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.(AU)

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.(AU)

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.(AU)

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.(AU)

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.(AU)

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.(AU)

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.