Update on the taxonomy and the clinical and laboratory characteristics of pigmented anaerobic gram-negative rods.

Pigmented anaerobic gram-negative rods are currently categorized as 17 species distributed in three genera: Prevotella, Porphyromonas, and Bacteroides. These organisms are often encountered in clinical specimens but are also found as part of the indigenous flora on various mucosal surfaces. Several studies are presently assessing the association of individual species with health and disease. For example, Porphyromonas gingivalis and Porphyromonas endodontalis are key putative pathogens in adult periodontitis and root canal infections, respectively. Porphyromonas asaccharolytica is prevalent in extraoral infections. The Porphyromonas species of animal origin have been isolated from infected bite wounds in humans. Isolates closely resembling Bacteroides levii have been recovered from various types of human infections. According to preliminary reports, Prevotella intermedia tends to be associated more often with periodontal disease than with a healthy oral cavity. In the laboratory, enzyme profiling facilitates the identification of these pigmented rods. Beta-Lactamase production is more common among prevotella species (30%-50%) than among Porphyromonas species (< 10%).

Isolation of Legionella from water samples using various culture methods.

The efficacy of a non-selective medium and two selective media were compared for the isolation of legionellas from water samples. The effect of acid wash treatment for decontamination of the water samples on the isolation frequency of legionellas was also studied. The 236 samples were taken from cooling, humidifying and drinking water systems; 21% were legionella-positive when inoculated directly on modified Wadowsky-Yee (MWY) medium and 26% were positive when concentrated (x 200) before cultivation on MWY or CCVC media. Inoculation on MWY medium after concentration followed by decontamination by the acid-wash technique gave the highest isolation frequency (31%). The lowest frequency (8%) was found with the non-selective BCYE alpha medium. An isolation frequency of 28% was achieved with the BCYE alpha medium after concentration and acid-wash treatment of the samples. Forty per cent of the samples were positive for legionellas when the results from all the culture methods were combined. Not all the legionella-positive samples were identified by a single culture method. Ninety-three of the 95 positive samples were detected with the two best combinations of three culture methods. The best culture method for detecting legionellas depended on the source of the water sample. Some water quality characteristics, like temperature and organic matter content, affected the isolation frequency of Legionella spp.

The efficacy of tinidazole in naturally occurring periodontitis in dogs: bacteriological and clinical results.

The efficacy of tinidazole in addition to a single course of scaling was studied in 14 dogs with periodontitis. Three test teeth, two with periodontitis and one with healthy periodontium, were selected per dog. Subgingival bacterial samples were taken, and clinical examination was carried out at each of four visits (0, 14, 90 and 180 days). The bacterial samples were cultured anaerobically using selective and nonselective media. All teeth in the dentition, except one diseased test tooth with periodontitis were scaled at the first visit and tinidazole or placebo administered twice a day for 7 days. The mean probing depth of the diseased test pockets was significantly more reduced in tinidazole+scaling (T1S1) than scaling alone (T0S1) group at all visits compared to baseline values. The most significant decreases of bacterial counts in T1 or T0 groups were found in agar corroding Gram-negative rods in both diseased and healthy T1S1 pockets and in slimy Gram-negative rods in diseased T1S0 pockets between visits 1 and 2. The intergroup comparisons showed that Gram-positive cocci decreased significantly more in S1 pockets as well as sporeforming Gram-positive rods in diseased S0 pockets of T1 than T0 group. The highest number of isolates was found in the group of pigmented Gram-negative anaerobe rods, mainly Porphyromonas spp. The percentage of Porphyromonas gingivalis-like isolates decreased to zero and Porphyromonas endodontalis-like isolates increased in all test teeth of T1 group at 14 days. It is concluded that tinidazole has good efficacy against P. gingivalis-like bacteria which seem to be periodontal pathogens in dogs.

Current perspectives on anaerobic infections: diagnostic approaches.

