, we describe a 71 year-old man who developed severe native valve endocarditis complicated by aortic valvular destruction and perivalvular abscess, requiring emergent surgical intervention. Molecular sequencing enabled identification of P. micra.

Multicenter study of antimicrobial susceptibility of anaerobic bacteria in Korea in 2012.

BackgroundPeriodic monitoring of regional or institutional resistance trends of clinically important anaerobic bacteria is recommended, because the resistance of anaerobic pathogens to antimicrobial drugs and inappropriate therapy are associated with poor clinical outcomes. There has been no multicenter study of clinical anaerobic isolates in Korea. We aimed to determine the antimicrobial resistance patterns of clinically important anaerobes at multiple centers in Korea.MethodsA total of 268 non-duplicated clinical isolates of anaerobic bacteria were collected from four large medical centers in Korea in 2012. Antimicrobial susceptibility was tested by the agar dilution method according to the CLSI guidelines. The following antimicrobials were tested: piperacillin, piperacillin-tazobactam, cefoxitin, cefotetan, imipenem, meropenem, clindamycin, moxifloxacin, chloramphenicol, metronidazole, and tigecycline.ResultsOrganisms of the Bacteroides fragilis group were highly susceptible to piperacillin-tazobactam, imipenem, and meropenem, as their resistance rates to these three antimicrobials were lower than 6%. For B. fragilis group isolates and anaerobic gram-positive cocci, the resistance rates to moxifloxacin were 12-25% and 11-13%, respectively. Among B. fragilis group organisms, the resistance rates to tigecycline were 16-17%. Two isolates of Finegoldia magna were non-susceptible to chloramphenicol (minimum inhibitory concentrations of 16-32 mg/L). Resistance patterns were different among the different hospitals.ConclusionsPiperacillin-tazobactam, cefoxitin, and carbapemems are highly active β-lactam agents against most of the anaerobes. The resistance rates to moxifloxacin and tigecycline are slightly higher than those in the previous study.

Antibiotic susceptibility of bacteria isolated from diabetic foot infections and prospects for empiric antibiotic therapy in Ouagadougou (Burkina Faso)

The aim of this study was to study the antibiotic susceptibility of bacteria isolated from diabetic foot infections to help improve empiric antibiotic prescription in Ouagadougou, where bacteriological testing is rarely possible. This cross-sectional study took place from July 1, 2011, to June 30, 2012, in the departments of internal medicine and general and gastrointestinal surgery in the Yalgado Ouédraogo teaching hospital. Bacteria were isolated from diabetic foot infections and their antibiotic sensitivity was tested by the qualitative method (Kirby-Bauer). The study included 64 patients, with a median age of 57 years (interquartile range: 48-75) and a M/F sex ratio of 1.37. Among them, 39 had received antibiotics before hospitalization. Among the 71 samples, 62 cultures (87%) were positive: 53 for a single microbe (85%) and 9 for two microbes (15%). Microorganisms were mainly aerobic and anaerobic Gram-positive cocci (76%), including Staphylococcus aureus (SA) (33%) and Streptococcus spp (18%). These Gram-positive cocci were highly sensitive to amoxicillin-clavulanic acid and oxacillin. No methicillin-resistant SA (MRSA) were isolated. Enterobacteriaceae (24 %) were highly susceptible to imipenem and ticarcillin, but not to ceftriaxone or ciprofloxacin. No extended-spectrum beta-lactamase Enterobacteriaceae (ESBL) were isolated. Pseudomonas aeruginosa was highly susceptible to ciprofloxacin and imipenem. Despite our study's limitations, our findings show that most diabetic foot infections can be successfully treated with standard antibiotics.

Anaerobic blood culture isolates in a Norwegian university hospital: identification by MALDI-TOF MS vs 16S rRNA sequencing and antimicrobial susceptibility profiles.

We investigated 197 anaerobic isolates recovered from blood cultures in the period 2009-2013. The isolates included were Bacteroides spp., Clostridium spp., Prevotella spp., Fusobacterium spp. and Gram-positive anaerobic cocci (GPAC). Identification results by MALDI-TOF MS were compared to those obtained by 16S rRNA sequencing, and the MICs of benzylpenicillin, clindamycin, piperacillin-tazobactam, meropenem and metronidazole were determined by Etests. The MALDI-TOF MS correctly identified 94.9% of the anaerobes to the genus level, and 86.8% to the species level, with errors mainly among the non-fragilis Bacteroides spp. and GPAC. About 73.3% of the isolates were non-susceptible to penicillin, mainly due to high resistance rates in the Bacteroides spp. (99.2%) and Prevotella spp. (69.2%). About 18.5% of the isolates were clindamycin resistant. Piperacillin-tazobactam had an excellent activity against all anaerobes except the non-fragilis Bacteroides spp., of which 43.8% were non-susceptible. The clinical significance of such a high resistance rate is unclear. Meropenem and metronidazole were the most active antibiotics, with 96.9% and 97.9% of the isolates being susceptible.

