Survival of anaerobes in original specimens transported by overnight mail services

Overnight mail delivery was evaluated for its effect on the recovery of facultative and anaerobic microbes in cultures of clinical specimens from patients. Ten clinical specimens, which were collected at different geographic locations and during different weather conditions, were cultured at the site and after overnight delivery to a distant laboratory. Forty-five facultative anaerobic isolates and 48 anaerobes were recovered. There was no significant difference in numbers of strains or relative quantities recovered in cultures of transported and nontransported specimens. With proper collection, transport, and inoculation of specimens, overnight delivery did not compromise recovery of clinically relevant microbes.

A retrospective review of cases of anaerobic empyema and update of bacteriology

We conducted a retrospective study to update the bacteriology of 46 cases of anaerobic empyema that were originally studied between 1976 and 1993 at the Wadsworth Anaerobic Bacteriology Clinical Research Laboratory (Los Angeles). Anaerobic bacteriologic studies were completed for all 46 pleural fluid specimens, and aerobic bacteriologic studies were completed for 41 of these specimens. Thirty-seven clinical charts were available for review. A total of 161 anaerobic isolates (3.5 per patient) representing 64 species or groups were recovered. The most common isolates were as follows: Fusobacterium nucleatum (19); Prevotella oris-buccae group (13, 9 of which were P. oris); Bacteroides fragilis group (11, 4 of which were B. fragilis); pigmented Prevotella species (17, 8 of which were in the Prevotella intermedia-nigrescens group); Peptostreptococcus species (17, 9 of which were Peptostreptococcus micros); Eubacterium species (7); Lactobacillus species (8); Actinomyces species (7); and Clostridium species (7). Nineteen if the cases were of purely anaerobic etiology; of these, eight were caused by a single organism: F. nucleatum (five cases); B. fragilis (two cases); and Prevotella mangus (one case). Of the 45 aerobic isolates (1.1 per patient), viridans streptococci were most common (21 isolates), followed by group D nonenterococcal streptococcus (four isolates). Only nine gram-negative rods (six enteric and three nonenteric organisms) and one Staphylococcus aureus isolate were recovered. The susceptibility to penicillin of 64 isolates was examined with the use of the spiral gradient method; 21 (33%) of these isolates were beta-lactamase positive (MICs ranged from 1.1 to > or = 54 micrograms/mL vs < or = 0.27 micrograms/mL for beta-lactamase-negative strains).

Vasculitides associated with infections, immunization, and antimicrobial drugs

Many pathogenic microbes can induce a complex series of immunologic, endothelial-cell, and hemorheological activation cascades and dysfunctions and can cause interactions of various components of the vessel wall with formed and noncellular elements of the blood. These interactions can result in manifold vasculitides. This article reviews the pathogenetic, clinicopathologic, and therapeutic aspects of infection-related vasculitides; it includes a brief discussion of parasitic, drug-related, and immunization-associated vasculitides as well as of the infection-related features of vasculitides of the central nervous system, retinal vasculitides, ecthyma gangrenosum, and erythema nodosum. Viruses are mainly associated with small-vessel vasculitides, whereas bacterial infections affect vessels of all sizes, including the aorta. The vasculitides associated with fungal infection usually are characterized by erythema nodosum and involve large vessels. The search for microbes as causes of or contributors to vasculitides should continue. Infectious vasculitides may become increasingly important as the number of immunocompromised patients grows.

Fatal sepsis due to a beta-lactamase-producing strain of Fusobacterium nucleatum subspecies polymorphum

A patient with Waldenström's macroglobulinemia was treated empirically with imipenem for sepsis related to oropharyngeal infection and responded within 24 hours. When blood cultures yielded Streptococcus agalactiae, the regimen was changed to ampicillin and gentamicin. The patient's condition rapidly deteriorated, and she died 3 days later. After her death, a strain of Fusobacterium nucleatum subspecies polymorphum producing beta-lactamase (PEN-Y; group 2a) was isolated from blood cultures. A literature review revealed increasingly frequent isolation of beta-lactamase-producing strains of F. nucleatum. Thus strains of F. nucleatum isolated from blood and other specimens from patients with serious infections should be tested for beta-lactamase production.

