Presence Of Anaerobes Research Articles

Comparison of pefloxacin with ceftazidime in severe bronchopulmonary infections

In a prospective open randomized multicentre trial pefloxacin (400 mg twice daily, orally) or ceftazidime (2 g twice daily iv) were given to 82 and 88 patients, respectively, with serious bronchopulmonary infection, defined as: infection occurring in high risk patients, or infection that had failed to respond to previous antimicrobials, or infection by a multiresistant pathogen. An additional nitroimidazole was allowed if the culture demonstrated the presence of anaerobes considered pathogenic. Efficacy analysis was possible in 139 patients, 70 in the ceftazidime group, 69 in the pefloxacin group. In the efficacy population, 93 bacterial strains were isolated in the pefloxacin group and 89 in the ceftazidime group. There were more Streptococcus spp. in the ceftazidime group (21) than in the pefloxacin group (14) (P = 0.06). A successful clinical response was observed in 45 patients give pefloxacin (65.2%) and 51 patients given ceftazidime (72.9%). The difference was not statistically significant. There were two relapses with pefloxacin and six with ceftazidime. In the pefloxacin group 86 pathogens (91%) and in the ceftazidime group 78 pathogens (88%) were eradicated. There were 18 and 13 adverse reactions with ceftazidime and pefloxacin, respectively. In this study, pefloxacin was as effective and as safe as ceftazidime in the treatment of severe bronchopulmonary infections.

Some special problems in the determination of viable counts of groundwater microorganisms

Factors affecting viable cell counts in groundwater or sediments were studied with samples from the Segeberg Forest test area in northern Germany. There was very little variation in results with the season (April, August, November) or depth of sampling; generally there were 10(3)-10(4) aerobic cells per ml or g sediment. Long incubation times resulted in higher cell counts; groundwater samples required 4-5 weeks, and sediment extracts had to be cultured for 7 weeks. Total cell counts in sediment were 10(2)-10(4) cell/g higher than viable cell counts of aerobes. This was explained partly by the additional presence of anaerobes and partly by the observation that some morphotypes may not have grown under our conditions. Viable cell counts were not influenced by cell extraction from the sediment with either Na-pyrophosphate or groundwater extracts. However, iron-precipitating or manganese-oxidizing bacteria were better extracted with sterile groundwater. The microflora of wells was more numerous than that of the free aquifer; consequently it was better to pump off all well water before aquifer water was sampled. The diameter of the well was also important; thinner tubes had higher cell counts than those with wider diameter. For sampling, wells should be at least 1 year old, since young wells contain higher numbers of microorganisms due to underground disturbances from the drilling. Turbid water samples could be clarified by filtration, but this reduced the viable counts by 1-2 orders of magnitude. Two different media inoculated with a sample dilution resulted in the same cell counts, but their microbial diversity was different. Storage of groundwater samples before processing resulted in up to 17-fold increases in cell counts and loss of diversity in the first 24 hours. Cell numbers decreased slowly during longer storage.

BSAVA EDUCATION COMMITTEE COMMISSIONED ARTICLE: Anaerobic bacteria: a cause of infection?

ABSTRACTThis review article considers the evidence available for a significant role of obligate anaerobes in infections of small animals.The presence of anaerobes in the normal flora and the meaning of the terms aerobe and anaerobe both in relation to the bacterial metabolism and laboratory culture is discussed.The reported findings of anaerobes in clinical veterinary conditions are reviewed. The particular importance of the non‐sporing (non‐clostridial) anaerobes in traumatic and endogenous infections and the mixed nature, both in terms of different anaerobes and mixed aerobes and anaerobes of such infection are considered.Some experimental evidence for the pathogenicity of obligate anaerobes and their complex role in mixed infections is given.Observations on the use of antibiotics for treatment of suspected anaerobic infections are discussed and the possible implications to laboratory procedures for antibiotic sensitivity testing.

The role of vaginal secretory immunoglobulin A, Gardnerella vaginalis, anaerobes, and Chlamydia trachomatis in postabortal pelvic inflammatory disease.

