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Biomedical subjects

E J Baron

Publications and source records attributed to E J Baron.

At least 37 records · Page 2Linked to original sources
PubMed1993

Bactericidal activity of selected antimicrobial agents against Bilophila wadsworthia and Bacteroides gracilis.

Bactericidal assays of Bacteroides gracilis (six strains) and Bilophila wadsworthia (12 strains) in brucella broth with appropriate supplements were performed by the time-kill kinetic method. Antimicrobial agents tested were ampicillin/sulbactam (final concentrations, 16/8 micrograms/mL), ticarcillin/clavulanate (128/2 micrograms/mL), imipenem (8 micrograms/mL), cefoxitin (32 micrograms/mL), chloramphenicol (16 micrograms/mL), clindamycin (4 micrograms/mL), and metronidazole (16 micrograms/mL). Although all antimicrobial agents tested inhibited growth of all Bilophila strains during the first 24 hours, bactericidal activity was variable; only metronidazole was uniformly bactericidal. Most strains of Bilophila showed 1-2 log increases in growth at 6 hours with clindamycin and chloramphenicol. With chloramphenicol, some Bilophila strains tested showed regrowth starting at 30 hours. B. gracilis strains were generally more susceptible to all agents tested. Metronidazole, ticarcillin/clavulanate, chloramphenicol, and imipenem were most active. Several strains of B. gracilis were not killed by ampicillin/sulbactam, clindamycin, or cefoxitin. Activity was variable among strains and antimicrobial agents.

Anti-Bacterial Agents↗
PubMed1993

Development and evaluation of a blood-free medium for determining growth curves and optimizing growth of Rochalimaea henselae.

Two strains of Rochalimaea henselae were used to optimize a blood-free growth medium. Seven agar bases, four broths, and combinations of eight supplements were evaluated. Acceptable growth was achieved in media containing Fildes solution and hemin, with the best growth demonstrated in brucella broth or on brucella agar with 6 to 8% Fildes solution and 250 micrograms of hemin per ml. R. henselae utilized hemin in concentrations six times that utilized by Rochalimaea quintana. Erythrocyte membrane was necessary to achieve the full growth-promoting effect of rabbit blood.

Agar↗
PubMed1992

A microbiological comparison between acute and complicated appendicitis.

Bacteria recovered from appendiceal specimens from 20 patients with acute appendicitis were compared with those recovered from 19 patients with complicated (gangrenous or perforative) appendicitis. Specimens of both peritoneal fluid and appendiceal tissue from patients with acute appendicitis yielded smaller numbers and fewer species of bacteria in culture than did specimens from patients with more complicated disease (2.3 strains per specimen for the former; 9.9 strains per specimen for the latter). Bacteria were recovered from all 13 cultures of specimens of appendiceal tissue and from 13 of 18 cultures of specimens of peritoneal fluid obtained from patients with gangrenous and perforative appendicitis; however, only eight of 17 cultures of appendiceal specimens and seven of 18 cultures of peritoneal fluid specimens from patients with acute appendicitis yielded bacteria. These findings suggest that some bacteria traverse the intact appendiceal wall prior to perforation and that progressive infection and subsequent tissue damage and necrosis allow larger numbers and varieties of bacteria to move through appendiceal wall tissue and into the peritoneal cavity.

Acute Disease↗
PubMed1992

Cellular fatty acids in Fusobacterium species as a tool for identification.

Identification of fusobacteria from clinical specimens currently requires analysis of metabolic end products by gas-liquid chromatography in addition to certain biochemical and enzymatic tests because of the relative biochemical inactivity of these bacteria. Even the finding of pointed, thin gram-negative cells on Gram-stained slides can no longer be relied on for identification of Fusobacterium nucleatum, since at least four other species of fusobacteria have been seen to exhibit similar morphology. We examined 46 clinical isolates and six American Type Culture Collection type strains of fusobacteria by conventional methods and by the Microbial ID Systems MIDI software package for analyzing cellular fatty acid patterns measured by capillary column gas-liquid chromatography. Distinctive patterns of major fatty acids could be used to reliably identify most clinical isolates to the species level. The MIDI system identified 89% of the isolates correctly and provides an alternative to conventional methods.

