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PubMed1999

Down-regulation of MARCKS-related protein (MRP) in macrophages infected with Leishmania.

Leishmania, a protozoan parasite of macrophages, has been shown to interfere with host cell signal transduction pathways including protein kinase C (PKC)-dependent signaling. Myristoylated alanine-rich C kinase substrate (MARCKS) and MARCKS-related protein (MRP, MacMARCKS) are PKC substrates in diverse cell types. MARCKS and MRP are thought to regulate the actin network and thereby participate in cellular responses involving cytoskeletal rearrangement. Because MRP is a major PKC substrate in macrophages, we examined its expression in response to infection by Leishmania. Activation of murine macrophages by cytokines increased MRP expression as determined by Western blot analysis. Infection with Leishmania promastigotes at the time of activation or up to 48 h postactivation strongly decreased MRP levels. Leishmania-dependent MRP depletion was confirmed by [3H]myristate labeling and by immunofluorescence microscopy. All species or strains of Leishmania parasites tested, including lipophosphoglycan-deficient Leishmania major L119, decreased MRP levels. MRP depletion was not obtained with other phagocytic stimuli including zymosan, latex beads, or heat-killed Streptococcus mitis, a Gram-positive bacterium. Experiments with [3H]myristate labeled proteins revealed the appearance of lower molecular weight fragments in Leishmania-infected cells suggesting that MRP depletion may be due to proteolytic degradation.

Animals↗

PubMed2000

Acute phlegmonous jejunitis and viridans streptococcal peritonitis associated with bronchial carcinoma.

A 61-y-old man developed acute non-specific phlegmonous jejunitis associated with relatively mild diffuse peritonitis. Bacteriological cultures of the abundant peritoneal fluid resulted in only growth of viridans streptococci (Streptococcus mitis and S. salivarius). Antibiotic treatment had a favourable effect, but a hitherto unknown bronchial cancer led to his death 5 months later. It is assumed that this peculiar case was the result of the immunosuppressive effect related to the malignant neoplasm (opportunistic infection).

Acute Disease↗

PubMed1994

Bacteremia due to viridans streptococcus in neutropenic patients with cancer: clinical spectrum and risk factors.

Between 1988 and 1991, 26 episodes of bacteremia due to viridans streptococci occurred in 25 neutropenic patients undergoing intensive chemotherapy for hematologic malignancies. Complications related to the bacteremia were observed in 10 episodes: unilateral pulmonary infiltrates (4), acute respiratory distress syndrome (ARDS) (4), hypotension (3), and endocarditis (2). All patients with ARDS had received high doses of cytosine arabinoside and had bacteremia due to Streptococcus mitis. Death occurred in three patients (12%) but was possibly related to bacteremia in only one case. Case patients who had received prophylaxis with quinolones were compared with matched control patients who received similar prophylaxis but who did not have bacteremia due to viridans streptococci. Multivariate analysis of predisposing factors showed that high doses of cytosine arabinoside (P = .01), the presence of mucositis (P = .02), and the absence of previous therapy with parenteral antibiotics (P = .01) were independent risk factors for the development of viridans streptococcal bacteremia. Of 259 patients who had received quinolone prophylaxis during the study period, 22 (8.5%) developed an episode of viridans streptococcal bacteremia as compared with three episodes (3.7%) in 82 patients who had received a quinolone and penicillin (P = .07). However, the latter three episodes were caused by strains with decreased susceptibility to penicillin, thus suggesting that resistance to penicillin might limit the use of this antibiotic as a prophylactic agent in the future.

4-Quinolones↗

PubMed2004

Oropharyngeal carriage of macrolide-resistant viridans group streptococci: a prevalence study among healthy adults in Belgium.

