Inhibitory effects and mechanism of antifungal action of the natural cyclic depsipeptide, aureobasidin A against Cryptococcus neoformans.

Cryptococcosis is an opportunistic fungal infection caused mainly by Cryptococcus neoformans. The aim of the present study was to evaluate the inhibitory effect of aureobasidin A on C. neoformans with special focus on its mode of action. The effect of aureobasidin A on cell membrane ergosterol content, cell wall permeability, membrane pumps activities, the total oxidant status (TOS) and melanin production was evaluated. Cytotoxicity and cell hemolysis, and laccase (LacI) and ß1,2-xylosyltransferase (Cxt1p) gene expression were also evaluated. Aureobasidin A reduced melanin production and increased extracellular potassium leakage at 0.5 × MIC concentration. This peptide has no effect on fungal cell wall integrity. Cell membrane ergosterol content was decreased by 29.1% and 41.8% at 0.5 × MIC and 1 × MIC concentrations (2 and 4 µL/mL) in aureobasidin A treated samples, respectively. TOS level was significantly increased without activation of antioxidant enzymes. Lac1 gene was over-expressed (11.7-fold), while Cxt1p gene was down regulated (0.2-fold) following treatment with aureobasidin A. Overall, our results indicated that aureobasidin A inhibits C. neoformans growth by targeting different sites in fungal cells and it may be considered as a promising compound to use as an antifungal in treatment of clinical cryptococcosis.

Expression of Major Efflux Pumps in Fluconazole-Resistant Candida albicans.

INTRODUCTION: Resistance to azole antifungals is considered as a significant problem in Candida albicans infections. Several molecular mechanisms of fluconazole resistance including alterations in the gene encoding the target enzyme ERG11 or overexpression of efflux pump genes including CDR1, CDR2, MDR1, MDR2 and FLU1 have been reported. The aim of this study was to investigate overexpression of efflux pump genes including CDR1, CDR2, MDR1, MDR2 and FLU1 in fluconazole- resistant C. albicans. MATERIAL AND METHODS: In this study, a total of 97 clinical isolates of C. albicans were isolated from hospitalized children in Children medical center, an Iranian referral hospital. Fluconazole susceptibility testing of C. albicans was performed using the broth microdilution method according to the CLSI guideline. Expression of CDR1, CDR2, MDR1, MDR2 and FLU1 genes was measured using quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR) and 18SrRNA gene was used as a housekeeping gene. RESULTS: Among 97 C. albicans isolates, 5 strains were categorized as fluconazoleresistant. Overexpression of CDR1, CDR2 and MDR2 genes was found in all isolates. MDR1 overexpression was observed in four resistant isolates. None of the resistant strains displayed increases in FLU1 transcript levels. CONCLUSION: Overexpression of the CDR1, CDR2, MDR1 and MDR2 genes might play an important role in fluconazole-resistant C. albicans. No link between expression of FLU1 and fluconazole resistance was found.

Management of hospital infection control in iran: a need for implementation of multidisciplinary approach.

Nosocomial, or hospital-acquired, infections are considered the most common complications affecting hospitalized patients. According to results obtained from studies conducted in the Children Medical Center Hospital, a teaching children's hospital and a tertiary care referral unit in Tehran, Iran, improvements in infection control practices in our hospital seem necessary. The aim of this study was to identify risk management and review potential hospital hazards that may pose a threat to the health as well as safety and welfare of patients in an Iranian referral hospital. Barriers to compliance and poor design of facilities, impractical guidelines and policies, lack of a framework for risk management, failure to apply behavioral-change theory, and insufficient obligation and enforcement by infection control personnel highlight the need of management systems in infection control in our hospital. In addition, surveillance and early reporting of infections, evaluation of risk-based interventions, and production of evidence-based guidelines in our country are recommended.

Seroprevalence of antibodies to diphtheria, tetanus and pertussis among healthy adolescents and adults in Iran.

Serologic data on diseases that are preventable by vaccine are useful to evaluate the success of immunization programs. In this study we evaluated the serologic levels of antibodies to diphtheria, tetanus, and pertussis. In a cross sectional study, a total of 360 people aged 10-25 years were randomly selected and classified by sex and age (10-14, 15-20, 21-25 years). Overall, 78.8% of people aged 10-25 years had fully protected levels of diphtheria antibody (> or = 0.1 IU/ML), and 89.7% had fully protected levels of tetanus antibody (> or = 0.1 IU/ML), 94.3% of women aged 15-25 years had anti tetanus antibody sufficient to protect against neonatal tetanus (> or = 0.1 IU/ML). Antibodies to Pertussis toxin (PT) were found in 44.2% samples but only 1.4% had fully protective levels. Antibodies to PT increased with age, ranging from 33.5% in aged 10-14 years to 54.6 % in aged 21-25 years. No differences were found between male and female, except for diphtheria in age group 21-25 years. Results of this study reveal that diphtheria and tetanus (dT) are efficient between booster doses. About pertussis, most people are susceptible to pertussis and increased PT antibodies with age suggest acquired asymptomatic Bordeella pertussis infection. Also B. pertussis infections in adolescents and adults are of concern, as they are the most important source of transmission of pertussis to young, unprotected infants. So one booster dose in adolescents and adults (as CDC recommended), to reduce mortality and morbidity in infants, is therefore suggested.

