Cely Barreto da Silva

Analysis of the microbial load in instruments used in orthopedic surgeries

BACKGROUND Because of advances in technology, the number of orthopedic surgeries, mainly hip and knee replacement surgeries, has increased, with a total of 150,000 prosthetic surgeries estimated per year in the United States and 400,000 worldwide. METHODS We used an exploratory cross-sectional study, with a quantitative approach to determine the microbial load in instruments used in orthopedic surgeries, quantifying and identifying the microbial growth genus and species, according to the surgical potential of contamination that characterizes the challenge faced by the Material and Sterilization Center at the Institute of Orthopedics and Traumatology of Hospital das Clinicas of the School of Medicine of the University of Sao Paulo, Brazil.The orthopedic surgical instruments were immersed, after their use, in sterilized distilled water, sonicated in an ultrasonic washer, and posteriorly agitated. Subsequently, the wash was filtrated through a 0.45-mum membrane and incubated in aerobic and anaerobic mediums and in medium for fungi and yeasts. RESULTS In clean surgeries, 47% of the instruments were contaminated; in contaminated surgeries, 70%; and, in infected surgeries, 80%. Regardless of the contamination potential of the surgeries, the highest quantitative incidence of microorganism recovery was located in the 1 to 100 colony-forming unit range, and 13 samples presented a microbial growth potential >300 colony-forming units. Regardless of the contamination potential of the surgeries, there was a convergence in the incidence of negative-coagulase Staphylococcus growth (28%, clean surgeries; 32%, contaminated surgeries; and 29%, infected surgeries) and Staphylococcus aureus (28%, contaminated surgeries; and 43%, infected surgeries). CONCLUSION Most of the microorganisms recovered from the analyzed instruments (78%) were vegetative bacteria that presented their death curve at around 80 degrees C, characterizing a low challenge considering the processes of cleaning and sterilization currently employed by the Material and Sterilization Center. Fewer microorganisms were recovered from instruments used in clean surgeries in comparison with those used in contaminated and infected surgeries.

Antibacterial properties of cyanoacrylate tissue adhesive: Does the polymerization reaction play a role?

Purpose: To ascertain if the polymerization reaction also contributes additionally to the antibacterial effects of two commonly used cyanoacrylate tissue adhesives. Materials and Methods: Fresh liquid ethyl-cyanoacrylate (EC) and N-butyl-cyanoacrylate (BC) adhesives were applied onto 6-mm sterile filter paper discs. In the first group, the adhesive-soaked discs were immediately placed onto confluent monolayer cultures of bacteria, allowing the polymerization reaction to proceed while in culture. In the second group, the adhesive-soaked disc was allowed to first polymerize prior to being placed onto the bacterial cultures. Four types of bacteria were studied: Staphylococcus aureus, Streptococcus pneumoniae, Escherichia coli, and Pseudomonas aeruginosa. Immediately after the discs were applied, the cultures were incubated at 35° C for 24 h. Bacterial inhibitory halos were measured in the cultures at the end of the incubation period. Results: For EC, exposure of the bacteria to the cyanoacrylate polymerization reaction increased the bacterial inhibitory halos in Streptococcus pneumonia, Staphylococcus aureus and Escherichia coli. For BC, it increased the bacterial inhibitory halos in Staphylococcus aureus and Streptococcus pneumoniae. No inhibitory halos were observed in Pseudomonas aeruginosa. The bactericidal effect was higher in actively polymerizing EC, compared to previously polymerized EC in Staphylococcus aureus, Streptococcus pneumoniae, and Escherichia coli; however, no such differences were observed for BC. Conclusions: The polymerization reaction may also be an important factor in the antibacterial properties of EC and BC.

Evaluation of the in vitro antimicrobial activity of an ethanol extract of Brazilian classified propolis on strains of Staphylococcus aureus

Staphylococcus aureus (S. aureus) is one of the most frequent causes of hospital acquired infections. With the increase in multiple drug resistant strains, natural products such as propolis are a stratagem for new product discovery. The aims of this study were: to determine the in vitro antimicrobial activity of an ethanol extract of propolis; to define the MIC50 and MIC90 (Minimal Inhibitory Concentration – MIC) against 210 strains of S. aureus; to characterize a crude sample of propolis and the respective ethanol extract as to the presence of predetermined chemical markers. The agar dilution method was used to define the MIC and the high performance liquid chromatography (HPLC) method was used to characterize the samples of propolis. MIC results ranged from 710 to 2,850 µg/mL. The MIC50 and MIC90 for the 210 strains as well as the individual analysis of American Type Culture Collection (ATCC) strains of Methicillin-susceptible Staphylococcus aureus (MSSA) and Methicillin-resistant Staphylococcus aureus (MRSA) were both 1,420 µg/mL. Based on the chromatographic analysis of the crude sample and ethanol extracted propolis, it was concluded that propolis was a mixture of the BRP (SP/MG) and BRP (PR) types. The results obtained confirm an antimicrobial activity in relation to the strains of the S. aureus tested.