Bacterial Typing Techniques↗
PubMed1992

Bilophila wadsworthia isolates from clinical specimens.

Bilophila wadsworthia is an anaerobic, gram-negative, asaccharolytic, bile-resistant, catalase-positive bacillus that is usually urease positive and was originally recognized in specimens of peritoneal fluid and tissue from patients with appendicitis. Additional isolations from clinical specimens, including a scrotal abscess, mandibular osteomyelitis, axillary hidradenitis suppurativa, pleural fluid, joint fluid, and blood, are described here.

Adult↗
PubMed1990

The microbiology of chronic sinus disease in children with respiratory allergy.

Chronic maxillary sinusitis is common in children with respiratory allergy and is associated with increased morbidity. The bacteriology of chronic sinus disease in these children has not been adequately evaluated. Between May 1987 and January 1988, 12 children (aged 3 to 9 years), all with documented respiratory allergy and chronic respiratory symptoms consistent with chronic sinusitis (greater than 30 days), were fully evaluated. History, physical examination, complete blood count, nasal smear, and Waters x-ray were done. All patients had opacification of one or both maxillary sinuses, failed to respond to multiple courses of antibiotics, and subsequently underwent maxillary sinus aspiration and irrigation. Specimens were cultured for aerobic and anaerobic organisms with standard technique, and sensitivities were obtained. Culture results revealed a single organism (Moraxella [Branhamella] catarrhalis) in five patients, one patient yielded M. catarrhalis plus Streptococcus species, three were negative, and three patients grew multiple organisms (two with multiple aerobic streptococcal species and one patient with aerobic streptococci and Peptostreptococcus). All children received appropriate culture-directed antimicrobial therapy. Sequential biweekly follow-up revealed progressive radiographic clearing and significant symptomatic improvement. M. catarrhalis is a common pathogen, whereas anaerobic organisms are unusual as a cause of chronic maxillary sinusitis in allergic children. Some children, despite negative cultures, may benefit from maxillary sinus irrigation.

Child↗
PubMed1990

The bacteriology of gangrenous and perforated appendicitis--revisited.

By using optimum sampling, transport, and culture techniques in patients with gangrenous or perforated appendicitis, we recovered than has previously been reported. Thirty patients older than 12 years with histologically documented gangrenous or perforated appendicitis had peritoneal fluid, appendiceal tissue, and abscess contents (if present) cultured. Appendiceal tissue was obtained so as to exclude the lumen. A total of 223 anaerobes and 82 aerobic or faculatative bacteria were recovered, an average of 10.2 different organisms per specimen. Twenty-one different genera and more than 40 species were encountered. Bacteroides fragilis group and Escherichia coli were isolated from almost all specimens. Within the B. fragilis group, eight species were represented. Other frequent isolates included Peptostreptococcus (80%), Pseudomonas (40% [P. aeruginosa, 23.3%, other Pseudomonas spp., 16.7%]), B. splanchnicus (40%), B. intermedius (36.7%), and Lactobacillus (36.7%). Interestingly a previously undescribed fastidious gram-negative anaerobic bacillus was isolated from nearly one half of all patients. This organism was found to have low DNA homology (by dot blot) with the known organisms most closely resembling it.

Adolescent↗
PubMed1990

Short prereduced anaerobically sterilized (PRAS) biochemical scheme for identification of clinical isolates of bile-resistant Bacteroides species.

The rapid identification of isolates of bile-resistant Bacteroides species has clinical and therapeutic relevance because of differences in their patterns of susceptibility and virulence. Five hundred twenty-one strains of bile-resistant Bacteroides species that were previously identified by conventional biochemical methods were reexamined to determine the minimum essential parameters necessary for correct identification. Rapid tests for bile resistance, indole production, and catalase were combined with a novel scheme for biochemical determination of saccharolytic activity on arabinose, trehalose, rhamnose, and/or xylan that included the postincubation addition of bromthymol blue for visual pH determination. Organisms were inoculated into prereduced anaerobically sterilized (PRAS) carbohydrates directly from plates, and identification was complete within 24 h of obtaining a pure culture. Ninety-three percent of bile-resistant Bacteroides species from routine clinical specimens were identified correctly by this scheme; a small number of other indole-positive strains, B. splanchnicus, B. eggerthii, and B. stercoris, were misidentified as B. uniformis.