Increase resistant rates and ESBL production between E. coli isolates causing urinary tract infection in young patients from Iran

Emerging antimicrobial resistance rates and Extended-spectrum beta-lactamase producing Escherichia coli recovered from urinary tract infections (UTI) is an increasing problem in specific regions, limiting therapeutic options. One hundred E. coli isolates causing UTI in patients with age from 2 months to 12 years admitted at CMC in the period of April 2009 to March 2010 were tested for antibiotic susceptibility using the disk diffusion method. Surprisingly high resistance rates were recorded for E. coli against TMP/SMX (84%), cefalotin (66%), cefuroxime (50%), cefixime (50%) and ceftriaxone (45%). Antimicrobial susceptibility of E. coli isolates was followed by meropenem (98%), amikacin (95%), nitrofurantoin (91%) and gentamicin (68%). Extended spectrum beta-lactamase production, was observed in 32% of community and 42% of nosocomial isolates. The results of this study and numerous observations regarding the increasing resistance to these antibiotics, in several countries, emphasize the need for local population-specific surveillance for guiding empirical therapy for UTI in children.

Optimizing of Nutrients for High Level Expression of Recombinant Streptokinase Using pET32a Expression System.

Streptokinase (SK) is being increasingly used in the treatment of acute myocardial infarction and ischemic stroke. The feeding control method using substrate balance equations is vital to maintain the preferred specific growth rate for the high-level expression of recombinant proteins. In this study, initial experiments on chemical and temperature inducible expression systems were carried out to identify appropriate expression conditions to improve production of recombinant Streptokinase. Streptokinase gene of group C Streptococci was cloned into prokaryotic expression vector pET32a. Gene expression was optimized by changing levels of glucose, tryptone, and MgSO4 in the media and temperature-inducible expression system and recombinant protein was confirmed by western blot analysis with anti streptokinase sera of immunized rats. Among the various expression systems used, the quantity of recombinant streptokinase produced in the medium containing 2.4% glucose was more than two-fold compared to the medium containing 0.2% glucose. In addition, temperature induction system (37°C) was found to result in higher productivities compared to room temperature. In conclusion we have demonstrated that significant improvement in the streptokinase yield can be obtained by modifying the media and feeding of substrate. These results indicate that efficient process control strategy is important for the mass production of streptokinase.

Lethal toxic encephalopathy due to childhood shigellosis or Ekiri syndrome.

Lethal toxic encephalopathy due to shigellosis or Ekiri syndrome is a rare complication of shigellosis with a high fatality rate. Data are very limited on factors that can predict this encephalopathy, so we evaluated clinical and laboratory characteristics for these patients. In this study children with extreme toxicity and convulsions followed by rapid neurological deterioration resulting in brain edema and fatal outcome without sepsis and severe dehydration were selected as having lethal toxic encephalopathy. There were 1295 children with shigellosis during the 10 years of the study. Five children (0.4%) had lethal toxic encephalopathy due to shigellosis. Death occurred following rapid neurological detoriation resulting in brain edema despite intensive treatment. Evidence of brain edema may be a prediction factor for death. Early recognition of encephalopathy and measures to prevent brain edema may improve patient outcome.

Increase resistant rates and ESBL production between E. coli isolates causing urinary tract infection in young patients from Iran.

Emerging antimicrobial resistance rates and Extended-spectrum beta-lactamase producing Escherichia coli recovered from urinary tract infections (UTI) is an increasing problem in specific regions, limiting therapeutic options. One hundred E. coli isolates causing UTI in patients with age from 2 months to 12 years admitted at CMC in the period of April 2009 to March 2010 were tested for antibiotic susceptibility using the disk diffusion method. Surprisingly high resistance rates were recorded for E. coli against TMP/SMX (84%), cefalotin (66%), cefuroxime (50%), cefixime (50%) and ceftriaxone (45%). Antimicrobial susceptibility of E. coli isolates was followed by meropenem (98%), amikacin (95%), nitrofurantoin (91%) and gentamicin (68%). Extended spectrum beta-lactamase production, was observed in 32% of community and 42% of nosocomial isolates. The results of this study and numerous observations regarding the increasing resistance to these antibiotics, in several countries, emphasize the need for local population-specific surveillance for guiding empirical therapy for UTI in children.