Determination of the minimum suppressing concentration to metronidazole in representatives of obligate and optional anaerobic microflora of periodontal pockets

BACKGROUND: Due to the long period of use of metronidazole in medical dental practice, today it is relevant to study the sensitivity and the minimum inhibitory concentration of reference and clinical strains of obligate anaerobic microbiota to metronidazole in periodontitis. AIM: Determination of sensitivity and minimum suppressive concentration of reference and clinical strains of obligate anaerobic microbiota to metronidazole in periodontitis. MATERIALS AND METHODS: Strains of obligate anaerobic microbiota of periodontal pockets with moderate periodonitis were isolated from 30 patients. The study was carried out by the cassette micromethod, which is a modification of the method for determining the sensitivity by serial dilution in a dense agar medium. RESULTS: As a result of the study, it was found that many of the microbes found in periodontal pockets have a relatively low sensitivity to metronidazole (MIC from 4 to 12 g / ml). This circumstance is obviously due to the fact that this antibacterial chemotherapy drug has been used for a long time in periodontal practice. CONCLUSIONS: In this regard, in order to increase the effectiveness of local antibacterial therapy, this chemotherapy drug must be combined with antiseptics that have a pronounced antibacterial effect against periodontal pathogenic microflora, for example, Metrogyl Dent gel, containing, along with metronidazole, the antiseptic chlorhexidine, as well as the use of physical hardware methods of exposure to create significant the concentration of the antibacterial drug in the mucous membrane and in the contents of periodontal pockets, which can be done using phonophoresis.

Is tactical algorithmization possible for infectious lesions of the spine? Literature review

Non-specific infectious lesions of the spine present a severe clinical problem due to the high risk of the septic complications and possible mortality. The late diagnosis and subjective treatment options could lead to complicated course of disease, progression of vertebral destruction, development of neurological disorders, as well as multi-resistance of bacteria due to the empiric antibacterial chemotherapy. The modern algorithms of diagnosis and treatment should be aimed at improving the quality of care for patients with infectious spondylitis. A literature review on the current concept of their assessment, including a step-by-step description of the Vertebral Osteomyelitis Guideline Team (VOGT) strategy, and the classifications of Pola (NCPS) and Homagk (SSC) is presented.

In Vitro Inhibition of Staphylococcus aureus subsp. aureus (ATCC® 6538™) by Artemether-Lumefantrine Tablets: A Comparative Study of Three Dosage Strengths

Purpose: Antibiotics are progressively failing in the fight against infections due to S. aureus because the bacterium has an outstanding ability to acquire multi-antibiotic resistance and become resistant to most antibiotics. Multi-drug resistant S. aureus poses a major threat to the foundation upon which standard antibacterial chemotherapy stands, hence the need to consider non-antibiotic solutions to manage invasive bacterial infections. This study investigated the inhibitory activities of three dosage strengths of artemether-lumefantrine tablets against Staphylococcus aureus subsp. aureus (ATCC® 6538™) and determined the minimum concentrations of the tablets that are able to completely inhibit growth of the bacterium in vitro. Methods: The agar dilution and broth macrodilution techniques were used to determine the susceptibility of the Staphylococcus aureus subsp. aureus (ATCC® 6538™) strain to artemether-lumefantrine 20/120mg, 40/240mg and 80/480mg tablets. Results: The most active inhibitor was artemether-lumefantrine 80/480mg tablet with a minimum inhibitory concentration value of 2.5mg/mL while artemether-lumefantrine 20/120mg and 40/240mg tablets exhibited moderate but equal activities against the test strain. Conclusions: The study has revealed that artemether-lumefantrine, an antimalarial drug, also has anti-staphylococcal properties and inhibits S. aureus in vitro. This study presents the first report on the in vitro activity of artemether-lumefantrine tablet against S. aureus and suggests the need to consider it as an alternative in the treatment of staphylococcus infections.