Oligonucleotide probes to the 16S ribosomal RNA: implications of sequence homology and secondary structure with particular reference to the oral species Prevotella intermedia and Prevotella nigrescens

Eight oligonucleotides based upon regions of the small subunit 16S ribosomal RNA gene sequences were analysed against a background of their position within the molecule and their two-dimensional structure to rationalise their use in recognising Prevotella intermedia and Prevotella nigrescens. The 41 clinical isolates from both oral and respiratory sites and two reference strains were subjected to DNA-DNA hybridisation and multilocus enzyme electrophoresis to confirm their identity. Alignment of oligonucleotide probes designated I Bi-2 to I Bi-6 (for P. intermedia) and 2Bi-2 (for P. nigrescens) with the 16S rRNA suggested that these probes lacked specificity or were constructed from hypervariable regions. A 52-mer oligonucleotide (designated Bi) reliably detected both species. Because of the high degree of concordance between the 16S rRNAs of both species, it was necessary to vary the stringency of hybridisation conditions for detection of both species. Thus probe I Bi-I recognised P. intermedia while I Bi-I detected both P. intermedia and P. nigrescens at low stringency. However, under conditions of high stringency only P. nigrescens was recognised by probe 2Bi-I. These probes were highly specific and did not hybridise with DNA from the closely related P. corporis, nor other periodontal pathogens such as Fusobacterium nucleatum, Actinobacillus actinomycetemcomitans, Treponema denticola and several pigmented species such as Prevotella melaninogenica, P. denticola, P. loescheii, Porphyromonas asaccharolytica, Py. endodontalis, Py. gingivalis, Py. levii, and Py. macacae.

Preliminary evidence of endotoxic activity of Bilophila wadsworthia

In this study we describe two properties of the Gram-negative bacterium Bilophila wadsworthia, namely the ability to clot Limulus lysate and the capacity to induce the production of tissue factor-like procoagulant activity by human mononuclear cells in vitro. Although exhibited at a lower degree when compared with those of typical Gram-negative bacteria or Gram-negative endotoxin those activities may account in part for Bilophila's pathogenicity. The capacity indeed to induce fibrin formation through the interaction with mononuclear cells suggests one mechanism by which the microorganism might cause abscess formation in the host. Moreover, since this activity is dependent on the number of Bilophila interacting with mononuclear cells, we hypothesize that this biological activity is closely influenced by growth environment.

In vitro activities of two new glycylcyclines, N,N-dimethylglycylamido derivatives of minocycline and 6-demethyl-6-deoxytetracycline, against 339 strains of anaerobic bacteria

The in vitro activities of the N,N-dimethylglycylamido derivatives of minocycline (DMG-MINO) and 6-demethyl-6-deoxytetracycline (DMG-DMDOT) were compared with those of minocycline, tetracycline, clindamycin, and metronidazole by using the National Committee for Clinical Laboratory Standards-approved Wadsworth agar dilution method. The MICs of DMG-MINO, DMG-DMDOT, and metronidazole at which 90% of the strains were susceptible (0.5, 1, and 1 micrograms/ml, respectively) were lower than those for clindamycin, minocycline, and tetracycline (4, 8, and 32 micrograms/ml, respectively). All of the strains of anaerobes tested, except one strain of Bacteroides ovatus (MIC, 16 micrograms/ml), were susceptible to DMG-MINO and DMG-DMDOT at 8 micrograms/ml.

Preliminary study using species-specific oligonucleotide probe for rRNA of Bilophila wadsworthia

Portions of the 16S RNA from a urease-positive Bilophila wadsworthia strain were sequenced, and a probe was constructed. The probe was end labeled with [32P]ATP and polynucleotide kinase and hybridized on a nylon filter (by dot blot hybridization) to the immobilized rRNA of 12 B. wadsworthia strains and eight other anaerobic isolates. The probe efficiently hybridized only to the Bilophila strains. Cross-reactivity at high RNA levels (2,000 ng) was observed with one strain of Bacteroides thetaiotamicron and one strain of Bacteroides fragilis (with 10x SET buffer [20x SET buffer is 0.5 M NaCl, 0.03 M Tris, and 2 mM EDTA]) but was not seen at lower RNA levels or with 5x SET buffer. When tested against mixed cultures of aerobic and anaerobic isolates representative of appendiceal abscess flora, the probe did not react with mixed cultures containing no Bilophila cells and could detect > or = 10(5) Bilophila CFU/ml when the mixture was seeded with Bilophila cells. This probe is of potential use in the rapid identification of pure isolates and in the direct identification of B. wadsworthia in clinical specimens.

