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Biomedical subjects

I Brook

Publications and source records attributed to I Brook.

At least 271 records · Page 15Linked to original sources
PubMed1988

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.

Abscess↗
PubMed1988

Management of infection following intra-abdominal trauma.

Intra-abdominal infections following abdominal trauma often involve the gastrointestinal aerobic and anaerobic bacterial flora. These organisms possess various virulence factors and exhibit potential synergy between them. The intra-abdominal infection is biphasic, with the Enterobacteriaceae as the major pathogens in the peritonitis stage, and the Bacteroides fragilis group predominant in the abscess stage. Experiments with animals and experience in human beings support the need to use single or combined antimicrobial agent therapy that is effective against both Enterobacteriaceae and the B fragilis group.

Abdominal Injuries↗
PubMed1988

Effect of antimicrobial therapy on bowel flora and bacterial infection in irradiated mice.

Mice exposed to 10 Gy cobalt-60 radiation were given intramuscular antimicrobial therapy of gentamicin, or metronidazole, or a combination of the two. Mortality in the mice treated with metronidazole alone or in combination with gentamicin occurred earlier than in the controls (P less than 0.001). Microorganisms were recovered from the blood, spleen, and liver of the metronidazole-treated mice earlier than from other groups. The predominant organisms recovered from these animals were Enterobacteriaceae. Quantitative cultures of the ileal flora showed a decrease in the number of aerobic, facultative anaerobic and strict anaerobic bacteria after irradiation, and a subsequent increase only in the number of strict aerobic bacteria. As compared to untreated mice, a rapid decrease (by 8.8 logs) in the number of anaerobic flora occurred in the mice treated with metronidazole 5 days after irradiation. This was followed by a rapid increase in the number of aerobic organisms which coincided with the earlier mortality in this group. These data suggest that antimicrobial agents that decrease the number of the strict anaerobic component of the gut flora enhance systemic infection by aerobic or facultative anaerobic bacteria, and this facilitates mortality after irradiation.

Animals↗
PubMed1988

Synergy between spiramycin and metronidazole in the treatment of polymicrobial infections.

The in-vitro and in-vivo activity of metronidazole and spiramycin, singly or in combination, was tested in the eradication of infection caused by Bacteroides spp. alone and in combination with Neisseria gonorrhoea, Staphylococcus aureus, Streptococcus pyogenes or Str. faecalis. The in-vitro tests consisted of determinations of the MICs with or without the addition of a constant amount of the other antimicrobials. The MICs of metronidazole for B. melaninogenicus, B. fragilis and B. bivius were significantly reduced by the addition of 0.125 mg/l spiramycin. The in-vivo tests were carried out in mice and consisted of measurements of the effects of the antimicrobial agents on the bacterial contents of abscesses induced by subcutaneous injection of bacterial suspension. Combined therapy of mixed infections showed further significant reduction of the numbers of Bacteroides spp. in seven of 12 combinations and of the aerobic and facultative bacteria in four of 12 combinations. Furthermore, a reduction in the number of facultative anaerobes was noted in mixed infections with Bacteroides spp. which were treated with metronidazole alone. The synergy in vitro and in vivo between metronidazole and spiramycin may have important clinical implications in the treatment of polymicrobial aerobic-anaerobic infections.

Abscess↗
PubMed1988

Pathogenicity of capsulate and non-capsulate members of Bacteroides fragilis and B. melaninogenicus groups in mixed infection with Escherichia coli and Streptococcus pyogenes.

The relationships between capsulate and non-capsulate Bacteroides fragilis strains and Escherichia coli, and between capsulate and non-capsulate strains of the B. melaninogenicus group and Streptococcus pyogenes, were studied in a subcutaneous abscess model in mice. Selective antimicrobial agents directed against either aerobic or anaerobic bacteria were used alone or in combination to explore the effect of eradication of one component of the mixed infection. Single agent therapy effective against both aerobic and anaerobic flora was also employed. Single therapy of mixed infection directed at the elimination of only one organism (S. pyogenes, E. coli or Bacteroides sp.) caused significant reductions in the numbers of sensitive organisms and also smaller yet significant decreases in the numbers of insensitive organisms. However, the abscesses were not eliminated after such therapy. Combination therapy or use of a single agent (cefoxitin) directed against the aerobic and anaerobic components of the infection was more effective. Non-capsulate Bacteroides spp. became capsulate after passage in mice mixed with either S. pyogenes or E. coli. Therapy directed at the elimination of S. pyogenes and E. coli did not prevent the emergence of capsulate Bacteroides spp. These data demonstrate the synergy between all members of the B. fragilis group and E. coli and between the B. melaninogenicus group and S. pyogenes, and reiterate the need to direct antimicrobial therapy at the eradication of the aerobic and anaerobic components of mixed infections.

Abscess↗
PubMed1988

Aerobic and anaerobic bacteriology of purulent nasopharyngitis in children.

