Black-pigmented Gram-negative Anaerobes Research Articles

Porphyromonas asaccharolytica liver abscess

The black pigmented Gram-negative anaerobes, Porphyromonas species, have been isolated from clinical specimens in cases of central nervous system, dental–oral, pleuropulmonary and genitourinary infections and bacteremia. Herein, we report an unusual case of liver abscess caused by Porphyromonas asaccharolytica that has not been previously reported.

Black pigmented gram-negative anaerobes: April 21–23, 1992 Antalya, Turkey

Black pigmented gram-negative anaerobes: April 21–23, 1992 Antalya, Turkey

Susceptibility of Prevotella intermedia/Prevotella nigrescens (and Porphyromonas gingivalis) to Propolis (Bee Glue) and other Antimicrobial Agents

Black-pigmented Gram-negative anaerobes such as Porphyromonas gingivalis and Prevotella intermedia are suspected pathogens in adult periodontitis, whereas Prevotella nigrescens has been associated with health. Antimicrobial resistance among bacteria from this group has been reported in the past decade. This research aimed to evaluate and compare the susceptibility profile of 17 P. intermedia/P. nigrescens isolates recovered from patients with periodontitis and three reference strains to six antimicrobials, prescribed in dentistry in Brazil, and propolis (bee glue). The antimicrobial agents tested were tetracycline, penicillin, clindamycin, erythromycin, metronidazole, meropenem and six ethanolic extracts of propolis (EEPs) from Brazil. The reference strains P. gingivalis ATCC 33277 and P. intermedia ATCC 25611 were used for determination of minimum bactericidal concentration (MBC) and for time-kill assay to the EEPs. All of the strains were susceptible to penicillin, erythromycin, meropenem, metronidazole and 95% of them (n=19) to tetracycline. Thirty six percent (n=7) of the P. intermedia/P. nigrescens strains tested were resistant to clindamycin. As for propolis activity, all strains were susceptible and the minimum inhibitory concentration values ranged from 64 to 256 μg/mL. For the reference strains P. gingivalis ATCC 33277 andPrevotella intermedia ATCC 25611 the MBC was 256 μg/mL and death was observed within 3 h of incubation for P. gingivalis and within 6 h for P. intermedia. The action of propolis (bee glue) against suspected periodontal pathogens suggests that it may be of clinical value.

Relationship between intra-uterine bacterial contamination, endotoxin levels and the development of endometritis in postpartum cows with dystocia or retained placenta

A study was conducted to investigate the relationship between intra-uterine bacterial contamination, endotoxin levels and the development of endometritis in cows that experienced a dystocia or retained their placenta. Fifteen healthy cows, 31 cows with retained placenta (RP) and 13 cows that had dystocia were clinically examined 1 or 2 days after parturition when a uterine swab for bacteriological examination was taken. In addition, plasma and uterine lochia samples were collected to determine lipopolysaccharide (LPS) and the plasma IgG anti-LPS concentrations. Subsequently, 15 RP and 6 dystocia cows were initially left untreated and another uterine swab was collected at 2 and 4 wk postpartum. Immediately after calving, RP cows had significantly higher LPS levels in uterine lochia (average of 2.24 × 10 4 Endotoxin Units (EU)/mL) as compared to dystocia and healthy postpartum cows (average of 0.10 and 0.26 EU/mL, respectively). However, plasma LPS levels were below the detection limit (<0.036 EU/mL platelet-rich plasma) in all groups of cows. IgG anti-LPS levels in plasma were not significantly different between the 3 groups immediately postpartum (average of 26, 16 and 44 Median Units (MU)/mL) for healthy, dystocia and RP cows, respectively), but they were significantly lower when compared to plasma IgG anti-LPS levels of healthy cows at more than 2 months postpartum (mean 83 MU/mL). High LPS levels in lochia at 1 or 2 days postpartum were significantly related to abnormal cervical discharge, the presence of Escherichia coli , black pigmented Gram-negative anaerobes and Clostridium spp. shortly after calving, and Arcanobacterium pyogenes and Gram-negative anaerobes in the uterus at 14 days postpartum. These results suggest that the presence of E. coli and LPS (endotoxins) in lochia early postpartum favor the development of uterine infections by A. pyogenes and Gram-negative anaerobes later postpartum. LPS were not observed in plasma, suggesting that either they are not absorbed into the blood, or they are efficiently detoxified by IgG anti-LPS or other detoxification mechanisms.

Antibacterial effects of endodontic irrigants on black-pigmented Gram-negative anaerobes and facultative bacteria

The antibacterial effect of endodontic irrigants was evaluated against four black-pigmented Gram-negative anaerobes and four facultative anaerobic bacteria by means of the agar diffusion test. All solutions used were inhibitory against all bacterial strains tested. A 4% NaOCl solution provided the largest average zone of bacterial inhibition of this study that was significantly superior when compared with the other solutions, except 2.5% NaOCl (p < 0.05). Based on the averages of the diameters of the zones of bacterial growth inhibition, the antibacterial effects of the solutions could be ranked from strongest to weakest as follows: 4% NaOCl; 2.5% NaOCl; 2% chlorhexidine; 0.2% chlorhexidine, EDTA, and citric acid; and 0.5% NaOCl.

