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Biomedical subjects

I Brook

Publications and source records attributed to I Brook.

At least 487 records · Page 27Linked to original sources
PubMedDate not supplied

The role of beta-lactamase-producing bacteria in the persistence of streptococcal tonsillar infection.

The failure of penicillin to eradicate group A beta-hemolytic streptococci (GABHS) is a growing problem. This review summarizes current data concerning the role of aerobic and anaerobic beta-lactamase-producing bacteria in the persistence of tonsillar infection caused by GABHS. Clinical studies have demonstrated the recovery of beta-lactamase-producing bacteria and detectable levels of the enzyme beta-lactamase in cultures of core tonsillar specimens in greater than 80% of the patients. The predominant bacteria have been Bacteroides melaninogenicus, Bacteroides oralis, Bacteroides ruminicola, and Staphylococcus aureus. These organisms have emerged in about one-third of patients after one course of penicillin therapy and can be transferred to patient's household contacts. These organisms were present in tonsillar cultures in higher numbers in children with acute tonsillitis who did not respond to penicillin therapy than in those who were cured. Protection of GABHS by beta-lactamase-producing organisms has been demonstrated in vitro and in vivo. Several studies, including a recent double-blinded study, have demonstrated the ability of clindamycin to eradicate the streptococcal carrier state and to prevent recurrent infection in selected patients.

Animals↗
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Anaerobic infections in childhood.

Anaerobic bacteria are part of the normal flora of mucous membranes and outnumber aerobic bacteria in the oral cavity and gastrointestinal tract. Anaerobes can be isolated from pediatric patients with various infections when appropriate techniques for transportation and cultivation of samples are employed. Frequently anaerobes are isolated in combination with other facultative or aerobic bacteria. The genera or groups of anaerobes most frequently isolated from pyogenic infections in children are (in order of decreasing frequency) OFFteroides, Clostridium, gram-positive cocci, Fusobacterium, gram-positive rods (Eubacterium, Lactobacillus, Propionibacterium, Actinomyces, and Bifidobacterium), and gram-negative cocci (Veillonella and Acidaminococcus). Clostridium perfringens causes bacteremia and wound infections. Clostridium botulinum can produce a paralytic toxin that causes a lethal illness in adults and a paralytic syndrome in infants. Clostridium difficile can cause antibiotic-associated colitis or diarrhea. Bacteroides fragilis is most frequently involved in intraabdominal infections, infections of the female genital tract, subcutaneous abscesses, and bacteremia. Bacteroides melaninogenicus and Bacteroides oralis are the predominent anaerobes in orofacial infections and aspiration pneumonia. Fusobacterium species are pathogens in aspiration pneumonia, brain abscesses, and orofacial infections. Anaerobic gram-positive cocci can be recovered from all types of infections but predominate in respiratory tract and intra-abdominal infections. Recognition of the pathogenic qualities of the various anaerobic organisms can assist in their prompt identification and in the initiation of appropriate therapy.

Actinomyces↗
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Role of beta-lactamase-producing bacteria in the failure of penicillin to eradicate group A streptococci.

Ninety-eight children who had acute tonsillitis due to Group A beta-hemolytic streptococci were treated for 10 days with orally administered penicillin B, potassium. Surface tonsillar cultures were obtained before therapy, at the end of therapy and 10, 21 and 42 days after termination of therapy. The cultures obtained before and after completion of treatment were processed for aerobic and anaerobic organisms, while the other cultures were processed only for Group A beta-hemolytic streptococci. On the basis of bacteriologic results 62 patients were considered "cured" (Group A) and 36 "failed" (Group B) following therapy. Before therapy 18 isolates of beta-lactamase-producing organisms (BLPO) were detected in 16 (26%) children in Group A; after therapy 30 BLPO were detected in 19 (30%) children. In contrast, before therapy 40 BLPO were recovered from 25 (69%) children in Group B; this number increased to 62 BLPO in 31 (86%) of those children. The study demonstrates an association between failure to eradicate Group A beta-hemolytic streptococci and the presence of aerobic and anaerobic BLPO.

Acute Disease↗
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Anaerobic osteomyelitis in children.

