Facultative Gram-positive Cocci Research Articles

Cultivation of Peptidiphaga gingivicola from subgingival plaque: The first representative of a novel genus of Actinomycetaceae.

A novel bacterium was isolated from the subgingival plaque of a patient with periodontal disease. Bacterial strain BA112T is a facultative Gram-positive coccus. It metabolizes alanine, arginine, glycine, histidine, leucine, proline, serine and tyrosine, but does not appear to use carbohydrates. Urease, esculin, indole, catalase and nitrate reduction tests were all negative. Major cellular fatty acids were C18:0 , C12:0 , C16:0 , C18:1 w9c and C20:0 . The genome was sequenced and is 2.4Mbp in length and has 64% GC content. Based on phylogenetics of the 16S rRNA sequence and concatenated alignments of 37 conserved proteins, BA112T belongs to the family Actinomycetaceae but is located on a branch of the tree without currently named members. Based on our phenotypic and phylogenetic studies, we propose that BA112T is the first known representative of a new genus, for which the name Peptidiphaga gingivicola gen. nov., sp. nov. is proposed. The type strain is BA112T .

Microbial flora of root canal–treated teeth associated with asymptomatic periapical radiolucent lesions

This study aimed to investigate the composition of microflora in endodontically treated teeth associated with asymptomatic periapical lesions in southern Chinese patients. Twenty-four teeth which had received nonsurgical root canal treatment more than 4 years previously, and which presents an acceptable coronal restoration with a periapical radiolucent area, were re-treated nonsurgically. Bacteriological samples were obtained after removal of the old root canal filling. The samples were inoculated on enriched trypticase soy agar and four selective media for incubation at 37 degrees C in both a carbon dioxide-enriched atmosphere and anaerobically. Eighteen teeth that had received gutta-percha root canal fillings were grouped for analysis, 12 (66.7%) of which contained cultivable microorganisms. The total colony forming units per ml of transport medium ranged from 0 to 2.3 x 10(5). The number of bacterial genera recovered ranged between 0 and 6, with facultative gram-positive cocci being the most prevalent group of bacteria isolated. Facultative anaerobic bacteria were present in all, whereas strict anaerobic bacteria were found in 3 out of the 12 teeth with positive growth. The size of the periapical rarefaction did not show any relationship with the quantity of microorganisms recovered. Coagulase-negative staphylococci, streptococci and Pseudomonas aeruginosa were most frequently isolated in this group of patients. The possible origin of these organisms is discussed.

The role of encapsulated anaerobic bacteria in synergistic infections

The effect of encapsulation on the virulence, survival, and protection of anaerobic bacteria from phagocytosis is reviewed. Support for the importance of encapsulated Gram-negative anaerobic rods (Bacteroides sp., Prevotella sp. and Porphyromonas sp.), anaerobic and facultative Gram-positive cocci (AFGPC) was provided by their higher recovery rate in oropharyngeal infections, abscesses and blood, compared to their number in the normal flora. The pathogenicity of Bacteroides, Fusobacterium, Clostridium, and AFGPC was studied by inoculating them into mice and observing their ability to induce subcutaneous abscesses. Encapsulated Bacteroides, Fusobacteria, and AFGPC generally induced abscesses, whereas non-encapsulated organisms did not. However, many of the strains that had only a minimal number of encapsulated organisms (< 1%) survived in the abscesses, and they became heavily encapsulated when inoculated with other viable or non-viable encapsulated bacteria. Thereafter, these strains were able to induce abscesses when injected alone. Encapsulated Gram-negative anaerobic rods and AFGPC-induced bacteraemia and translocation, and increased the mortality of the infected animals more often than did the non-encapsulated form of the same strains. As determined by using selective antimicrobial therapy and quantitative cultures of abscesses induced in mice, possession of a capsule generally made Gram-negative anaerobic rods more important than their aerobic counterparts. Synergistic potentials were seen between encapsulated Gram-negative anaerobic rods and all tested aerobic bacteria and most AFGPC, and also between most AFGPC and Pseudomonas aeruginosa or Staphylococcus aureus. These studies demonstrated the importance of encapsulated anaerobes in mixed infections.

