Production of clavulanic acid and cephamycin C by Streptomyces clavuligerus under different fed-batch conditions

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

INFLUENCE of GLYCEROL and ORNITHINE FEEDING on CLAVULANIC ACID PRODUCTION BY Streptomyces clavuligerus

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Clavulanic acid production processes in a tower bioreactor with immobilised cells

The feasibility of using Streptomyces clavuligerus ATCC 27064 bioparticles supported on alginate gel containing alumina to produce clavulanic acid (CA) was investigated. To this end, effectiveness factors for spherical bioparticles, relating respiration rates of immobilised and free cells, were experimentally determined for various dissolved oxygen (DO) levels and bioparticle radii. Monod kinetics was assumed as representative of the oxygen consuming reaction, while internal oxygen diffusion was considered the limiting step. A comparison was made of the results from a tower bioreactor operating under batch, repeated-batch and continuous conditions with immobilised bioparticles. The theoretical curve of the effectiveness factor for the zero-order reaction model, considering an inert nucleus - the dead core model - was very well fitted to the experimental data. The results of the bioprocess indicated that the batch operation was the most efficient and productive, requiring a do concentration in the reactor above 60% of the saturation value. (C) 2007 Elsevier B.V. All rights reserved.

Optimisation of the glycerol-to-ornithine molar ratio in the feed medium for the continuous production of clavulanic acid by Streptomyces clavuligerus

Amino acids are well metabolized by Streptomyces clavuligerus during the production of clavulanic acid using glycerol as main carbon and energy source. However, only a few amino acids such as arginine and ornithine are favorable for CA biosynthesis. The aim of this work was to optimize the glycerol:ornithine molar ratio in the feed medium containing only these compounds to maximize CA production in continuous cultivation. A minimum number of experiments were performed by means of a simple two-level full-factorial central composite design to investigate the combined effect of glycerol and ornithine feeding on the CA concentration during the intermittent and continuous process in shake-flasks. Statistical analysis of the experimental data using the response surface methodology showed that a glycerol-to-ornithine molar ratio of approximately 40:1 in the feed medium resulted in the highest CA concentration when fermentation was stopped. Under these optimized conditions, in bench-scale fermentor runs, the CA concentration reached more than double the concentration obtained in shake-flasks runs. (C) 2009 Elsevier B.V. All rights reserved.

Clavulanic acid production by immobilized cells if Streptomyces clavuligerus

A clavulanic acid production process with immobilized Streptomyces clavuligerus cells was investigated. Cells were immobilized in diatomaceous earth, calcium alginate gel as well as in the form of natural pellets and cultivated in shake flasks in a medium containing glycerol and soytone as the carbon and nitrogen sources, respectively. In all experiments growth occurred in the first 48 h and glycerol consumption after 72 h, while clavulanic acid production was observed between 48 and 60h, with gradual degradation after this period. The natural pellets presented higher product concentration as compared with the cells immobilized in supports. However, calcium alginate was found to be the best support in relation to cell retention capacity.

Influence of free amino acids on clavulanic acid production by Streptomyces clavuligerus in synthetic medium

The effect of nitrogen source on clavulanic acid production was investigated in shake flasks. Media containing asparagine plus one of several different amino acids or a combination of two amino acids was tested. The best result, ca. 180 mg/L clavulanic acid, CA, in 60 h, was obtained with the lysine-tyrosine pair In an aerated and agitated fermentor this medium led to CA concentrations of ca. 210 mg/L, a remarkable production for synthetic medium utilization. Amino acids analysis during cultivation indicated that, while asparagine was consumed rapidly, lysine and tyrosine were metabolized slowly, promoting CA production.

Kinetic studies on clavulanic acid degradation

Clavulanic acid (CA), a potent beta-lactamase inhibitor, is very sensitive to pH and temperature. It is produced by Streptomyces clavuligerus and to optimize both the fermentation step and the downstream process, the expression of the hydrolysis kinetics has to be determined. In the present work the CA degradation rate from various sources was investigated at temperatures of 10, 20, 25, 30 and 40degreesC and PH values of 6.2 and 7.0. The results showed that first-order kinetics explained very well the hydrolysis kinetics and the Arrhenius equation could be applied to establish a relationship between the degradation rate constant and temperature, at both pHs. It has been observed that CA from fermentation medium was much more unstable than that from standard solution and from a commercially available medicine. Also, it was observed that CA was more stable at PH 6.2 than at pH 7.0, irrespective of the CA source. (C) 2004 Elsevier B.V. All rights reserved.

