A split-mouth study on microbiological profile in clinical healthy teeth and implants related to key inflammatory mediators.

This split-mouth study investigated the correlation of the qualitative and quantitative bacterial composition in dental plaque around clinically healthy periodontal and peri-implant subgingival sites with the levels of selected pro- and anti-inflammatory cytokines and the inflammatory infiltrate in the soft tissue surrounding a healthy dental implant and natural tooth in the same patient. Nine patients, all in good health and non-smokers, were studied. All of the patients were highly motivated in terms of oral hygiene and had healthy natural teeth and at least one healthy implant. After three sessions of professional oral care, clinical parameters were recorded. A sample of subgingival plaque was harvested with a sterile curette from the buccal side of the selected implants and teeth. The plaque samples were cultured to quantify the total microbiota and the number of obligate and facultative bacterial strains. Simultaneously, from the lingual/palatal aspect of the same implants and teeth the keratinized periodontal and peri-implant soft tissues were biopsied for cytokine expression and histomorphometric analysis. The tissue biopsies were halved: the real-time reverse transcriptase-polymerase chain reaction (PCR) was performed to detect active TNF-alpha, IL-1beta, IL-8, and TGF-beta2 and distribution, composition, quantification of inflammation were assessed in parallel. The patients harbored no periodontopathogens and the microbiological composition of the plaque taken from implant sites did not differ from that harvested from teeth. No significant differences were seen between implants and teeth for both proand anti-inflammatory cytokines. Even the histological examination showed no significant epithelial changes, although slight perivascular lymphocytic infiltration was seen in some biopsies.

The erythromycin-resistance in S. pyogenes does not limit the human polymorphonuclear cell antimicrobial activity.

In order to highlight the potential erythromycin immunomodulatory properties related to different antibiotic resistance patterns in Streptococcus spp., we evaluated the influence of the macrolide on the PMNs primary functions against erythromycin-susceptible (Ery-S) and erythromycin-resistant (Ery-R) S. pyogenes strains. A total of 438 S. pyogenes were isolated over the period 2005-2007. On the basis of the triple disk testing, 345 out of 438 S. pyogenes isolates were Ery-S and 93 were Ery-R; among the resistant strains, 65 displayed the cMLSB phenotype, 23 had the M phenotype and 5 had iMLSB phenotype. Concerning antibacterial activity of PMNs, our results showed that erythromycin did not modify bacterial uptake, but significantly increased the phagocyte intracellular killing, compared with controls, for both Ery-S and Ery-R strains. Consequently, this report underlines that in immunocompetent hosts the dichotomy between the in vitro resistance and clinical trial data for antimicrobial agents should be thoroughly re-evaluated.

Improved phagocyte response by co-amoxiclav in renal transplant recipients.

BACKGROUND: Infectious diseases are a major source of morbidity and mortality for immunosuppressed transplant recipients and the antimicrobial chemotherapy can be often less effective in these individuals, because the contribution of underlying host defenses is absent. METHODS: The influence of co-amoxiclav on the functions of polymorphonuclear granulocytes (PMNs) from renal transplant recipients were investigated. RESULTS: PMNs from renal transplant recipients showed a diminished phagocytic activity with reduced phagocytosis and bactericidal activity against intracellular Klebsiella pneumoniae, compared to that seen with PMNs from healthy subjects. Co-amoxiclav significantly elicited the functions of PMNs from uremic patients, resulting in an increased percentage of ingested klebsiellae and in a higher bactericidal effect (98-99%), compared with the drug-free control system. When PMNs were collected from renal transplant recipients treated with co-amoxiclav a significant high increase in both phagocytosis and killing activity were detected, showing the co-amoxiclav capability of "restoring" even in vivo the depressed primary functions of PMNs. CONCLUSIONS: The interesting beneficial properties of co-amoxiclav, which result in restoring the phagocyte-dependent response in renal transplant patients both in vitro and in vivo, may make this drug more suitable for the treatment of infections in patients with defects of phagocyte functions.

Impact of co-amoxiclav on polymorphonuclear granulocytes from chronic hemodialysis patients.

