Aerobic and anaerobic bacterial flora of crural ulcers

In a group of 600 patients treated in the Metropolitan Dermatological Hospital in Warsaw bacteriological examination were carried out of swabs from the untreated crural ulcers. In 95% of these cultures growth of pathological aerobic organisms was obtained. Coagulase-positive staphylococci (St. aureus) and Gram-negative bacteria (Pseudomonas aeruginosa, Proteus vulgaris, Enterobacter sp and E. coli) prevailed. In 27% of cases the cultured strains were resistant to the generally available antibiotics. In the second group in 70 patients no growth of anaerobes exclusively was noted. Pathological aerobes and anaerobes in the same case were found in 45% of cultures. In the remaining ones pathogenic aerobes were present with a similar frequency as in the preceding group. Of the anaerobes the most frequently cultured species were Gram-negative bacteria such as Bacteroides melaninogenicus, Bacteroides sp, and Bacteroides fragilis. Among pathogenic anerobic cocci Peptostreptococcus and Peptococcus were most frequent. In 2 cases spore-forming anaerobic bacteria (Clostridium perfringens) were obtained. Forty-eight percent of anaerobes were resistant to the commonly used antibiotics.     

Bacteriological study of epidermal cysts

The aim of this study was to determine whether bacterial infection plays a significant role in the inflammatory process of epidermal cysts. Samples from 152 patients (115 cases of inflamed and 37 of uninflamed epidermal cysts) were subjected to aerobic and anaerobic bacterial culture and the isolates were investigated. The rate of bacterial growth and the recovered anaerobes were significantly greater in the inflamed than the uninflamed epidermal cysts. However, it is difficult to determine whether recovered isolates from epidermal cysts represent "infection" or "colonization". In conclusion, this study revealed the predominance of anaerobes in inflamed cysts, strongly suggesting that anaerobes play a role in the inflammatory process.     

Microbiology of infected hemangiomas in children

Bacterial infections are a common complication of hemangiomas in children. The objective of this study was to establish the aerobic and anaerobic microbiology of infected hemangiomas. A retrospective 8-year review of clinical and microbiology laboratory records from patients with secondarily infected hemangiomas was carried out. Specimens from infected sites were processed for the presence of aerobic and anaerobic bacteria. Bacterial growth was present in 32 of 38 specimens. Aerobic bacteria alone were recovered in 12 infected hemangiomas (37.5%), anaerobic bacteria alone in 8 (33%), and mixed aerobic and anaerobic flora in 12 (37.5%). A total of 80 isolates (47 aerobes and 33 anaerobes) were recovered, giving an average of 2.5 isolates per specimen (1.5 aerobes and 1.0 anaerobes). The highest number of isolates were recovered in infections of the perineum (3.7 per site) and the legs (2.8 per site). The predominant aerobic isolates were Staphylococcus aureus, group A beta-hemolytic streptococci, and Enterobacteriaceae. The predominant anaerobes were Peptostreptococcus sp., gram-negative bacilli, and Fusobacterium sp. Organisms that belong to the mucous membranes close to the lesions predominated in infections next to those membranes. The polymicrobial etiology of secondarily infected hemangiomas and the association of bacterial flora with the anatomic site of the lesions is thereby demonstrated.     

Microbiology of infected epidermal cysts

Specimens from 231 epidermal cyst abscesses were inoculated on media supportive for growth of aerobic and anaerobic bacteria. Of these, 192 yielded bacterial growth. Aerobic or facultative bacteria only were recovered in 84 specimens (44%), anaerobic bacteria only in 57 specimens (30%), and mixed aerobic and anaerobic bacteria in 51 specimens (26%). A total of 315 isolates (162 anaerobes and 153 aerobes) were recovered. An average of 0.8 aerobic or facultative isolates per infected cyst were recovered, and this number was unrelated to the cysts' anatomic sites. However, the number of anaerobic bacteria varied; they were isolated more frequently in perirectal (1.5 isolates per specimen), vulvovaginal (1.4), and head (1.1) infections, and less frequently in trunk (0.7) and extremities (0.4) infections. The predominant aerobic or facultative bacteria were Staphylococcus aureus (81 isolates), group A streptococcus (9 isolates), and Escherichia coli (7 isolates). The predominant anaerobic organisms were Peptostreptococcus species (85 isolates) and Bacteroides species (55 isolates, including 12 Bacteroides melaninogenicus and 9 Bacteroides fragilis groups). The study highlights the polymicrobial nature and predominance of anaerobes in cyst abscesses in the perirectal, vulvovaginal, and head areas.     

