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Biomedical subjects

I Brook

Publications and source records attributed to I Brook.

At least 19 recordsLinked to original sources
PubMed1992

Diagnosis and management of parotitis.

Of all the salivary glands, the parotid gland is most commonly affected by an inflammatory process. Infections of the parotid gland range from acute to severe. Assessment of the disease process should differentiate local primary parotid infection from systemic infection when this gland is also involved as part of a generalized inflammatory condition. Viral parotitis can be caused by paramyxovirus (mumps), Epstein-Barr virus, coxsackievirus, and influenza A and parainfluenza viruses. Acute suppurative parotitis is generally caused by Staphylococcus aureus, Streptococcus species, and rarely, gram-negative bacteria. Anaerobic bacteria, mostly Peptostreptococcus species and Bacteroides species, and pigmented Porphyromonas species and Prevotella species have been recently recognized as an important cause of this infection. beta-Lactamase-producing organisms can be isolated in almost three fourths of the patients. Predisposing factors to suppurative infections are dehydration, malnutrition, oral neoplasms, immunosuppuration, sialolithiasis, and medications that diminish salivation. Pus, aspirated from a suppurative parotic abscess, should be plated on media that are supportive for the growth of aerobic and anaerobic bacteria, mycobacteria, and fungi. Early and proper antimicrobial therapy may prevent suppuration. Initial empiric therapy that is directed against both aerobic and anaerobic bacteria may be required until a specific causal diagnosis is available. Surgical drainage may be indicated when pus has formed. This may prevent complications and facilitate recovery.

Diagnosis, Differential↗
PubMed1992

Encapsulation and pilus formation of Bacteroides spp. in normal flora abscesses and blood.

The presence of encapsulated and piliated Bacteroides spp. (mostly Bacteroides fragilis and melaninogenicus groups was investigated in isolates from blood, abscesses and normal flora. Of the strains of Bacteroides spp. isolated 45 of 54 (83%) recovered from blood and 31 of 40 (78%) found in abscesses were encapsulated. In contrast, only seven of 71 (10%) similar strains isolated from the faeces or pharynx of healthy persons were encapsulated (P < 0.001). Pili were observed in three of 54 (6%) of strains isolated from blood, 30 of 40 (75%) of those recovered from abscesses (P < 0.001), and 49 of 71 (69%) of those found in normal flora (P < 0.001). The predominance of encapsulated forms in all strains of B. fragilis and B. melaninogenicus in blood as well as in abscesses suggests an increased virulence of these compared with non-encapsulated isolates. In contrast, the presence of pili in Bacteroides spp. recovered mostly from abscesses and normal flora suggests that this structure may play a role in the ability of these organisms to adhere to mucous membranes and may interfere with their ability to spread systemically. These findings illustrate the morphological differences that may be observed in Bacteroides spp. from various anatomical sites.

Abscess↗
PubMed1992

The management of acute, serous and chronic otitis media: the role of anaerobic bacteria.

Otitis media (OM) is a common childhood disease and one which can cause significant morbidity. A knowledge of the pathogens responsible for OM enables the most appropriate treatment regimen to be selected and thus minimizes further complications which may require hospital admission and surgery. The microbiology of acute, serous and chronic OM is reviewed, with particular regard to the role of anaerobic bacteria. Anaerobes, mainly Gram-positive cocci, have been recovered from 25% of the ear aspirates of patients with acute otitis media. In a study of serous OM, anaerobic bacteria were recovered in 12% of the culture-positive aspirates. The predominant anaerobes were Gram-positive cocci and pigmented Prevotella. Several studies have reported the recovery of anaerobes from about 50% of patients with chronic OM and those with cholesteatoma. The predominant anaerobes were Gram-positive cocci, pigmented Prevotella, Porphyromonas sp., Bacteroides spp. and Fusobacterium spp. Many of these organisms produce beta-lactamase which might have contributed to the failure of the patients to respond to penicillins. The appropriate antimicrobial therapy for acute, serous and chronic otitis media is discussed.

Acute Disease↗
PubMed1992

Aerobic and anaerobic microbiology of external otitis.

Microbiological and clinical data from 46 patients with external otitis were retrospectively evaluated. Specimens were processed for isolation of aerobic and anaerobic bacteria. A total of 42 aerobic bacteria, 22 anaerobic bacteria, and 3 Candida albicans organisms were recovered. Aerobic bacteria only were isolated from 31 patients (67%), anaerobic bacteria only were isolated from 8 (17%), and mixed aerobic and anaerobic bacteria were isolated from 4 (9%). C. albicans alone was recovered from two patients (4%), and the organism was mixed with aerobic bacteria in one case (2%). The most common isolates were Pseudomonas aeruginosa (19 instances), Peptostreptococcus species (11), Staphylococcus aureus (7), and Bacteroides species (5). One isolate was recovered from 30 patients (65%), 2 isolates were recovered from 11 (24%), and 3 isolates were recovered from 5 (11%). beta-Lactamase activity was detected in 32 isolates recovered from 27 specimens (59%). These data illustrate the polymicrobial nature of external otitis in one-third of the patients and the role of anaerobic bacteria in one-quarter of them. Further prospective studies are warranted for evaluating the role of anaerobic bacteria in this infection and the therapeutic implications of these findings.