Phagocyte-dependent host defenses are frequently impaired in maintenance hemodialysis patients who show an increased susceptibility to infections. In these individuals, the course of infections can be more aggressive than in normal hosts, and the antibiotic of choice should have a high antimicrobial effect without impairing host defenses. Hence, in uremic patients, the antibiotic enhancement of phagocyte functions may be of potential clinical importance in the outcome of bacterial infections. Because we demonstrated previously that co-amoxiclav had beneficial properties that result in enhancement of the microbicidal functions of human polymorphonuclear cells (PMNs) from healthy subjects, we investigated the influence of this combination on the activities of PMNs from chronic hemodialysis patients against Klebsiella pneumoniae, a human pathogen that can pose severe problems in patients whose immunity is impaired. PMNs from chronic dialysis patients showed a diminished in vitro phagocytic efficiency with a reduced phagocytosis and bactericidal activity towards intracellular K. pneumoniae compared with that seen in PMNs from healthy subjects. When co-amoxiclav was added to PMNs from chronic hemodialysis patients, it was able to restore the depressed primary functions of PMNs, resulting in a significant high increase in both phagocytosis or killing activity. A similar pattern was detected with PMNs collected from hemodialysis patients treated with co-amoxiclav. The results of the present study provide evidence that co-amoxiclav is able to induce stimulation of depressed phagocytic response of PMNs from patients on chronic hemodialysis, restoring their primary functions both in vitro and in vivo.

Clarithromycin mediated the expression of polymorphonuclear granulocyte response against streptococcus pneumoniae strains with different patterns of susceptibility and resistance to penicillin and clarithromycin.

There is an urgent need for antibiotics that can be used in the therapy of infections caused by penicillin-resistant Streptococcus pneumoniae, the incidence of which is often associated with considerable morbidity and mortality. Antibiotics that can interact positively with the immune response and that also possess microbicidal properties might significantly contribute to improving the outcome of S. pneumoniae infections. Therefore, in the present study we investigated the effect of clarithromycin, an extended spectrum macrolide currently used in the treatment of respiratory tract infections, on the in vitro interaction between human polymorphonuclear granulocytes (PMN) and three strains of S. pneumoniae with different susceptibility or resistance patterns to both penicillin and clarithromycin. At a concentration of one-half the minimal inhibitory concentration (MIC), clarithromycin significantly enhanced human PMN functions, particularly intracellular bactericidal activity, against all the S. pneumoniae strains, including resistant ones. This finding may help to explain clarithromycin activity in vivo despite apparent resistance in vitro. Preexposure of PMNs to one-half the MIC of clarithromycin had no effect on either phagocytosis or intracellular killing, ruling out a direct antibiotic action on PMNs. Preexposure of streptococci to clarithromycin increased the susceptibility of S. pneumoniae to the bactericidal mechanisms of human PMNs compared with untreated bacteria, indicating that this macrolide may partly reduce bacterial virulence via changes in S. pneumoniae.

In vitro compared activity of telithromycin and azithromycin against northwest Italian isolates of Streptococcus pyogenes and Streptococcus pneumoniae with different erythromycin susceptibility.

AIMS: This study compared the in vitro activity of telithromycin with that of azithromycin against 438 Streptococcus pyogenes and 198 Streptococcus pneumoniae, isolated over the period 2005-2007 from specimens of different human origin obtained in three Piemonte Region's hospitals. METHODS AND RESULTS: The determination of antimicrobial activity was evaluated by the microdilution broth method and the erythromycin-resistant (Ery-R) phenotypes by the triple-disc test. Exactly 78.8% of S. pyogenes and 69.2% of S. pneumoniae were erythromycin-susceptible (Ery-S). Concerning S. pyogenes, telithromycin was active against M and inducible MLS(B), subtype-C, phenotypes but not against constitutive MLS(B) strains. Telithromycin acted well against all S. pneumoniae, irrespective of their mechanism of macrolide-resistance. On the contrary, the Ery-R isolates, both S. pyogenes and S. pneumoniae, were resistant to azithromycin. CONCLUSIONS: Our results indicate that macrolide resistance in streptococci still persist in northwest Italy (21.2% of S. pyogenes and 308% of S. pneumoniae) and that telithromycin is confirmed as being extremely active even against recent clinical Ery-R streptococcal isolates. SIGNIFICANCE AND IMPACT OF THE STUDY: The present study emphasizes that an active surveillance of the phenotype distribution and antibacterial resistance in streptococci is essential in guiding the effective use of empirical treatment option for streptococcal infections, also at regional level.