Gram-positive anaerobic cocci

Peptostreptococcus micros in primary endodontic infections as detected by 16S rDNA-based polymerase chain reaction

A 16S rDNA-based polymerase chain reaction (PCR) method was used to detect Peptostreptococcus micros in primary root canal infections. Samples were collected from 50 teeth having carious lesions, necrotic pulps, and different forms of periradicular diseases. DNA extracted from the samples was amplified using the PCR assay, which yielded a specific fragment of P. micros 16S rDNA. P. micros was detected in 6 of 22 root canals associated with asymptomatic chronic periradicular lesions (27.3%), 2 of 8 teeth with acute apical periodontitis (25%), and 6 of 20 cases of acute periradicular abscess (30%). In general, P. micros was found in 14 of 50 cases (28%). There was no correlation between the presence of P. micros and the occurrence of symptoms. Findings suggested that P. micros can be involved in the pathogenesis of different forms of periradicular lesions.

Development of a PCR assay specific for Peptostreptococcus anaerobius

Peptostreptococcus anaerobius is a gram-positive anaerobic coccus that is widely distributed in the normal human flora. The organism has also been implicated as a causative agent of several systemic infections, including endocarditis and infections of the genitourinary and gastrointestinal tracts. Its role in oral disease is less well defined, although it has been implicated in periodontal disease, gingivitis and root canal infections. Identification of P. anaerobius in clinical samples is currently reliant upon traditional culture and biochemical methods. The aim of this study was to develop a novel PCR assay for the detection of P. anaerobius and to attempt detection of this organism in oral samples. PCR primers specific for P. anaerobius DNA were developed by alignment of bacterial 16S ribosomal RNA gene sequences and selection of sequences specific at their 3' ends for P. anaerobius. When used in a PCR assay, positivity for P. anaerobius DNA was indicated by the amplification of a 943-bp product. The primers were shown to be specific for P. anaerobius DNA, as no PCR products were obtained when genomic DNA from a wide range of other Peptostreptococcus species and other oral bacteria were used as templates. The PCR assay was then applied to the detection of P. anaerobius DNA in subgingival plaque samples from adult periodontitis patients and pus aspirates from subjects with acute dento-alveolar abscesses. All of 60 subgingival plaque samples from 16 patients were negative for P. anaerobius DNA. None of the 43 pus samples analysed contained P. anaerobius DNA. These results suggest that P. anaerobius is not a major pathogen in adult periodontitis and dento-alveolar abscesses. The PCR assay is a more rapid, sensitive and specific alternative to culture-based methods for identification of P. anaerobius in clinical samples.

Heterogeneity within the gram-positive anaerobic cocci demonstrated by analysis of 16S-23S intergenic ribosomal RNA polymorphisms

Peptostreptococci are gram-positive, strictly anaerobic bacteria which, although regarded as members of the commensal human microflora, are also frequently isolated from sites of clinical infection. The study of this diverse group of opportunist pathogens has been hindered by an inadequate taxonomy and the lack of a valid identification scheme. Recent re-classification of the Peptostreptococcus family into five distinct genus groups has helped to clarify the situation. However, this has been on the basis of 16S rRNA sequence determinations, which are both time-consuming and expensive. The aim of the present study was to evaluate the use of PCR-amplified ribosomal DNA spacer polymorphisms for the rapid differentiation of the currently recognised taxa within the group of anaerobic gram-positive cocci. A collection comprising 19 reference strains with representatives of each of the 15 species, two close relatives and two of the well-characterised groups, together with 38 test strains was studied. All strains were identified to species group level by phenotypic means. Amplification of the 16S-23S intergenic spacer region (ISR) with universal primers produced distinct banding patterns for all the 19 reference strains and the patterns could be differentiated easily visually. However, of the 38 test strains, less than half could be speciated from ISR analysis alone. Only five groups produced correlating banding patterns for all members tested (Peptoniphilus lacrimalis, P. ivorii, Anaerococcus octavius, Peptostreptococcus anaerobius and Micromonas micros). For other species, either the type strain differed significantly from other species members (e.g., A. hydrogenalis) or there appeared to be considerable intra-species variation (e.g., A. vaginalis). Partial 16S rRNA gene sequences for the 'trisimilis' and 'betaGAL' groups showed that both are most closely related to the Anaerococcus group. This work highlights the heterogeneous nature of a number of Peptostreptococcus species and hence the need for still further revision of the taxonomy of this important group of pathogens.