OBJECTIVES: Viridans group streptococci (VGS) are gaining significance as reservoirs of resistance determinants for respiratory tract pathogens. Our aim was to investigate healthy adults for oropharyngeal carriage of VGS that are resistant to macrolides, as well as to other common antibiotics. METHODS: Macrolide-resistant VGS were isolated from throat samples of 154 healthy Belgian adults, and phenotyped and genotyped for erm(A), erm(B) and mef(A). In vitro susceptibilities to 10 antimicrobials and the presence of tetracycline resistance genes were also determined. RESULTS: Carriage was detected in 71% of the population screened, from whom 157 unique, macrolide-resistant VGS were isolated. A constitutive (cMLS) phenotype was present in 105 isolates, of which 102 isolates carried either erm(B) or erm(B) + mef(A). The remaining three isolates did not present with any of the genes studied. All 45 isolates showing the M phenotype carried mef(A). The least abundant inducible (iMLS) isolates (n = 7) carried either erm(B) or erm(B) + mef(A). The most abundant macrolide-resistant VGS species was Streptococcus mitis (51%). Co-resistance to tetracycline was identified in 114 isolates, of which tet(M) was present in 105, tet(O) in two and both tet(M) and tet(O) in one, while the remaining six isolates did not present with either gene. tet(M) was also present in four tetracycline susceptible and two intermediately resistant isolates. Fluoroquinolone resistance (ciprofloxacin MIC > or = 4 mg/L) was detected in 16 isolates. Resistance to telithromycin, penicillin and chloramphenicol was appreciably low. CONCLUSIONS: This study highlights a high oropharyngeal carriage of macrolide-resistant VGS and its co-resistance to tetracycline and fluoroquinolones among healthy Belgian adults.

Adolescent↗

PubMed2004

Nosocomial bloodstream infections due to viridans streptococci in haematological and non-haematological patients: species distribution and antimicrobial resistance.

OBJECTIVES: We studied the species distribution and antimicrobial susceptibility of viridans streptococci (VS) isolates causing nosocomial bloodstream infections (BSIs) in Finnish hospitals. PATIENTS AND METHODS: Patients with nosocomial BSIs due to VS were identified through a hospital-wide prospective laboratory-based surveillance in two university and two regional hospitals during September 1998-August 2001. Isolates of VS were sent to the reference laboratory for species confirmation and antimicrobial susceptibility testing. RESULTS: A total of 2038 nosocomial BSIs were identified; 108 (5%) of the BSIs were caused by VS. Of the VS BSIs, 66% were in patients with a haematological malignancy, 14% in patients with a solid tumour and 18% in patients who had undergone surgery preceding the infection. The most common species group identified was Streptococcus mitis (82%). High-level penicillin resistance (> or = 4 mg/L) and cefotaxime resistance (> or = 4mg/L) were present in 5% and 4% of isolates, respectively; both were detected only in haematological patients. However, in non-haematological patients, resistance to erythromycin (17%), and reduced susceptibility to levofloxacin (14%) and penicillin (19%) were common. CONCLUSIONS: The resistance problems in VS are not limited to haematological patients. These findings may have significant clinical implications in the choice of both empirical antibiotic and antimicrobial prophylaxis regimens.

Anti-Infective Agents↗

PubMed2005

Susceptibilities of periodontopathogenic and cariogenic bacteria to antibacterial peptides, {beta}-defensins and LL37, produced by human epithelial cells.

OBJECTIVES: Antimicrobial peptides are one of the factors involved in innate immunity. The susceptibility of periodontopathogenic and cariogenic bacteria to the major antimicrobial peptides produced by epithelia was investigated. METHODS: Synthetic antimicrobial peptides of human beta-defensin-1 (hBD1), hBD2, hBD3 and LL37 (CAP18) were evaluated for their antimicrobial activity against oral bacteria. They included Actinobacillus actinomycetemcomitans (20 strains), Porphyromonas gingivalis (6), Prevotella intermedia (7), Fusobacterium nucleatum (7), Streptococcus mutans (5), Streptococcus sobrinus (5), Streptococcus salivarius (5), Streptococcus sanguis (4), Streptococcus mitis (2) and Lactobacillus casei (1). RESULTS: Although the four peptides had bactericidal activity against all bacteria tested, the degree of antibacterial activity was variable against the different strains and species. The antibacterial activity of hBD1 was lower than that of the other peptides. Among the bacteria tested in this study, F. nucleatum was highly susceptible to hBD3 and LL37, and S. mutans was highly susceptible to hBD3. We measured the Zeta-potential, representing the net charge of whole bacteria, to study the relationship between susceptibility to cationic peptide and the net charge of the bacteria. Although we found some correlation in A. actinomycetemcomitans strains, we did not find a definite correlation with all the bacterial species. CONCLUSIONS: These results indicate that beta-defensins and LL37 have versatile antibacterial activity against oral bacteria.