Screening of wild type Streptomyces isolates able to overproduce clavulanic acid

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Dextran sulfate/Triton X two-phase micellar systems as an alternative first purification step for clavulanic acid

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Antibiotic treatment schemes for very severe community-acquired pneumonia in children: a randomized clinical study

Objective. To compare clinical response to initial empiric treatment with oxacillin plus ceftriaxone and amoxicillin plus clavulanic acid in hospitalized children diagnosed with very severe community-acquired pneumonia (CAP).Methods. A prospective randomized clinical study was conducted among children 2 months to 5 years old with a diagnosis of very severe CAP in the pediatric ward of São Paulo State University Hospital in Botucatu, São Paulo, Brazil, from April 2007 to May 2008. Patients were randomly divided into two groups by type of treatment: an oxacillin/ceftriaxone group (OCG, n = 48) and an amoxicillin/clavulanic acid group (ACG, n = 56). Analyzed outcomes were: time to clinical improvement (fever and tachypnea), time on oxygen therapy, length of stay in hospital, need to widen antimicrobial spectrum, and complications (including pleural effusion).Results. The two groups did not differ statistically for age, sex, symptom duration before admission, or previous antibiotic treatment. Time to improve tachypnea was less among ACG patients than OCG patients (4.8 +/- 2.2 versus 5.8 +/- 2.4 days respectively; P = 0.028), as was length of hospital stay (11.0 +/- 6.2 versus 14.4 +/- 4.5 days respectively; P = 0.002). There were no statistically significant differences between the two groups for fever improvement time, time on oxygen therapy, need to widen antimicrobial spectrum, or frequency of pleural effusion.Conclusions. Both treatment plans are effective in treating very severe CAP in 2-monthto 5-year-old hospitalized children. The only analyzed outcome that favored amoxicillin/clavulanic acid treatment was time required to improve tachypnea.

Antimicrobial resistance of aerobes and facultative anaerobes isolated from the oral cavity

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Phenotype characterization of Staphylococcus species strains isolated from buffalo (Bubalus bubalis) milk

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efeito da lavagem peritoneal com bupivacaína na sobrevida de ratos com peritonite fecal

BACKGROUND AND OBJECTIVES: Based on the knowledge of the anti-inflammatory and anti-bacterial actions of local anesthetics (LA), the objective of this study was to determine the effects of peritoneal lavage with bupivacaine on survival of mice with fecal peritonitis. METHODS: Forty-eight Wistar mice, weighing between 300 and 330 g (311.45 ± 9.67 g), undergoing laparotomy 6 hours after induction of peritonitis were randomly divided in 4 groups: 1 - Control, without treatment (n = 12); 2 - Drying of the abdominal cavity (n = 12); 3 - Lavage with 3 mL NS and posterior drying of the abdominal cavity (n = 12); and 4 - Lavage with 8 mg.kg -1 (± 0.5 mL) of 0.5% bupivacaine added to 2.5 mL of NS followed by drying out of the abdominal cavity (n = 12). Animals that died underwent necropsy and the time of death was recorded. Surviving animals were killed on the 11 th postoperative day and underwent necropsy. RESULTS: Group 1 presented a 100% mortality rate in 52 hours, 100% mortality rate in Group 2 in 126 hours, and Group 3 presented a 50% mortality rate in 50 hours. Animals in Group 4 survived. Survival on the 11 th day was greater in groups 3 and 4 than in Groups 1 and 2 (p < 0.001) and greater in Group 4 than in Group 3 (p < 0.01). CONCLUSIONS: Peritoneal lavage with a solution of bupivacaine diluted in NS was effective in preventing death for 11 days in 100% of animals with fecal peritonitis. © Sociedade Brasileira de Anestesiologia, 2008.

Determinação da resistência de Staphylococcus aureus: Um desafio?

The aim of this study was to identify the resistance profile of Staphylococcus aureus strains, in relation to induced clindamycin resistance, and to detect oxacillin resistance by the routine phenotypic methods. The strains were isolated from nasal or lingual swabs taken from healthy adult carriers with no medical history of hospitalization or antibiotic treatment. Eighteen strains were distinguished by the different patterns generated by pulsed field gel electrophoresis (PFGE). Four (22.2%) of these showed sensitivity to clindamycin by the conventional antibacterial susceptibility test, but demonstrated inducible resistance to it by the D-test. One strain (5.6%) was characterized as borderline oxacillin-resistant S. aureus (BORSA), and another (5.6%) as CA MRSA (community-associated methicillin-resistant Staphylococcus aureus). Both of these strains were shown to be cefoxitin susceptible by the disk diffusion test. The polymerase chain reaction (PCR) failed to detect the mecA gene in this last strain and it was thus classified as BORSA. These results show the importance of incorporating the D-test into the routine lab tests for S. aureus inducible clindamycin resistance and also of including the cefoxitin resistance test among the phenotypic methods for MRSA characterization.

Pneumonias

Pneumonia is an infectious disease with great morbidity and mortality worldwide. According to the current guidelines recommendations the authors reviewed the treatment of community-acquired pneumonia (CAP) and hospital-acquired pneumonia (HAP). In this paper will be presented data about etiology, clinics and diagnostic tools. © Copyright Moreira Jr. Editora.