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Effects of different acidulants on growth of 'Streptococcus milleri group' strains isolated from various sites of the human body.

Growth of human clinical isolates of Streptococcus constellatus, Strep. intermedius and Strep. anginosus in HCl-, acetate and lactate acidified media was investigated. Under aerobic conditions, Strep. constellatus and Strep. anginosus were significantly more tolerant to all the acidulants than was Strep. intermedius. Under anaerobic conditions, Strep. anginosus and Strep. intermedius were significantly more tolerant to acetic acid (pH < 4.5) than Strep. constellatus.

Acetates↗

Evaluation of clinical characteristics and bacterial isolates in dogs with bacterial keratitis: 97 cases (1993-2003).

OBJECTIVE: To evaluate clinical characteristics and breeds affected with bacterial keratitis and compare patterns of resistance in bacterial isolates over time in dogs. DESIGN: Retrospective cross-sectional study. ANIMALS: 97 dogs with bacterial keratitis. PROCEDURE: Dogs with bacterial keratitis were identified from teaching hospital medical records at the Universities of Tennessee and Florida during the years 1993 to 2003. Data were collected pertaining to breed, Schirmer tear test results, treatments administered at the time of initial examination, bacterial species isolated, and resistance to selected antimicrobials. RESULTS: 66% of the dogs were brachycephalic, 54% had tear production < 15 mm/min, and 29% were receiving a corticosteroid at the time of initial examination. The most common bacteria isolated were Staphylococcus intermedius (29%), beta-hemolytic Streptococcus spp (17%), and Pseudomonas aeruginosa (21%). Staphylococcus intermedius isolates had limited resistance to certain antimicrobials. More than 80% of beta-hemolytic Streptococcus spp isolates were resistant to neomycin, polymyxin B, and tobramycin. Isolates of P aeruginosa were susceptible to tobramycin and gentamicin and had limited resistance to ciprofloxacin and enrofloxacin. Among bacterial species isolated, there was no evidence of development of antimicrobial resistance over time. CONCLUSIONS AND CLINICAL RELEVANCE: Data suggested that administration of ciprofloxacin or a combination of a first-generation cephalosporin and tobramycin may be used in the treatment of bacterial keratitis while awaiting results of bacterial culture and susceptibility testing. Evidence suggests that current methods of medical management of bacterial keratitis are not associated with increased antimicrobial resistance.

Animals↗

[Viridans streptococci in human infections: identification and susceptibility to antibiotics].

A method for the speciation of viridans streptococci (devoided of group antigens) is described. The major identification criteria are based on the reaction of a series of biochemical tests such as acid production in lactose, inuline, raffinose, mannitol and sorbitol, hydrolysis of arginine, esculin and Na hippurate, and production of polysaccharides in 5% sucrose media. A total of 460 strains were isolated from human specimens and identified as follows: 118 Streptococcus mitis, 102 S. sanguis II, 75 S. Sanguis I, 87 S. milleri (Streptococcus MG-intermedius), 28 S. mutans, 25 S. salivarius, 14 S. morbillorium, 2 S. uberis and 9 unspeciated. Susceptibility to antibiotics was studied for 318 strains: 63% of them were susceptible to all drugs tested; 37% of the strains were resistant to one or several antibiotics as follows: 34% to tetracycline, 8.5% to macrolides and related drugs, 5.3% to streptomycin and/or kanamycin (MIC greater than 2,000 micrograms/ml), 5% to penicillin (MIC = 1-4 micrograms/ml) and 4% to chloramphenicol.

Anti-Bacterial Agents↗

Antibodies in normal and diseased pulps reactive with microorganisms isolated from deep caries.

Immunoglobulin molecules in the supernatant fluids (SF) from pulpal explant cultures have been observed to react with microorganisms implicated in infections of root canals. In this study, the reactivity of immunoglobulin molecules in the SF from normal and irreversible pulpitis pulps to six strains of predominant microorganisms isolated from the immediate layer of carious lesions above the pulps used for explant cultures was investigated using an enzyme-linked immunosorbent assay. Two ATCC strains of Eubacterium were also included in this assay. Specific antibodies to Lactobacillus casei subsp. casei, Lactobacillus casei subsp. rhamnosus, Lactobacillus acidophilus (I), (II), Streptococcus mutans, Bacteroides intermedius, Eubacterium brachy, and Eubacterium alactolyticum in the SF from the normal and irreversible pulpitis tissues were observed with a large variation of antibody levels in both groups. Immunodiffusion assays of the SF revealed that IgG was the major class of immunoglobulin in the normal as well as the irreversible groups. The presence of natural antibodies in the normal pulps suggested a possible protective role of antibodies during the invasive process of caries.