The role of neuraminidase in haemagglutination and adherence to colon WiDr cells by Bacteroides fragilis.

The role of neuraminidase in haemagglutination and adherence to colon WiDr cells by eight strains of Bacteroides fragilis and four strains of oral black-pigmented gram-negative anaerobes was studied. Neuraminidase treatment resulted in a very small increase of haemagglutination by some of the strains but had no effect on adherence to WiDr cells by all bacterial strains tested except one strain of Prevotella intermedia (HG 110). Inhibition of neuraminidase had no effect on haemagglutination or adherence, nor was any correlation found between haemagglutinating ability and neuraminidase activity in the B. fragilis strain. The results indicated that haemagglutination and adherence of B. fragilis to WiDr cells were not mediated by neuraminidase.

Black-pigmented Gram-negative anaerobes in endodontic infections

Necrotic dental root canal infections are polymicrobial infections dominated by anaerobic bacteria. The number of different species in one canal is usually low, approx. 4–7 species. The species isolated most frequently belong to the genera Prevotella, Porphyromonas, Fusobacterium, Peptostreptococcus, Eubacterium and Streptococcus. The frequency of isolation of black-pigmented Gram-negative anaerobes in endodontic infections varies from 25% to <50%. Pr. intermedia is the most commonly found pigmented species, followed by Pr. denticola and two Porphyromonas species, P. gingivalis and P. endodontalis. Several studies have shown that P. gingivalis and P. endodontalis are closely related to the presence of acute symptoms in endodontic infections, whereas other black-pigmented Gram-negative anaerobes are not. However, several other species may also be involved in acute infections. Moreover, Porphyromonas species have occasionally been isolated from cases with no symptoms. Although Porphyromonas spp. are clearly related to symptoms at the beginning of therapy, they are not important for the prognosis of the treatment.

Black-pigmented Gram-negative anaerobes in genito-urinary tract and pelvic infections

Black-pigmented Gram-negative anaerobes are part of the normal vaginal flora and contribute to a range of superficial and deep genital infections. Prevotella melaninogenica is found in moderate numbers (104−6 cfu/g) in healthy women; the numbers and detection rates increase in anaerobic vaginosis (where it may be a significant contributor to changed microbial metabolic activity that gives the signs and symptoms of this condition) and in other vaginal infective conditions. Pr. melaninogenica is also part of the mixed flora in deep pelvic infections: endometritis, post-partum and post-abortal uterine infections; salpingitis and tubo-ovarian abscesses; PID and pelvic abscesses. Porphyromonas asaccharolytica is probably not a vaginal commensal, but may be isolated from patients with vaginal or pelvic disease. It is more specifically associated with superficial abscesses (e.g. Bartholin's abscess) and ulcers of the genitalia and perineum. P. asaccharolytica was the commonest species isolated from men with genital ulcers of various primary causes and ranging in severity from superficial balanitis/balanoposthitis to synergic gangrene.

Black-pigmented gram-negative anaerobes in endodontic infections.

Necrotic dental root canal infections are polymicrobial infections dominated by anaerobic bacteria. The number of different species in one canal is usually low, approx. 4-7 species. The species isolated most frequently belong to the genera Prevotella, Porphyromonas, Fusobacterium, Peptostreptococcus, Eubacterium and Streptococcus. The frequency of isolation of black-pigmented Gram-negative anaerobes in endodontic infections varies from 25% to > 50%. Pr. intermedia is the most commonly found pigmented species, followed by Pr. denticola and two Porphyromonas species, P. gingivalis and P. endodontalis. Several studies have shown that P. gingivalis and P. endodontalis are closely related to the presence of acute symptoms in endodontic infections, whereas other black-pigmented Gram-negative anaerobes are not. However, several other species may also be involved in acute infections. Moreover, Porphyromonas species have occasionally been isolated from cases with no symptoms. Although Porphyromonas spp. are clearly related to symptoms at the beginning of therapy, they are not important for the prognosis of the treatment.

Interactions between black-pigmented Gram-negative anaerobes and other species which may be important in disease development

Interactions between black-pigmented Gram-negative anaerobes and other species which may be important in disease development

The importance of black-pigmented Gram-negative anaerobes in human infections

Black-pigmented Gram-negative anaerobic rods are found on mucosal surfaces as indigenous flora. With mucosal damage due to disease, trauma or surgery, these organisms may invade tissues and set up infection. Other important factors determining whether or not infection results include 'inoculum' size, synergy with other organisms and production of virulence factors that include capsules, lipopolysaccharide, attachment factors, proteases, collagenase, neuraminidase, and phospholipase A; also, they may have fibrinolytic and anti-phagocytic activity and may degrade complement and IgG and IgM. Pigmented anaerobes are found in all types of infections including such serious infections as bacteraemia, endocarditis, intracranial abscess, necrotizing pneumonia and necrotizing fasciitis, generally as part of a mixed infecting flora, and they play a key role in experimental mixed infections. They dominate or are prominent in infections involving organisms originating in the oropharynx, such as central nervous system, head and neck, dental and pleuropulmonary infections. Therapy of infections involving pigmented anaerobes includes surgery plus antimicrobial agents; a significant percentage of strains produce beta-lactamase. Much remains to be done to determine the relative importance of the various taxa of black-pigmented Gram-negative anaerobes and of the different virulence factors produced by them.