This article discusses when to look for anaerobes, anaerobic infections as clues to other problems in patients, and underlying clinical conditions as clues to the nature of anaerobic infections. Diagnostic approaches, identification methods, and susceptibility testing are reviewed.

Peritonsillar abscess. Clinical and microbiologic aspects and treatment regimens.

This prospective study shows that acute peritonsillar abscess can be successfully treated by three-point puncture and aspiration. The results (recurrence in 19%) are comparable with published data on drainage of the peritonsillar space through the incision procedure. By proper selection of patients, the rate of recurrences can be further reduced. Because the occurrence of Streptococcus pyogenes in the aspirate seems to be associated with a favorable prognosis of therapy with puncture and antibiotics only, testing for the presence of this bacterial species might give a useful clue to the type of treatment needed. If the bacterial culture shows mixed aerobic and anaerobic flora, but not S pyogenes, and if the patient has a history of recurrent tonsillitis, incision or proceeding directly to tonsillectomy may be the best therapeutical choice.

Evaluation of the RapID ANA II and API ZYM systems for identification of Actinomyces species from clinical specimens.

Classification and identification of fermentative actinomycetes are labor-intensive and problematic. In this study, we evaluated the applicability and reliability of the RapID ANA II system (Innovative Diagnostic Systems, Inc., Atlanta, Ga.) and the discriminatory value of the API ZYM system (Societes Analytab Products Inc., La Balme Les Grottes, France) in the identification of Actinomyces-like bacteria by using conventional methods as a reference. Eighty-five strains, including 71 isolates from mixed anaerobic infections and 14 reference strains, were tested. The RapID ANA II system correctly identified all Actinomyces odontolyticus strains and 65% of Actinomyces israelii strains. All Arcanobacterium haemolyticum strains were misidentified as Actinomyces pyogenes. The most common isolates in the study were Actinomyces meyeri-like organisms, 84% of which, however, were aerotolerant. The identification of these aerotolerant strains thus remains unresolved and warrants further studies. New characteristics and changes to the conventional API ZYM enzyme profiles are suggested. The API ZYM enzyme profiles of A. odontolyticus and A. israelii were very similar, the only discriminating enzyme being alpha-fucosidase. In differentiation between A. pyogenes and Arcanobacterium haemolyticum, the production of beta-glucuronidase by the former and the production of acid phosphatase by the latter are suggested as new helpful characteristics for use in clinical laboratories. In summary, the RapID ANA II and API ZYM systems can be used as rapid preliminary methods in the identification of Actinomyces species but accurate identification requires supplementary conventional tests and gas-liquid chromatography.

Comparison of the nasal bacterial floras in two groups of healthy subjects and in patients with acute maxillary sinusitis.

The nasal bacterial flora was studied in 183 healthy men entering military service (entry group), 103 healthy recruits in service (service group), and 185 recruits with acute maxillary sinusitis. The 267 nasal and ipsilateral sinus aspirate findings in the same patients with acute maxillary sinusitis were compared pairwise. In the entry group presumed sinus pathogens were only rarely isolated from the nasal cavities: Haemophilus influenzae in 4%, Streptococcus pneumoniae in 1%, Branhamella catarrhalis in 3%, and Streptococcus pyogenes in 0%. The corresponding isolation frequencies in the service group were 19, 13, 3, and less than 1%, respectively, and those in the group with acute maxillary sinusitis were 61, 25, 7, and 6%, respectively. Suppression of the major components of the normal nasal flora, Corynebacterium sp., coagulase-negative staphylococci, Propionibacterium acnes, and Staphylococcus aureus, was seen in the group with acute maxillary sinusitis and also occasionally in the service group. When a sinus aspirate culture yielded a presumed sinus pathogen, the same pathogen was found in the nasal samples in 91% of the cases. The predictive value of a pathogen-positive nasal finding was highest (93.8%) for S. pyogenes, followed by 77.7% for H. influenzae and 68.7% for S. pneumoniae, and lowest (20%) for B. catarrhalis.

Bacteriological findings of acute maxillary sinusitis in young adults.

