Highly antibiotic-resistant Clostridium difficile isolates from Iranian patients.

AIMS: Little is known about the resistance rate and susceptibility profile of Clostridium difficile isolates in Iran. Therefore, the aim of present study is to assess the rate of drug-resistant C. difficile. METHODS AND RESULTS: During a 6-year period, four hospitals submitted 735 stool specimens from patients suspected for C. difficile infections to the anaerobic bacteriology laboratory. The 46 C. difficile isolates were subjected to disc diffusion and minimum inhibitory concentration (MIC) Test Strips. All isolates were susceptible to vancomycin (VAN) while the highly resistant phenotypes of metronidazole (MTZ) (67·4%), moxifloxacin (78·3%), ciprofloxacin (69·5%) and tetracycline (82·6%) were observed. Of more concern, 67·3% of C. difficile isolates displayed multidrug-resistant phenotypes. More than half of the isolates (n = 27, 58·6%) were coresistant to ciprofloxacin and moxifloxacin. The MIC90 of VAN was ≤2 mg l-1 , whereas this value for MTZ, ciprofloxacin, moxifloxacin and tetracycline was higher than the resistance breakpoints. According to the comparison of interpretive categories for two tests, the categorical agreement was less than 90% for VAN, ciprofloxacin and tetracycline. CONCLUSIONS: The disc diffusion method can be used to detect the isolates with reduced susceptibility to MTZ or moxifloxacin. The high rate of resistance to fluoroquinolones highlights the possibility of the emergence of hypervirulent strains in our settings. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides data regarding the high level of resistance against multiple antibiotics except VAN.

Field efficacy of expanded polystyrene and shredded waste polystyrene beads for mosquito control in artificial pools and field trials, Islamic Republic of Iran.

Concerns about traditional chemical pesticides has led to increasing research into novel mosquito control methods. This study compared the effectiveness of 2 different types of polystyrene beads for control of mosquito larvae in south-east Islamic Republic of Iran. Simulated field trials were done in artificial pools and field trials were carried out in 2 villages in an indigenous malaria area using WHO-recommended methods. Application of expanded polystyrene beads or shredded, waste polystyrene chips to pool surfaces produced a significant difference between pre-treatment and post-treatment density of mosquitoes (86% and 78% reduction respectively 2 weeks after treatment). There was no significant difference between the efficacy of the 2 types of material. The use of polystyrene beads as a component of integrated vector management with other supportive measures could assist in the control of mosquito-borne diseases in the Islamic Republic of Iran and neighbouring countries.

Field efficacy of expanded polystyrene and shredded waste polystyrene beads for mosquito control in artificial pools and field trials, Islamic Republic of Iran

Concerns about traditional chemical pesticides has led to increasing research into novel mosquito control methods. This study compared the effectiveness of 2 different types of polystyrene beads for control of mosquito larvae in south-east Islamic Republic of Iran. Simulated field trials were done in artificial pools and field trials were carried out in 2 villages in an indigenous malaria area using WHO-recommended methods. Application of expanded polystyrene beads or shredded, waste polystyrene chips to pool surfaces produced a significant difference between pre-treatment and post-treatment density of mosquitoes [86% and 78% reduction respectively 2 weeks after treatment]. There was no significant difference between the efficacy of the 2 types of material. The use of polystyrene beads as a component of integrated vector management with other supportive measures could assist in the control of mosquito-borne diseases in the Islamic Republic of Iran and neighbouring countries

Survey of microbial quality of drinking water in rural areas of Kashan-Iran in second half of 2008.

The objective of the study is surveying microbial quality of drinking water in Kashan rural areas and determining the rural population that using safe water in terms of microbial quality in second-half of 2008. In this cross-sectional study, microbial quality of water in all rural areas was determined in 3 stages based on 3 parameters as Total Coliforms, Fecal Coliforms and Heterotrophic Plate Count (HPC). The results of this study illustrates that 100.0, 47.71 and 92.99% population in under coverage and non under coverage areas of Kashan Rural Water and Wastewater Company (KRWWC) and all Kashan rural areas, respectively using safe water in terms of Fecal Coliforms and 98.4, 21.2 and 88.00% population in under coverage and non under coverage areas of KRWWC rural areas and all Kashan rural areas, respectively using safe water in terms of Total Coliforms. There is also a meaningful difference in microbial quality between under coverage and non-under coverage rural areas. The results of this study express that the fecal contamination in under coverage rural areas is excellent, but there is a bad condition in non-under coverage areas. Generally, the microbial quality in all Kashan rural areas is approximately equal to national microbial criteria. Its been also illustrated that the role of KRWWC in supplying safe drinking water in terms of microbial quality for rural population is very important.