First confirmed case of spondylodiscitis with epidural abscess caused by Parvimonas micra

Parvimonas micra was renamed species as within Gram-positive anaerobic cocci and rarely causes severe infections in healthy people. We report the first confirmed case of spondylodiscitis with epidural abscess caused by P.micra in a healthy women. The patient has a pain in low back and anterior left thigh. Magnetic resonance imaging and computed tomography detected the affected lesion at the L2 and L3 vertebral bodies. All isolates from the surgical and needle biopsy specimens were identified as P.micra by 16S rRNA and MALDI-TOF. In this case, P.micra showed high sensitivity to antimicrobial therapy. She was successfully treated with debridement and sulbactam/ampicillin, followed by oral metronidazole for a total of 10 weeks. The causative microorganisms of spondylodiscitis are not often identified, especially anaerobic bacteria tend to be underestimated. On the other hand, antimicrobial therapy for spondylodiscitis is usually prolonged. Accordingly, we emphasize the importance of performing accurate identification including anaerobic bacteria.

Bacterial profiles and proteolytic activity in peri-implantitis versus healthy sites

Peri-implantitis is a biofilm-induced destructive inflammatory process that, over time, results in loss of supporting bone around an osseointegrated dental implant. Biofilms at peri-implantitis sites have been reported to be dominated by Gram-negative anaerobic rods with a proteolytic metabolism such as, Fusobacterium, Porphyromonas, Prevotella and Tannerella, as well as anaerobic Gram-positive cocci. In this study, we hypothesized that protease activity is instrumental in driving bone destruction and we therefore compared the microbial composition and level of protease activity in samples of peri-implant biofluid (PIBF) from 25 healthy subjects (H group) and 25 subjects with peri-implantitis (PI group). Microbial composition was investigated using culture techniques and protease activity was determined using a FITC-labelled casein substrate. The microbial composition was highly variable in subjects both in the H and PI groups but one prominent difference was the prevalence of Porphyromonas/Prevotella and anaerobic Gram positive cocci which was significantly higher in the PI than in the H group. A subgroup of subjects with peri-implantitis displayed a high level of protease activity in the PIBF compared to healthy subjects. However, this activity could not be related to the presence of specific bacterial species. We propose that a high level of protease activity may be a predictive factor for disease progression in peri-implantitis. Further longitudinal studies are however required to determine whether assessment of protease activity could serve as a useful method to identify patients at risk for progressive tissue destruction.

Anaerococcus degenerii sp. nov., isolated from human clinical specimens

Four clinical isolates of gram-positive strict anaerobic cocci were isolated from four different human mixed anaerobic infections. The taxonomical status of the four strains could not be established using standard identification techniques. The biochemical features of the strains were established and their taxonomic position was determined using 16S rRNA sequencing. The four strains form a homogeneous phenotypical and genotypical cluster. A new Anaerococcus species is proposed for these isolates: Anaerococcus degenerii sp. nov. The type strain is UMCG-104T = DSM29674T (accession number AM176528).

Evaluation of Antibiotic Susceptibility of Gram-Positive Anaerobic Cocci Isolated from Cancer Patients of the N. N. Blokhin Russian Cancer Research Center.

In total, 81 nonduplicate gram-positive anaerobic cocci (GPAC) were involved in this study. The GPAC were isolated from samples collected from cancer patients between 2004 and 2014. Species identification was carried out by matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). The majority of isolates were identified as Finegoldia magna (47%) and Peptoniphilus harei (28%). The susceptibility of six species of GPAC was determined for eight antibiotics according to E-test methodology. Furthermore, all isolates were susceptible to imipenem, vancomycin, and linezolid. Susceptibility to penicillin G, amoxicillin/clavulanate, metronidazole, ciprofloxacin, and levofloxacin varied for different species. One Finegoldia magna isolate was multidrug-resistant (i.e., parallel resistance to five antimicrobial agents, including metronidazole, was observed). Two Parvimonas micra isolates were highly resistant to metronidazole (MIC 256 μg/mL) but were sensitive to other tested antibiotics.

Bloodstream infections due to Peptoniphilus spp.: report of 15 cases

Peptoniphilus spp. are Gram-positive anaerobic cocci (GPAC) that were formerly classified in the genus Peptostreptococcus. This study describes 15 cases of Peptoniphilus spp. bloodstream infection (BSI) diagnosed from 2007 to 2011 using 16S rDNA sequencing in patients with pneumonia, pre-term delivery, soft tissue infection or colon or bladder disease. Seven out of 15 (47%) of these cases had polymicrobial BSIs. One of the isolates was closely related to P. duerdenii (EU526290), while the other 14 isolates were most closely related to a Peptoniphilus sp. reference strain (ATCC 29743) and P. hareii (Y07839). Peptoniphilus is a rare but important cause of BSI.

