Species Of Anaerobic Bacteria Research Articles

Expression and characterization of spore coat CotH kinases from the cellulosomes of anaerobic fungi (Neocallimastigomycetes)

Anaerobic fungi (Neocallimastigomycetes) found in the guts of herbivores are biomass deconstruction specialists with a remarkable ability to extract sugars from recalcitrant plant material. Anaerobic fungi, as well as many species of anaerobic bacteria, deploy multi-enzyme complexes called cellulosomes, which modularly tether together hydrolytic enzymes, to accelerate biomass hydrolysis. While the majority of genomically encoded cellulosomal genes in Neocallimastigomycetes are biomass degrading enzymes, the second largest family of cellulosomal genes encode spore coat CotH domains, whose contribution to fungal cellulosome and/or cellular function is unknown. Structural bioinformatics of CotH proteins from the anaerobic fungus Piromyces finnis shows anaerobic fungal CotH domains conserve key ATP and Mg2+ binding motifs from bacterial Bacillus CotH proteins known to act as protein kinases. Experimental characterization further demonstrates ATP hydrolysis activity in the presence and absence of substrate from two cellulosomal P. finnis CotH proteins when recombinantly produced in E. coli. These results present foundational evidence for CotH activity in anaerobic fungi and provide a path towards elucidating the functional contribution of this protein family to fungal cellulosome assembly and activity.

Microbiological Examination of Clinical Material in Halitosis Patients

Abstract Regarding oral biofilm aspects, there has been strong evidence for a microbiotic component in the aetiology of halitosis. Many oral microbiota have protheolytic and putative activity, but there have been no studies investigating the association of microbiota in oral biofilms with halitosis. The objective of this study was to determine species of oral microbiota in the periodontal area and dorsal part of tongue biofilm, and how their quantitative amounts differ in halitosis patients. The clinical bacterial material from halitosis patients (altogether 98 persons, volatile sulphur compounds (VSC) on average 380 ppb) was taken from periodontal pockets and the dorsal part of the tongue for microbiological diagnostics of anaerobic bacteria, using polymerase chain reaction (PCR) tests for the comparison of bacterial quantity. The study showed the primary aetiology factors of halitosis in Latvia, and offers possible versions of microbiological diagnostics of halitosis. Even though the examination of halitosis patients and determination of VSC using a halimeter is technically simpler and cheaper, the determination of aetiological factors and their combinations using microbiological examination of clinical material with PCR tests are more precise. A characteristic ecological niche of anaerobic bacteria is not only the anaerobic environment of periodontal pockets, but also the microbiota of the dorsal part of the tongue. Additionally, some anaerobic bacteria species (Porohyromonas gingivalis, Tannerella forsythia, Treponema denticola, Prevotella intermedia) in larger amounts are found on the microbiome of the tongue. Therefore, it is advisable to begin microbiological diagnostics in halitosis patients with quantitative diagnostics of Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, Treponema denticola on the biofilm of the tongue coating.

Bacterial vaginosis - diagnostic dilemma and implications

Background/Aim. Bacterial vaginosis (BV) is one of the most common microbial dysbiosis, characterized by a decrease of Lactobacillus spp. with an increase of other anaerobic bacteria species [Gardnerella (G.) vaginalis, Atopobium (A.) vaginae, Prevotella spp, Mobiluncus spp, etc.] causing serious gynecological and obstetric complications. There-fore, it is particularly important to have accurate and reliable diagnostic standards. The aim of this study was to compare the results of various diagnostic methods for detecting BV, such as Amsel, Nugent, and Ison and Hay criteria, as well as multiplex quantitative real-time polymerase chain reaction (mqRT-PCR) test. Methods. This study involved vaginal swabs from 235 patients of reproductive age. Nugent criteria were used as the ?gold standard? compared with Amsel and Ison/Hay criteria as well as mqRT-PCR test based on the detection and quantification of G. vaginalis, A. vaginae, Lactobacillus spp., and total concentration of bacterial DNA. The kappa coefficient was employed to measure agreement between tests. Results. Our analysis demonstrated excellent agreement between Ison/Hay criteria and Nugent scores (kappa = 0.95), good agreement between Amsel and Nugent criteria (kappa = 0.78), while between Nugent criteria and mqRT-PCR test agreement was moderate (kappa = 0.59). Total agreements of Ison/Hay, Amsel, and mqRT-PCR against Nugent scores were 94.9%, 90.2%, and 74%, respectively. Nugent methods classified the highest number of intermediate patients - 60 (25.2%). The largest number of BV patients was detected by the mqRT-PCR method, while the largest number of healthy patients was detected by Amsel criteria. Conclusion. The mqRT-PCR is the best choice for BV diagnosis because it is more efficient at differentiating patients with intermediate results. Compared to Amsel and Nugent methods that group patients into 2 or 3 categories, the mqRT-PCR method recognizes other conditions of vaginal flora important for correct diagnoses and application of better therapeutic approaches, as well as preventing possible clinical consequences of this dysbiosis.