MICROBIOLOGY OF SECONDARILY INFECTED DIAPER DERMATITIS

Specimens obtained from 67 infants with secondarily infected diaper dermatitis were cultured for aerobic and anaerobic bacteria. Bacteria growth was obtained in 58. Aerobic facultative bacteria or Candida sp. only were present in 28 patients (48%), anaerobic bacteria only in 11 (19%), and mixed anaerobic with aerobic, facultative, or yeast flora was present in 19 (33%). Ninety-one bacterial or fungal isolates were recovered (1.6 per specimen), 54 (0.9 per specimen) aerobic or facultative bacteria, 8 (0.1 per specimen) Candida sp., and 31 (0.6 per specimen) strict anaerobes. The predominant aerobic and facultative bacteria were Staphylococcus aureus (23 isolates), Streptococcus sp. (16), and Escherichia coli (6). The predominant anaerobes included Bacteroides sp. (12, including 9 Bacteroides fragilis group) and Peptostreptococcus sp. (11). Single bacterial isolates were recovered in 32 (55%) patients, 18 of which were S. aureus. Twenty-five beta-lactamase-producing bacteria were detected in 22 (51%) of the 43 tested patients. These included 16 S. aureus and 6 B. fragilis group. These data highlight the importance of anaerobic bacteria in the polymicrobial nature of secondarily infected diaper dermatitis.     

Microbiology of infected poison ivy dermatitis

We report the aerobic and anaerobic microbiology of secondarily infected poison ivy dermatitis. The study involved retrospective review of clinical and microbiology laboratory records of patients with secondarily infected poison ivy lesions. Bacterial growth was noted in 33 specimens. Aerobic or facultative anaerobic bacteria only were present in 18 (55%) patients, anaerobic bacteria only in seven (21%), and mixed anaerobic-aerobic bacteria in eight (24%). Forty-five isolates were recovered (1.4 per specimen): 27 aerobic or facultative anaerobic bacteria, and 18 strict anaerobes. The predominant aerobic and facultative anaerobic bacteria were Staphylococcus aureus (13 isolates) and group A beta-haemolytic streptococci (six). The predominant anaerobes were Peptostreptococcus spp. (seven isolates), pigmented Prevotella and Porphyromonas spp. (four) and Fusobacterium spp. (two). Single bacterial isolates were recovered in 18 (55%) patients, eight of which were S. aureus. Nineteen of the organisms isolated from 16 (48%) patients produced the enzyme beta-lactamase. Organisms that resided in the mucous membranes close to the lesions predominated in those infections. Enteric gram-negative rods and Bacteroides fragilis group predominated in leg and buttock lesions. Group A beta-haemolytic streptococci, pigmented Prevotella and Porphyromonas and Fusobacterium spp. were most frequently recovered from lesions of the finger, face and neck. The polymicrobial aetiology of secondarily infected poison ivy lesions, and the association of bacterial flora with the anatomical site of the lesions, are demonstrated.     

Aerobic and anaerobic microbiology of chronic venous ulcers

Abstract
Background The role of bacteria in the pathogenesis of chronic venous leg ulcers (CVLU) is unclear. The objective of the study was to establish the aerobic and anaerobic bacteriology of CVLU.
Methods A retrospective review was carried out of the clinical and microbiological laboratory records obtained from patients with CVLU. Microorganisms were grown from 43 specimens obtained from 41 patients.
Results Aerobic or facultative bacteria alone were present in 18 (42%) specimens, anaerobic bacteria only in three (7%), and mixed aerobic–anaerobic flora in 22 (51%).
In total, there were 97 isolates, 64 aerobic or facultative and 33 anaerobic, an average of 2.3 isolates per specimen (1.5 aerobes and 0.8 anaerobes). The predominant aerobic organisms were Staphylococcus aureus (26 isolates), group D streptococci (5), and Escherichia coli (5). The predominant anaerobes were Peptostreptococcus spp. (15), Bacteroides fragilis group (6), Propionibacterium acnes (4), and Prevotella spp. (3).
Conclusions CVLU have a polymicrobial aerobic–anaerobic flora.     