Amino Acid Sequence↗

PubMed1993

The bacterial etiology of conjunctivitis in early infancy. Eye Prophylaxis Study Group.

The authors conducted this study to determine the etiologic agents of conjunctivitis in early infancy. From 1985 to 1990, 630 infants enrolled in a randomized, controlled, double-masked study of eye prophylaxis were observed for 60 days after delivery for signs of conjunctivitis. The following isolates were categorized as pathogens: Haemophilus influenzae, Streptococcus pneumoniae, Neisseria cinerea, Klebsiella pneumoniae, and Chlamydia trachomatis. Using conditional logistic regression for analysis of 97 infant pairs, the authors identified isolates categorized as pathogens almost exclusively among cases (odds ratio (OR) = 18.0, 95% confidence interval (CI) 2.3-128). Among the microorganisms which have not usually been regarded as pathogens in the etiology of infant conjunctivitis, Streptococcus mitis was the only microorganism associated with an increased risk of conjunctivitis (OR = 5.3, 95% CI 1.8-15.0). The findings concerning the species of bacteria most often associated with conjunctivitis, as well as the finding that method of delivery is unimportant, suggest that bacteria were transmitted to the infants' eyes after birth and not from the birth canal.

Adult↗

PubMed1991

Postsepsis bradycardia in children with leukemia.

OBJECTIVE: We observed sinus bradycardia in a small number of children with hematologic malignancies who were recovering from sepsis. Our objective was to define this symptom complex and attempt to delineate its etiology. DESIGN: Retrospective chart review. SETTING: A pediatric ICU in a children's oncology hospital. PATIENTS: Children admitted to the ICU over a 24-month period who developed persistent bradycardia (heart rate less than 5% for age for greater than 1 hr) after an episode of sepsis. MEASUREMENTS AND MAIN RESULTS: Seven children developed postsepsis bradycardia. Six patients had a primary diagnosis of acute myelogenous leukemia and one patient had acute lymphocytic leukemia. All patients had positive blood cultures (Streptococcus mitis, n = 4; Escherichia coli, n = 2; and Klebsiella pneumoniae, n = 1). All seven children were clinically recovering from sepsis when the bradycardia developed. Neither hypotension nor other symptom was associated with the bradycardia. No therapy was given for the bradycardia. Echocardiograms and ECGs were normal in all patients, except for the presence of bradycardia. Bradycardia persisted for 24 to 72 hrs. After that time, heart rates slowly increased to the normal range for age. CONCLUSIONS: We speculate that this syndrome may result from alterations in beta-adrenergic receptor function or an unidentified humoral factor produced by the invading organism or as part of the host's response to sepsis. Prior drug therapy or the underlying illness may predispose to this condition, since all the patients had acute leukemia. As the bradycardia was clinically insignificant, invasive therapeutic or diagnostic strategies were not indicated.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2005

Viridans streptococci bacteremia in children with malignancy: relevance of species identification and penicillin susceptibility.

Our aim was to determine the significance of species identification and penicillin susceptibility of viridans streptococci in children with malignancies. Streptococcus mitis accounted for 58% of invasive viridans streptococcal infections of which 51% were penicillin-nonsusceptible. There was no significant association between species or penicillin susceptibility pattern and clinical presentation or outcome.

Anti-Bacterial Agents↗

PubMed2006

Identification of oral bacteria associated with crevicular epithelial cells from chronic periodontitis lesions.