Antibodies, Bacterial↗

[Clinical and bacteriological significance of the Streptococcus milleri group in deep neck abscesses].

Streptococcus constellatus, S. intermedius, and S. anginosus, the three species of the S. milleri group, form part of the normal flora most commonly found in the mouth, throat, gastrointenstinal tract, and genital tract. The S. milleri group has become known as an important pathogen in abscess disease, but little attention has been paid to their role in deep neck abscesses. We have treated 9 patients with deep neck abscesses relating to the S. milleri group since 1991, and regarded this group as an important pathogen also in these abscesses. We studied the frequency of the S. milleri group isolated from deep neck abscesses in our cases and from the literature and discuss clinical significance and bacteriological pathogenesis. Cases numbered 27 treated at our facility since 1991 and 200 cases reported in the Japanese literature since 1990. Of our 9 cases, 4 originated from acute pharyngitis, 3 from peritonsillar abscesses, and 2 from odontogenic infection. Serious complications such as mediastinitis, cervical necrotizing fasciitis, sepsis accompanied by disseminated intravascular coagulation, and spondylitis of the cervical vertebrae were seen in 4 cases. Among organisms isolated, the S. milleri group appeared to be a pathogen contributing to abscess formation and to serious complications. The genus Streptococcus was most frequently isolated both in our 27 cases (66.7%) and the 200 in the literature (45.5%). Among species of the genus Streptococcus, the S. milleri group numbered the highest in our cases at 33.3% but only 8.5% in the literature. Cases in the literature, however, contained many unknown species of Streptococci--31.5% vs. 18.5% in our cases. alpha-streptococcus was frequently reported in the literature among unknown species of Streptococci--36 of 63. Culture-negative cases were also numbered more in the literature than in our case--29.0% vs. 18.5%. Special conditions and procedures are required to suitably isolate and detect the S. milleri group. Since not all facilities use identical techniques in routine bacteriological examination, a considerable number of the S. milleri group could be missed in unknown species of Streptococci or alpha-streptococcus and culture-negative cases. The detailed pathogenesis of the S. milleri group remains to be clarified. Infection by normal flora on mucosa is thought to occur due to an imbalance between organisms and host defense in deep neck abscesses. Some strains of the S. milleri group have been reported to produce many tissue-destroying enzymes such as collagenase and hyaluronidase. The co-existence of the S. milleri group with some anaerobe strains has also been suggested to accelerate inflammation. We discuss the mechanism inducing the massive release of cytokines through T cell response to certain exotoxins produced by S. milleri group, as reported in toxic shock-like syndrome due to the group A beta-streptococcus and in alpha-streptococcal shock syndrome due to viridans streptococci (alpha-streptococci).

Abscess↗

[Susceptibility of bacterial isolates from the equine respiratory tract to trimethoprim, sulfadoxine, sulfadimethoxine and combinations of these compounds].

Using a broth microdilution technique, the in vitro susceptibility of bacterial isolates from the equine respiratory tract to trimethoprim, sulfadoxine, sulfadimethoxine, and combinations of these compounds was determined. The bacterial strains (n = 88) isolated recently from horses with respiratory symptoms belonged to the following species: Streptococcus equi subsp. zooepidemicus (n = 34), Streptococcus equi subsp. equi (n = 22), Staphylococcus aureus (n = 9), Klebsiella pneumoniae (n = 7), Rhodococcus equi (n = 4), Pseudomonas spp. (n = 3) and Escherichia coli (n = 3). In addition, two isolates of Enterobacter spp. and one isolate of Streptococcus equisimilis, Staphylococcus intermedius, Proteus mirabilis and Serratia marcescens were examined. For determination of susceptibility of an organism the following minimal inhibitory concentrations (MIC) were fixed as limiting values: Trimethoprim < or = 0.5 microgram/ml, sulfadoxine < or = 32 micrograms/ml, sulfadimethoxine < or = 32 micrograms/ml, trimethoprim/sulfadoxine < or = 0.5/32 micrograms/ml, trimethoprim/sulfadimethoxine < or = 0.5/32 micrograms/ml. As expected, Rhodococcus-equi-isolates were resistant to the antimicrobials tested. However, most of the clinically more common isolates showed a high degree of susceptibility to the combinations. The fractional inhibitory concentration (FIC) indices indicated synergism of the combination-partners in a wide range. According to these in vitro results, application of trimethoprim/sulfonamide combinations for the initial therapy of equine respiratory tract infections can be recommended.