Comparison of a hydrocolloid dressing and paraffin gauze in the treatment of venous ulcers

In-patients with venous leg ulcers showed increased healing rates with a hydrocolloid dressing (Granuflex), as compared with a traditional paraffin gauze dressing (Jelonet), in a randomized sequential crossover trial, although the difference was not statistically significant. Bacteriological studies showed that the hydrocolloid dressing favoured growth of both aerobes and anaerobes in significantly greater numbers compared with paraffin gauze. Heavy bacterial colonization had no effect on the healing rates of the ulcers. Granuflex is said to produce an anaerobic environment--survival of Pseudomonas aeruginosa, a strict aerobe, under Granuflex dressings, makes this seem unlikely.     

Microbiology of infected pustular psoriasis lesions

BACKGROUND: Bacterial infections can occur in lesions of pustular psoriasis (PP). The objective of this study was to establish the aerobic and anaerobic microbiology of secondarily infected PP. METHODS: A retrospective 10-year review was carried out of clinical and microbiology laboratory records from patients with secondarily infected PP lesions, whose specimens of infected sites were processed for the presence of aerobic and anaerobic bacteria. RESULTS: Bacterial growth was noted in 23 specimens. Aerobic or facultative anaerobic bacteria only were present in 12 patients (52%), anaerobic bacteria only in four (17%), and mixed anaerobic-aerobic flora was present in seven (30%). Thirty-six isolates were recovered (1.6 per specimen), 23 aerobic or facultative bacteria and 13 strict anaerobes. The predominant aerobic and facultative bacteria were Staphylococcus aureus (15 isolates), Group D Enterococcus (two isolates), and Escherichia coli (two isolates). The predominant anaerobes were Peptostreptococcus spp. (six isolates) and Bacteroides fragilis group, Propionibacterium acnes, and pigmented Prevotella spp. in two each. Single bacterial isolates were recovered in 14 patients (61%), 11 of which were S. aureus. Nineteen of the organisms isolated from 18 patients (78%) produced the enzyme beta-lactamase. S. aureus was isolated from all body sites. Organisms that resided in the mucous membranes close to the lesions predominated in these infections. Enteric Gram-negative rods and Bacteroides fragilis group predominated in lesions on the legs and buttocks. Group A beta-hemolytic streptococci, pigmented Prevotella, and Fusobacterium spp. were most frequently recovered in lesions of the hand. CONCLUSIONS: The polymicrobial etiology of secondarily infected PP lesions and the association of bacterial flora with the anatomic site of the lesions were demonstrated.     

Quantification of bacteria in isolated pilosebaceous follicles in normal skin.

A technique for quantitating bacteria in isolated pilosebaceous follicles is described. This involves microdissection of the follicles from biopsies of skin, using the method of chemical pretreatment of skin to facilitate the separation of the epidermis and epidermal appendages from the dermis. The aerobic cocci and anaerobic diphtheroids in pilosebaceous follicles in 66 biopsies of scalp and 48 biopsies of skin of the upper back were quantitated using this technique. On the back, aerobic staphylococci were very sparse in normal follicles, indicating that their primary habitat on the skin must be on the skin surface rather than within follicles. Of 138 isolated follicles from skin of the upper back, 94 contained no aerobic cocci. Anaerobic organisms were present in high numbers within normal follicles. The geometric mean density of anaerobes in 138 isolated follicles from skin of the upper back was 3.8 X 10(4) diphtheroids per follicle. Eighty-eight follicles contained more than 10(4) anaerobic diphtheroids. Using data from scalp biopsies we found that there was a correlation between the weight of sebaceous glands and the density of anaerobes within the follicles attached to these glands (coefficient of correlation = 0.6).     