Bacterial invasion of host epithelial cells plays an important role in the pathogenesis of periodontal diseases; however, the interactions between subgingival species and the gingival crevice cells are not fully understood. This study determined the prevalence of a group of oral bacterial species on or in epithelial cells derived from periodontal pockets and the gingival crevice of subjects with periodontitis. Samples of epithelial cells were obtained from 120 sites with periodontal pockets > or =4 mm and 92 periodontally healthy sites from 49 patients (mean age 46.3+/-1.4 years; 43% males) with chronic periodontitis. Bacteria in or on epithelial cells were separated from unattached bacteria by Percoll density-gradient centrifugation. The presence and levels of 33 oral species were determined in epithelial cell samples by whole genomic DNA probes and the checkerboard method. The most frequently detected species were Porphyromonas gingivalis (42%), Treponema denticola (38%), Prevotella intermedia (37%), Streptococcus intermedius (36%), Campylobacter rectus (35%), Streptococcus sanguinis (35%) and Streptococcus oralis (34%). Species of Actinomyces were found in low prevalence and levels. The data indicated that there were more micro-organisms on or in epithelial cells obtained from periodontal pockets than from healthy sulci; however, no significant differences regarding the percentage and level of any specific species were found between these sites. Veillonella parvula, S. oralis, Streptococcus gordonii and Streptococcus mitis tended to be more prevalent in sites without disease. These findings demonstrated that a wide range of oral species may be detected on or in crevicular epithelial cells from sites with periodontitis and from periodontally healthy sulci.

Bacteria↗

PubMed2004

Inhibitory effects of cranberry juice on attachment of oral streptococci and biofilm formation.

Cranberry juice is known to inhibit bacterial adhesion. We examined the inhibitory effect of cranberry juice on the adhesion of oral streptococci strains labeled with [3H]-thymidine to saliva-coated hydroxyapatite beads (s-HA). When the bacterial cells were momentarily exposed to cranberry juice, their adherence to s-HA decreased significantly compared with the control (P < 0.01). Their hydrophobicity also decreased dependently with the concentration of cranberry juice. We also evaluated the inhibitory effect of cranberry juice on biofilm formation. By using a microplate system, we found that the high molecular mass constituents of cranberry juice inhibited the biofilm formation of the tested streptococci. The inhibitory activity was related to the reduction of the hydrophobicity. The present findings suggest that cranberry juice component(s) can inhibit colonization by oral streptococci to the tooth surface and can thus slow development of dental plaque.

Adult↗

PubMed1990

Prevention of gram-positive and Candida albicans infections using teicoplanin and fluconazole: a randomized study in neutropenic children.

We have shown that the combination of teicoplanin (T) and ceftriaxone (C) given once daily as first-line empirical antimicrobial therapy is very effective (85%) and safe in febrile neutropenic children (ICAAC, 1988). Like others (ICAAC, 1989) we have stressed the new life-threatening problems with Streptococcus mitis and Strep. sanguis. Considering the regular sensitivity of Gram-positive organisms to T, it is possible that the introduction of the glycopeptide at the onset of aplasia may be helpful. The high incidence of fungal infection or superinfection supports the routine use of an effective antifungal agent when fever is still present or relapse occurs. Our study was designed to assess the prevention of (1) staphylococcal and streptococcal infections using T when the central catheter is being placed, and (2) candida infection by the simultaneous use of a new anti-mycotic agent fluconazole (F) administered once-daily. Patients were randomized into two arms of the study. Arm A received T 6 mg/kg/d and F 3 mg/kg/d starting when the catheter was put in place. If fever occurred, C 50 mg/kg/d and amikacin (A) 15 mg/kg/d were added and T increased to 10 mg/kg/d. If a febrile relapse occurred, amphotericin B was added. In arm B the combination of the three agents T 10 mg/kg/d, C 50 mg/kg/d and A 15 mg/kg/d was started only if there was fever. Amphotericin B was used in febrile relapses. Forty-six patients were eligible (23 in each arm; no statistically significant differences between the two groups). The mean age of the patients was 8 years and mean duration of aplasia 23 and 24 d. Results were as follows: arm A the duration of T + F alone was 10 d, 22 patients had a febrile episode with 1 Gram-positive, 11 Gram-negative and one candida strain isolated in eight patients. C + A were effective in 72% of these patients. There were no deaths. In arm B, fever occurred in all patients during the first 6 d, with eight Gram-positive and six Gram-negative organisms isolated in nine patients. C + T + A were successful in 83% of patients. A bacterial superinfection was documented in four patients, candida superinfection in seven patients and one patient died from Candida parakrusei septicaemia. When the total amount of C and A used in both arms was compared, there was a reduction in 20% of the two agents in arm A, but T was equivalent in both arms. Treatment was well tolerated in both arms.(ABSTRACT TRUNCATED AT 400 WORDS)

Acute Disease↗

PubMed1994

All forms of human IgA antibodies bound to antigen interfere with complement (C3) fixation induced by IgG or by antigen alone.

