In vitro comparison of the antimicrobial effect of calcium hydroxide mixed with different vehicles on infected root canals

The main purpose of root canal treatment is to eliminate microorganisms and their by-products. The use of antimicrobial agents besides mechanical preparation ins necessary to achieve this goal. On the other hand, calcium hydroxide is ineffective in Killing some resistant microorganisms. The aim of this in vitro study was to compare the effectiveness of calcium hydroxide mixed with different vehicles [Distilled water, Sodium hypochlorite or Chlorhexidine] in disinfecting the root canal and dentin of the infected teeth. After root canal preparation of 130 single rooted teeth, they were sterilized and randomly divided into three experimental [n=40 in each grou] and two control groups. Then, the specimens were experimentally infected with E. faecalis and C. albicans during a period of 21 days. The infected specimens were exposed to the pastes of calcium hydroxide mixed with distilled water solution, CHX or NaOCl. Antimicrobial assessment was performed at 24h, 48h, 1 week and 2 week [n=10 in each time interval]. Microbial samples were obtained from the root canals before and after the experiment. Also, the dentin samples were obtained for evaluating dentin disinfection. The data were analyzed, using Two-way ANOVA test. This study showed that there was no significant difference between the three intracanal medicaments and also between the four periods of time [p>0.05]. However, the mixture of calcium hydroxide/distilled water did not completely eradicate E. faecalis from dentinal tubules at any period of time. According to the results of this study, calcium hydroxide mixed with CHX or NaOCl is better than calcium hydroxide mixed with distilled water for dentin disinfection in cases of persistent intracanal infection

Prevalence of anaerobic and aerobic bacteria in early onset neonatal sepsis

To determine prospectively the prevalence of anaerobic and aerobic infection in early onset [during 72 hours of age] neonatal sepsis, in Tehran Vali-e-Asr Hospital. Among all the live birth, neonates suspecting of having septicemia were investigated for isolation of microorganisms. Culture bottle containing enriched tryptic soy broth was used for standard blood culture system to detect aerobes and an ANAEROBIC/F bottle was inoculated using BACTEC 9120 continuous monitoring blood culture system to determine the growth of anaerobic bacteria. Among 1724 live births, 402 consecutive neonates suspecting of having septicemia were investigated for isolation of micro organism. A total of 27 episodes of early onset neonatal sepsis occurred with an incidence of 15.66 [11.6 aerobe + 4.0 anaerobe] per 1000 live births. Aerobic bacteria were the major etiological agents, accounting for 20 cases. 7 [26%] cases had positive blood cultures with anaerobic bacteria. Propionibacterium and Peptostreptococccus [amongst anaerobic] and coagulase-negative staphylococci and staphylococcus aureus [amongst aerobic] were the most commonly isolated organisms. Comparison of clinical findings and demographic characteristics between aerobic and anaerobic infection did not have a significant statistical difference. Our impression is that while anaerobic bacteremia in the newborn infants can occasionally cause severe morbidity and mortality, majority of cases experience a self limited illness with transient bacteremia

Determination of antimicrobial resistance pattern of staphylococcus aureus isolated from clinical specimens

Staphylococcus aureus is an important cause of nosocomial and community-acquired infections. The emergence of antibiotic resistance, especially in methicillin-resistant SA [MRSA] strains, has caused difficulties in treatment of such infections. The determination of antibiotic resistance patterns, particularly domestic patterns of Iran, is essential for appropriate treatment of MRSA infections and proper infection control measures in our country. The antibiotic resistance of 338 SA isolates from various clinical specimens was determined by disk agar diffusion [DAD], minimum inhibitory concentration [MIC] and polymerase chain reaction [PCR] methods. Using the DAD method, 47% [160/338] of the SA isolates were resistant to oxacillin, and only 6% [20/338] were resistant to vancomycin. By PCR, 48% [162/338] of the isolates had the mecA gene. The MIC of oxacillin in 93% of isolates was higher than 256 micro g/mL. The MRSA isolates, showed a high resistant to gentamicin [40.5%], erythromycin [40%], and ciprofloxacin [38%]. However, only a few of the SA isolates showed a high resistance to vancomycin [5%] or erythromycin [3.5%]. The results of this study can provide guidance for physicians toward a more appropriate treatment of SA infections in Iran, thereby preventing the emergence of further antibiotic resistance among SA. Our results also revealed the need for further investigations using a higher number of specimens representing a wider variety of locations to determine the antibiotic resistance patterns in our state more precisely