Anaerobiosis↗
PubMed1990

Evaluation of two single-plate incubation systems and the anaerobic chamber for the cultivation of anaerobic bacteria.

Three systems that are available for the incubation of anaerobic organisms were evaluated to assess their ability to support the growth of 25 anaerobic stock strains and to successfully recover anaerobic bacteria from clinical specimens. These were the anaerobic chamber, the Anaerobic Pouch System Catalyst-Free (Difco Laboratories, Detroit, Mich.), and the Bio-Bag Environmental Chamber Type A (Marion Scientific, Div. Marion Laboratories, Inc., Kansas City, Mo.). Three study centers were involved, the Wadsworth Anaerobe Laboratory (Los Angeles, Calif.), the Good Samaritan Hospital (San Jose, Calif.), and the Massachusetts General Hospital (Boston). A total of 171 anaerobic organisms were isolated from 49 clinical specimens that were cultured at the three test centers. Of these, 169 (99%) were recovered from media that were incubated in the anaerobic chamber, 163 (95%) were recovered from the Anaerobic Pouch, and 147 (86%) were recovered from the Bio-Bag. A similar trend was seen with the stock strains, in which the anaerobic chamber often supported better growth of the organisms than did either of the bag systems.

Anaerobiosis↗
PubMed1990

Selective medium for isolation of Bacteroides gracilis.

A new medium selective for Bacteroides gracilis was developed. The medium is tryptic soy agar (Difco Laboratories, Detroit, Mich.) containing nalidixic acid, teicoplanin, sodium formate, sodium fumarate, and potassium nitrate. All 18 strains of B. gracilis tested grew with only minimal inhibition. Most of the other 214 organisms tested, including most Bacteroides species, other anaerobes, and a substantial number of facultative anaerobes, were significantly inhibited by the medium. In a diagnostic study of 49 clinical specimens (28 patients with intra-abdominal infection, mostly gangrenous or perforated appendicitis), four strains of B. gracilis were isolated (from 4 different patients) on B. gracilis selective agar but were not detected on standard media.

Agar↗
PubMed1990

Gangrenous and perforated appendicitis with peritonitis: treatment and bacteriology.

A comparison of single-agent antimicrobial therapy in the treatment of patients with perforated or gangrenous appendicitis and peritonitis was performed in a double-blind, randomized, prospective trial. Pathologic documentation of advanced appendicitis and positive intraoperative specimen cultures were required for inclusion in the study. Ceftizoxime (2 gm every 12 hours) and cefoxitin (2 gm every six hours) were compared. There were no significant differences between the treatment groups. Ninety-seven percent of patients treated with ceftizoxime and 89% of those treated with cefoxitin were cured or improved; there was no mortality in either group. By the use of optimal sampling, transport, and culture techniques, the number and diversity of bacteria recovered from these patients with advanced appendicitis were found to be much larger than previously suspected. Peritoneal fluid, abscess contents (if present), and appendiceal tissue (obtained so as to exclude the lumen) were cultured from all patients. An average number of 3.1 aerobic or facultative bacteria species and 8.5 anaerobic species were isolated from each specimen. Twenty-eight different genera and more than 55 species were encountered, including a previously undescribed fastidious gram-negative anaerobic bacillus. Bacteroides fragilis group and Escherichia coli were isolated from almost all specimens, and within the B fragilis group, eight species were represented. The recovery of such an unexpectedly large and diverse flora may be the reason for the therapeutic failures in these patients. We conclude that single-agent antimicrobial therapy in patients with advanced appendicitis and peritonitis is both safe and effective, and, with ceftizoxime, can be accomplished by a twice-daily dosing regimen.