Twenty-six pediatric patients with osteomyelitis caused by anaerobic bacteria are presented. The etiologic factors were chronic mastoiditis (7 patients), decubitus ulcers (5), chronic sinusitis (4), periodontal abscesses (3), bites (3), paronychia (2), trauma (1) and scalp infection after fetal monitoring (1). Seventy-four organisms (2.8 isolates/specimen), including 63 anaerobes (2.4/specimen), and 11 facultative and aerobic bacteria (0.4/specimen) were recovered. The predominant organisms were anaerobic cocci (29 isolates), Bacteroides sp. (21), Fusobacterium sp. (8), Streptococcus sp. (5) and Clostridium sp. (4). The organisms generally reflected the microbial flora of the mucous surface adjacent to the infected site. Ten beta-lactamase-producing organisms were recovered from 7 (27%) patients. These included all isolates of the Bacteroides fragilis (4) and of Staphylococcus aureus (3), 2 of the 12 Bacteroides melaninogenicus group and 1 of 3 Bacteroides oralis. The clinical, diagnostic and therapeutic aspects of anaerobic osteomyelitis in children are discussed.

Adolescent↗
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Balanitis caused by group B beta-hemolytic streptococci.

A case of acute balanitis in an adult is described. Group B beta-hemolytic streptococci type 3 were recovered from an aspirate of the infected area and from the cervical canal of the patient's sexual consort. The patient and his consort were treated with oral ampicillin for ten days. After therapy the patient's infection cleared, and group B beta-hemolytic streptococci were not recovered from his consort. This case illustrates another aspect of disease due to group B beta-hemolytic streptococci in adults.

Adult↗
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Aerobic and anaerobic microbiology of necrotizing fasciitis in children.

Specimens obtained from eight children with necrotizing fasciitis (NF) were cultured for aerobic and anaerobic bacteria. A total of 21 isolates were recovered, 13 anaerobic and 8 aerobic or facultatives. The facultative organism Streptococcus pyogenes was present alone in two (25%) instances, and mixed aerobic and anaerobic bacteria were isolated in six (75%). The predominant isolates were Peptostreptococcus spp. (6 isolates, including 3 Peptostreptococcus magnus). S. pyogenes (4), Bacteroides fragilis group (3), Clostridium perfringens (2), Escherichia coli (2), and Prevotella spp. (2). Organisms similar to the ones isolated from the NF aspirates were recovered in the blood of all patients except one. These included S. pyogenes (3 isolates). B. fragilis group (2), E. coli (1), and P. magnus (1) and Clostridium perfringens (1). All patients underwent surgical fasciotomy, and four required skin grafting. Antimicrobials were administered to all children. Despite extensive resection and intense supportive therapy, three patients died from sepsis accompanied by shock acidosis and disseminated intravascular coagulation. These findings illustrate the polymicrobial aerobic-anaerobic flora of NF in children.

Acidosis↗
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Microbiology of nonbullous impetigo.

Our objective was to establish the aerobic and anaerobic microbiology of nonbullous impetigo (NI) in children. We used a retrospective review of clinical microbiology laboratory and patients' records. Specimens were obtained from 40 patients with NI lesions and showed bacterial 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. fragilis 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 NI lesions.

Adolescent↗
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Increased resistance of encapsulated Bacteroides fragilis to clindamycin.

The antimicrobial susceptibility and in vitro growth curve of 4 nonencapsulated and 4 encapsulated isolates of Bacteroides fragilis were determined for clindamycin. The MIC of the nonencapsulated isolates was 1-2 dilutions less (0.062-0.25 microgram/ml) than the MIC for their encapsulated counterparts (0.25-0.5 microgram/ml). No difference was noted in the bacterial growth of the nonencapsulated or encapsulated isolates when incubated without clindamycin. The decline in the number of nonencapsulated isolates was significantly lower (p < 0.05) as compared to the encapsulated isolates when incubated with 0.1 or 0.4 microgram/ml of clindamycin. These results illustrate the higher susceptibility of nonencapsulated B. fragilis isolates to clindamycin as compared to their encapsulated counterparts. Since B. fragilis becomes more encapsulated during the infectious process, this finding underscores the advantage of early antimicrobial prophylaxis and therapy.

Bacterial Capsules↗
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Aerobic and anaerobic bacteria in tonsils of children with recurrent tonsillitis.