Effect of Photodynamic Antibacterial Chemotherapy Combined with Antibiotics on Gram-Positive and Gram-Negative Bacteria

The well-known and rapidly growing phenomenon of bacterial resistance to antibiotics is caused by uncontrolled, excessive and inappropriate use of antibiotics. One of alternatives to antibiotics is Photodynamic Antibacterial Chemotherapy (PACT). In the present study, the effect of PACT using a photosensitizer Rose Bengal alone and in combination with antibiotics including methicillin and derivatives of sulfanilamide synthesized by us was tested against antibiotic-sensitive and antibiotic-resistant clinical isolates of Gram-positive S. aureus and Gram-negative P. aeruginosa. Antibiotic-sensitive and resistant strains of P. aeruginosa were eradicated by Rose Bengal under illumination and by sulfanilamide but were not inhibited by new sulfanilamide derivatives. No increase in sensitivity of P. aeruginosa cells to sulfanilamide was observed upon a combination of Rose Bengal and sulfanilamide under illumination. All tested S. aureus strains (MSSA and MRSA) were effectively inhibited by PACT. When treated with sub-MIC concentrations of Rose Bengal under illumination, the minimum inhibitory concentrations (MIC) of methicillin decreased significantly for MSSA and MRSA strains. In some cases, antibiotic sensitivity of resistant strains can be restored by combining antibiotics with PACT.

Targeting the Nonmevalonate Pathway inBurkholderia cenocepaciaIncreases Susceptibility to Certain β-Lactam Antibiotics

ABSTRACTThe nonmevalonate pathway is the sole pathway for isoprenoid biosynthesis inBurkholderia cenocepaciaand is possibly a novel target for the development of antibacterial chemotherapy. The goals of the present study were to evaluate the essentiality ofdxr, the second gene of the nonmevalonate pathway, inB. cenocepaciaand to determine whether interfering with the nonmevalonate pathway increases susceptibility toward antibiotics. To this end, a rhamnose-inducible conditionaldxrknockdown mutant ofB. cenocepaciastrain K56-2 (B. cenocepaciaK56-2dxr) was constructed, using a plasmid which enables the delivery of a rhamnose-inducible promoter in the chromosome. Expression ofdxris essential for bacterial growth; the growth defect observed in thedxrmutant could be complemented by expressingdxr in transunder the control of a constitutive promoter, but not by providing 2-C-methyl-d-erythritol-4-phosphate, the reaction product of DXR (1-deoxy-d-xylulose 5-phosphate reductoisomerase).B. cenocepaciaK56-2dxrshowed markedly increased susceptibility to the β-lactam antibiotics aztreonam, ceftazidime, and cefotaxime, while susceptibility to other antibiotics was not (or was much less) affected; this increased susceptibility could also be complemented byin transexpression ofdxr. A similarly increased susceptibility was observed when antibiotics were combined with FR900098, a known DXR inhibitor. Our data confirm that the nonmevalonate pathway is essential inB. cenocepaciaand suggest that combining potent DXR inhibitors with selected β-lactam antibiotics is a useful strategy to combatB. cenocepaciainfections.

Antimicrobial Chemotherapy has a Linear Relationship to the Proportion of Gram-Negative Isolates from Pediatric Burn Wounds

Wound infection in burns is a relevant cause of morbidity and mortality in children. We aimed to determine the relationship between antibacterial chemotherapy and Gram-negative burn wound colonization and infection. All children admitted to the pediatric intensive care unit for burn trauma from June 1, 2005 to January 31, 2013 were included. We obtained 141 wound samples, of which 88 (65.7%) showed growth of Gram-positive bacteria. Treatment with antimicrobial chemotherapy was necessary in 23 (31.1%) patients. The proportion of Gram-negative isolates seems to increase linear from 12.5% (95% confidence interval (CI): 4.4%–28.7%) without antibacterial chemotherapy to 36.8% (95% CI: 25.5%–49.6%) with one to 48.9% (95% CI: 35.3%–62.8%) with 2 antimicrobial agents. The Odds ratio for a Gram-negative isolate, in comparison to patients without antibacterial chemotherapy, increased from 4.083 (95% CI: 1.140–15.961) for one administered substance to 6.708 (95% CI: 1.832–26.786) if 2 or more were used. Conclusion We found that antibacterial chemotherapy seems to facilitate burn wound colonization and results in an increased number of gram-negative isolates from children with burn wounds.