Hydrolytic enzymes liberated by black-pigmented Gram-negative anaerobes

Hydrolytic enzymes liberated by black-pigmented Gram-negative anaerobes

Black-pigmented Gram-negative anaerobes

Black-pigmented Gram-negative anaerobes

Black-pigmented Gram-negative Anaerobes. FEMS symposium proceedings. Antalya, Turkey, 21-23 April 1992.

Black-pigmented Gram-negative Anaerobes. FEMS symposium proceedings. Antalya, Turkey, 21-23 April 1992.

Black-pigmented Gram-negative anaerobes in genito-urinary tract and pelvic infections

Black-pigmented Gram-negative anaerobes are part of the normal vaginal flora and contribute to a range of superficial and deep genital infections. Prevotella melaninogenica is found in moderate numbers (10(4-6) cfu/g) in healthy women; the numbers and detection rates increase in anaerobic vaginosis (where it may be a significant contributor to changed microbial metabolic activity that gives the signs and symptoms of this condition) and in other vaginal infective conditions. Pr. melaninogenica is also part of the mixed flora in deep pelvic infections: endometritis, post-partum and post-abortal uterine infections; salpingitis and tubo-ovarian abscesses; PID and pelvic abscesses. Porphyromonas asaccharolytica is probably not a vaginal commensal, but may be isolated from patients with vaginal or pelvic disease. It is more specifically associated with superficial abscesses (e.g. Bartholin's abscess) and ulcers of the genitalia and perineum. P. asaccharolytica was the commonest species isolated from men with genital ulcers of various primary causes and ranging in severity from superficial balanitis/balanoposthitis to synergic gangrene.

Occurrence of plasmids in black-pigmented Gram-negative anaerobes

Occurrence of plasmids in black-pigmented Gram-negative anaerobes

Classification and typing methods of black-pigmented Gram-negative anaerobes

Until recently, black-pigmented Gram-negative anaerobes were classified as 'black-pigmented Bacteroides'. At present, 11 distinct species are recognized in this group. Because of major differences with Bacteroides fragilis, the type species of the genus Bacteroides, new genera have been proposed: Porphyromonas for three asaccharolytic species, and Prevotella for the saccharolytic species. Typing methods have been developed for some species of black-pigmented Gram-negative anaerobes. These include biotyping and serotyping, but relatively few types can be distinguished with these methods. Recently, DNA restriction endonuclease analysis has been used for typing of P. gingivalis, Pr. intermedia and P. endodontalis strains. Great heterogeneity was observed within all three species. This typing method can be useful for epidemiological studies.

Hydrolytic enzymes liberated by black-pigmented Gram-negative anaerobes

Hydrolytic enzymes liberated by black-pigmented Gram-negative anaerobes

Black-pigmented Gram-negative anaerobes in periodontitis

Black-pigmented Gram-negative anaerobes have been associated with periodontal disease and tooth loss since they were first isolated by Burdon in 1928. Porphyromonas gingivalis, which is usually not isolated from children, adolescents or adults with no periodontal breakdown, has been recognized as one of the most important periodontopathogens. Its presence is strongly correlated with deep periodontal pockets, which are assumed to be its main habitat. Correlations have been shown also with attachment loss, clinical inflammation and serum antibody levels, indicating an aetiological role in the periodontal disease. Their pathogenicity in animal models resembling periodontal disease is documented. They are frequently isolated from periodontal abscesses. The relationship between Prevotella intermedia and periodontal disease is not clear. It is frequently isolated from advanced periodontitis, often as the only black-pigmented Gram-negative anaerobic species; however, the prevalence in adults with no periodontal breakdown is high. It is found frequently in periodontal abscesses and in acute necrotizing and ulcerative gingivitis. Serogroup I is found predominantly in deep periodontal pockets, whereas all serogroups (I-III) are found in shallow pockets and gingivitis. No conclusive difference in pathogenicity between serogroups has been found. Pr. melaninogenica, Pr. denticola and Pr. loescheii are frequently found in the gingival crevice in preschool children and other age groups with gingivitis, but are seldom found in deep periodontal pockets.

Interactions between black-pigmented gram-negative anaerobes and other species which may be important in disease development.

Interactions between black-pigmented gram-negative anaerobes and other species which may be important in disease development.