The role of encapsulated anaerobic bacteria in synergistic infections

The effect of encapsulation on the virulence, survival, and protection of anaerobic bacteria from phagocytosis is reviewed. Support for the importance of encapsulated Gram-negative anaerobic rods ( Bacteroides sp., Prevotella sp. and Porphyromonas sp.), anaerobic and facultative Gram-positive cocci (AFGPC) was provided by their higher recovery rate in oropharyngeal infections, abscesses and blood, compared to their number in the normal flora. The pathogenicity of Bacteroides, Fusobacterium, Clostridium, and AFGPC was studied by inoculating them into mice and observing their ability to induce subcutaneous abscesses. Encapsulated Bacteroides, Fusobacteria, and AFGPC generally induced abscesses, whereas non-encapsulated organisms did not. However, many of the strains that had only a minimal number of encapsulated organisms ( < 1%) survived in the abscesses, and they became heavily encapsulated when inoculated with other viable or non-viable encapsulated bacteria. Thereafter, these strains were able to induce abscesses when injected alone. Encapsulated Gram-negative anaerobic rods and AFGPC-induced bacteraemia and translocation, and increased the mortality of the infected animals more often than did the non-encapsulated form of the same strains. As determined by using selective antimicrobial therapy and quantitative cultures of abscesses induced in mice, possession of a capsule generally made Gram-negative anaerobic rods more important than their aerobic counterparts. Synergistic potentials were seen between encapsulated Gram-negative anaerobic rods and all tested aerobic bacteria and most AFGPC, and also between most AFGPC and Pseudomonas aeruginosa or Staphylococcus aureus. These studies demonstrated the importance of encapsulated anaerobes in mixed infections.

Irrigation With 0.06% Chlorhexidine in Naturally Occurring Gingivitis. II. 6 Months Microbiological Observations

In an examiner blind positive/negative controlled 6-month study, the efficacy of supragingival irrigation with 0.06% chlorhexidine gluconate on the marginal and subgingival microflora in naturally occurring gingivitis was evaluated. The 222 patients enrolled in the study were assigned to one of four groups: Group 1: Once daily irrigation with 300 ml water followed by irrigation with 200 ml 0.06% chlorhexidine gluconate (experimental); Group 2: Twice daily rinsing with 15 ml 0.12% chlorhexidine (positive control); Group 3: Once daily irrigation with 500 ml water (irrigation control) and Group 4: Sodium fluoride dentifrice for normal oral hygiene only (negative control). All groups received the same sodium fluoride dentifrice for tooth brushing. All patients received a supra- and subgingival oral prophylaxis after baseline examination and at the end of the investigation. Plaque samples were analyzed from 105 patients at baseline, 93 patients at 3 months and 88 patients at 6 months. The 6-months results demonstrated that, when compared with tooth brushing alone, adjunctive supragingival irrigation with 0.06% chlorhexidine gluconate was most effective by significantly reducing (P less than or equal to 0.008) both log10 CFU and % of Gram-negative anaerobic rods and black-pigmented Bacteroides. Chlorhexidine rinse also significantly (P less than or equal to 0.008) reduced log10 CFU of black-pigmented Bacteroides at 6 months. Both chlorhexidine regimens significantly (P less than or equal to 0.008) increased the % of Gram-positive facultative cocci compared to water irrigation at 3 months. Water irrigation had a limited effect on any of the assessed bacterial groups (log10 CFU and %).(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro activity of daptomycin-metronidazole combinations against mixed bacterial cultures: Reduced activity of metronidazole againstBacteroides species in the presence ofEnterococcus faecalis

The in vitro activity of daptomycin-metronidazole combinations against mixed cultures of gram-positive facultative cocci and strains of the Bacteroides fragilis group was investigated. Metronidazole did not influence the high activity of daptomycin against strains of Staphylococcus aureus, Staphylococcus epidermidis and Enterococcus faecalis in the absence or presence of the co-cultured Bacteroides strains. In contrast, the Enterococcus faecalis isolates protected the co-cultured Bacteroides strains against the killing effect of metronidazole, even at a concentration four- or eightfold the MIC of metronidazole. Killing curve experiments confirmed this protective effect of different isolates of Enterococcus faecalis.