Bacteriological findings in 339 sinus secretions obtained by puncture were investigated in 238 young adult patients with acute maxillary sinusitis. Aerobic and anaerobic cultures were performed immediately. A total of 76% of the secretions were positive. The most common pathogens isolated were Haemophilus influenzae (50%), Streptococcus pneumoniae (19%), Streptococcus pyogenes (5%), and Branhamella catarrhalis (2%). Coagulase-negative staphylococci and Staphylococcus aureus were isolated in 8 and 1% of the specimens, respectively. The staphylococci were almost invariably present in low numbers and, therefore, probably represented nasal contamination. Other aerobic species were found only occasionally. Anaerobes were isolated in 5% of the secretions. In one-half of these, a low concentration of Propionibacterium acnes was the sole anaerobe that was found, and it was usually mixed with a facultative organism (suggestive of contamination with nasal flora). Only 2% of the sinuses were considered to have true anaerobic infections (high concentrations of several species typical of anaerobic infection), indicating that anaerobes are not a significant cause of acute maxillary sinusitis in a young adult population. The high recovery of H. influenzae in this study indicates that aminopenicillins may be more appropriate choice than conventional penicillin in the antimicrobial therapy of acute maxillary sinusitis (only 2 of 168 H. influenzae strains produced beta-lactamase).

Macroscopic purulence, leukocyte counts, and bacterial morphotypes in relation to culture findings for sinus secretions in acute maxillary sinusitis.

Macroscopic purulence, leukocyte counts, and bacterial morphotypes in Gram-stained smears were investigated in 335 sinus secretions (240 aspirates and 95 injection aspirates) obtained by puncture in 234 young patients with acute maxillary sinusitis. Over 90% of the 147 aspirates macroscopically classified as purulent also contained high numbers of leukocytes (greater than 20 per oil immersion field). A total of 82% of the 147 macroscopically purulent aspirates and 79% of the 156 aspirates containing high numbers of leukocytes yielded presumed sinus pathogens by culture in quantities of greater than 10(3) CFU/ml. Streptococcus pneumoniae or Streptococcus pyogenes was associated relatively more often (92 or 87%, respectively) with high numbers of leukocytes than Haemophilus influenzae, which was not infrequently (29%) recovered from the less purulent aspirates. When a bacterial morphotype was seen in the Gram-stained smear, a corresponding sinus pathogen was isolated in quantities of greater than 10(3) CFU/ml in 92% of aspirates. Other bacterial species (most often staphylococci) were usually isolated in low numbers and were almost never seen in the smear, suggesting nasal contamination. The 95 injection aspirates behaved, to a large extent, like diluted aspirates, with the exception that there was a higher frequency of probable nasal contamination. Macroscopic purulence, high leukocyte counts, and bacterial morphotypes seen in Gram-stained smears each predicted well the isolation of a presumed sinus pathogen and in some cases supported the significance of an otherwise doubtful culture finding. However, the macroscopic appearance of the secretion should not be used to screen samples for culture, because in several cases H. influenzae grew from nonpurulent samples as well.

Problems encountered in clinical anaerobic bacteriology.

Despite the rapid progress made in the technology of anaerobic bacteriology during the last 15 years, substantial variation in the practices and resources of different laboratories still exists. All steps, from the collection of the specimen to final identification, may involve pitfalls. Aspirated pus and tissue samples that are anaerobically transported are always preferable to swabs. Failure to examine gram-stained preparations and wet mounts and to inoculate the specimen promptly onto fresh supplemented media, including selective media, is still common. Generating and maintaining anaerobiosis requires careful monitoring. Plates often are discarded prematurely. The results of final identification with PRAS (prereduced, anaerobically sterilized) biochemicals and gas-liquid chromatography usually arrive too late to guide the clinician to proper therapy. Preliminary tests, along with growth on selective and differential media, are essential for prompt identification of clinically significant anaerobes. Future efforts should be directed toward diminishing the heavy work load of anaerobe laboratories by developing simpler and more rapid procedures.