In-vitro activity of clinafloxacin (CI-960) and PD 131628-2 against anaerobic bacteria

The antimicrobial activities of two new quinolones, CI-960 and PD 131628-2 were determined against 339 strains of anaerobic bacteria and compared to cefoxitin, imipenem and metronidazole. The NCCLS-approved Wadsworth agar dilution technique with Brucella-lysed blood agar was used throughout the study. Breakpoints of the new quinolones are 2 mg/L, and breakpoints for cefoxitin, imipenem and metronidazole are 32, 8 and 16 mg/L, respectively. CI-960 displayed excellent activity, inhibiting all strains tested at 1 mg/L. PD 131628-2 inhibited 94% of Bacteroides fragilis, 75% of other B. fragilis group isolates, 87% of Prevotella spp, 79% of the Fusobacterium mortiferum-varium group, 74% of non-sporing gram-positive bacilli, and 89-100% of Clostridium spp other than Clostridium difficile at 2 mg/L. None of the eight strains of C. difficile was inhibited at 2 mg/L although they were inhibited at 4 mg/L. PD 131628-2 inhibited all strains of other Bacteroides spp, Porphyromonas spp, and Fusobacterium nucleatum at < or = 1 mg/L.

In vitro activity of DU-6859a against anaerobic bacteria

The activity of a new quinolone agent, DU-6859a, against 330 strains of anaerobic bacteria was determined by using the National Committee for Clinical Laboratory Standards-approved Wadsworth brucella laked blood agar method; the activity of DU-6859a was compared with those of amoxicillin-clavulanate (2:1), chloramphenicol, ciprofloxacin, clindamycin, fleroxacin, imipenem, lomefloxacin, metronidazole, sparfloxacin, and temafloxacin. DU-6859a and chloramphenicol inhibited all of the isolates at concentrations of 1 and 16 micrograms/ml, respectively; amoxicillin-clavulanate, imipenem, and metronidazole inhibited > or = 94% of the isolates at their respective breakpoints (8, 8, and 16 micrograms/ml). MICs of DU-6859a at which 90% of the strains were susceptible were 1 to 5 twofold dilutions lower than those of the other quinolones for every group of organisms. MICs of DU-6859a at which 90% of the strains were susceptible (total numbers of strains tested are in parentheses) were < or = 0.25 micrograms/ml for Bacteroides fragilis (57), other B. fragilis group species (84), Bilophila wadsworthia (15), Clostridium species (27) (including C. difficile, C. perfringens, and C. ramosum), Fusobacterium nucleatum (16), Fusobacterium mortiferum-F. varium group species (10), Peptostreptococcus species (20), non-spore-forming gram-positive rods (20), and Prevotella species (25).

Inactivation of anaerobic bacteria by various photosensitized porphyrins or by hemin

The photodynamic effects of deuteroporphyrin (DP), hematoporphyrin derivative (HPD), hematoporphyrin (HP), or protoporphyrin (PP) on a variety of anaerobic microorganisms were examined in this study. The majority of the species, among the 350 strains tested, were inhibited by concentrations of < or = 2.5 micrograms/ml of light-activated DP. Species found to be resistant to this treatment included Bilophila wadsworthia, Fusobacterium mortiferum, Fusobacterium varium, and Bacteroides gracilis. These species were inhibited by concentrations of > 60 micrograms/ml of DP. The porphyrin-producing species, Porphyromonas and Prevotella spp, were all inhibited by < or = 2.5 micrograms/ml DP and light. Comparing the photodynamic activity of the porphyrins used on Porphyromonas strains resulted in the following pattern: DP > HPD > HP > PP. Porphyromonas spp., Gram-positive cocci, and many Gram-positive rods (excluding clostridia) were inactivated by hemin (a metal-containing porphyrin) at 10-20 micrograms/ml. Hemin inhibitory action was not affected by light. Binding and insertion of DP into bacteria (both inactivated and non-inactivated strains by DP and light) were monitored by the characteristic fluorescence band of bound DP at 622 nm. Porphyromonas spp. bound DP tightly, whereas only low binding was seen with B. wadsworthia and other DP-resistant species. High binding of DP to B. wadsworthia can be achieved by pretreatment of the bacteria with imipenem or cefoxitin, beta-lactam agents known to interfere with the integrity of the cell wall. If cell wall integrity is disturbed (e.g., by these agents), inactivation of B. wadsworthia by DP can occur.

In vitro activity of grepafloxacin (OPC-17116) against anaerobic bacteria

In vitro activity of the quinolone grepafloxacin (OPC-17116) was compared with that of ciprofloxacin, fleroxacin, clindamycin, imipenem, and metronidazole by using the NCCLS-approved Brucella-base-laked blood agar dilution method and breakpoints, when available. Clindamycin, metronidazole, and imipenem inhibited > or = 98% of Bacteroides fragilis at the breakpoint; grepafloxacin, ciprofloxacin, and fleroxacin inhibited 83%, 6%, and 0, respectively, at 2 micrograms/ml. Grepafloxacin inhibited 39% of other B. fragilis group species isolated (80) at breakpoint (< or = 2 micrograms/ml) compared with 100% for metronidazole and imipenem, 83% for clindamycin, 6% for ciprofloxacin, and 1% for fleroxacin. Grepafloxacin demonstrated substantially better activity against B. fragilis than did ciprofloxacin or fleroxacin; overall activity against anaerobes was marginally better than that of ciprofloxacin or fleroxacin.

