Biocompatibilidade e biodegradabilidade de micropartículas de poli-lactato-co-glicolato na ceratite infecciosa em coelhos / Biocompatibility and biodegradability of poly-latic-co-glycolatic microparticles in the infectious keratitis in rabbits

Avaliaram-se a biocompatibilidade e a biodegradabilidade do sistema de liberação controlada de poli-lactato-co-glicolato (PLGA) no tratamento com ciprofloxacina das ceratites por Staphylococcus aureus em coelhos. Foram utilizados 20 coelhos, distribuídos em quatro grupos (G). Os animais dos G1, G3 e G4 foram inoculados com 2,5µL da bactéria - 108UFC, no estroma corneano. Os do G2 não receberam a aplicação do inóculo. O tratamento foi realizado com solução salina básica para os animais do G1, micropartículas de PLGA contendo ciprofloxacina nos animais dos G2 e G4 e colírio de ciprofloxacina naqueles do G3. Suabe e biópsia da superfície ocular foram coletados para cultura. Apenas um animal do G1 apresentou cultura positiva para S. aureus. Exame histológico revelou a presença bacteriana em todos os animais do G1 e em dois animais do G3. Também foi constatada reação inflamatória no local da aplicação do sistema de liberação controlada. O tratamento com micropartículas de PLGA foi eficiente no tratamento de ceratites bacterianas, ao eliminar por completo a presença do S. aureus, mas entretanto não foi completamente biocompatível e biodegradável após cinco dias.

The biocompatibility and biodegradability of the controlled delivery system of Poly-Latic-Co-Glucolatic (PLGA) in the treatment of Staphylococcus aureus keratitis with ciprofloxacin in rabbits were evaluated. Twenty rabbits divided into four groups (G) were used. G1, G3 and G4 animals were inoculated with bacterial 2.5µL (108CFU) in the corneal stroma, and G2 animals did not receive the application of inoculum. The treatment was performed with basic saline solution in G1 rabbits, micro particles of PLGA containing ciprofloxacin in G2 and G4 animals, and ciprofloxacin eye drops in G3 rabbits. Swab and biopsy of the ocular surface were collected for culture. Only one animal in G1 had positive culture for S. aureus in the processed material. Histological examination showed a bacterial presence in all animals in G1 and two animals in G3. Inflammatory reaction was noted at the application site of the controlled release. Data analysis showed that treatment with micro particles of PLGA was effective in treating bacterial keratitis, completely eliminating the presence of S. aureus, but it was not being completely biocompatible and biodegradable after five days.

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA): molecular background, virulence, and relevance for public health

Staphylococcus aureus and coagulase-negative Staphylococcus (CoNS) are frequently found in nosocomial environments as the main pathogen in several infections. In 1961, reports of nosocomial S. aureus resistant to methicillin, the drug of choice against penicillin-resistant strains, required new alternatives and vancomycin started being used to treat infections caused by methicillin-resistant S. aureus (MRSA). Community-acquired methicillin-resistant S. aureus (CA-MRSA) was first reported in 1990 affecting patients without risk factors for infection with MRSA of hospital origin. MRSA of community origin harbor the genes responsible for the synthesis of Panton-Valentine leukocidin (PVL), a toxin associated with skin and soft tissue infections and that carries the staphylococcal cassette chromosome mec (SCCmec) type IV. CA-MRSA emergence has caused great impact on the worldwide medical community since the presence of this pathogen in patients without risk factors represents a high risk to public health.

Liberação intraocular de ofloxacina associada a lente de contato biossintética em ceratite bacteriana experimental em cães / Introcular release of ofloxacin associated with biosynthetic contact lens in experimental bacterial keratitis in dogs

Avaliou-se a concentração de ofloxacina liberada por uma lente de contato de membrana de celulose biossintética, para tratamento de ceratite bacteriana experimental em cães, pela inoculação de Staphylococcus aureus intraestromal. Comparou-se o tratamento com a lente de contato biossintética impregnada com ofloxacina à terapia tópica convencional. Realizou-se avaliação microbiológica e dosagem de ofloxacina no humor aquoso por meio do método de cromatografia líquida de alto rendimento (HPLC). Houve diferença estatística na contagem de colônias bacterianas entre os olhos com ceratite e os demais grupos, no primeiro dia de coleta. O biomaterial, impregnado com ofloxacina, promoveu liberação gradual durante o período de avaliação, aos três e sete dias; no terceiro dia, o grupo tratado com a lente de contato obteve mediana de 3,72μg/mL, enquanto o grupo tratado com colírio resultou em 49,56μg/mL. Apesar do valor inferior, o grupo com lente de contato atingiu a concentração inibitória mínima, sendo eficaz no controle da infecção bacteriana.