In a prospective study of 129 women undergoing induced first-trimester abortion, 14 (10.9%) contracted postabortal pelvic inflammatory disease (PID). Samples of vaginal secretion for quantitation of secretory immunoglobulin A (sIgA) as well as isolates from cervix/urethra for the culture of anaerobes and aerobes, including Bacteroides fragilis et melaninogenicus and Gardnerella vaginalis, were obtained at the preoperative visit. Two blood samples from each woman with postabortal PID were analysed for antibodies against G. vaginalis. Twenty-five per cent of women with a history of PID developed postabortal PID, and 25% with vaginitis contracted postabortal infection (p less than 0.001 and p less than 0.005). Twenty-five per cent of women harboring C. trachomatis at the time of abortion developed infection. The presence of anaerobes or G. vaginalis was not associated with the frequency of postabortal PID (all p-values greater than 0.1). One woman with postabortal PID produced a culture positive for G. vaginalis and a rise in specific antibody titer. The levels of vaginal sIgA were not significantly associated with a positive history of PID (p greater than 0.6), with postabortal PID (p greater than 0.4) or with the presence of anaerobes or G. vaginalis at the time of abortion (p greater than 0.3). However, significantly elevated levels of sIgA were found in women harboring C. trachomatis (p less than 0.05). Thus, the study could not demonstrate any correlation between vaginal sIgA and PID, but increased sIgA in Chlamydia-positive women. A history of PID and vaginitis entailed a significant risk of contracting postabortal PID.

Quantitative microbiology of pressure sores in different stages of healing.

The quantitative microbiology of 25 pressure sores in different stages of healing was examined in 25 patients with spinal cord injury. When grossly necrotic tissue was present (stage 1), 5.8 isolates per patient with a density of 6.4 log10/g was recovered, with comparable findings for aerobes and anaerobes. In the absence of necrotic tissue but with the presence of undermining (stage 2), 1.5 aerobic and 0.2 anaerobic isolates were recovered per patient with a mean density of 2.7 and 0.1 log10/g of tissue for aerobic and anaerobic isolates, respectively. The lesions were almost sterile in patients with no necrotic tissue and no undermining (stage 3). Foul smell was always associated with the presence of anaerobes in deep tissue cultures, however, six patients with nonfoul-smelling lesions yielded anaerobes. A 75% quantitative concordance was seen between swab and biopsy culture results. The quantitative concordance between peripheral and central biopsy culture results was 63%, showing variability in results from different sampling areas. No relationship was observed between the density of microorganisms and the eventual outcome of the myocutaneous flap procedure.

Use of gas liquid chromatography in the clinical diagnosis of anaerobic pleuropulmonary infection

Evidence of anaerobic infection was sought in 83 patients with pulmonary disease with anaerobic culture and gas liquid chromatography (GLC) of mucopurulent sputum, or pleural fluid where appropriate. Saliva samples from nine healthy controls and 14 patients with cystic fibrosis were examined by the same methods to assess anaerobic content. Clinically significant anaerobic pleuropulmonary infection was not found in our patients with bronchitis, bronchiectasis and cystic fibrosis and occurred in only some of our patients with empyema and lung abscess. GLC of pleural fluid (empyema) or sputum (lung abscess) was helpful in identifying these cases, when a strongly positive reading was obtained. The gas liquid chromatogram was negative or only weakly positive in those patients where the presence of anaerobes was clinically insignificant, most probably resulting from contamination of the sputum samples by saliva. Results were rapidly available and the need for transtracheal aspiration to obtain specimens of bronchial secretion uncontaminated by mouth flora was avoided. The semiquantitative GLC would therefore appear to be a useful method for investigating specimens from patients with suspected anaerobic pleuropulmonary infection.

Anaerobic bacteria in bone and joint infections.

The etiologic importance of anaerobic microorganisms in bone and joint infections in certain settings has recently been emphasized. These settings include recovery of Actinomyces species, hematogenously acquired infection, the presence of anaerobes in pure culture, and prosthetic-joint infection. Frequently, mixed aerobic-anaerobic bone or joint infection develops as a consequence of infection in adjacent areas. The incidence with which anaerobes are present in these settings is undoubtedly underestimated and may often be unappreciated in regard to the selection of therapeutic agents. Therefore, a practical approach to the treatment of infections involving anaerobes that is based on our current knowledge is necessary. Animal models are now available for study of anaerobic osteomyelitis. In conjunction with prospective human studies utilizing careful microbiologic techniques, it should be possible to determine the significance of anaerobic bacteria when a polymicrobial flora is present in bone and joint infections.