Evaluation of the in vitro activity of levornidazole, its metabolites and comparators against clinical anaerobic bacteria

This study evaluated the in vitro anti-anaerobic activity and spectrum of levornidazole, its metabolites and comparators against 375 clinical isolates of anaerobic bacteria, including Gram-negative bacilli (181 strains), Gram-negative cocci (11 strains), Gram-positive bacilli (139 strains) and Gram-positive cocci (44 strains), covering 34 species. Minimum inhibitory concentrations (MICs) of levornidazole, its five metabolites and three comparators against these anaerobic isolates were determined by the agar dilution method. Minimum bactericidal concentrations (MBCs) of levornidazole and metronidazole were measured against 22 strains of Bacteroides fragilis. Levornidazole showed good activity against B. fragilis, other Bacteroides spp., Clostridium difficile, Clostridium perfringens and Peptostreptococcus magnus, evidenced by MIC90 values of 0.5, 1, 0.25, 2 and 1mg/L, respectively. The activity of levornidazole and the comparators was poor for Veillonella spp. Generally, levornidazole displayed activity similar to or slightly higher than that of metronidazole, ornidazole and dextrornidazole against anaerobic Gram-negative bacilli, Gram-positive bacilli and Gram-positive cocci, especially B. fragilis. Favourable anti-anaerobic activity was also seen with levornidazole metabolites M1 and M4 but not M2, M3 or M5. For the 22 clinical B. fragilis strains, MBC50 and MBC90 values of levornidazole were 2mg/L and 4mg/L, respectively. Both MBC50/MIC50 and MBC90/MIC90 ratios of levornidazole were 4, similar to those of metronidazole. Levornidazole is an important anti-anaerobic option in clinical settings in terms of its potent and broad-spectrum in vitro activity, bactericidal property, and the anti-anaerobic activity of its metabolites M1 and M4.

Antibiotic susceptibility profiles of anaerobic pathogens in The Netherlands

The antibiotic susceptibility profile of the Bacteroides fragilis group, Gram-positive anaerobic cocci (GPAC), Fusobacterium spp., Prevotella spp., Veillonella spp. and Bilophila wadsworthia for amoxicillin, amoxicillin–clavulanic acid, clindamycin and metronidazole was determined. Human clinical isolates were isolated between 2011 and 2013 at the Microbiological Diagnostic Laboratory of the University Medical Center Groningen, The Netherlands and subjected to MALDI-TOF MS identification and susceptibility testing using E-test for MIC determination.Differences in clindamycin susceptibility between species of the B. fragilis group and GPAC were observed, with Bacteroides ovatus and Peptoniphilus harei having the highest resistance rates. Compared to other European countries, in The Netherlands the MIC90 for clindamycin of fusobacteria is low. Metronidazole resistance was first encountered in the genus Prevotella in 2013, but not in species of GPAC as reported in Belgium and Bulgaria. The differences in clindamycin resistance between the different European countries and reports of metronidazole resistance within the genera Prevotella and GPAC warrant more extensive susceptibility studies on anaerobic pathogens.

Detecting Gram-Positive Anaerobic Cocci Directly From the Clinical Samples by Multiplex Polymerase Chain Reaction in Odontogenic Infections

Gram-positive anaerobic cocci (GPAC) can be isolated as pathogens from odontogenic infections. Culturing GPAC is time consuming and labor intensive. The objectives of the present study were to examine the utility of polymerase chain reaction (PCR) in directly detecting the presence of GPAC in clinical samples obtained from patients with odontogenic infections and to compare the distribution of GPAC in infected and healthy tissue. In the present case-control study, the infected tissue from patients and oral mucosal swabs from healthy control subjects were subjected to anaerobic culture and direct PCR analysis for the presence of GPAC. The McNemar, chi-square, and Fisher exact tests and kappa analysis were used for the statistical analyses. P < .05 was regarded as significant. The patient group included 13 men and 14 women, including 9 patients diagnosed with granulation of tooth extraction, 6 with impacted tooth follicles, 4 with peri-implantitis, 3 with abscesses, 2 with epithelial cysts, 2 with infected cysts, and 1 with an oroantral fistula. The control group included 14 men and 12 women. All the patient and control samples contained at least 1 GPAC. The groups did not differ by method of determining GPAC presence, but more microorganisms were detected when clinical samples were directly used for PCR analysis than when cultured bacteria were used (P= .001). The presence of GPAC in infected tissue cannot be directly related to the development of odontogenic infections. PCR performed directly on clinical material is a sensitive and specific method that can detect GPAC and save time.

Peptoniphilus rhinitidis sp. nov., isolated from specimens of chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is an inflammatory disorder of the nasal cavity and paranasal sinus related to bacterial infection. A previous study suggested that a specific bacterial group may have an important role in the course of CRS. In this study, bacteria isolated from CRS patients were characterized. A total of 15 strains were identified as Gram-positive anaerobic cocci (GPAC), which were able to utilize peptone as a sole carbon source. Sequencing of the 16S ribosomal RNA gene revealed that the isolates were closely related to members of the genus Peptoniphilus (>97% similarity) within the Clostridiales Family XI. Incertae Sedis. Genotypic and phenotypic characterization suggests that these isolates represent a novel species of the genus Peptoniphilus associated with CRS. The type strain of Peptoniphilus rhinitidis is 1–13T (=KCTC 5985T = JCM 17448T).