Analysis of the Microbiome on the Surface of Corroded Titanium Dental Implants in Patients with Periimplantitis and Diode Laser Irradiation as an Aid in the Implant Prosthetic Treatment: An Ex Vivo Study.

The paper presents the optimization of diode laser irradiation of corroded dental implants in order to reduce the number of microorganisms associated peri-implantitis. The research included the identification of microorganisms on the surface of removed dental implants in patients with peri-implantitis and the assessment of the biocidal effectiveness of the diode laser against these microorganisms. Laser desorption/mass spectrometry (MALDI-TOF MS) was used to identify microorganisms and metagens were examined by next generation sequencing (NGS). Irradiation was performed with a diode laser with a wavelength of λ = 810, operating mode: 25 W/15.000 Hz/10 μs, average = 3.84 W with the number of repetitions t = 2 × 15 s and t = 3 × 15 s. The structure and surface roughness of the implants were analysed before and after laser irradiation by optical profilometry and optical microscopy with confocal fixation. In total, 16 species of Gram-positive bacteria and 23 species of Gram-negative bacteria were identified on the surface of the implants. A total of 25 species of anaerobic bacteria and 12 species with corrosive potential were detected. After diode laser irradiation, the reduction in bacteria on the implants ranged from 88.85% to 100%, and the reduction in fungi from 87.75% to 96.77%. The reduction in microorganisms in the abutment was greater than in the endosseous fixture. The applied laser doses did not damage, but only cleaned the surface of the titanium implants. After 8 years of embedding, the removed titanium implant showed greater roughness than the 25-year-old implant, which was not exposed to direct influence of the oral cavity environment. The use of a diode laser in an optimised irradiation dose safely reduces the number of microorganisms identified on corroded dental implants in patients with peri-implantitis.

Polymicrobial Anaerobic Meningitis Detected by Next-Generation Sequencing: Case Report and Review of the Literature

BackgroundAnaerobic meningitis is a severe central nervous system infection associated with significant neurological sequelae and high mortality. However, the precise detection of causative pathogen(s) remains difficult because anaerobic bacteria are difficult to culture. Next-generation sequencing is a technology that was developed recently and has been applied in many fields. To the best of our knowledge, the use of next-generation sequencing for cerebrospinal fluid analysis in the diagnosis of anaerobic meningitis has been rarely reported.Case presentationHere, we report a case of polymicrobial anaerobic meningitis diagnosed using next-generation sequencing of cerebrospinal fluid in a 16-year-old girl. Five species of anaerobic bacteria (Porphyromonas gingivalis, Prevotella enoeca, Campylobacter rectus, Fusobacterium uncleatum, and Actinomyces israelii) were detected by next-generation sequencing and treated with antibacterial agents (ceftriaxone, vancomycin, and metronidazole). The patient responded well to antibacterial treatment. Further inspection revealed bone destruction at the base of the skull, which further confirmed that these bacteria had originated from the oral cavity. One month later, the patient's condition improved significantly. At the same time, we performed a literature review on anaerobic meningitis using studies published in the last 20 years.ConclusionsThis case emphasizes the importance of applying metagenomic next-generation sequencing to clinch the clinical diagnosis for patients with central nervous system infection. Metagenomic next-generation sequencing has been reported to be an important diagnostic modality for identifying uncommon pathogens.