Effect of short-term lead exposure on PTZ-induced seizure threshold in mice.

This study was designed to determine the effect of different concentrations of lead acetate on seizure threshold. Balb\c male mice were randomly divided into one control group provided with tap water and four experimental groups received lead acetate in drinking water for 30 days at concentrations of 50, 100, 200 and 400 ppm. Intravenous infusion of pentylenetetrazole (PTZ) was used to induce seizure signs and elapsed time was recorded to calculate the threshold dose. At the end of the experiments blood samples were taken to measure the blood lead level. Threshold doses of PTZ were significantly lower in 100, 200 and 400 ppm lead exposed groups for the induction of all seizure stages. Blood lead level increased in all experimental groups compared to control dose-dependently. Considering the lack of any response induced by 50 ppm concentration of lead, it may be concluded that 100 ppm of lead was the minimal effective dose. Therefore, lead acetate at a concentration of 100 ppm that produces similar blood level in human populations approves the enhancement of convulsive attack risk. Considering the effect of low levels of lead in the reduction of seizure threshold, more investigations should be carried out to clarify the exact mechanisms.

Sensitive determination of bisphenol A and bisphenol F in canned food using a solid-phase microextraction fibre coated with single-walled carbon nanotubes before GC/MS.

A reliable and sensitive method for simultaneous determination of bisphenol A (BPA) and bisphenol F (BPF) in canned food by gas chromatography-mass spectrometry (GC/MS) is described after extraction and pre-concentration by a new solid-phase microextraction (SPME) adsorbent. The potential of single-walled carbon nanotubes (SWCNTs) as SPME adsorbent for the pre-concentration of environmental contaminants has been investigated in recent years. This work was carried out to investigate the feasibility of SWCNTs as a headspace SPME adsorbent for the determination of bisphenol derivatives in canned food. Potential factors affecting the extraction efficiency, including extraction time, extraction temperature, desorption time, desorption temperature, and salinity were optimized. Calibration curves were linear (r(2)> or = 0.994) over the concentration range from 0.30 to 60 microg kg(-1). For both target analytes, the limit of detection (LOD) at signal-to-noise (S/N) ratio of 3 was 0.10 microg kg(-1). In addition, a comparative study between the SWCNT and a commercial polydimethylsiloxane (PDMS) SPME fibre for the determination of bisphenol derivatives in canned food was conducted. SWCNT fibre showed higher extraction capacity, better thermal stability (over 350 degrees C) and longer life span (over 150 times) than the commercial PDMS fibre. The method was successfully applied to determine BPA in canned food samples which were purchased from local markets. BPA was found in some of the samples within the concentration range from 0.5 to 5.2 microg kg(-1).

Using irradiation treatment for reduction of anaerobic bacteria from a wastewater treatment plant.

This study was done to investigate the reduction of anaerobic bacteria (Clostridium perfringens) by ultrasound irradiation technology (USI). C. perfringens is the most important of the sulfite-reducing clostridia and is normally present in human and animal feces. Clostridial spores survive longer than coliforms, Escherichia coli or enterococci, and are consequently used as an indicator of past fecal pollution. The spores are not always inactivated by chlorination, but are not a hazard to health in potable water. C. perfringens are very resistant to chlorine and other drinking-water disinfectants. Conventional water treatment practices including chlorination are sometimes inadequate for inactivation of C. perfringens. Ultrasound irradiation is able to inactive C. perfringens through a number of physical and chemical effects arising from acoustic cavitation. The phenomenon of cavitation, which involves formation, growth, and violent collapse of vapour bubbles in a liquid media, is known to generate a high-intensity pressure, which affects the cell and C. perfringens' viability. Cavitations disrupt C. perfringens. Ultrasound irradiation at a frequency of 42 kHz was used to expose aqueous suspension of C. perfringens to evaluate the disinfection efficacy of ultrasound irradiation. Results indicated a significant increase in reduction of C. perfringens with increasing ultrasound time. C. perfringens was inactivated by 99.98% after 90 min.

The removal of H2S from process air by diffusion into activated sludge.