Adolescent↗
PubMed1992

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.

Bacteria, Aerobic↗
PubMed1992

Recovery of Bacteroides fragilis group from clinical specimens following antimicrobial therapy.

Over a period of 14 years (1973-1987), 3165 specimens submitted to the microbiology laboratory demonstrated the recovery of anaerobic bacteria. A total of 988 Bacteroides fragilis group isolates were recovered (0.3 isolates per specimen). Bacteroides fragilis accounted for 62% of the total of all B. fragilis group isolates, Bacteroides thetaiotaomicron for 15%, Bacteroides vulgatus for 8%, Bacteroides ovatus for 7%, Bacteroides distasonis for 6%, and Bacteroides uniformis for 2%. Of the 988 B. fragilis group isolates, 310 (31%) were recovered after the administration of antimicrobial therapy, and 129 (13%) were the single isolate recovered from the infected site at that time. The recovery rate of all members of B. fragilis group after the administration of antimicrobial therapy, when isolated alone or when mixed with other bacteria, was similar. The data illustrate the equal ability of all members of the B. fragilis group to persist in and to contribute to the inflammatory process; and provide further support for their pathogenic role.

Bacteroides Infections↗
PubMed1992

Diagnosis and management of anaerobic infections of the head and neck.

Anaerobic bacteria are important pathogens in head and neck infections such as chronic otitis media, chronic sinusitis, chronic mastoiditis, head and neck abscesses, cervical adenitis, parotitis, and postoperative infection. Bacteroides sp (Bacteroides melaninogenicus group, Bacteroides oralis, and Bacteroides fragilis group), Peptostreptococcus sp, and Fusobacterium sp predominate. The observed recent increase in the number of beta-lactamase-producing strains of Bacteroides sp isolated in head and neck infections has been associated with increased failure rates of the penicillins in the management of these infections. The pathogenicity of these organisms is expressed through their ability not only to survive penicillin therapy but also to shield penicillin-susceptible pathogens from the drug. Because of these direct and indirect virulent characteristics of anaerobic bacteria, appropriate antimicrobial therapy must be directed against all pathogens in mixed infections.

Bacteria, Anaerobic↗
PubMed1992

Changes in the microbial flora of airline headset devices after their use.

The bacterial flora of 20 headset devices were evaluated before and after they were worn for 1 hour. Bacteria were recovered from all headsets, and their number increased from a mean (+/- standard deviation) of 60 +/- 5 organisms per device to 650 +/- 51 organisms per device (P less than .001). The predominant organisms recovered were Staphylococcus spp, Streptococcus spp, Propionibacterium spp, and Peptostreptococcus spp. This study demonstrates the presence of potential pathogens in headset devices, as well as the increase in the number of these pathogens after the headsets have been worn for 1 hour.

Adolescent↗
PubMed1992

Quinolone therapy in the management of infection after irradiation.

Ionizing radiation increases the recipient's susceptibility to local and systemic infection by endogenous and exogenous microorganisms. Most infections involve fatal Gram-negative septicemia, but those associated with trauma may be polymicrobial. The use of quinolone antimicrobial agents in the treatment of these infections in irradiated mice is reviewed. Quinolones were effective in controlling systemic endogenous Gram-negative infection following irradiation. Supplementation of quinolone therapy with penicillin prevented treatment failures due to Streptococci, and increased survival. Quinolones were found also to be effective in management of systemic exogenous infections due to orally ingested Klebsiella pneumoniae and Pseudomonas aeruginosa. A 21-day course of therapy of K. penumoniae infection was superior to a 7-day therapy. The effectiveness of quinolones in the management of these infections may be attributed to local inhibition of the offending organism's growth within the gut lumen, while preserving the anaerobic gut flora and their systemic antibacterial activity. Administration of agents effective against anaerobic bacteria may be required for the management of polymicrobial infections. Supplementing antianaerobic therapy with a quinolone can control the Gram-negative bacterial component of the infection and prevent Enterobacteriaceae translocation and mortality. The availability of an oral, as well as parenteral, route of administration, the advantage of achieving selective inhibition of potential pathogens in the gut, and the ability to treat systemic infection make the quinolones promising agents for the therapy of endogenous and exogenous infections after irradiation.