Potential role of anaerobic cocci in impaired human wound healing

Although more than 80% of infected and 70% of noninfected leg ulcers have been shown to harbor anaerobic organisms, their role in mediating impaired wound healing in the skin is frequently overlooked. There is now increasing evidence that the gram-positive anaerobic cocci play a role (both directly and indirectly) in mediating impaired wound healing in vivo. This article discusses the mechanisms by which these microorganisms may interfere with the inflammation, repair, and remodeling phases of the wound healing process.

Physical and genetic map of the Finegoldia magna (formerly Peptostreptococcus magnus) ATCC 29328 genome

A physical and genetic map of Finegoldia magna (formerly Peptostreptococcus magnus) ATCC 29328 chromosome was constructed. The order of rare cleavage restriction fragments was determined by double digestion with the restriction enzymes I-CeuI, SgrAI, ApaI and PmeI, cross-hybridization and ApaI-linking clones. The size of the circular chromosome of F. magna was estimated to be 1.9 Mb. This strain also had a 200-kb megaplasmid. The chromosome contained four rrn operons, and the orientation of two rrn operons was opposite to the others. Fragment analysis of Peptostreptococcus anaerobius ATCC 27337(T) chromosome suggested that its size was much smaller than that of F. magna ATCC 29328.

In vitro activity of gemifloxacin compared to seven other oral antimicrobial agents against aerobic and anaerobic pathogens isolated from antral sinus puncture specimens from patients with sinusitis

Using a microbroth method for aerobes and agar dilution for anaerobes, we studied the comparative in vitro activity of gemifloxacin, three fluoroquinolones, two macrolides and two beta-lactams, against 207 aerobic and 162 anaerobic antral sinus puncture isolates. Gemifloxacin was active at < or = 0.25 ug/mL against 198/207 [96%] aerobes and 127/162 [78%] anaerobes or 325/369 [88%] of all isolates and was the most active quinolone on a weight basis against Gram-positive organisms. All Haemophilus and Moraxella species were susceptible to < or =0.06 ug/mL of gemifloxacin. Thirty-five anaerobic isolates [35/162, 22%] required > or =0.5 ug/mL of gemifloxacin for inhibition, including all Prevotella species [all except one strain of P. bivia were susceptible to < or = 2 ug/mL] and occasional strains of Bacteroides uniformis, Bacteroides fragilis, Bilophila wadsworthia, Peptostreptococcus magnus, Peptostreptococcus micros, Propionibacterium acnes, and Veillonella species. All fusobacteria were susceptible to < or =0.25 ug/mL of gemifloxacin. Based on our in vitro study results, we conclude that gemifloxacin may offer a therapeutic alternative for sinus infections.

Phospholipid analogue profiles of Peptostreptococcus, Micromonas, and Finegoldia species analysed by fast atom bombardment mass spectrometry

Species of Peptostreptococcus cause a variety of infections, primarily abscesses of soft tissues, joints, and mucous membranes. The aim of this study was to compare the phospholipid analogue profiles of Peptostreptococcus species, represented by P. anaerobius, P. asaccharolyticus, P. indolicus, P. lacrimalis, and P. prevotii; Micromonas micros (P. micros) and Finegoldia magna (P. magnus). After anaerobic growth on blood-FAA, lipids extracted by chloroform-methanol (2:1 v/v) were purified, then analysed by fast atom bombardment mass spectrometry (FAB-MS) in negative ion mode. The major peaks with mass to charge (m/z) 719, 721, and 749, corresponded to phosphatidylglycerol analogues, namely PG (32:1), PG (32:0), and PG (34:0), which have been found previously in Lactobacillus spp., Clostridium difficile, and Staphylococcus spp. Other major peaks observed, with m/z 619, 647, 665, 675, 677, 687, 691, 693, 701, 703, 707, 733, and 746 have also been reported in one or more of these three species. However, other major peaks found here in Peptostreptococcus, Micromonas, and Finegoldia have not been described elsewhere; these are 501, 514, 515, 618, 659, 673, 676, 688, 690, 692, 694, 700, 706, 715, 718, 722, and 750. We conclude that Peptostreptococcus, Micromonas, and Finegoldia isolates are chemically unique.Key words: Peptostreptococcus, Micromonas, Finegoldia, phospholipids, FAB-MS.