Animals↗

Growth of Viridans streptococci on human serum alpha1-acid glycoprotein.

Viridans streptococci have emerged as major opportunistic pathogens. We suggest that for these bacteria to proliferate in vivo and cause disease, they must utilize host tissue components. We have therefore examined the ability of all recognized species of viridans streptococci to liberate and utilize the constituent sugars of the glycans of the extensively sialylated human serum alpha1-acid glycoprotein (AGP) as the sole source of carbohydrate to support in vitro growth. Analysis of residual glycans following bacterial growth was performed by high-pH anion exchange chromatography with pulsed amperometric detection and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Only those species which produced sialidase-namely, Streptococcus oralis, S. intermedius, and S. defectivus--grew on AGP. The extent of degradation of glycans was dependent on the particular glycosidases produced by the bacteria. S. defectivus produced only a sialidase which released the terminal N-acetylneuraminic acid residues of the glycans, and the liberated sugar was utilized. S. intermedius also produced beta-galactosidase and beta-N-acetylglucosaminidase, which removed galactose and N-acetylglucosamine from desialylated glycans, all of which again were utilized by the organism. S. oralis produced beta-galactosidase, beta-N-acetylglucosaminidase, and alpha-fucosidase and novel alpha- and beta-mannosidases which were apparent only from the analysis of the residual sugars of AGP. S. oralis cleaved all the sugars from AGP except for 22% of the N-acetylglucosamine. The residual N-acetylglucosamine residues remaining were those linked to the asparagine of the peptide backbone. All the monosaccharides released by S. oralis from AGP, with the exception of fucose, were utilized. Sialidase production may be a key factor for growth of these species of viridans streptococci on glycoproteins in vivo, since they are commonly associated with extra-oral diseases, with S. oralis emerging as an important pathogen.

Acetylglucosaminidase↗

[Clinical significance of the Streptococcus milleri group in peritonsillar abscesses].

Few researchers have microbiologically studied peritonsillar abscesses in detail, and their results have been conflicting. Although Streptococcus pyogenes (Group A beta-streptococcus) is commonly considered an important pathogen in this infection, recent studies have demonstrated the recovery of many other streptococci mainly consisting of alpha-streptococci. Few studies have identified these streptococci at the species level, however. We studied details of bacteriology in 31 cases of peritonsillar abscess treated between 1991 and 2000. The Streptococcus milleri group was most frequently isolated (25.8%), followed by Eikenella corrodens (9.7%), Staphylococcus aureus (6.5%), and S. pyogenes (3.2%). The S. milleri group, consisting of 3 species of Streptococcus constellatus, S. intermedius, and S. anginosus, forms part of the normal flora most commonly found in the mouth, throat, gastrointestinal tract, and genital tract. These species have become known as an important pathogen in abscess disease but little attention has been paid to their role in peritonsillar abscesses. To adequately culture the S. milleri group, incubation in air containing carbon dioxide or in an anaerobic condition is required, and then the differentiation of the 3 species requires the biochemical reactivity tests. Since hemolytic patterns of the S. milleri group vary, we studied the population of alpha-, beta-, and gamma-hemolytic strains among 36 strains of this group. We found 32 (88.8%) to be alpha-hemolytic. Although not all alpha-hemolytic strains belong to the S. milleri group, a considerable number of this group could be missed among alpha-streptococci isolated from the peritonsillar abscess. As antibiotics began being used widely, normal flora such as the S. milleri group may have become an important pathogen in peritonsillar abscesses due to an imbalance between organisms and host defense.