The infected foot of the diabetic patient: quantitative microbiology and analysis of clinical features.

The quantitative deep-tissue microbiology of the infected feet of 32 patients with diabetes mellitus was studied, and the clinical features of the patients were analyzed. Techniques of specimen collection designed to avoid contamination from surface flora were used to study amputated lower limbs. Cultures of deep tissue from six patients yielded only aerobes, and for one patient, only anaerobes. Cultures for 25 patients yielded a mixture of aerobes and anaerobes. A mean of 4.81 species (2.84 aerobes and 1.97 anaerobes) were isolated from each patient. The density of growth of anaerobes, however, was significantly higher than that of aerobes. Culture specimens obtained by curettage of the base of the ulcer correlated better with results of deep-tissue culture than did those obtained by needle aspiration or swab of the ulcers. The most frequently isolated organisms were Bacteroides species, anaerobic streptococci, group D streptococci, Clostridium species, and Proteus species. The presence of anaerobes was associated with a higher frequency of fever and foul-smelling lesions and with the presence of a foot ulcer. Prior antibiotic therapy did not appear to influence the nature of the microorganisms isolated. The polymicrobial nature of this disease should be considered when antimicrobial therapy is indicated.

Isolation and identification of anaerobic organisms from the male and female urogenital tracts.

Since Bacteroides spp may play an important role together with Gardnerella vaginalis in the pathogenesis of non-specific vaginitis and balanoposthitis, anaerobic organisms were isolated and identified from 34 female and 20 male patients attending a department of genitourinary medicine, and the results compared with the clinical findings and the presence of other routinely isolated pathogens. Twenty-three different organisms were recovered from 13 of the 20 men; of these organisms, 20 were of the Bacteroides spp. Most isolates were of the B melaninogenicus/oralis group, which forms part of the commensal vaginal flora in women. A definite association between the presence of anaerobes and other pathogens needs to be firmly established, as this obviously causes important complications in treating these conditions.

Can direct gas-liquid chromatography of clinical samples detect specific organisms?

A total of 1929 samples was analyzed by direct gas-liquid chromatography and the volatile fatty acid (VFA) patterns of the positive samples were compared with the results of culture. There was no correlation between any bacterial genus or species and the detailed VFA patterns although the presence of butyric or valeric acids, or both, was generally associated with the presence of anaerobes and that of acetic acid was generally associated with aerobic bacteria; however, the technique could not predict the nature of the subsequent bacterial isolate. There was also poor correlation between the VFA pattern in a given sample and the VFA pattern(s) of anaerobic bacteria subsequently isolated from that sample.

Clinical aspects of anaerobic infection

Summary This paper is a review of clinical aspects of anaerobic infections considered in the light of current anaerobic cultural techniques. Three themes recur from clinical observations, first, that certain conditions predispose to anaerobic suppuration—compromised blood supply, tissue destruction or antecedent infection with aerobic bacteria or viruses. These conditions produce low oxidation-reduction potential (Eh) favourable for growth of anaerobes. Second, that anaerobes are secondary invaders in which the inaugural event is spread of normal flora beyond the confines of mucocutaneous barriers. The third observation is that at the infected site there is, in many anaerobic infections, a complex bacteriological flora. The classical idea of, ‘one organism, one disease’ is no longer tenable in these situations. Clinical clues to the possible presence of anaerobes as a cause of infection include, site of infection (on or close to mucosal surfaces), presence of foul-smelling discharge, severe tissue necrosis, gas in tissues, failure to culture aerobes where sepsis is obvious, and failure of chemotherapy when drugs inactive against anaerobes are used. Anaerobic infections in the head and neck, chest, abdominal cavity, female pelvis and soft tissues are described in detail, relating clinical features, site of- infection and bacterial pathogens—emphasising the role of anaerobes.