Microbiology of Nonbullous Impetigo

Abstract: Our objective was to establish the aerobic and anaerobic microbiology of nonbullous impetigo (Nl) in children. We used a retrospective review of clinical microbiology laboratory and patients'records. Specimens were obtained from 40 patients with Nl lesions and showed bacteriai growth. Aerobic or facultative anaerobic bacteria only were present in 24 patients (60%), strict anaerobic bacteria only in 5 patients (12.5%), and mixed anaerobic-aerobic flora was present in 11 patients (27.5%). Sixty-four isolates were recovered (1.6 per specimen): 43 aerobic or facultative, and 21 anaerobic. The predominant aerobic and facultative bacteria were Staphylococcus aureus (29 isolates). Group A beta hemolytic streptococcus (GABHS) (13 Isolates), and Escherichia coli (1 isolate). The predominant anaerobes were Peptostreptococcus spp. (12), pigmented Prevotella spp. (5), Fusobacterium spp. (2), and Bacteroides fragilis (1). Single bacterial isolates were recovered in 17 patients (42.5%), 13 of which were S. aureus. S. aureus alone or mixed with GABHS or Peptostreptococcus spp. were isolated from all body sites. Mixed flora of Peptostreptococcus spp. with Prevotella spp. or Fusobacterium spp. was mostly found in infections of the head and neck, while E. coli mixed with B. fragills and Peptostreptococcus spp. were isolated from one infection of the buttocks area. Thirty-three organisms isolated from 32 patients (80%) produced the enzyme beta-lactamase. This study demonstrates the polymicrobial aerobic-anaerobic microbiology of Nl lesions.     

Correlations between epithelial cells and bacterial populations in bacteriological skin samples

The purposes of this study were to determine whether the variability in populations of skin bacteria observed between individuals is related to the number of epithelial cells removed during the skin scrubbing procedure and also whether any particular group of microorganisms can be directly associated with epithelial cells. Foreheads of 31 subjects were sampled using the cup scrubbing method, and bacterial populations were quantified as: total anaerobes, aerobes, Propionibacterium spp., aerobic coryneforms, and Micrococcaceae. Epithelial cells were counted in a haemocytometer. Correlation coefficients were positive between total bacterial populations and epithelial cell counts, with the largest values of 0.64 for Propionibacterium spp., 0.58 for Micrococcaceae, and 0.15 for aerobic coryneforms. High epithelial cell counts were always associated with high bacterial populations, but high bacterial counts occurred, in some instances, with low epithehal cell counts; epithelial cells are not, therefore, responsible for variations in bacterial populations in all cases. Stained smears of epithelial cells from subjects from whom aerobic coryneforms were not cultured showed microcolonies of presumptive anaerobic diphtheroids, closely associated with epithelial cells. These findings and the high correlation between Propionibacterium spp. and epithelial cells suggests a re-examination of the location of anaerobes in the stratum corneum.     

The infectious aetiology of tropical ulcer—a study of the role of anaerobic bacteria

We have cultured anaerobic bacteria from patients with tropical ulcers. Fusobacteria were isolated most frequently. Anaerobes were always present, together with aerobes or facultative anaerobes, particularly in early phase ulcers, suggesting that the combination of organisms is important in the pathogenesis of the disease. Spirochaetes were identified in material examined by light and electron microscopy, but were not cultured.     

Anaerobes in genitourinary infections in men.

Urethral and sub-preputial swabs from 150 men were examined. There was a strong association between the isolation of anaerobic bacteria, particularly Bacteroides spp, and a clinical diagnosis of balanoposthitis, non-specific urethritis (NSU), or both. Aerobic bacteria formed the predominant flora in 28 healthy controls whereas anaerobes were predominant in specimens from 79 patients with balanoposthitis, from 24 with NSU, and from 19 with both. Bacteroides spp were the commonest isolates in all patient groups; B asaccharolyticus, B melaninogenicus ss intermedius, B ureolyticus, and B bivius were the most common species. The results obtained with the two swabs were identical except that Gardnerella vaginalis was isolated from the urethral swab only in five patients.     