Adult↗
PubMed1989

Bilophila wadsworthia, gen. nov. and sp. nov., a unique gram-negative anaerobic rod recovered from appendicitis specimens and human faeces.

Strongly catalase-positive Gram-negative anaerobic rods were isolated from approximately half of all intra-abdominal specimens received from patients with gangrenous and perforated appendicitis, and subsequently also from normal faecal specimens. The organism was originally detected on Bacteroides-bile-aesculin (BBE) agar, and grew slowly on non-selective anaerobic media containing blood. It was stimulated by bile and differed from other known genera by being urease- and catalase-positive, and by reducing nitrate. It did not reduce sulphate. Other anaerobic Gram-negative rods showed no homology by DNA dot-blot hybridization. The thermal melting profile of chromosomal DNA showed 39-40 mol% G + C. The whole-cell fatty acid methyl ester profile included cyclic and branched long-chain acids, and differed from those of all other anaerobes that have been tested. beta-Lactamase was not detected. The name Bilophila wadsworthia gen. nov., sp. nov. is proposed for this organism.

Appendicitis↗
PubMed1989

Comparison of three methods for detection of Cryptosporidium oocysts in a low-prevalence population.

Four hundred fecal specimens which had been received for routine ova and parasite examination were concentrated by Formalin-ether sedimentation. Sediments were examined as saline and iodine-stained wet preparations and were stained with rhodamine-auramine O and a commercially available monoclonal fluorescent-antibody stain for oocysts of Cryptosporidium species. Examination with the fluorescent stains detected cryptosporidia in both positive specimens (0.5% prevalence), and routine direct wet-preparation examination detected cryptosporidia in one of them. Detection of only low numbers of positive specimens in our nonrisk population argues against routine use of specific and expensive stain reagents.

Animals↗
PubMed1988

Visual and clinical analysis of Bac-T-Screen urine screen results.

Of 337 urine specimens evaluated, 75 of the 113 that showed positive readings on the Bac-T-Screen urine-screening instrument were found by subsequent semiquantitative culture to yield either less than 10,000 CFU of mixed bacteria per ml or no growth (less than 100 CFU/ml by our criteria). We tried to determine what factors contributed to the positive Bac-T-Screen results by examining the 75 Bac-T-Screen-positive urine specimens with three visual methods: Gram staining, hemacytometer chamber counting, and filtering through a 5.0-microns-pore-size nitrocellulose filter with subsequent microscopic examination of the stained filter. Somatic cells and other particles present in those urine specimens that yielded positive readings by the Bac-T-Screen included epithelial cells in 43%, crystals and amorphous material in 33%, and leukocytes in 17% of the specimens. There was no relationship between the numbers of particles seen in urine and the magnitude of the relative absorbance reading obtained with the Bac-T-Screen. A retrospective chart review was conducted for patients with positive Bac-T-Screen results and negative cultures. Of the 75 patients, 6 were thought to have urinary tract infections on the basis of clinical criteria; the majority of the remaining 69 patients had clinical histories revealing systemic or urogenital conditions consistent with shedding of particles in the urine. A positive reading by the Bac-T-Screen system seemed to be related to the presence of somatic cells and other particles in urine; bacteriuria was not always detectable in these cases.

Bacteriuria↗
PubMed1988

Novel application of video image processing to biochemical and antimicrobial susceptibility testing.

ALADIN (Analytab Products, Plainview, N.Y.) is an automated instrument that uses video imaging (computer-assisted guided video camera) for the determination of biochemical and antimicrobial susceptibility test reactions. This collaborative investigation compared video-generated results obtained with ALADIN with visually determined findings. Both approaches were used to view identical reactions. Overall agreement for biochemical and antimicrobial susceptibility tests was greater than 95%. This study demonstrates that video imaging is an acceptable approach for determining microbial responses to biochemical and antimicrobial agents and may provide, with appropriate computer modifications, more accurate and reproducible results than are possible by visual scrutiny.

Bacteria, Anaerobic↗