Tonsils were obtained from 50 children suffering from recurrent tonsillitis. Patients' ages ranged from 2.5 to 17 years (mean 6 years); 29 were males and 21 females. The tonsils were sectioned in half after heat searing of the surface and the core material was cultured for aerobic and anaerobic microorganisms. Mixed aerobic and anaerobic flora was obtained in all patients, yielding an average of 7.8 isolates (4.1 anaerobes and 3.7 aerobes) per specimen. There were 207 anaerobes isolated. The predominant isolates were 101 Bacteroides sp (including 10 B fragilis group, and 47 B melaninogenicus group), 29 Fusobacterium sp, 34 Gram-positive anaerobic cocci (25 Peptococcus sp and 9 Peptostreptococcus sp) and 16 Veillonella sp. There were 185 aerobic isolates. The predominant isolates were 41 alpha-hemolytic streptococci, 24 Staphylococcus aureus, 19 beta-hemolytic streptococci (11 group A, 4 group B, and 2 each group C and F), 14 Haemophilus sp (including 12 H influenzae type B) and 5 H parainfluenzae. Beta-lactamase production was noted in 56 isolates recovered from 37 tonsils. These were all isolates of S aureus (24) and B fragilis (10), 15 of 47 B melaninogenicus (32%), 5 of the 12 B oralis (42%), and 2 of 12 H influenzae type B (17%). Our findings indicate the polymicrobial aerobic and anaerobic nature of deep tonsillar flora in children with recurrent tonsillitis, and demonstrate the presence of many beta-lactamase-producing organisms in 74% of the patients.

Adolescent↗
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Intracranial complications of sinusitis in children. A sequela of periapical abscess.

The cases of two children with periapical abscess in the upper incisors, sinusitis, and intracranial abscess are described. The ethmoid and maxillary sinuses were involved in both patients. Subdural empyema occurred in both, and one of the children had also cerebritis and brain abscess. Anaerobic bacteria were isolated from the infected subdural empyemas. Peptostreptococcus intermedius and microaerophilic streptococci were recovered in one patient and Fusobacterium sp in the other. Surgical drainage and appropriate antimicrobial therapy resulted in complete eradication of the infection in both patients. The role of anaerobic bacteria and the therapy directed against them in periapical abscess and the sinusitis and intracranial abscess which follow are discussed.

Brain Abscess↗
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Microbiology of abscesses of the head and neck in children.

Specimens from 36 children with abscesses of the neck and 31 children with abscesses of the head were cultured for aerobic and anaerobic bacteria. Antimicrobial therapy was administered to 51 of the 67 patients (76%) prior to sample collection. In specimens obtained from neck infections, aerobic bacteria only were recovered in 24 (67%), anaerobic bacteria only in seven (19%), and mixed aerobic and anaerobic bacteria in five (14%). In abscesses of the head, aerobic bacteria only were recovered in 11 (35%), anaerobic bacteria only in eight (26%), and mixed aerobic and anaerobic bacteria in 12 (39%). Of a total of 52 isolates recovered from neck abscesses (1.4 per specimen), 34 were aerobes (0.9 per specimen), and 18 were anaerobes (0.5 per specimen). Of a total of 62 isolates recovered from head abscesses (2.0 per specimen), 20 were aerobes (0.6 per specimen), and 42 were anaerobes (1.4 per specimen). The most frequently recovered organism in neck infection was Staphylococcus aureus (20 isolates), and the most frequently recovered organism in head infection was Bacteroides sp (19 isolates). beta-Lactamase activity was detected in 36 isolates recovered in 21 abscesses (46%). Correlation between the predisposing conditions and the bacteria recovered showed a higher recovery of anaerobes in patients with dental infection or manipulation, tonsillitis, and fetal monitoring. Staphylococcus aureus was associated with trauma. This study demonstrated the importance of anaerobic bacteria in abscesses in the head and neck, especially in infections originating from sites where these organisms are the predominant flora.

Abscess↗
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Comparison of the microbiology of group A and non-group A streptococcal tonsillitis.

We studied the microbial flora of tonsils removed from 20 children who suffered from recurrent group A beta-hemolytic streptococcal (GABHS) tonsillitis and 20 who had tonsillar hypertrophy following recurrent non-GABHS tonsillitis. Similar polymicrobial aerobic and anaerobic flora were recovered from the cores of the tonsils in each group. beta-Lactamase-producing bacteria (BLPB) were recovered more often in the group with GABHS. This difference was due mostly to the lower incidence of beta-lactamase-producing strains of Branhamella catarrhalis and Bacteroides sp in hypertrophic tonsils following non-GABHS tonsillitis. beta-Lactamase-producing Staphylococcus aureus was found with equal frequency in both groups. These findings demonstrate that although BLPB are recovered more often in recurrently inflamed tonsils following GABHS infection, BLPB also can be found in hypertrophic tonsils following non-GABHS tonsillitis.