Adolescent↗

Intravenous metronidazole therapy for Bacteroides fragilis meningitis.

A 69-year-old man developed meningitis due to Bacteroides fragilis and Streptococcus MG-intermedius, which progressed during chloramphenicol and nafcillin therapy to the extent that he seemed near death, with frank pus covering the spinal cord at surgery. Treatment with intravenous metronidazole and penicillin G was curative. After multiple trauma, a 20-year-old man developed meningitis due to Escherichia coli and B fragilis. He failed to respond to chloramphenicol alone, but responded to combined treatment with chloramphenicol and metronidazole. The right frontal sinus and epidural space abscesses were drained and a right frontal lobe abscess was excised. Metronidazole may be a uniquely effective agent for treatment of meningitis due to susceptible strains of Bacteroides fragilis.

Adult↗

Analysis of intestinal flora of a patient with congenital absence of the portal vein.

A 14-year-old female patient, admitted for a closer examination of liver tumour (hepatocellular adenoma), was diagnosed as having a congenital absence of the portal vein. The blood ammonia level (approximately 120 micrograms dl-1) in the superior mesenteric vein was markedly low compared to the normal value of 300-350 micrograms dl-1 in the portal vein. The decreased ammonia concentration and urease activity of the patient's faeces were demonstrated. The dominant intestinal flora in the faeces of the patient, before operation, was Bifidobacterium sp., Bifidobacterium breve, Bifidobacterium lonqum, Lactobacillus plantarum, and after the operation Bacteroides vulgatus, Veillonella parvula, Peptococcus magnus Bifidobacterium longum. In contrast, Bifidobacterium bifidum, Bacteroides ureolyticus, Bacteroides ovatus and Bacteroides distasonis, B. ovatus, Bifidobacterium adolescentis were dominant flora in the faeces of two healthy volunteers, respectively. Among microorganisms isolated from the patient, Morganella morganii, Candida sp., Eubacterium aerofacience and Eubacterium rectale were strongly positive in urease activity in vitro; Streptococcus mitior, Staphylococcus intermedius, Micrococcus kristinae, Selenomonas ruminantum, Bacteroides ureolyticus and Lactobacillus casei ss. pseudoplantarum from the healthy volunteers. These results imply the homeostatic regulation system of faecal ammonia concentration by urease-producing microorganisms in the patient.

Adolescent↗

[Clinical relevance of the Streptococcus milleri group in head and neck infections].

Streptococcus constellatus, S. intermedius, and S. anginosus, the 3 species of the S. milleri group, form part of the normal flora commonly found in the mouth, throat, and gastrointestinal and genital tracts. This group has become known as an important pathogen in infections and abscesses, but data on the anatomical distribution of these species is lacking in relation to clinical significance. We obtained 275 strains of the S. milleri group from different departments at our hospital over the last 3 years, including 54 strains from dental surgery, 47 from internal medicine, 44 from otolaryngology (head and neck), 43 from surgery, 32 from gynecology, 17 from urology, 16 from dermatology, 11 from brain surgery, 6 from pediatrics, 3 from orthopedics, and 2 from opthalmology. The 44 strains from head and neck were found in 42 patients,--23 with primary infection and 19 with secondary infection induced by cancer treatments. The primary infection group included 4 deep neck abscesses, 1 peritonsillar abscess, 5 tonsillitis, 4 paranasal sinusitis, 3 congenital aural fistula infections, 2 dental infections, 2 paranasal sinus cysts, 1 supprative parotitis, and 1 postoperative wound infection. The secondary infection group included 7 postoperative wound infections, 3 postoperative pulmonary infections, 3 laryngitis and pharyngitis, 3 terminal pneumonias, and 3 infections of the local recurrence site. The S. milleri group was the only isolated organism in 13 cases (56.5%) of primary infection and in 5 (26.3%) of secondary infection. Among other organisms from the primary infection group, no so-called major pathogens were found. Antimicrobial susceptibility tests of the S. milleri group showed that 50% were resistant to CCL and 33% to CTM. ABPC, CPDX, and CFDN were also found to be less sensitive, although no resistant strains were detected. To adequately culture the S. milleri group, incubation in air containing carbon dioxide or in an anaerobic atmosphere is required, and differentiation of the 3 requires biochemical reactivity tests. Since not all facilities use identical techniques in routine bacteriological examination, a considerable number of the S. milleri group could be missed in unknown species of alpha-,beta-, and gamma-streptococci and culture-negative cases. With antibiotics now being used widely, normal flora such as the S. milleri group may have become an important pathogen in head and neck infections due to an imbalance between organisms and host defense.