The Numerical Simulation of the rivalry between aerobic and anaerobic bacteria species in a chemostat model

We investigate a chemostat model that contains interaction between two bacteria species, the aerobic species, and a facultative anaerobic species. The competition is restricted on the dissolved oxygen where the aerobic species consumes the oxygen for growth, on the other hand, the facultative anaerobic species do not need the dissolved oxygen for growth. We found that the aerobic growth rate is more extensive compared to that of its competition, the anaerobic species. During our study of the chemostat system, we found three equilibria solutions. The first one is found at the initial dissolved oxygen concentration with the condition of both species washed out. The second equilibrium point is seen when both the dissolved oxygen and the aerobic species present, and finally, the third equilibrium point is found when the dissolved oxygen and the facultative anaerobic species present. We used MATLAB software to simulate these aforementioned three equilibria.

Mycoremediation of Soils Polluted with Trichloroethylene: First Evidence of Pleurotus Genus Effectiveness

Trichloroethylene (TCE) is a proven carcinogenic chlorinated organic compound widely used as a solvent in industrial cleaning solutions; it is easily found in the soil, air, and water and is a hazardous environmental pollutant. Most studies have attempted to remove TCE from air and water using different anaerobic bacteria species. In addition, a few have used white-rot fungi, although there are hardly any in soil. The objective of the present work is to assess TCE removal efficiency using two species of the genus Pleurotus that have not been tested before: Pleurotus ostreatus and Pleurotus eryngii, growing on a sandy loam soil. These fungi presented different intra- and extracellular enzymatic systems (chytochrome P450 (CYP450), laccase, Mn peroxidase (MnP)) capable of aerobically degrading TCE to less harmful compounds. The potential toxicity of TCE to P. ostreatus and P. eryngii was firstly tested in a TCE-spiked liquid broth (70 mg L−1 and 140 mg L−1) for 14 days. Then, both fungi were assessed for their ability to degrade the pollutant in sandy loam soil spiked with 140 mg kg−1 of TCE. P. ostreatus and P. eryngii improved the natural dissipation of TCE from soil by 44%. Extracellular enzymes were poorly expressed, but mainly in the presence of the contaminant, in accordance with the hypothesis of the involvement of CYP450.

Clinical Features of Cases with Anaerobic Infection, Distribution of Anaerobic Bacteria and Fatality in Anaerobic Bacteremia

Introduction: This study aimed to determine the distribution of anaerobic bacteria species, which are the causative agents of infection, in order to investigate the epidemiological and clinical characteristics of the cases and evaluate fatality in cases with an aerobic bacteremia. Materials and Methods: One hundred and twenty-five cases who were determined with 148 isolates of anaerobic bacteria were included into this study at Ankara Numune Training and Research Hospital Medical Microbiology Laboratory between January 2014-February 2018. The specimens requested to undergo anaerobic evaluation and transported to the laboratory under anaerobic suitable conditions were prepared with Gram staining and inoculated in the Schaedler agar. After appropriate incubation, the identification of isolated anaerobic bacteria at the level of species was performed by using matrix-assisted laser desorption time-of-flight (MALDI-TOF MS). Results: Of the 125 cases who had an anaerobic infection, 60% were males, and mean age was 52.69 ± 18.5 years. Intra-abdominal and skin and soft tissue infections were the most common source of infection. One hundred and twenty-eight clinical specimens (78 abscesses, 50 blood cultures) which were sent from cases were identified with 148 anaerobic bacteria species. We detected the most common isolated species as Bacteriodes spp., Actinomyces spp. and Clostridium spp., respectively. The most common anaerobic bacteria species isolated from blood cultures of 50 cases with anaerobic bacteremia were Bacteroides spp., Clostridium spp., and intra-abdominal infection was the most common source for anaerobic bacteremia. Fusobacterium nucleatum (5/6; 83.3%) was the most frequent species in Fusobacterium bacteremia. F. nucleatum bacteremia was detected in an older population and was often associated with underlying malignancy. F. necrophorum bacteremia occurred in a younger population without underlying comorbidities and was diagnosed as Lemierre’s syndrome. Fatality rate was 51% in anaerobic bacteremia. Fatality was significantly higher in patients who were followed up in the intensive care unit and had high Charlson index (p< 0.05). Conclusion: MALDI-TOF MS has become an important method for the identification of anaerobic bacteria with its reliable results in a very short time. The most common anaerobic microorganism was Bacteroides spp., and the two most frequent sources of infection were intraabdominal and skin and soft tissue infections. We observed that most of the cases with F. nucleatum bacteremia had malignancy and an older population. The case with F. necrophorum bacteremia was young and had no underlying comorbidities. In this study, fatality rate (51%) was detected high in anaerobic bacteremia. Therefore, the routine use of anaerobic blood culture bottles is important for the identification and for the effective treatment of cases with anaerobic bacteremia.