Review of early research on anaerobes

It has been one hundred years since the appearance of the first clinical paper on infection involving anaerobic bacteria, an article that also detailed recovery of and description of the organisms responsible for the infection. We pay tribute to the author of that landmark paper, André Veillon, in celebration of the centennial of this important occasion.

Morphological response of Bilophila wadsworthia to imipenem: correlation with properties of penicillin-binding proteins

The penicillin-binding protein (PBP) patterns of six strains of Bilophila wadsworthia were investigated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis and subsequent fluorography of membrane preparations labelled with [3H]benzylpenicillin. The PBP profiles among the strains were similar; generally, seven to nine PBP-reactive bands could be visualized; their molecular weights ranged from 31 to 137 kDa. The relative affinities of the PBPs of four strains of B. wadsworthia for imipenem were examined and correlated with the morphological responses of the cells to imipenem. Morphological changes were examined by light and electron microscopies. Light microscopy revealed that at low concentrations (less than the MIC), imipenem induced the formation of rounded and bulging cells; rarely, elongation without filamentation was observed. In the presence of imipenem at the MIC, spheroplast formation was observed. Scanning and transmission electron microscopies revealed round forms together with larger, multilobate cells in the presence of subinhibitory concentrations of imipenem, suggesting that new growth sites were initiated while cell division was inhibited. Peeling of the outer membrane was also seen. Spheroplasts were very large (up to 30 microns in diameter) and stable in aqueous solution. Inhibition of the PBPs could be seen in the presence of low imipenem concentrations.

In vitro activity of Bay Y3118 against anaerobic bacteria

The antimicrobial activity of a new quinolone, Bay Y3118, was determined against 326 strains of anaerobic bacteria and compared with the activities of ampicillin-sulbactam, cefotetan, clindamycin, imipenem, metronidazole, and sparfloxacin. The National Committee for Clinical Laboratory Standards-approved Wadsworth agar dilution technique with Brucella-laked blood agar was used throughout the study. Breakpoints used to determine the percent susceptible were 2 micrograms/ml for Bay Y3118 and sparfloxacin, 4 micrograms/ml for clindamycin, 8 micrograms/ml for imipenem, 16 micrograms/ml for metronidazole and ampicillin-sulbactam, and 32 micrograms/ml for cefotetan. Species tested included Bacteroides fragilis (57 strains), other B. fragilis group species (79 strains), Bacteroides gracilis (10 strains), other Bacteroides spp. (9 strains), Prevotella spp. (30 strains), Porphyromonas spp. (9 strains), Fusobacterium spp. (36 strains), Bilophila wadsworthia (14 strains), Clostridium spp. (36 strains), Peptostreptococcus spp. (20 strains), and gram-positive non-spore-forming rods (26 strains). Bay Y3118 inhibited all but 1 of 326 anaerobic bacteria tested at the breakpoint level or lower.

Trimethoprim-sulfamethoxazole prophylaxis in granulocytopenic patients with acute leukemia: evaluation of serum antibiotic levels in a randomized, double-blind, placebo-controlled Department of Veterans Affairs Cooperative Study

Despite widespread use of trimethoprim-sulfamethoxazole (TMP-SMZ) for prophylaxis in neutropenic patients, questions remain regarding its efficacy, toxicity, the risk of selection of resistant isolates, and the relation of its activity to selective decolonization vs. the attainment of direct inhibitory levels within blood and tissues. We evaluated the effect of TMP-SMZ (160/800 mg orally every 12 hours) in 42 adult granulocytopenic patients (< 100 absolute neutrophils/mm3, mean duration 13.3 days) undergoing chemotherapy for acute leukemia at 11 participating Veterans Administration Medical Centers in a randomized, double-blind, placebo-controlled trial. No significant differences in survival, frequency of bacteremia, overall infections, use of systemic antimicrobial therapy, or adverse effects, including myelosuppression, were observed between patients receiving TMP-SMZ vs. those receiving placebo. All patients acquired trimethoprim-resistant organisms. Concentrations of trimethoprim in serum were significantly lower before febrile episodes than when patients were afebrile. These results suggest that the purported activity of TMP-SMZ may be related to the serum concentration achieved. Moreover, the results highlight the need for additional study of the value of antibiotic prophylaxis in neutropenic patients.