4-Quinolones↗
PubMed1992

Microbiologic factors of stump wound infection.

Specimens from 52 patients with stump wound infection (SWI) were studied for aerobic and anaerobic bacteria. Bacterial growth was present in 44 specimens. Only aerobic or facultative bacteria were recovered in 19 specimens, only aerobic bacteria in 12 and mixed aerobic, facultative and anaerobic bacteria in 13. One hundred and three isolates were recovered (2.3 per specimen)-58 aerobic or facultative (1.3 per specimen) and 45 anaerobic (1.0 per specimen). The predominant isolates were anaerobic cocci (17), Bacteroides species (13 isolates), Staphylococcus aureus (12) and Escherichia coli (11). Polymicrobial infection occurred in 36 instances. S. aureus was more commonly isolated and anaerobic bacteria were less commonly isolated in SWI of the arms, compared with legs. These data highlight the polymicrobial aerobic-anaerobic cause of SWI.

Adult↗
PubMed1992

Synthetic trehalose dicorynomycolate and antimicrobials increase survival from sepsis in mice immunocompromised by radiation and trauma.

When mammalian antimicrobial defenses are compromised by radiation, death from sepsis may occur. Tissue trauma in irradiated hosts significantly increases mortality from bacterial infections and makes antimicrobial treatments more difficult than when individuals are subjected to trauma or radiation alone. We determined that postirradiation therapy with the immunomodulator synthetic trehalose dicorynomycolate (S-TDCM) and antimicrobials increases survival in mice after lethal irradiation and tissue trauma. Single agent therapy with systemic oxacillin, gentamicin, ofloxacin, and S-TDCM did not increase survival. Topical treatment of the injury with gentamicin cream in addition to systemic therapy with oxacillin or S-TDCM was necessary to enhance survival. Therapy with gentamicin and S-TDCM had a synergistic effect on survival. Therapies combining augmentation of non-specific host defense mechanisms with antimicrobials may be valuable in treating irradiated patients also sustaining tissue trauma.

Animals↗
PubMed1992

Short and long courses of ofloxacin therapy of Klebsiella pneumoniae sepsis following irradiation.

Exposure to whole-body irradiation is associated with fatal gram-negative sepsis. The optimal length of therapy of such infection is not established. The effect of short and long courses of oral therapy with the quinolone ofloxacin for orally acquired Klebsiella pneumoniae infection was tested in B6D2F1 mice exposed to 8.0 Gy of bilateral radiation from 60Co. A dose of 10(8) organisms was given orally 4 days after irradiation, and therapy was started 1 day later. Cultures of the ileum 7 days after irradiation showed the recovery of K. pneumoniae in 7 of 10 untreated mice and in 3 of 20 treated with ofloxacin. However, 14 days after irradiation K. pneumoniae was isolated in 5 of 6 untreated mice, in 7 of 9 that received the short course of therapy, and in one of those that received the long course of therapy (P less than 0.05). At Day 7, K. pneumoniae was isolated from the livers of 6 of 10 untreated mice, and from none of those receiving ofloxacin (P less than 0.05). At 14 days, K. pneumoniae was isolated in 4 of 6 untreated animals, in 4 of 9 that received the short course of therapy, and in none of the mice that received the long course of therapy (P less than 0.05). Only 3 of 20 (15%) untreated mice survived for 30 days as compared to 11 of 20 (55%) mice treated for 7 days with ofloxacin and 18 of 20 (90%) mice treated for 21 days with ofloxacin (P less than 0.05). These survival data illustrate the efficacy of a 21-day course over a 7-day course of ofloxacin therapy for orally acquired K. pneumoniae infection in irradiated hosts.

Animals↗
PubMed1992

Therapies for radiation injuries: research perspectives.

Exposure to radiation damages the immune, hematopoietic, and gastrointestinal components of the host defense system. This may lead to serious endogenous or exogenous infections. When radiation injury is combined with other physical trauma, e.g., burn or wound, the resulting damage to these systems is synergistic, and treatment for infection requires multiple approaches. This paper reviews successful single and combined therapeutic modalities for infections in irradiated mice and irradiated mice inflicted with trauma that are currently conducted at the Armed Forces Radiobiology Research Institute. The models of endogenous and exogenous infection and combined injury are described. The management of wounds infected with bacteria, exogenous systemic infection due to gram-negative enteric bacteria, and the chemoprophylaxis of enteric-derived systemic infection with quinolones is described. Infections can be treated successfully with proper antimicrobial therapy. In gamma- and neutron-irradiated mice, the immunomodulator trehalose dimycolate (TDM) was effective in treating endogenous infection. TDM with the antimicrobial ceftriaxone was effective in treating exogenous infection due to Klebsiella pneumoniae. Improvement in managing infection in irradiated and injured hosts will require further research using these diagnostic and therapeutic modalities. Accurate biological dosimetry is critical in determining if victims are at risk of developing infection. We found that radiation induced changes in plasma diamine oxidase activity; monitoring these changes was a useful indicator of the severity of radiation injury.