Evaluation of the effectiveness of manual and automated dialyzers reprocessing after multiple reuses

A cross-sectional study was conducted to evaluate the effectiveness of manual and automated dialyzer reprocessing. Dialyzers were filled with fluid thioglycollate medium from blood and dialysate chambers after being reprocessed and chemically sterilized with 0.2% peracetic acid. They were incubated for 14 days at 35°C ± 2°C, and microbiologic analysis was performed. Microorganisms were identified in 3 of the 11 samples (27.3%) from the blood chambers: Sphingomonas paucimobilis (2/3) and Penicillium spp (1/3) and in 11 of the 11 samples (100%) from the dialysate chambers: S paucimobilis (7/11), Stenotrophomonas maltophilia (4/11), Pseudomonas aeruginosa (3/11), Candida spp (1/11), and Acinetobacter baumannii (1/11). Of the 4 manually reprocessed dialyzers, gram-positive bacillus were identified in 1 sample (25%) from the blood chamber, and Bacillus spp and Burkholderia spp were identified in 1 sample (25%) from the dialysate chamber. The dialyzers reprocessing can pose risks safety because of exposure patient to microorganisms.

Avaliação da ação antimicrobiana de soluções multiuso para desinfecção de lentes de contato hidrofílicas, in vitro

PURPOSE To evaluate the efficacy of disinfecting solutions in hydrophilic contact lenses (CL). METHODS Two multi-use solutions denominated solution A (0.001% polyquaternium-1 and 0.0005% myristamidopropyl dimethylamine) and solution B (0.0001% polyaminopropyl biguanide) were used. The solutions were tested in hydrophilic contact lenses infected with Pseudomonas aeruginosa (ATCC27583), Staphylococcus epidermidis (ATCC1226), Klebsiella pneumoniae (ATCC13883), Staphylococcus aureus (ATCC25923) and Candida albicans (ATCC 10231) and the decrease in microorganisms growth after the hydrophilic contact lenses were cleaned with the respective solutions was verified. The manufactures instructions were followed. RESULTS A decrease of 90% of Pseudomonas aeruginosa, Staphylococcus epidermidis, Staphylococcus aureus, Candida albicans and a decrease 100% of Klebsiella pneumoniae was observed. CONCLUSION The solutions decreased the amount of microorganisms tested.OBJETIVO: Avaliar a influencia da acao antimicrobiana das solucoes multiuso para desinfeccao de lentes de contato hidrofilicas. METODOS: Duas solucoes multiuso denominadas solucao A (poliquaternario-1 a 0,001% e miristamidopropil dimetilamina a 0,0005%) e solucao B (poliaminopropil biguanida a 0,0001%) foram testadas em lentes de contato hidrofilicas contaminadas com Pseudomonas aeruginosa (ATCC27583), Staphylococcus epidermidis (ATCC1226), Klebsiella pneumoniae (ATCC13883), Staphylococcus aureus (ATCC25923) e Candida albicans (ATCC 10231) para verificar a quantidade de reducao do crescimento dos microrganismos apos o enxague com as solucoes. Foram seguidas as instrucoes preconizadas pelos fabricantes. RESULTADOS: Houve reducao de 90% do crescimento de Pseudomonas aeruginosa, Staphylococcus epidermidis, Staphylococcus aureus e Candida albicans. Nao houve crescimento de Klebsiella pneumoniae. CONCLUSAO: As solucoes testadas neste trabalho mostraram reducao do numero de microrganismos testados.

In vitro antimicrobial analysis of aqueous humor after topical application of moxifloxacin hydrochloride 0.5

Purpose To evaluate the in vitro antimicrobial activity of aqueous humor in patients who had preoperative topical application of moxifloxacin hydrochloride 0.5%. Setting Department of Ophthalmology, Santa Casa de Misericórdia de São Paulo, Brazil. Design Comparative case series. Methods Twenty‐nine eyes from 29 cataract surgery patients were included in this study. In the study group (n = 15 eyes), 3 topical applications of moxifloxacin hydrochloride 0.5% were administered preoperatively; in the control group (n = 14 eyes), no topical applications were administered. Aqueous humor samples were collected and stored in sterile microtubes at −80°C until analysis. Antimicrobial analysis was performed using standard strains with standard sterile filter paper disks. Inhibition halos were measured in millimeters, and both bactericidal and bacteriostatic effects were analyzed. Results Inhibition halos were observed on most of the study group plates except those with Streptococcus pneumoniae: Escherichia coli (13.93 mm ± 0.64 [SD]), Klebsiella pneumoniae (10.63 ± 0.61 mm), Staphylococcus aureus (7.47 ± 0.68 mm), and S epidermidis (4.20 ± 3.33 mm) The differences between the mean inhibition halo diameters were statistically significant (P < .0001) in all samples. No bactericidal effect was observed against any of the microorganisms studied. Conclusions After topical application of moxifloxacin 0.5%, aqueous humor showed bacteriostatic effect against E coli, K pneumoniae, S aureus, and S epidermidis. No bactericidal effect was observed against any of the microorganisms evaluated. No antimicrobial effect against S pneumoniae was observed. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.