MICROBIOLOGY OF INFECTED ATOPIC DERMATITIS

Background. Bacterial infections occur frequently in lesions of atopic dermatitis (AD). The objectives of the study were to establish the aerobic and anaerobic microbiology of secondarily infected AD. Methods. A retrospective review was carried out of clinical and microbiology laboratory records and of data obtained from patients with secondarily infected AD lesions, whose specimens of infected sites were processed for the presence of aerobic and anaerobic bacteria. Results. Bacterial growth was noted in 41 specimens. Aerobic or facultative anaerobic bacteria only were present in 15 patients (36%), anaerobic bacteria only in eight (20%), and mixed anaerobic-aerobic flora was present in 18 (44%). Seventy- two isolates were recovered (1.8 per specimen), 34 aerobic or facultative bacteria, 35 strict anaerobes, and three Candida sp. The predominant aerobic and facultative bacteria were Staphylococcus aureus (12 isolates). Group A beta hemolytic streptococcus in five isolates, and Escherichia coli in four. The predominant anaerobes were peptostreptococcus spp. (13 isolates), pigmented Prevotella and Porphyromonas spp. in eight, and Fusobacterium spp. in four isolates. Single bacterial isolates were recovered in 14 patients (34%), seven of which were S. aureus. Twenty-one of the organisms isolated from 16 patients (39%) produced the enzyme beta-lactamase. Organisms that resided in the mucous membranes close to the lesions predominated in these infections. Enteric gram-negative rods and bacteroides fragilis group predominated in lesions on legs and buttocks. Group A beta-hemolytic streptococci, pigmented Prevotella, and Porphyromonas and Fusobacterium spp. were most frequently recovered in lesions of the finger, scalp, face, and neck. Conclusions. The polymicrobial etiology of secondarily infected AD lesions and the association of bacterial flora with the anatomic site of the lesions are demonstrated.     

The microbiology of infected and noninfected leg ulcers

BACKGROUND: A clinical study was undertaken to investigate and compare specifically the aerobic and anaerobic microbiology of infected and noninfected leg ulcers. METHODS: Leg ulcers, defined as being infected on the basis of clinical signs, were swab sampled and investigated for aerobic and anaerobic microorganisms using stringent isolation and identification techniques. RESULTS: Two hundred and twenty isolates were cultured from 44 infected leg ulcers, in comparison with 110 isolates from 30 noninfected leg ulcers. Statistical analysis indicated a significantly greater mean number of anaerobic bacteria per infected ulcer (particularly Peptostreptococcus spp. and Prevotella spp.) in comparison with the noninfected ulcer group (2.5 vs. 1.3, respectively) (P < 0.05). Also, anaerobes represented 49% of the total microbial composition in infected leg ulcers compared with 36% in noninfected leg ulcers. The mean numbers of aerobes per wound in the two ulcer groups were not statistically different (P > 0.05). The study failed to demonstrate a clear correlation between commonly implicated facultative pathogens and wound infection. The isolation rate of Pseudomonas aeruginosa was generally low and, although Staphylococcus aureus was a frequent isolate in both wound types, it was more prevalent in noninfected leg ulcers. CONCLUSIONS: This study has demonstrated the complex aerobic-anaerobic microflora which exists in leg ulcers, the prevalence of anaerobes in infected wounds, and a poor correlation between the presence of specific aerobic pathogens and wound infection. In view of these findings, the role of microbial synergistic interactions in the pathogenesis of chronic wound infection may be of greater clinical importance than the isolated involvement of any specific potential pathogen.     

Bacteriological examination of inflamed epidermal cysts: a survey between 2008 and 2009 at a hospital in southern Taiwan

BackgroundInflamed epidermal cysts are common clinical conditions, and they frequently form abscesses. We designed a study to delineate the bacteriology of inflamed epidermal cysts.MethodsWe enrolled 61 adult patients with inflamed epidermal cysts characterized by surface erythema, with or without tenderness, or localized abscess formation within the cyst cavity. Incision and drainage of the cysts were performed, and the contents were sent for aerobic and anaerobic bacterial culture. The locations of the cyst and culture results were recorded for statistical analysis.ResultsA total of 61 cysts and 122 cultures were obtained. The most common locations of the inflamed cysts were the face, neck, and scalp (34.4%), followed by the trunk (32.8%), then the buttocks, inguinal areas, perineum, and axillae (16.4%), and the extremities (16.4%). The culture results were positive in 88.5% of patients, and anaerobes were more frequently isolated than were aerobes. Pure aerobes represented 31.1% of the cultures; pure anaerobes, 36.1%, and combined aerobes and anaerobes, 21.3% (n = 13). The most common anaerobic organisms found were Propionibacterium spp (40.8%), followed by Peptostreptococcus spp (36.7%), Staphylococcus saccharolyticus (14.4%), Prevotella (4.1%), Bacteroides fragilis (2.0%), and Fusobacterium spp (2.0%). The most commonly isolated aerobes were Staphylococcus spp (40%), followed by Enterobacter spp (11.3%), Proteus mirabilis (8.5%), Citrobacter diversus (8.5%), Klebsiella pneumoniae (5.7%), Corynebacterium (5.7%), Morganella morganii (2.9%), Enterococcus faecalis (2.9%), group A β-hemolytic streptococcus (2.9%), Pseudomonas aeruginosa (2.9%), and Providencia rettgeri (2.9%).ConclusionsBoth aerobic and anaerobic microorganisms were present in the inflamed epidermal cysts, although the anaerobic bacteria, specifically, Propionibacterium spp and Peptostreptococcus spp, were isolated slightly more frequently. Antibiotics directed against anaerobes may be considered in the treatment regimen for inflamed epidermal cysts.     