비피(鼻皮) 증류액의 항균, 소염, 항산화 작용에 대한 연구

Objectives : The purpose of the study is to test the antibacterial, anti-in flammatory and antioxidant effects of BPH, which is composed of Pini Densiflorae Nodi Lignum and Querci Acutissimae Fructus, Angelicae Gigantis Radix, Cnidii Rhizoma, Angelicae Dahuricae Radix, Angelicae Tenuissimae Radix. Method : Antibacterial and anti-inflammatory effects of BPH on Propionibacterium acnes, one of anaerobic bacteria species were evaluated by measuring the levels of 2,2-diphenyl-1-picrylhydrazyl (DPPH) elimination and lipid peroxidation. Result : When BPH was applied to CCD-986sk (Human normal fibroblast) to confirm the level of cytokine(tumor necrosis factor-alpha, interleukin-8), its level increased in p roportion to that of BPH's concentration, which indicated dose-dependent relationship. Using the Disk diffusion to measure the bacterial growth inhibition zone varying BPH concentration, it was found that the antibacterial effect of BPH was less than that of erythromycin, the control group, but was higher than that of saline, and it increased with higher concentrations. In a liquid culture medium containing BPH, the growth rate of Propionibacterium acnes was decreased by more than 10% at 25% BPH. After adding P. acnes to THP-1 monocyte, and treated it with BPH, and measuring the concentration of TNF-a and IL-8, it was observed that the amount of TNF-a and IL-8 significantly decreased depending on the level of BPH concentration. The ability to eliminate DPPH increased with higher BPH concentration. The inhibition of lipid peroxidation was increased by BHT treatment in a dose-dependent manner. Conclusion : Using Propionibacterium acnes , an anaerobic bacteria, we confirmed that BPH has antibacterial, anti-inflammatory and antioxidant effects.

Non-contiguous finished genome sequence and description of Bacteroides neonati sp. nov., a new species of anaerobic bacterium.

Bacteroides neonati strain MS4T, is the type strain of Bacteroides neonati sp. nov., a new species within the genus Bacteroides. This strain, whose genome is described here, was isolated from a premature neonate stool sample. B. neonati strain MS4T is an obligate anaerobic Gram-negative bacillus. Here we describe the features of this organism, together with the complete genome sequence and annotation. The 5.03 Mbp long genome exhibits a G+C content of 43.53% and contains 4,415 protein-coding and 91 RNA genes, including 9 rRNA genes.

Non-contiguous finished genome sequence and description of Anaerococcus pacaensis sp. nov., a new species of anaerobic bacterium.

Anaerococcus pacaensis strain 9403502T, is the type strain of Anaerococcus pacaensis sp. nov., a new species within a new genus Anaerococcus. This strain, whose genome is described here, was isolated from a blood sample. A. pacaensis strain 9403502T is an obligate anaerobic Gram-positive coccus. Here we describe the features of this organism, together with the complete genome sequence and annotation. The 2.36 Mbp long genome exhibits a G+C content of 35.05% and contains 2,186 protein-coding and 72 RNA genes, including 3 rRNA genes.

화피, 석류피, 염부수백피 추출물의 항산화 및 항균 효과

Objectives : This study was conducted to measure the antioxidative and antimicrobial activities of water- and ethanol-extracts from Betula platyphylla var. japonica, Punica granatum and Rhus javanica against various species of anaerobic bacteria. Methods : In order to evaluate the antioxidative and antimicrobial activities of water- and ethanol-extracts, DPPH radical scavenging and superoxide dismutase (SOD)-like activities were measured in various species such as Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Candida albicans and Propionibacterium acnes that induce skin inflammation. Also the total amount of phenol in each water- and ethanol-extract was measured to identify its role in the antioxidative and antimicrobial activities of water- and ethanol-extracts from Betula platyphylla var. japonica, Punica granatum and Rhus javanica. The antibacterial activity of the extracts was measured by confirming the lowest concentrations in disk diffusion and minimum inhibitory concentration (MIC) tests. Results : It was observed that RJE (Rhus javanica-EtOH extracts) show the highest content of total phenol. In addition, for RJE the total phenol content was higher from samples taken from domestic sources than from samples taken from foreign sources. DPPH radical scavenging activity was increased by treatment with PGE (Punica granatum-EtOH extracts), RJE and RJW (Rhus javanica-water extracts). It was observed that SOD-like activity was highest in the treatment with PGE. All of the extracts showed antimicrobial activity on S. epidermidis, S. aureus, P. acnes and E. coli, including those from Punica granatum, and it was noted that the activity was higher with RJE than with RJW. Conclusions : These results provide evidence that ethanol extracts of Punica granatum and Rhus javanica may have a beneficial role as antioxidants and antibiotics. Extracts from domestic samples of Betula platyphylla var japonica appeared to have a greater efficacy than extracts from foreign samples.