Cultures of aerobic and anaerobic bacteria were obtained from the inferior nasal meatus of 25 children with purulent nasopharyngitis and from 25 controls. Microorganisms were isolated from all specimens. A total of 98 isolates (3.9 per patient), 45 aerobes (1.8 per patient) and 53 anaerobes (2.1 per patient), were isolated in patients with purulent nasopharyngitis. Seventy-three isolates (2.9 per patient), 47 aerobes (1.9 per patient) and 26 anaerobes (1.0 per patient) were found in the controls. The organisms recovered in statistically significantly higher numbers in patients with nasopharyngitis were Streptococcus pneumoniae, Haemophilus sp., Peptostreptococcus spp., Fusobacterium spp., and Bacteroides spp. The organisms recovered in significantly higher numbers in controls were Staphylococcus aureus and Propionibacterium acnes. beta-Lactamase activity was detected in 19 isolates recovered from 15 individuals (9 patients and 6 controls). These findings demonstrate the aerobic-anaerobic polymicrobial flora associated with purulent nasopharyngitis. Further studies are indicated to evaluate the pathogenic role of these organisms in this condition.

Bacteria, Aerobic↗
PubMed1988

Recovery of anaerobic bacteria from clinical specimens in 12 years at two military hospitals.

Examination of 15,844 clinical specimens submitted over 12 years (1973 to 1985) to the anaerobic microbiology laboratories in two military hospitals demonstrated the recovery of anaerobic bacteria in 4,458 (28.1%) specimens. The specimens yielded 6,557 anaerobic isolates (1.47 isolates per specimen). Bacteroides spp. accounted for 43% of all isolates; anaerobic gram-positive cocci, 26%; Clostridium spp., 7%; and Fusobacterium spp., 4%. Bacteroides spp. predominated in abscesses, obstetrical and gynecological (OBG) infections, abdominal infections, cysts, wounds, and tumors. Members of the Bacteroides fragilis group accounted for 44% of all Bacteroides spp., and of them, B. fragilis was mostly isolated in abscesses, wounds, abdomen, and blood. Pigmented Bacteroides spp. accounted for 21% of all Bacteroides sp. isolates and were mostly isolated in sinus, eye, chest, bone, and ear infections. Bacteroides melaninogenicus accounted for 42% of this group's isolates. Bacteroides bivius accounted for 9% of Bacteroides spp., and most isolates were found in OBG infections. Anaerobic gram-positive cocci were mostly isolated in OBG infections, abscesses, and wounds. The predominant anaerobic gram-positive cocci were Peptostreptococcus magnus (18%), Peptostreptococcus asaccharolyticus (17%), Peptostreptococcus anaerobius (16%), and Peptostreptococcus prevotii (13%). Clostridium spp. were mostly isolated from wounds, abscesses, abdominal infections, and blood. The predominant strain was Clostridium perfringens (48%). Fusobacterium spp. were recovered in abscesses and abdominal and OBG infections. The predominant isolate was Fusobacterium nucleatum (47%). These data illustrate the relative frequency of the different anaerobic bacteria in a variety of infections and demonstrate the predominance of certain isolates at different sites.

Bacteria, Anaerobic↗
PubMed1988

Beta-lactamase-producing bacteria in head and neck infection.

We have summarized our experience in recovery of beta-lactamase-producing bacteria (BLPB) in head and neck infection (HNI). These HNI include conjunctivitis, serous and chronic otitis media, cholesteatoma, chronic mastoiditis, chronic sinusitis, adenoiditis, recurrent tonsillitis in children and adults, peritonsillar abscess, and retropharyngeal abscess. Beta-lactamase-producing bacteria were found in 262 (51%) of 513 patients with HNI; 72% had aerobic BLPB and 57% had anaerobic BLPB. The infections, where these organisms were most frequently recovered, were adenoiditis (85% of patients), tonsillitis in adults (82%) and children (74%), retropharyngeal abscess (71%), and chronic otitis media (57%). The predominant BLPB were Staphylococcus aureus (49% of patients with BLPB), the Bacteroides-melaninogenicus group (28%), the Bacteroides fragilis group (20%), Pseudomonas aeruginosa (13%), Hemophilus influenzae (5%), and Branhamella catarrhalis (3%). The high incidence of recovery of BLPB in head and neck infections may have important implications on the antimicrobial management of these infections.

Bacterial Infections↗
PubMed1988

The swollen neck. Cervical lymphadenitis, parotitis, thyroiditis, and infected cysts.

Swelling of the neck can result from a variety of causes, both infectious and noninfectious. This article describes the major causes of neck swelling from the more common infectious processes in the neck--cervical lymphadenitis, parotitis, thyroiditis, and infected cysts. The etiology and pathogenetic considerations, clinical manifestations, differential diagnosis, therapy, and prevention are discussed for each of these conditions.

Cysts↗
PubMed1988

The role of beta-lactamase-producing bacteria in respiratory tract infections.