Adjuvants, Immunologic↗
PubMed1991

Microbiological studies of decubitus ulcers in children.

Specimens from 58 children with decubitus ulcers were cultured for aerobic and anaerobic bacteria. Aerobic bacteria only were present in 29 (50%) ulcers, anaerobic bacteria only were recovered in 5 (9%), and mixed aerobic and anaerobic flora were present in 24 (41%). A total of 132 isolates (79 aerobes, 53 anaerobes) were recovered, an average of 2.3 isolates per specimen (1.4 aerobes, 0.9 anaerobes). The smallest number of isolates was recovered in ulcers of the skull (1.7 per site), and the highest number of isolates was found in ulcers of the buttocks (4.1 per site). The predominant isolates were Staphylococcus aureus (25 isolates), Peptostreptococcus species (22), Bacteroides fragilis group (10), and Pseudomonas aeruginosa (7). Forty-two of the organisms isolated from 38 (66%) patients produced the enzyme beta-lactamase. Most of the S aureus isolates were recovered from ulcers of the hand and the leg. Organisms that resided in the mucous membranes close to the ulcer predominated in the wounds next to these areas. Enteric gram-negative rods, group D streptococci, and B fragilis group predominated in ulcers of the buttocks. Group A streptococci, Haemophilus influenzae, Bacteroides melaninogenicus group, and Fusobacterium species were most frequently recovered in ulcers of the skull. The polymicrobial etiology of decubitus ulcers in hospitalized children and the association of bacterial flora with the anatomical site of the ulcer are demonstrated.

Adolescent↗
PubMed1991

The effect of antimicrobial therapy on mixed infections with Bacteroides species. Is eradication of the anaerobes important?

Antimicrobial agents were used alone or in combinations in order to explore their effect on mixed aerobic-anaerobic infections. Subcutaneous abscesses were induced in mice by single and mixed infections of Bacteroides fragilis, Bacteroides melaninogenicus, Staphylococcus aureus, Streptococcus pyogenes, Streptococcus faecalis, Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa. The infected animals were treated for 5 days with spiramycin, gentamicin or metronidazole alone, or metronidazole combined with spiramycin or gentamicin. Animals were killed 5 days after inoculation and the bacterial contents of the abscesses determined. Infection induced by a single species of bacteria always responded to appropriate antimicrobial therapy. In infections caused by two species of organisms, however, therapy directed at either the Bacteroides sp. (with metronidazole) or the aerobes or facultative anaerobes (with spiramycin or gentamicin) was effective not only in significantly reducing the numbers of the target organism but also, in 13 of 24 instances, in reducing to a small extent the numbers of the other bacteria. Despite this phenomenon, in no instance did therapy with a single agent eliminate the infection and eradicate the untargeted organism. The combination of spiramycin and metronidazole increased the reduction in numbers of B. melaninogenicus in single-organism infections and of Bacteroides sp. in mixed infections with S. aureus and S. pyogenes. These findings support the need to aim treatment at all components of mixed infections.

Abscess↗
PubMed1991

Oral aminoglycoside and ofloxacin therapy in the prevention of gram-negative sepsis after irradiation.

To investigate whether oral gentamicin or ofloxacin therapy protects against gram-negative sepsis after irradiation, B6D2F1 mice were exposed to 7.5 Gy of radiation from 60Co, infected with 10(7) Pseudomonas aeruginosa or Klebsiella pneumoniae orally 3 days after irradiation, and treated with oral (15 mg/kg/day) or intramuscular (im; 7.5 mg/kg/day) gentamicin or oral (40 mg/kg/day) ofloxacin. For P. aeruginosa, gentamicin therapy was started orally 10 and 24 h and im 24 h after inoculation. For K. pneumoniae, gentamicin was started orally 24, 48, and 72 h and im 24 h after inoculation; ofloxacin was started 24 h after inoculation. Mice that received oral gentamicin early (10 h for P. aeruginosa, 24 h for K. pneumoniae), im gentamicin, or oral ofloxacin showed significantly (P less than .05) reduced colonization, translocation, and mortality compared with mice that received oral gentamicin late. These data support the use of selective antimicrobial therapy to reduce colonization, translocation, and mortality from gram-negative bacteria in irradiated animals.

Administration, Oral↗