Increased urinary excretion of a 3-(3-hydroxyphenyl)-3-hydroxypropionic acid (HPHPA), an abnormal phenylalanine metabolite of Clostridia spp. in the gastrointestinal tract, in urine samples from patients with autism and schizophrenia

A compound identified as 3-(3-hydroxyphenyl)-3-hydroxypropionic acid (HPHPA) was found in higher concentrations in urine samples of children with autism compared to age and sex appropriate controls and in an adult with recurrent diarrhea due to Clostridium difficile infections. The highest value measured in urine samples was 7500 mmol/mol creatinine, a value 300 times the median normal adult value, in a patient with acute schizophrenia during an acute psychotic episode. The psychosis remitted after treatment with oral vancomycin with a concomitant marked decrease in HPHPA. The source of this compound appears to be multiple species of anaerobic bacteria of the Clostridium genus. The significance of this compound is that it is a probable metabolite of m-tyrosine (3-hydroxyphenylalanine), a tyrosine analog which depletes brain catecholamines and causes symptoms of autism (stereotypical behavior, hyperactivity, and hyper-reactivity) in experimental animals.

Activity of a novel carbapenem, doripenem, against anaerobic pathogens

Doripenem, a synthetic 1-β-methyl carbapenem, has a broad-spectrum of activity against almost all species of anaerobic bacteria, including all Bacteroides fragilis group species, most with MIC 90 results at ≤1 μg/mL (with the exception of Sutterella wadsworthensis). Against Clostridium difficile strains, it has a narrow range of inhibitory concentrations (1–4 μg/mL) that “may be achievable in the colon”, potentially resulting in lower disease rates. It has been shown to be active in vitro against strains isolated from a variety of clinical infections, including bacteremias, diabetic foot and other soft tissues infections and in intra-abdominal and pelvic sites. In addition, a study of a pyometrium animal model of mixed infections noted a better microbiologic response than with imipenem. Two phase 3 multinational clinical trials of complicated mixed aerobic/anaerobic intra-abdominal infections noted “noninferiority” of doripenem when compared with meropenem, but in vitro against the anaerobes, it was “more potent than meropenem, ertapenem, … and similar to imipenem”. Doripenem activity against anaerobes seems comparable with the other extant carbapenems. Although resistance among anaerobic bacteria to this agent is possible, it remains relatively rare.

Ethanol and acetate production by Clostridium ljungdahlii and Clostridium autoethanogenum using resting cells

Combined gasification and fermentation technologies can potentially produce biofuels from renewable biomass. Gasification generates synthesis gas consisting primarily of CO, CO(2), H(2), N(2), with smaller amounts of CH(4), NO(x), O(2), C(2) compounds, ash and tars. Several anaerobic bacteria species can ferment bottled mixtures of pure synthesis gas constituents. However, there are challenges to maintaining culture viability of synthesis gas exposed cells. This study was designed to enhance culture stability and improve ethanol-to-acetate ratios using resting (non-growing) cells in synthesis gas fermentation. Resting cell states were induced in autotrophic Clostridium ljungdahlii cultures with minimal ethanol and acetate production due to low metabolic activity compared to growing cell production levels of 5.2 and 40.1 mM of ethanol and acetate. Clostridium autoethanogenum cultures were not induced into true resting states but did show improvement in total ethanol production (from 5.1 mM in growing cultures to 9.4 in one nitrogen-limited medium) as well as increased shifts in ethanol-to-acetate production ratios.