The concentration of ofloxacin released by contact lens made of biosynthetic cellulose membrane was evaluated for the treatment of experimental bacterial keratitis in dogs by intrastromal inoculation of Staphylococcus aureus. The biosynthetic contact lens impregnated with ofloxacin was compared with the conventional topical therapy. The microbiological evaluation and the determination of ofloxacin in aqueous humor were evaluated by high performance liquid chromatography (HPLC). There was not statistical difference in the counting of bacterial colonies among the eyes with keratitis and other groups, on the first day of collection. The biomaterial, impregnated with ofloxacin, promoted gradual release during the evaluation period, at three and seven days; on the third day, the group treated with the contact lens obtained a median of 3.72μg/mL, while the group treated with eye drops resulted in 49.56μg/mL. Despite the lower value, the group with contact lens reached the minimum inhibitory concentration, which was effective in controlling the bacterial infection.

Identification and antimicrobial susceptibility of Staphylococcus from home-treated peritoneal dialysis patients

Staphylococcus aureus is the main agent of infections during peritoneal dialysis (PD). The presence of S. aureus in the nasal cavity has been extensively studied and suggested as a risk factor of dialysis-related infections, whereas coagulase-negative Staphylococcus (CNS) species are frequently considered part of the normal human microbiota. The aim of this study was to identify Staphylococcus in the nasal cavity, pericatheter skin and peritoneal effluent from PD patients, as well as to evaluate the antimicrobial activity evolution in vitro. Thirty-two chronic PD patients were observed during 12 months and had nasal and pericatheter skin samples collected for culture. When peritonitis was detected, samples were also collected from the peritoneal effluent for culture. The activity of several antimicrobial drugs (penicillin G, oxacillin, cephalothin, ofloxacin, netilmicin and vancomycin) against different Staphylococcus species was measured by using the agar drug diffusion assay (Kirby-Bauer method). Staphylococcus was separated into S. aureus, S. epidermidis and other CNS species in order to determine the in vitro resistance level. S. epidermidis resistance to oxacillin progressively increased during the study period (p < 0.05). Resistance to ofloxacin was inexpressive, whereas resistance to netilmicin and vancomycin was not detected. Of the oxacillin-resistant species (n = 74), 83 percent were S. epidermidis, 13 percent other CNS and 4 percent S. aureus (p < 0.05). Regarding multi-drug resistant strains (n = 45), 82 percent were S. epidermidis, 13 percent other CNS, and 5 percent S. aureus (p < 0.05). This study shows the relevance of resistance to oxacillin and CNS multi-drug resistance, particularly concerning S. epidermidis, in PD patients.

Impact of malnutrition on immunity and infection

Malnutrition may be a consequence of energy deficit or micronutrient deficiency. It is considered the most relevant risk factor for illness and death, particularly in developing countries. In this review we described the magnitude of this problem, as well as its direct effect on the immune system and how it results in higher susceptibility to infections. A special emphasis was given to experimental models used to investigate the relationship between undernutrition and immunity. Malnutrition is obviously a challenge that must be addressed to health authorities and the scientific community.(AU)

Bacterial biofilms with emphasis on coagulase-negative staphylococci

In addition to their capacity to attach to surfaces, various groups of microorganisms also produce an extracellular polymeric substance known as "slime". This slime forms a thin layer around cells known as biofilm. Thus, biofilm structure comprises bacterial cells and an extracellular polymeric substance. It also presents a defined architecture, providing the microorganisms with an excellent protective environment and favoring the exchange of genetic material between cells as well as intercellular communication. The ability to produce biofilm is observed in a large group of bacteria, including coagulase-negative staphylococci (CNS) which are the predominant microorganisms of normal skin flora and have been implicated as the causative agents of hospital infections. Bacteremia caused by these agents is common in immunodepressed persons, in patients with cancer, in adult and neonatal intensive care units (ICU) and in patients using catheters or other prosthetic devices. The pathogenicity of CNS infections is probably related to the production of slime, which adheres preferentially to plastic and smooth surfaces, forming a biofilm that protects against attacks from the immune system and against antibiotic treatment, a fact hindering the eradication of these infections. The main objective of the present review was to describe basic and genetic aspects of biofilm formation and methods for its detection, with emphasis on biofilm creation by CNS and its relationship with diseases caused by these microorganisms which are becoming increasingly more frequent in the hospital environment.

Risk of peritonitis during peritoneal dialysis in carriers of Staphylococcus aureus and coagulase-negative staphylococci