Polyclonal human secretory IgA1 and IgA2 antibodies to a bacterial protein antigen Streptococcus mutans AgI/II, and polyclonal human serum IgA1 and IgA2 antibodies to staphylococcal alpha-toxin, were found to interfere with antigen-mediated C3b fixation. In fluid phase, immune complexes of antigen and IgA failed to fix C3b, whereas antigen-IgG complexes did fix C3b. Partial removal of glycan chains with Streptococcus mitis SK96 glycosidases diminished the capacity of IgA antibodies to interfere with antigen-mediated C3b fixation by the alternative complement pathway. The authors conclude that native serum or secretory IgA antibodies suppress C3b fixation, and that the glycan chains play a significant role in maintaining this property.

Antibodies, Anti-Idiotypic↗

PubMed1991

Predominant cultivable flora in pericoronitis.

The predominant cultivable flora in pericoronitis was investigated by culturing pus from affected sites in 20 patients. Twenty colonies were picked at random from non-selective plates and identified using conventional biochemical and physiological tests, analysis of metabolic end-products by gas chromatography and protein profile analysis. The most frequently isolated organisms were Prevotella (Bacteroides) intermedia, Peptostreptococcus micros, Veillonella species, Fusobacterium nucleatum and Streptococcus mitis. Porphyromonas (Bacteroides) gingivalis was not isolated and asaccharolytic Eubacterium species were virtually absent. The predominant cultivable microflora in pericoronitis was found to be highly anaerobic in nature and superficially similar to that found in chronic periodontitis, although proposed marker organisms of severe periodontitis were absent.

Adolescent↗

PubMed2004

Alkali-resistant bacteria in root canal systems.

The aim of this study was to isolate and identify alkali-resistant bacteria from the dentin of infected root canals. Bacteria from homogenized dentin powder made up from infected root canal walls from human teeth were cultured on buffer-enriched Brain Heart Infusion agar supplemented with 4% sheep blood (BHI-blood agar), adjusted to pH 7.0, 9.0 or 10.0. Incubation took place for 7 days at 37 degrees C in an anaerobic glove box. Bacterial strains selected according to colony and morphology were subcultured in buffer-enriched BHI broth adjusted to pH 9.0, 10.0 or 11.0 to confirm their growth as alkali-resistant bacteria. Polymerase chain reaction amplification using specific primer sets and 16S rDNA sequence analysis was performed for identification of alkali-resistant isolates. In the present study, 37 teeth extracted from 37 patients were used for preparation of the dentin powder samples. Bacteria were detected in 25 samples when standard BHI-blood agars (pH 7.0) were used. Of these, 29 strains from 15 samples were alkali resistant, 25 strains growing at pH 9.0 and 4 at pH 10.0. The alkali-resistant strains included Enterococcus faecium (10 strains) and Enterococcus faecalis (2 strains), Enterobacter cancerogenus (1 strains), Fusobacterium nucleatum (1 strains), Klebsiella ornithinolytica (2 strains), Lactobacillus rhamnosus (2 strains), Streptococcus anginosus (2 strains), Streptococcus constellatus (3 strains), and Streptococcus mitis (2 strains). Three strains were also identified as bacteria of genus Firmicutes or Staphylococcus at the genus level. The present study showed that many bacterial species in infected root canal dentin were alkali-resistant at pH 9.0 and/or pH 10.0, and belonged mainly to the genus Enterococcus.

Adolescent↗

PubMed2005

Detection of heat shock proteins but not superantigen by isolated oral bacteria from patients with Behcet's disease.