Bacterial Infections↗
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Treatment of otitis externa in children.

Inflammation of the external auditory canal can be localised or diffuse, and acute or chronic. Predisposing conditions include external trauma, loss of the canal's protective coating, maceration of the skin from water or humidity, and glandular obstruction. Acute otitis externa is generally caused by Pseudomonas aeruginosa or Staphylococcus aureus. Management of patients with otitis externa includes debridement, topical therapy with acidifying and antimicrobial agents, and systemic antimicrobial therapy when indicated. The management of patients with chronic otitis externa includes cleansing and debridement accompanied by topical acidifying and drying agents. This is followed by topical antibiotics and corticosteroid preparations. Surgery is mainly used to allow cleansing and aeration and/or removal of the scarred tissue. Patients with acute localised otitis externa (furunculosis) are treated with local heat and systemic antibiotics in the inflammatory stage, and drainage in the abscess state. Mycotic external otitis is managed with topical acidifying and antifungal agents, while viral (herpes) infection is treated with topical and systemic aciclovir (acyclovir). Patients with necrotising (malignant) external otitis, which is mainly caused by P. aeruginosa and S. aureus, are treated with systemic antibiotics and, rarely, by surgical debridement. Therapy for eczematous otitis externa is first directed at the secondary infection, and thereafter at the primary dermatological condition. Prevention of recurrent external otitis is aimed at minimising ear canal trauma and the avoidance of exposure to water. Preventative use of topical acidifying agents or 70% alcohol is also advocated.

Child↗
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Microbiological studies of the bacterial flora of the external auditory canal in children.

The aerobic and anaerobic bacterial flora of the external auditory canal (EAC) was studied in 72 children. Aerobes only were isolated in 58 patients (80%) and anaerobic bacteria only in 2 (3%). Mixed aerobic and anaerobic isolates were recovered in 12 cases (17%). There were 122 aerobic and 15 anaerobic isolates accounting for 1.7 aerobes and 0.2 anaerobes per specimen. The most common aerobic isolates were Staphylococcus epidermidis (56 isolates), alpha hemolytic streptococcus (13) and Pseudomonas aeruginosa (8). The two anaerobic organisms recovered were Proprionibacterium acnes (13 isolates) and Peptococcus sp. (2). These findings demonstrate the polymicrobial bacterial flora of EAC in children where aerobic facultative and anaerobic bacteria are part of the normal flora.

Bacteria↗
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Quantitative measurement of beta lactamase in tonsils of children with recurrent tonsillitis.

Tonsils were obtained from 50 children suffering from recurrent tonsillitis. The tonsils' core material was cultured for aerobic and anaerobic microorganisms. Beta lactamase production was assayed in all isolates and beta lactamase activity was measured in the contents of each tonsil. Mixed aerobic and anaerobic flora was obtained in all patients, yielding an average of 7.9 isolates (4.4 anaerobes and 3.5 aerobes) per specimen. Beta lactamase production was noted in 58 isolates recovered from 39 tonsils (78%). These were all 21 isolates of S. aureus and 10 B. fragilis, 18 of 45 B. melaninogenicus (40%), 7 of 14 B. oralis (50%), and 2 of 13 H. influenzae type B (15%). Beta lactamase activity was detected in 33 of the 39 (85%) tonsils which harbored beta lactamase-producing bacteria, and in none of the 11 tonsils which had no beta lactamase-producing bacteria. Our findings indicate the polymicrobial nature of deep tonsillar flora in children with recurrent tonsillitis, and demonstrate the presence of detectable beta lactamase activity in the tonsillar tissue in most of the tonsils which harbored beta lactamase-producing organism.

Bacteroides↗
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Effect of silver nitrate application on the conjunctival flora of the newborn: and the occurrence of clostridial conjunctivitis.

Newborn conjunctival cultures were obtained from 35 babies prior to silver nitrate application and 48 hours later. On initial culture, 46 facultative bacteria and 27 anaerobes were recovered; 48 facultative and 18 anaerobes were recovered after 48 hours. Haemophilus vaginalis, Bacteroides species and anaerobic cocci decreased in numbers, whereas S. epidermidis, Micrococcus and Propionibacterium acnes increased during this time interval. Clostridial species were isolated from two cases who developed conjunctivitis, along with Peptostreptococcus in one of the cases. In vitro experiments demonstrated lack of killing of C. perfringens in silver nitrate concentrations of 0.1 percent, even after 24 hours exposure.

Bacteria↗