Apparent culture-negative prosthetic valve endocarditis caused by Peptostreptococcus magnus

In two patients with prosthetic valve endocarditis due to Peptostreptococcus magnus, blood cultures in the BacT/Alert and BACTEC 9240 systems were signal negative. The capability of the BacT/Alert system to detect various Peptostreptococcus species was assessed. P. magnus and P. anaerobius could not be detected, and subcultures remained negative. The growth in conventional media of these two species and other Peptostreptococcus species was similar.

Peptostreptococcus micros smooth and rough genotypes in periodontitis and gingivitis

BACKGROUND

Two genotypes can be distinguished within the species Peptostreptococcus micros: a smooth (Sm) and a rough (Rg) type. To date no systematic study has been performed on the prevalence and proportion of both types in untreated periodontitis patients and subjects without destructive periodontal disease. Therefore, the present study was performed to investigate: 1) the relative importance of the Sm and the Rg genotype of P micros in periodontitis and gingivitis; 2) the correlation between smoking and the 2 genotypes of P micros; and 3) the systemic antibody response against the 2 genotypes in relation to the periodontal condition and smoking.

METHODS

A total of 104 untreated periodontitis patients and 41 individuals with gingivitis underwent clinical examination and microbiological sampling. Pocket samples were cultured anaerobically on blood agar plates to determine the prevalence and proportion of the Sm and Rg types of P micros. Serum antibody titers against both types of P micros were determined in all subjects by enzyme-linked immunosorbent assay (ELISA) using whole bacterial cells as antigen. Additionally, in a representative group of subjects, the antigen specificity of the serum antibodies was assessed by immunoblotting experiments.

RESULTS

The prevalence of the Sm genotype was higher in subjects with periodontitis (94%) compared to subjects with gingivitis (59%), whereas the prevalence of the Rg type was not significantly different (38% versus 29%). Similar analyses were performed for subgroups of smokers and non-smokers; within the periodontitis group, the prevalence of the Sm type was not different between smokers and non-smokers (96% and 92%, respectively), whereas the prevalence of the Rg type was higher in smokers (48%) compared to non-smokers (19%). No difference in prevalence of both types was observed between smokers and non-smokers within the gingivitis group. The titers and specificity of P micros-specific immunoglobulins in periodontitis patients were not different from those in gingivitis subjects, nor were they related to smoking status or culture-positivity.

CONCLUSIONS

The results of this study suggest that both the Sm and the Rg genotypes of P micros are part of the normal oral microbiota. However, the elevated prevalence of the Sm genotype in periodontitis and the elevated prevalence of the Rg type in periodontitis patients who smoke implies that both types can behave as opportunistic pathogens in destructive periodontal disease.

Peptostreptococcus micros coaggregates with Fusobacterium nucleatum and non-encapsulated Porphyromonas gingivalis

Coaggregation is one of the potential colonization strategies of oral microorganisms, often involving fimbrial structures in the interactions. In this study, the coaggregation characteristics of the rough and smooth genotypes of the periodontal pathogen Peptostreptococcus micros were compared to investigate the role of the fibril-like structures of the rough genotype in coaggregation. Of the 11 oral species tested, only Fusobacterium nucleatum strains and non-encapsulated Porphyromonas gingivalis strains coaggregated with P. micros. No differences in coaggregation between the smooth type (Sm), the rough type (Rg) and the smooth variant of the Rg type (Rg(Sm)) of P. micros were observed. Heat-stable, periodate-sensitive structures on P. micros appeared to interact with heat- and protease-sensitive structures on F. nucleatum and P. gingivalis. These data indicate that these unimodal coaggregations are not mediated by the proteinaceous fibril-like structures of the Rg genotype, but by carbohydrates present on both genotypes of P. micros.

Comparative in vitro activities of amoxicillin-clavulanate against aerobic and anaerobic bacteria isolated from antral puncture specimens from patients with sinusitis

By an agar dilution method, the antimicrobial susceptibilities of antral sinus puncture isolates were studied. Pneumococci were generally susceptible to amoxicillin, azithromycin, and clarithromycin, but 17% of pneumococcal isolates were resistant to cefuroxime. Haemophilus influenzae isolates were resistant to amoxicillin and clarithromycin. beta-Lactamase production occurred in 69% of Prevotella species. One-third of Peptostreptococcus magnus isolates were resistant to azithromycin and clarithromycin. Cefuroxime had limited activity against Prevotella species and P. magnus. Levofloxacin was active against most isolates except peptostreptococci. Amoxicillin-clavulanate was active against all isolates, with the MIC at which 90% of the isolates were inhibited being < or = 1 microgram/ml.