Evaluation of silicon oil on bacterial growth

PURPOSE To analyze the antimicrobial properties of silicon oil (Óleo de Silicone®, Ophthalmos, Brazil) on in vitro bacterial growth of different microorganisms related to endophthalmitis. METHODS The following microorganisms were analyzed: (1) Pseudomonas aeruginosa (ATCC 27583); (2) Escherichia coli (ATCC 25922); (3) Staphylococcus aureus (ATCC 25923); (4) Staphylococcus epidermidis (ATCC 12228); (5) Candida albicans (ATCC 10231); (6) Klebsiella pneumoniae (ATCC 13883); and (7) Streptococcus pneumoniae (ATCC 49619). The plates were incubated at 35 ± 2ºC and its growth examined after 24 hours. An empty disk was placed in the center of each plate as a control. RESULTS No inhibition halos were verified in any of the plates containing the four different concentrations of the bacterial inocula. CONCLUSIONS The silicon oil 1000 cps does not have any effect on bacterial growth of any of the studied microorganisms.

Different Application Volumes of Ethyl-Cyanoacrylate Tissue Adhesive Can Change Its Antibacterial Effects against Ocular Pathogens In Vitro

Purpose: To analyze the antibacterial effects in vitro of ethyl-cyanoacrylate (EC) tissue adhesive in different application volumes. Methods: Volumes of 4, 6, 8, 10, 12, 14, 25, and 35 μ l of EC were applied onto the surface of monolayer cultures of Staphylococcus aureus (ATCC25924), Streptococcus pneumoniae (ATCC49619), Escherichia coli (ATCC25922), Pseudomonas aeruginosa (ATCC27853), and Klebsiella pneumoniae (ATCC13883). The diameter of each EC drop was measured, and the area of the circle of EC (formed after its application onto the monolayer culture) was calculated. The area of the antibacterial inhibitory halo surrounding the drop of EC on the monolayer culture was calculated. The ratio between the area of the EC and of the corresponding inhibitory halo was obtained for each EC volume and for each of the 5 types of bacteria studied. Results: EC volume-dependent inhibitory halos were seen in Staphylococcus aureus, Streptococcus pneumoniae, and Escherichia coli, but not in Pseudomonas aeruginosa or Klebsiella pneumoniae. Conclusion: The in vitro antibacterial effect of EC against Staphylococcus aureus, Streptococcus pneumoniae, and Escherichia coli varies in a dose-dependent fashion with its volume. No effect was observed against Pseudomonas aeruginosa and Klebsiella pneumoniae.

Antimicrobial In Vitro Evaluation of Corneal Storage Media using a Closed Chamber Study Model

Purpose: To evaluate in vitro the antimicrobial influence of the corneal storage media containing antibiotics using a closed chamber study model under the closest simulated environment of corneal preservation process. Materials and Methods: Samples of cornea storage media containing streptomycin and gentamicin (Optisol-GS®) were analyzed at different moments after its contamination with Staphylococcus aureus (ATCC25923). Samples were analyzed at 1, 2, 3, 4, 5, 6, 24, 48, 72 hours; 7 days; and 14 days after contamination. The samples were analyzed using a new study model system that consists of two closed coupled chambers. The upper chamber contained two culture media (chocolate agar and Sabouraud agar) and CO2 indicator (indication of bacterial aerobic activity). The inferior chamber contained supplemented solution with an antimicrobial inhibitor. The bacterial growth parameters were analyzed by the presence or absence of bacteria in chocolate agar and by color change of CO2 indicator when positive. First reading was performed after 24 hours, and, in the absence of bacterial growth, a second reading was carried out after 48 hours. Results: Color change in CO2 indicator was found in samples contaminated after 1, 2, and 3 hours on the first reading. On the second reading, we observed color change in all remaining samples, except for samples contaminated after 14 days. Conclusion: Samples of cornea storage media containing gentamicin sulphate and streptomycin sulphate in vitro showed viable Staphylococcus aureus for up to 7 days of contamination.

Avaliação da segurança do processamento de fresas intramedulares flexíveis Para cirurgia ortopédica

Objectives: To assess the efficacy of a standard operational procedure to clean flexible intramedullary bone reamers, as well as the sterilization level, and to show the cytotoxicity of the residual dirtiness of a flexible reamer used in care practice. Methods: Flexible intramedullary bone reamers were weighed before processing, after challenge contamination and after cleaning. They were contaminated with the Soil Test™, Geobacillus stearothermophilus suspension, in the concentration of 106 cfu/ml, and bovine bone flour. After processing, the samples were inoculated into a culture medium and incubated for 21 days. Residual dirtiness of a flexible intramedullary bone reamer used in practice was submitted to in vitro cytotoxicity test. Results: Despite being sterilized, the samples indicate to accumulated dirtiness and the processing was inefficient. Residual dirtiness presented a cytotoxic effect. Conclusion: It is recommended that the flexible design of reamers is discontinued by the lack of safety of reprocessing.