Reproducibility of microscopic and cultural data in repeated subgingival plaque samples.

In association studies, micro-organisms can only be recognized as suspects for playing a major rôle in the development of a pathological environment, if their destructive action goes along with a marked proportional increase of their numbers or if their first detection can be related to the clinical onset of the disease. Limitations in the reproducibility of repeated samples have to be taken into account, when changes of the microbial composition of subgingival environments are to be studied, and when local clinical changes are to be related to shifts in the composition of the pertaining microbiological compartment. To study reproducibility, a total of 109 sites was sampled repeatedly with sterile paperpoints at an interval of 7 to 10 days in 24 patients suffering from periodontal disease and 12 edentulous patients wearing successful and failing osseointegrated titanium implants. Using continuous anaerobic techniques, the samples were cultured on nonselective and selective media and were studied by darkfield microscopy. Both the intertest-agreements of frequencies of detection (kappa-statistics) as well as the discrepancies of proportions of bacterial groups and selected bacterial species were determined. The standard deviation of proportional differences between first and second samples ranged between 6.4% (fusiform organisms) and 17.2% (coccoid cells) for darkfield parameters, between 4.3% (B. melaninogenicus on ETSA/Kana.) and 14.0% (B. gingivalis on ETSA/Kana.) for selected bacterial species and between 6.9% (gram-negative anaerobic cocci) and 24.0% (gram-positive facultative cocci) for bacterial groups classified according to gram stain characteristics and atmospheric growth conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of the antimicrobial capability of an abrasive paste and chemical-soak denture cleaners

The objective of this research was to compare the ability of the two most popular methods for denture cleaning to remove plaque microorganisms from dentures. Dentu-Creme abrasive denture paste and Efferdent alkaline peroxide denture-cleanser soak were selected for study. Two trials were completed in which these materials were used alone and in combination along with a no-treatment control to determine the level of recoverable plaque bacteria from removable dentures. Plaque was allowed to accumulate for 48 or 72 hours in individuals with healthy oral mucosa during which time they refrained from all denture hygiene procedures. The results of two studies following similar double-blind cross-over designs were consistent in that soaking with the denture cleanser caused a significantly greater reduction of microorganisms than did brushing with the denture paste. Further, combining brushing with the soak did not reduce the level of recoverable microorganisms significantly more than soaking alone. Overall, brushing alone did not consistently remove more microorganisms than were observed in the no-treatment group. The denture-cleanser soak displayed broad antimicrobial activity against gram-negative anaerobic rods ( Fusobacterium sp.), gram-positive facultative cocci (streptococci), and gram-negative anaerobic cocci ( Veillonella sp.), as well as total recoverable microorganisms, which were all equally reduced by the denture-cleanser treatment. These results support the need for use of a denture cleanser in addition to brushing with a denture paste for proper denture hygiene.

Enhancement of growth of aerobic, anaerobic, and facultative bacteria in mixed infections with anaerobic and facultative gram-positive cocci

The potential for mutual enhancement of growth of seven strains of anaerobic and facultative gram-positive cocci (AFGPC), seven aerobic and facultative organisms, and two Bacteroides spp. commonly isolated with AFGPC in mixed infection was evaluated. Enhancement was studied by measuring the relative increase in the colony-forming units of the two bacterial components inducing subcutaneous abscesses in mice. Of the 56 combinations, AFGPC were enhanced in 6 and inhibited in 1. The aerobic and facultative bacteria were enhanced in 32 of the 42 combinations and depressed in none. The Bacteroides spp. were enhanced in 12 of the 14 combinations and suppressed in none. The organisms uniformly enhanced by AFGPC were Group A streptococci, Pseudomonas aeruginosa, and Bacteroides fragilis (all seven instances), followed by Escherichia coli (six of seven instances), Bacteroides asaccharolyticus and Klebsiella pneumoniae (five instances each), Staphylococcus aureus (four instances), and Group D streptococci (three instances). It is apparent that in mixed infection with AFGPC the rate of growth of Bacteroides spp. and facultative and aerobic bacteria is enhanced much more than the rate of growth of AFGPC.