Bactericidal activity of ertapenem against major intra-abdominal pathogens

Treatment of intra-abdominal infections remains a challenge owing to their polymicrobial nature and associated mortality risk. Treatment regimens must provide broad-spectrum coverage, including Gram-positive and Gram-negative aerobic and anaerobic bacteria of gastrointestinal origin. Ertapenem is a long-acting 1-β-methyl parenteral group 1 carbapenem antibiotic that has a broad antibacterial spectrum and once-daily dosing supported by clinical studies. It is active against Gram-positive and Gram-negative bacteria, including Enterobacteriaceae, Streptococcus pneumoniae and most species of anaerobic bacteria. The aim of this study was to measure the killing effects of ertapenem against a selected group of strains responsible for intra-abdominal infections. Gram-negative isolates comprised the following species: Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Klebsiella ozaenae, Enterobacter cloacae and Proteus mirabilis (extended-spectrum β-lactamase (ESBL) producers and non-producers). Gram-positive isolates comprised methicillin-susceptible Staphylococcus aureus (MSSA), Enterococcus faecalis and anaerobic Bacteroides fragilis. Ertapenem activity was tested by determination of minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs). Killing curves were performed in monocultures and co-cultures at selected antibiotic concentrations. Ertapenem showed a rapid and potent bactericidal activity in the first few hours of the kinetic curves against E. coli (6 log 10 colony-forming unit (CFU) reduction in the first 2 h), B. fragilis (4 log 10 CFU reduction in 4 h), MSSA (3 log 10 CFU reduction in 4–6 h), K. ozaenae (ESBL+), K. pneumoniae (ESBL+ and −), E. cloacae (ESBL−) in 1 h and P. mirabilis (ESBL+) in the first 2 h. The potent bactericidal activity of ertapenem compared with ceftriaxone and piperacillin/tazobactam was well demonstrated in the co-cultures of E. coli–B. fragilis and E. coli–B. fragilis–E. faecalis, whilst ertapenem was shown to be bactericidal at 24 h in the mixed culture of S. aureus–P. mirabilis. These results support the potent in vitro bactericidal activity of ertapenem against all multiresistant strains selected in this study and the use of this drug in the treatment of intra-abdominal infections.

Antimicrobial susceptibility variation of 50 anaerobic periopathogens in aggressive periodontitis: an interindividual variability study

The frequent use of antibiotics in developed countries has led to the emergence of widespread bacterial resistance. In this study, the interindividual variability of the antibiotic susceptibility of 50 putative microorganisms in aggressive periodontitis patients has been evaluated by means of VC (variation coefficient). A total of 60 microbial samples were collected from 20 adult patients diagnosed with aggressive periodontitis (2-4 samples by patient). Bacterial strains of Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, Fusobacterium nucleatum, and Peptostreptococcus micros were isolated according to Slots' rapid identification method. The susceptibilities to 10 antibiotics were studied: penicillin G (PEN), ampicillin (AMP), amoxicillin (AMX), amoxicillin/clavulanate (AMC), tetracycline (TET), doxycycline (DOX), ciprofloxacin (CIP), erythromycin (ERY), spiramycin (SPI) and clindamycin (CLIN), using the Disk Diffusion Susceptibility test (DDS test: Kirby-Bauer's modified method for anaerobic bacteria). The broth microdilution Minimum Inhibitory Concentration test was carried out as a control test. Among the 50 identified bacteria, 15 were P. gingivalis, 12 P. intermedia, 8 T. forsythia, 9 F. nucleatum, and 6 P. micros. The results of the DDS test show that penicillins (especially AMC, AMP, and AMX), cyclines (especially DOX) and CLIN are highly effective against the 50 anaerobic studied bacteria. CIP and ERY have the lowest efficacy against those bacteria. CIP shows a very variable activity according to anaerobic bacteria species, being particularly inactive against P. gingivalis and very efficient against T. forsythia and P. micros. SPI is also highly efficient but not against P. micros. The interindividual susceptibility of principal periodontal pathogens to antibiotics is not homogeneous and seems to vary according to bacterial species and antimicrobial molecules. This variability seems to be greater with older molecules (PEN, TET, ERY) than with more recent ones, which indicates more stable results (AMC, AMX, AMP, and DOX). P. intermedia appeared to be the bacteria most resistant to penicillins and showed the highest coefficient variation. Together with scaling and root planing, the combination of two antibiotics would therefore seem to be recommended in the treatment of aggressive periodontitis, particularly in the presence of P. intermedia.

In vitro activity of ertapenem: review of recent studies.