Staphylococcus aureus, Haemophilus influenzae, Bacteroides sp. (Bacteroides melaninogenicus, Bacteroides oralis, and Bacteroides fragilis), peptostreptococci and fusobacterium sp. are important pathogens in respiratory tract infections (RTI). These organisms are often recovered mixed with other aerobic, facultative and anaerobic bacteria. A recent increase in numbers of bet-lactamase producing strains of anaerobic gram-negative bacteria in RTI has been associated with increased failure rates of penicillins in eradication of these infections. These infections include chronic otitis media, chronic sinusitis and mastoiditis, chronic recurrent tonsillitis and lung abscesses. The indirect pathogenicity of these organisms is apparent through their ability not only to survive penicillin therapy but also to protect penicillin susceptible pathogens from that drug. These direct and indirect virulence characteristics of anaerobic bacteria require the administration of appropriate antimicrobial therapy directed against all pathogens in mixed infections.

Adult↗
PubMed1988

Effect of Streptococcus faecalis on the growth of Bacteroides species and anaerobic cocci in mixed infection.

The relationship between Streptococcus faecalis and anaerobic bacteria was studied in a subcutaneous abscess model in mice. Included in the study were one strain of S. faecalis, three strains each of the Bacteroides fragilis group and B. melaninogenicus group, and five strains of anaerobic cocci. The relationship between the organisms was studied by determining the individual change in colony-forming units (CFUs) of the two bacterial components that induces abscesses in mice, compared to the CFUs of each of the isolated when inoculated alone. Of the eleven combinations, the CFUs of S. faecalis increased in seven and decreased in two. The CFUs of anaerobic bacteria were never increased and were decreased in two. A mutual decrease in growth occurred only in the combinations of S. faecalis and B. melaninogenicus group. This study demonstrates the potential for pathogenicity of S. faecalis in mixed infections with the B. fragilis group and anaerobic cocci.

Abscess↗
PubMed1988

Role of anaerobic bacteria in aortofemoral graft infection.

A 10-year review of specimens of aortofemoral graft infection sent to the microbiology laboratory for cultures of anaerobic bacteria revealed the presence of these organisms in 13 of 16 specimens. Nineteen organisms (1.5 per patient) were isolated: 16 anaerobes and 3 aerobes. The predominant bacteria were anaerobic gram-positive cocci (six isolates), Propionibacterium acnes (five), and Bacteroides fragilis group (four). Polymicrobial infection was present in three patients, all with decubitus ulcers. Conditions predisposing to the infections were present in nine patients and included the presence of preoperative infections in the form of ulcer or toe gangrene in four, decubitus ulcer in three, reoperation in two, and diabetes mellitus in one. These data illustrate the potential importance of anaerobic bacteria in aortofemoral graft infection.

Aged↗
PubMed1988

Presence of anaerobic bacteria in conjunctivitis associated with wearing contact lenses.

Ten anaerobic bacterial species were found in conjunctival cultures obtained from six patients who wore contact lenses and developed conjunctivitis. In three instances the anaerobic bacteria were associated with facultative bacteria. The predominant anaerobic isolates were Peptostreptococcus species (three isolates), Bacteroides sp. (two), and Fusobacterium sp. (two). It was the practice of five of the six patients to wet their lenses with saliva. It is recommended that a culture for anaerobes be obtained from any patient who uses contact lenses and develops conjunctivitis.

Bacteria, Anaerobic↗
PubMed1988

Use of antibiotics in the management of postirradiation wound infection and sepsis.

Ionizing gamma irradiation depresses the host defenses and enhances the susceptibility of the immunocompromised host to local and systemic infection due to endogenous or exogenous microorganisms. Trauma and wounding act synergistically and decrease the survival after exposure to irradiation. The current antimicrobial agents suitable for controlling serious infections and their use in post irradiation local and systemic infection with and without trauma are discussed. The experience gained in managing immunocompromised patients following chemotherapy is reviewed. Empiric single agent or combination agent therapy should be directed at the eradication of potential gram-negative as well as gram-positive pathogens. The most important organisms known to cause these infections are Pseudomonas sp. and Enterobacteriaceae. Management of intra-abdominal infections following trauma should include early surgical correlation and antimicrobials directed against the Bacteroides fragilis group and Enterobacteriaceae. Staphylococcus aureus and Streptococcus pyogenes cause most skin and soft tissue infections following trauma. Chemoprophylaxis of enteric sources of systemic infection can be achieved by antimicrobials that selectively inhibit the Enterobacteriaceae sp. and preserve the anaerobic flora. The management of infection in the injured and irradiated host includes supportive and restorative therapy. Supportive therapy includes débridement and cleansing of wounds, fluids, immunoglobulin, and antimicrobials. Restorative therapy includes definite surgery repair and replenishment of the immune system by use of immunomodulators, growth factors, and bone marrow transplantation. Further studies are needed to examine the usefulness of presently available drugs and experimental agents in the irradiated and traumatized host.

Animals↗