Role of encapsulated anaerobic bacteria in synergistic infections.

The effect of encapsulation on the virulence, survival, and protection of anaerobic bacteria from phagocytosis is reviewed. Support for the importance of encapsulated Bacteroides sp. and anaerobic and facultative Gram-positive cocci (AFGPC) was provided by their higher recovery rate in oropharyngeal infections, compared to their number in the normal oral flora. Studies of the pathogenicity of anaerobic bacteria of the Bacteroides, Fusobacterium, and Clostridium genera and AFGPC are also presented. The organisms were inoculated into mice and their ability to induce subcutaneous abscesses was determined. Encapsulated Bacteroides, Fusobacteria, and AFGPC generally induced abscesses, whereas unencapsulated organisms did not. However, many of the strains that had only a minimal number of encapsulated organisms (less than 1%) survived in the abscess, and became heavily encapsulated when inoculated with other viable or nonviable encapsulated bacteria. These strains were thereafter able to induce abscesses when injected alone. Encapsulated Bacteroides sp. and anaerobic cocci induced bacteremia and translocation, and increased the mortality of the infected animals more often than did the unencapsulated form of the same strains. The relative importance of encapsulated anaerobes in relation to their aerobic and facultative counterparts in mixed infection was studied, using selective antimicrobial therapy and quantitative cultures of abscesses induced in mice. With few exceptions, possession of a capsule made Bacteroides sp. more important than their aerobic counterparts. Synergistic potentials were seen between encapsulated Bacteroides sp. and all tested aerobic bacteria and most AFGPC, and between most AFGPC and Pseudomonas aeruginosa or Staphylococcus aureus. These studies demonstrated the importance of encapsulated anaerobes in mixed infections.

The role of encapsulation in the pathogenesis of anaerobic Gram-positive cocci

The pathogenicity of 22 anaerobic and facultative Gram-positive cocci (AFGPC) was investigated by inoculating them into mice and determining their ability to cause subcutaneous abscesses. Only 11 heavily encapsulated isolates (greater than 50% of the cells were encapsulated) induced abscesses. However, when the other 11 isolates were injected with Bacteroides sp. or facultative and aerobic bacteria, abscesses were formed in 8 of the 11 combinations. The AFGPC recovered from the mixed infections contained many encapsulated cells. Encapsulation also occurred in cocci injected with capsular material or with Formalin-killed cells of Klebsiella pneumoniae or capsule-positive Bacteroides sp. After acquisition of capsules, these strains could induce abscesses on reinoculation in mice.

Evaluation of a lysis-centrifugation and biphasic bottle blood culture system during routine use.

An in-use evaluation of a commercially available lysis-centrifugation blood culture system (Isolator; Du Pont Co., Wilmington, Del.) is presented. The Isolator was compared with biphasic bottles containing Trypticase soy broth and agar for the detection of organisms in 3,129 paired blood samples. Of 272 potential pathogens recovered, 78% were detected by the Isolator system, and 69% were detected by the biphasic bottle. A total of 31% of these organisms were detected only by the Isolator, and 22% were detected only by the biphasic bottle. The Isolator demonstrated enhanced detection of facultative gram-negative bacilli, anaerobic bacteria, and polymicrobial cultures. The biphasic bottle was more effective for the recovery of facultative gram-positive cocci, especially Streptococcus pneumoniae. The two systems were equally effective for the recovery of yeasts. Contamination rates were 3% for the Isolator and 3.2% for the biphasic bottle. The results indicate that the Isolator system performs well in routine clinical use, but it should be complemented by another method to obtain optimal detection of bacteremia. The biphasic bottle provides an acceptable complementary system both in terms of utility and performance.