Ertapenem is a long-acting, 1beta-methyl parenteral Group 1 carbapenem antibiotic that has a broad antibacterial spectrum and once-a-day dosing supported by clinical studies. Ertapenem is active against both Gram-positive and Gram-negative bacteria, including Enterobacteriaceae, Streptococcus pneumoniae and most species of anaerobic bacteria. Isolates from a variety of infections (intra-abdominal infections, skin/soft-tissue infections, community-acquired pneumonia, pelvic infections and urinary tract infections) are inhibited by ertapenem. It has restricted activity against nosocomial pathogens such as Pseudomonas aeruginosa, Acinetobacter species, methicillin-resistant staphylococci and enterococci. Ertapenem has potent activity against the majority of anaerobic isolates from intra-abdominal infections, and against most of the aerobes isolated from these infections, with the exceptions of the nosocomial pathogens mentioned above. MIC(90)s for most species of Enterobacteriaceae were <1 mg/L, significantly lower than those of imipenem. MIC(90)s for most Bacteroides fragilis group isolates ranged from 1 to 4 mg/L, and MIC(90)s were species specific for Clostridium, ranging from 0.06 mg/L for Clostridium perfringens to 4 mg/L for Clostridium clostridioforme. Ertapenem was equivalent to or better than piperacillin-tazobactam in activity against most anaerobic species isolated from these infections, and was more potent than piperacillin-tazobactam and ceftriaxone against the most common skin pathogens (e.g. methicillin-susceptible Staphylococcus aureus). Ertapenem was highly active against most of the pathogens isolated from patients with community-acquired pneumonia, except for isolates of methicillin-resistant S. aureus (which are infrequent causes of community-acquired infection); these isolates were also resistant to ceftriaxone. Resistance to ertapenem is most commonly attributable to a variety of mechanisms including alterations in penicillin-binding proteins in Gram-positive organisms, and combinations of potent metallo-beta-lactamase enzymes, porin protein defects and efflux pumps in Gram-negative organisms.

Presence of anaerobic bacteroides in aerobically grown microbial granules.

Microbial granules were grown in a column-type sequential aerobic sludge blanket reactor inoculated with activated sludge flocs taken from a wastewater treatment plant and containing a medium with glucose as the main carbon source. The reactor selected for granules that could settle rapidly by employing a short settling time of 2 min. Matured granules with diameters between 2 and 3 micro m were examined for anaerobic bacteria as their presence can signal the onset of diffusion limitation problems that can potentially diminish granule stability due to the bacterial production of fermentation gases and organic acids under anaerobic conditions. To detect the anaerobes in the granules, clones were constructed from 16S rRNA PCR amplicons. Two sequence types associated with a strict anaerobe Bacteroides spp. were identified from these clones. Fluorescence in situ hybridization (FISH) followed by confocal laser scanning microscopy (CLSM) demonstrated that cells of Bacteroides spp. were concentrated at a depth of approximately 800 micro m below the surface of the granule. Cell enumeration using flow cytometry showed that the percentage of labeled cells of Bacteroides spp. compared to total bacterial cells in the granules was 0.56%. This is the first study to use a suite of culture-independent techniques to report the presence of a defined species of anaerobic bacteria in aerobically grown microbial granules.

Determination of diamino acids in peptidoglycans from anaerobic bacteria.

Peptidoglycans isolated from two Fusobacterium species of anaerobic bacteria were analyzed for constituent amino acids. Hydrolysis conditions were varied to optimize the yield of diamino acids from peptidoglycan. The o-phthalaldehyde derivatives of the diamino acid stereoisomers were separated by high-performance liquid chromatography (OPA-HPLC), and variations in the relative areas of the two peaks noticed during analysis of solid samples were attributed to sampling errors. Co-derivatization/injection experiments using standards of the meso and rac forms separated from commercial mixtures demonstrated that meso-2,6-diaminopimelic acid and meso-lanthionine were peptidoglycan components in Fusobacterium varium and Fusobacterium nucleatum, respectively. The protonated molecules of 2,6-diaminopimelic acid and lanthionine were detected in peptidoglycan hydrolyzates by off-line, flow-injection electrospray mass spectrometry (ESI-MS). In ESI-MS-MS experiments under identical collision-induced dissociation (CID) conditions, peptidoglycan-derived and standard diamino acids exhibited similar fragmentations. Fragmentation pathways are proposed for each diamino acid. The results confirm that the meso forms of two different diamino acids are utilized in the peptidoglycans of Fusobacterium species.