Humans↗

[Unusual cause of necrotized subacute pneumopathy].

We report a case of Streptococcus milleri (S. intermedius) pulmonary infection in a 66-year-old woman. The patient was a heavy smoker and had diabetes. The diagnosis was proven by transparietal pulmonary aspiration.

Aged↗

Sialidase activity of the "Streptococcus milleri group" and other viridans group streptococci.

Viridans group streptococci were examined for the production of sialidase (neuraminidase) activity, using the fluorescent substrate 4-methylumbelliferyl-alpha-D-N-acetylneuraminic acid in a simple and rapid (15-min) assay. Sialidase was produced by all strains of Streptococcus oralis and S. intermedius and by a majority of S. mitis strains. S. mutans, S. sobrinus, S. gordonii, S. sanguis, S. vestibularis, S. salivarius, S. anginosus, S. constellatus, "S. parasanguis," and the "tufted fibril group" were uniformly negative. Sialidase production may be a useful characteristic to assist in the identification of viridans group streptococci.

Humans↗

Nitrate-reducing bacteria on rat tongues.

Nitrite-producing bacteria (NPB) were isolated from tongues of laboratory rats. The most commonly found nitrite-producing organism was Staphylococcus sciuri, followed by Staphylococcus intermedius, Pasteurella spp., and finally Streptococcus spp. Both morphometric quantification of bacteria on tongue sections and enumeration of culturable bacteria (CFU) showed an increase in the density of bacteria towards the posterior tongue. Up to 65% of bacteria were located in the deep clefts on the posterior tongue. The proportion of culturable NPB in the total culturable microbial population increased from 6% (10(5) CFU cm-2) on the anterior tongue to 65% (10(7) CFU cm-2) on the posterior tongue. Different species compositions of NPB were found on different tongue sections with S. intermedius populations decreasing and S. sciuri and Pasteurella populations increasing towards the posterior tongue. Nitrite production was sensitive to oxygen, and significant nitrite production was only detected on the posterior tongue where the majority of bacteria are situated in deep clefts in the tongue surface. This study suggests the importance of bacteria in nitrite production, from nitrate, on the tongue. Nitrite produced on the tongue may subsequently form nitric oxide in the acidic environment of the stomach. Because of the antimicrobial properties of nitric oxide, a key role for nitrate-reducing tongue bacteria in host animal defense against food-borne pathogens in proposed.

Animals↗

Antimicrobial and toxic effects of established and potential root canal irrigants.

Three dilutions of the commonly used irrigant sodium hypochlorite (0.5%, 2.5%, and 5.25%) and the potential irrigants Peridex, chlorhexidine gluconate (0.12%), and Therasol were tested. Alcohol and saline served as controls also. The in vitro portion of this study used four different microorganisms (Streptococcus mutans, Peptostreptococcus micros, Prevotella intermedius, and Porphyromonas gingivalis) to determine antimicrobial effect. Presterilized 7-mm diameter Whatman paper disks soaked with the test solution were prepared, and disks were placed onto the previously seeded agar petri dishes. Each dish was incubated aerobically or anaerobically according to the microorganisms used. An in vivo animal model (guinea pig) was used to examine subcutaneous local tissue reactions using the same materials; 0.1 ml of each test solution was injected subcutaneously into predetermined locations on the animal dorsum. Test site histological examination was done 2 h, 2 days, and 2 wk after the injections. The results of this comparative study indicate Peridex (chlorhexidine gluconate) and Therasol may have good potential for endodontic usage.

Animals↗

Cross-reactions between alpha-streptococci and Omniserum, a polyvalent pneumococcal serum, demonstrated by direct immunofluorescence, immunoelectroosmophoresis, and latex agglutination.