Evaluation of lamoxactam in the treatment of severe bacterial infections.

We investigated the clinical efficiency and safety of lamoxactam for treatment of 28 episodes of infection in 26 adult patients (15 males and 11 females) whose ages ranged from 17 to 83 years (mean 48.7). 4 patients had 'ultimately fatal diseases' and the remaining 22 had 'nonfatal diseases'. The clinical condition at the beginning of treatment was 'critical' or 'poor' in 15 cases. Episodes of infection treated were: 14 intraabdominal, 9 bacteremia, 5 nephro-urinary, 3 osteomyelitis, and a miscellaneous group including pneumonia, soft tissue, parameningeal focus and infected V-P shunt. A total of 34 microorganisms were responsible for 25 episodes of infection. 15 and 10 episodes were mono- and polymicrobial, respectively. Isolated microorganisms included 13 aerobic facultative gram-negative bacillus, 5 facultative gram-positive cocci, and 16 anaerobes. Total dosage of lamoxactam administered by patient ranged from 24 to 234 g (mean 57.6 g), and mean duration of therapy was 15.2 days (range 8-42 days). The overall rate of clinical response to lamoxactam was excellent, amounting to 84% of episodes and 91% of patients. Local and general tolerance was good, and lamoxactam had to be discontinued only once during therapy due to an episode of neutropenia. Enterococcal colonization (5 of 26 patients, 19%) and superinfections (3 of 26 cases, 11.5%) were undesirably frequent in our patients. Lamoxactam seems to be an effective and safe single-agent therapy for many bacterial infections. The possibility of enterococcal colonization and superinfections should be monitored, specially in patients with urinary or intraabdominal infections.

Anaerobic radiometric detection of facultative Gram-positive cocci in blood.

Radiometric detection of facultative gram-positive cocci, particularly streptococci, has been reported to be suboptimal. A recently marketed anaerobic Bactec bottle (7C) with purportedly improved capability to detect facultative gram-positive cocci in blood was compared with the previously available bottle in a study of simulated bacteremia. The Bactec system detected all beta-hemolytic streptococci and enterococci tested. Detection of alpha-hemolytic streptococci was improved in general. However, detection of Streptococcus mutans, Streptococcus bovis and Streptococcus pneumoniae remained suboptimal under anaerobic conditions. A metabolic index unit threshold for positivity of 15 is recommended when employing the anaerobic Bactec bottle.

Direct inoculation procedure for the rapid classification of bacteria from blood culture.

A procedure was developed for 4-h identification of bacteria from blood culture. From a turbid blood culture bottle a 10- to 15-ml aliquot was drawn off and centrifuged. The pellet was utilized to inoculate a series of enzymatic and physiologic reactions. Three hundred eight positive blood cultures were tested including 222 strains of Enterobacteriaceae, 40 strains of facultative grampositive cocci, 26 strains of anaerobes, and 20 assorted strains. There was over 96.5% agreement between 4-h and conventional methods with the Enterobacteriaceae, 98% with facultative gram-positive cocci, 100% with anaerobes, and 99% with the assorted strains.

Reisolation of Staphylococcus salivarius from the human oral cavity.

Twenty-four strains of gram-positive facultative cocci, arranged primarily in small clusters, were isolated from the surface of the human tongue. With the exception of 14 catalase-negative isolates, these strains were identical in cultural and biochemical characteristics and in deoxyribonucleic acid base composition. All cultures produced viscous growth in both liquid and agar media. They fermented glucose anaerobically, reduced nitrate beyond nitrite, were benzidine-positive, and failed to grow in the presence of 5% NaCl or at 45 C. In addition, they exhibited guanine plus cytosine (G + C) contents of 55.4 to 58.3%. These isolates differed from strains of pediococci, aerococci, and micrococci which were included for comparison. On the basis of G + C content, these organisms appear to be intermediate between micrococci and staphylococci; however, on the basis of anaerobic glucose fermentation, it is suggested that they be placed in the genus Staphylococcus. It is proposed that they be recognized as S. salivarius.