The presence of Staphylococcus aureus in the nasal cavities and pericatheter skin of peritoneal dialysis patients put them at high risk of developing peritonitis. However, it is not clear whether the presence of coagulase-negative staphylococci (CNS) in the nasal passages and skin of patients is related to subsequent occurrence of peritoneal infection. The aim of the present study was to verify the relationship between endogenous sources of S. aureus and CNS and occurrence of peritonitis in patients undergoing peritoneal dialysis. Thirty-two patients on peritoneal hemodialysis were observed for 18 months. Staphylococcus species present in their nasal passage, pericatheter skin and peritoneal effluent were identified and compared based on drug susceptibility tests and dendrograms, which were drawn to better visualize the similarity among strains from extraperitoneal sites as well as their involvement in the causes of infection. Out of 288 Staphylococcus strains isolated, 155 (53.8 percent) were detected in the nasal cavity, 122 (42.4 percent) on the skin, and 11 (3.8 percent) in the peritoneal effluent of patients who developed peritonitis during the study. The most frequent Staphylococcus species were CNS (78.1 percent), compared with S. aureus (21.9 percent). Among CNS, S. epidermidis was predominant (64.4 percent), followed by S. warneri (15.1 percent), S. haemolyticus (10.7 percent), and other species (9.8 percent). Seven (64 percent) out of 11 cases of peritonitis analyzed presented similar strains. The same strain was isolated from different sites in two (66 percent) out of three S. aureus infection cases. In the six cases of S. epidermidis peritonitis, the species that caused infection was also found in the normal flora. From these, two cases (33 percent) presented highly similar strains and in three cases (50 percent), it was difficult to group strains as to similarity. Patients colonized with multidrug-resistant S. epidermidis...

Study on the susceptibility of Enterococcus faecalis from infectious processes to ciprofloxacin and vancomycin

Enterococcus faecalis is considered a pathogen responsible for hospital infections and, due to its frequent multi-resistant profile, has caused preoccupations among many medical authorities. The objective of this study was to determine the antimicrobial susceptibility of 74 strains isolated from blood cultures and purulent secretions to vancomycin and ciprofloxacin through the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) by using the Microdilution test. The results showed a greater efficacy of vancomycin compared to ciprofloxacin (98.6% of the strains were inhibited by vancomycin at lower concentrations: 0.06 - 1 mg/ml). However, in the MBC analysis 73% of the strains showed a MBC of vancomycin only at high concentrations (equal to or higher than 64 mg/ml). For ciprofloxacin, the strains showed a broad sensitivity with MICs and MBCs distributed along all the MIC classes. Results also revealed a probability that some strains are tolerant to vancomycin, which indicates the need of other tests to confirm this characteristic

Standardization the PCR technique for the detection of delta toxin in Staphylococcus spp

Coagulase-negative staphylococci (CNS), components of the normal flora of neonates, have emerged as important opportunistic pathogens of nosocomial infections that occur in neonatal intensive care units. Some authors have reported the ability of some CNS strains, particularly Staphylococcus epidermidis, to produce a toxin similar to S. aureus delta toxin. This toxin is an exoprotein that has a detergent action on the membranes of various cell types resulting in rapid cell lysis. The objectives of the present study were to standardize the Polymerase Chain Reaction (PCR) technique for the detection of the gene responsible for the production of delta toxin (hld gene) in staphylococcal species isolated from catheters and blood cultures obtained from neonates, and to compare the results to those obtained with the phenotypic synergistic hemolysis method. Detection of delta toxin by the phenotypic and genotypic method yielded similar results for the S. aureus isolates. However, in S. epidermidis, a higher positivity was observed for PCR (97.4 por cento) compared to the synergistic hemolysis method (86.8 por cento). Among CNS, S. epidermidis was the most frequent islate and was a delta toxin producer. Staphylococcus simulans and S. warneri tested positive by the phenotypic method, but their positivity was not confirmed by PCR for the hld gene detection. These results indicate that different genes might be responsible for the production of this toxin in different CNS species, requiring highly specific primers for their detection. PCR was found to be rapid and reliable method for the detection of the hld gene in S. aureus and S. epidermidis

Atividade anti Staphylococcus aureus de extratos de própolis (EP) de Apis mellifera preparados com diferentes concentrações de etanol / Anti Staphylococcus aureus activity of bee propolis extracts prepared with different ethanol concentrations

A própolis é muito utilizada na chamada medicina popular devido as suas propriedades terapêuticas, com destaque para a ação antibacteriana. Estudos mostram que a composição do extrato de própolis (EP) pode influenciar tal propriedade. Assim, a ação antibacteriana da própolis foi verificada em um total de 61 linhagens de Staphylococcus aureus, isoladas de recém-nascidos. Foram preparados onze EP, variando-se a proporção de etanol como agente extrator, desde 0 por cento (extrato aquoso) até etanol 100 por cento. Em todos os EP foram utilizados 25g de própolis bruta em 100 mL de solvente. O teste de sensibilidade foi o da diluição (por cento V/V) dos EP em ágar e obtenção da Concentração Inibitória Mínima (CIM). Foram realizados ensaios controle de ação antibacteriana do etanol. A ação antiestafilocócica foi diretamente proporcional ao etanol contido na solução solvente, atingindo valores não estatisticamente distintos e máximos para as soluções entre 70 e 90 por cento de etanol, sendo os valores de CIM 90 por cento entre 0,4 e 0,6 por cento V-V, com destaque para o EP preparado com etanol 70 por cento, que foi o mais eficiente (CIM 90 por cento = 0,42 por cento V/V). Assim concluiu-se que a ação antiestafilocócica da própolis é influenciada pela composição do extrato e, consequentemente, pela concentração do etanol usado para a sua preparação.