We isolated bacteria from periodontal sites and mixed saliva in eight patients with Behcet's disease and surveyed them to determine whether they produced heat shock proteins (HSPs) and superantigen. Cultivable bacterial compositions from periodontal sites and saliva were examined by anaerobic culture using blood agar plates. Gram-negative anaerobic rods such as Prevotella intermedia, Fusobacterium nucleatum, and Capnocytophaga species were predominant in the isolates from the subgingival plaque samples. The Streptococcus mitis group was the most common type isolated from the saliva samples. To detect the production of HSPs, Western blot analyses were performed using a polyclonal rabbit antibody to Escherichia coli DnaK and a monoclonal antibody to Helicobacter pylori Gro-EL. Sonic extracts of 27 of the strains (79.4%) reacted with the antibody against E. coli DnaK. Nine of these 34 strains (26.5%) were found to produce HSPs that reacted with antibody to H. pylori Gro-EL. A total of 54 isolates were examined for superantigen activity against human peripheral leukocytes. Twenty-five gram-negative clinical strains isolated from chronic periodontitis lesions and 20 ATCC strains of microorganisms were also examined. We could not detect any superantigen activity in 500x diluted supernatant of the strains isolated from the eight patients with Behcet's disease. The present study indicates that the anaerobic strains isolated from the oral cavity of these patients produce HSPs, the production being related to Bechet's disease.

Adult↗

PubMed2005

In-house validation of the BACTEC 9240 blood culture system for detection of bacterial contamination in platelet concentrates.

BACKGROUND: At present, only two commercially available automated culture systems are cleared by the FDA for the purpose of quality control (QC) testing for bacterial contamination of platelet (PLT) concentrates: the BacT/ALERT blood culture system (bioMérieux) and the Pall eBDS (Pall Corporation), both of which allow testing of leukoreduced apheresis as well as whole blood-derived PLTs. After the decision of the AABB to institute universal QC testing of PLT concentrates for evidence of bacterial contamination, in-house validation of the performance of our current blood culture system, the BACTEC 9240, was carried out for this purpose. STUDY DESIGN AND METHODS: Serial dilutions of nine species of bacteria commonly associated with PLT contamination were prepared in one single-donor apheresis PLT unit per organism. Four mL of dilutions containing less than 1 to greater than 10(3) colony-forming units (CFUs) per mL was inoculated into blood culture bottles (Standard 10 Aerobic/F, Becton-Dickinson Diagnostic Systems) and incubated in a BACTEC 9240 continuously monitored blood culture system. Positive bottles were removed from the system and subcultured to insure the identity of bacterial growth. RESULTS: With the exception of Streptococcus mitis, the BACTEC system provided a detection sensitivity of less than 10 CFUs per mL for Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Serratia marcescens, Klebsiella pneumoniae, Bacillus cereus, Enterobacter cloacae, and Pseudomonas aeruginosa. The limit of detection for the S. mitis test strain was 61 CFUs per mL. Detection of positive bottles ranged from 6.5 to 17.6 hours depending on the species tested and the cell density of the inoculum. Ongoing use of this system for bacterial detection yielded two true-positive samples from 3879 apheresis PLT products collected at our hospital-based donor center over 9 months. CONCLUSION: This study validates the use of the BACTEC 9240 continuously monitored blood culture system for the detection of low-level bacterial contamination in single donor apheresis PLTs in less than 24 hours.

Bacterial Infections↗

PubMed2000

Identification and nucleotide sequence of genes involved in the synthesis of lactocin 705, a two-peptide bacteriocin from Lactobacillus casei CRL 705.

The structural gene determinants of lactocin 705, a bacteriocin produced by Lactobacillus casei CRL 705, have been amplified from a plasmid of approximately 35 kb and sequenced. Lactocin 705 is a class IIb bacteriocin, whose activity depends upon the complementation of two peptides (705alpha and 705beta) of 33 amino acid residues each. These peptides are synthesized as precursors with signal sequences of the double-glycine type, which exhibited high identities with the leader peptides of plantaricin S and J from Lactobacillus plantarum, brochocin C from Brochotrix campestris, sakacin P from Lactobacillus sake, and the competence stimulating peptides from Streptococcus gordonii and Streptococcus mitis. However, the two mature bacteriocins 705alpha and 705beta do not show significant similarity to other sequences in the databases.

Amino Acid Sequence↗