In recent years several groups have used serological methods to demonstrate pneumococcal capsular antigens in sputum. In the present study 123 strains of alpha-hemolytic streptococci (including 97 strains from sputum or pharyngeal specimens) were tested for cross-reactions with a polyvalent antipneumococcal serum (Omniserum). Representatives of the following species were included: Streptococcus bovis, S. equinus, S. intermedius, S. lactis, S. milleri, S. mitis, S. mutans, S. sobrinus, S. salivarius, S. sanguis, S. suis, and Aerococcus viridans. Serological reactions were detected by direct immunofluorescence, immunoelectroosmophoresis, and latex agglutination. Fifteen (12%) of the strains gave positive reactions by all three methods. Positive reactions were also observed with another 32 strains (26%) with two of the methods, whereas 37 strains (30%) gave positive reactions by just one technique. Altogether 84 (68%) strains gave positive reactions with one or more of the methods. Latex agglutination gave positive reactions with 26 (21%) strains compared with 57 (46%) in immunofluorescence and 63 (51%) in immunoelectroosmophoresis. Absorption of the antiserum with one alpha-hemolytic strain reduced but did not entirely eliminate the cross-reactions with five tested strains. These findings indicate a potential risk of cross-reactions with polyvalent antipneumococcal serum in tests carried out on sputa or other specimens which may be contaminated with alpha-hemolytic streptococci.

Cross Reactions↗

Empyema thoracis and lung abscess caused by viridans streptococci.

We retrospectively studied the bacteriology and clinical features of empyema thoracis and lung abscess caused by viridans streptococci in 72 patients seen from January 1984 to September 1996. A total of 76 strains of viridans streptococci were isolated, of which the most common isolates were Streptococcus constellatus (21 strains), S. intermedius (17), and S. sanguis (10). Species belonging to the S. milleri group accounted for the majority (68%) of isolates. In 38 (53%) patients these organisms were recognized as the sole pathogens. Of the 72 patients, 53 had empyema, 14 had lung abscesses, and five had both empyema and lung abscess. Forty-six (64%) patients had underlying diseases. Of these, malignancies were the most common (17 patients), followed by diabetes mellitus (12 patients) and central nervous system diseases (10 patients). Of the 48 patients who underwent chest-tube drainage, 27 (56%) received further treatments, including intrapleural streptokinase (18 cases), surgery (9), and both intrapleural streptokinase and surgery (3). Two (14%) of the patients with lung abscess alone underwent surgical treatment. Although all viridans streptococcal isolates were susceptible to penicillin, the patients in the study had a high mortality (21%). Univariate and multivariate analysis of data for patients with empyema alone (n = 53) showed a significantly increased risk of death in those with underlying malignancy (OR = 16.0, p = 0.023) and those with non-S. milleri-group isolates (OR = 3.72, p = 0.030). These data imply a strong clinical significance of viridans streptococci in the pathogenesis of empyema and lung abscess, as well as the need for species identification of viridans streptococci in patients with pleuropulmonary diseases.

Adult↗

Use of modified norleucine-tyrosine broth in identification of Peptostreptococcus anaerobius.

Gas-liquid chromatography was employed to analyze the volatile and nonvolatile acids produced in modified norleucine-tyrosine (MNT) broth by various gram-positive cocci. The MNT broth consists of 0.5% Trypticase (BBL Microbiology Systems, Cockeysville, Md.), 0.5% yeast extract (Difco Laboratories, Detroit, Mich.), 0.2% L-norleucine, and 0.1% L-tyrosine. The microorganisms included reference strains and clinical isolates of Peptostreptococcus spp. (P. anaerobius, P. asaccharolyticus, P. indolicus, P. magnus, and P. prevotii), Staphylococcus spp. (S. aureus, S. epidermidis, and S. saccharolyticus), and Streptococcus spp. (S. agalactiae, S. intermedius, S. mutans, S. sanguis I, and S. sanguis II). Only Peptostreptococcus anaerobius strains produced caproic and valeric acids in MNT broth cultures. All 11 P. anaerobius strains produced valeric acid in MNT broth, and only 1 strain failed to produce caproic acid in the medium. This unique feature aids in rapid, reliable identification of P. anaerobius with a minimum number of tests.

Acids↗