Anaerobes in men with urethritis

Sixty-four men with non-gonococcal urethritis (NGU), seven with gonococcal urethritis (GU), and 30 who had no symptoms or signs of urethritis were studied. Chlamydia trachomatis was isolated from urethral specimens taken from 22% of the men with NGU, and 18% with GU, but not from those who did not have urethritis even though 20 (67%) of them had a history of NGU, GU, or both. The chlamydial isolation rate for men having NGU for the first time was 30%. Ureaplasma urealyticum was isolated from 42% of the men with NGU, 43% of men with GU, and 27% of those without urethritis.

In addition to aerobes anaerobes were isolated frequently from men whether or not they had urethritis, the most common being anaerobic Corynebacteria, peptococci, and micro-organisms of the Bacteroides-Fusobacteria group. There was no appreciable difference in the overall isolation of anaerobes from men with NGU (89%) or from those without disease (80%). The rate of isolation of a Gram-negative anaerobic bacillus from men with NGU (50%) was, however, strikingly different to that from men with GU (14%) or from those without disease (13%). Furthermore, this bacillus was recovered from 28 (56%) of 50 men with NGU who were considered chlamydia-negative and from 19 (61%) of 31 men who were both chlamydia-negative and ureaplasma-negative. The effect of antibiotic treatment was evaluated in a few patients only, so that although those from whom the Gram-negative bacillus was eliminated by tetracycline recovered clinically there is a need for a prospective therapeutic trial to evaluate further the importance of the bacillus.

     

Quantitative studies of vaginal bacteria.

A quantitative method of culture, based on a weighed sample and with results expressed as colony forming units (cfu)/g was assessed and used to investigate the vaginal flora of normal women and that of women with vaginal disease. Samples were collected by means of disposable plastic loops into modified proteose peptone water transport medium in preweighed bottles. Counts expressed as cfu/g of secretion were consistent, whereas counts expressed as cfu/ml were inconsistent. Results obtained with specimens manipulated on the open bench were the same as those from duplicate samples processed in an anaerobic chamber. The normal vaginal flora was predominantly aerobic--lactobacilli, coryneforms, and coagulase negative staphylococci--with counts of greater than or equal to 10(8) cfu/g for lactobacilli. These were also present in patients with candidosis, but the flora in patients with trichomoniasis, bacterial vaginosis, gonorrhoea, or chlamydial infection was predominantly anaerobic. The commonest anaerobes were Bacteroides spp, particularly B bivius; they were found in 55% of controls but at counts of 10(2) cfu/g lower than in the patients, most of whom had high counts of anaerobes (greater than 10(8) cfu/g). The isolation rate of Gardnerella vaginalis was not appreciably greater from patients with bacterial vaginosis, and the quantitative cultures on controls and patients who were G vaginalis positive were the same (approximately equal to 10(7) cfu/g). Quantitative studies show greater differences than qualitative cultures between normal controls and patients with vaginal infections, indicating that some symptoms and signs of such infections may be related to quantitative polymicrobial changes.     

Inguinal syndrome secondary to Prevotella bivia after accidental bite in orogenital sex

The authors report a case of an inguinal bubo in a young man caused by an anaerobe, Prevotella bivia, which was acquired during oral sexual intercourse. As far as the authors know, this is the first reported case of a sexually transmitted infection by Prevotella. Prevotella spp. inhabit the oral cavity and are highly prevalent in bacterial vaginosis, a polymicrobial syndrome resulting from replacement of the normal vaginal Lactobacillus spp. flora by high concentrations of anaerobic microorganisms such as Prevotella spp., Mobiluncus spp., Gardnerella vaginalis and other uncultivated anaerobes.