Emissions of H2S from publicly owned treatment works is a serious problem, therefore collection and treatment of these emissions is essential. In this work, the performance of a bench scale activated sludge system used for the removal of H2S from foul air was investigated, and the effects of H2S concentration (5 to 50 ppm,) on COD reduction and biomass settleability were studied. After biomass acclimation, the reactor was operated in a continuous mode at a hydraulic retention time of 5 h and a mean cell residence time of 6 days. Results showed that COD and H2S removal were 93.5 and 94.5%, respectively. Furthermore, H2S concentration up to 50 ppm, did not significantly affect the COD reduction. H2S loading rates of up to 7.5 mg(H2S) g(-1)MLSS, d(-1) were treated with greater than 94% efficiency. The only adverse effect of H2S that was observed was an increase in the sludge volume index at loading rates over 4.5 mg(H2S) g(-1)MLSS d(-1), at which bulking of the sludge occurred. Overall, the results indicate that H2S at concentrations usually emitted from wastewater treatment processes (lower than 50 ppm(v)), can be efficiently treated by diffusion into activated sludge without compromising the performance of the activated sludge process.

Study of natural organic matter fractions in water sources of Tehran.

Natural Organic Matters (NOMs) are abundant in natural water resources and in many ways may affect the unit operations in water treatment. Although, NOMs are considered harmless but they have been recognized disinfection by-products precursors (DBP(s)) during the chlorination process. Formation of DBP(s) highly depends on the composition and concentration of NOM, which can be broadly divided into two fractions of hydrophobic (humic) and hydrophilic (non-humic) substances. The objective of this study was to determine Natural organic matter and its fractions concentration in the surface water sources of Tehran. Water sampling was conducted monthly between May to July 2006 in three rivers Lar, Jajrood and Karaj as the main drinking water supplying sources in Tehran. Quantitative parameters of pH, EC, UV254 and DOC were studied based on to standard methods. The XAD-7 resin method was used for fractionation of NOM. Results showed that NOM concentrations in Lar, Jajrood and Karaj rivers were 8.53, 12.9 and 11.3 mg L(-1), respectively. The HPO (hydrophobic) fraction was predominant compared to the HPI (hydrophilic) fraction in the all of water samples. The mean of total percent of HPO and HPI fractions were about 57 and 43%, respectively. Since the hydrophobic NOM fraction exhibits higher trihalomethane formation potential (THMFP) than hydrophilic NOM, Tehran water chlorination exhibits higher THMFP than haloacetic acid formation potential (HAAFP). The information obtained from this study may be further employed in the design of the control technique and management strategies for the water treatment plant, especially for DBP(s) reduction.

The treatment of wastewater containing crude oil with aerated submerged fixed-film reactor.

An aerated submerged fixed-film (ASFF) bioreactor was developed to treat an artificial wastewater based on crude oil. Bee-Cell 2000 was used as support media having porosity of 87% and a specific surface area of 650 m2 m(-3). The system was able to achieve 70.87-93.12% removal efficiencies of Chemical Oxygen Demand (COD) in the organic loading rate range of 1.310 to 15.797 g COD m(-2) day(-1). Data gained exhibited that the effluent COD concentration ranged between 68.68 and 292.60 mg L(-1) at organic loadings experienced. Therefore, an ASFF process showed that it was feasible to treat high oily wastewater in order to meet the discharge standards.

Behavior of an aerated submerged fixed-film reactor (ASFFR) under simultaneous organic and ammonium loading.

The performance of an aerated submerged fixed-film reactor (ASFFR) under simultaneous organic and ammonium loading and its effect on nitrification was studied. Organic loadings varied in the range of 1.93 to 5.29 g chemical oxygen demand (COD) m-2 d-1 and NH4-N loadings were in the range of 116 to 318 mg NH4-N m-2 d-1. Increments of loading rates were obtained both by increasing the flow rate and increasing the influent substrate in individual pilot runs. Results showed that with organic loading rates up to 3.97 g COD m-2 d-1, complete nitrification was achievable. Although high organic loading such as 5.29 g COD m-2 d-1 could cause nitrification to stop, shifting to lower organic loadings made nitrification start and set rapidly to its previous steady-state concentrations. Comparison of results showed that in the ASFFR, nitrification would be severely affected by an organic loading rate of 5.29 g COD m-2 d-1 by increasing either the flow or the influent substrate. It should be noted that the average value of dissolved oxygen was 3.4 mg L-1 with an air supply of 15 L min-1, and there was no indication of oxygen limitation. The results of this study show the flexibility of ASFFRs under changing organic loads. Furthermore, for achieving complete nitrification and optimum application of these reactors for protecting receiving water from the environmental hazards of ammonium, the maximum organic loading that would present complete nitrification should be considered.

Development of the Regional Malaria Training Centre in Bandar-e Abbas, Islamic Republic of Iran.

The resurgence of malaria has highlighted the need for training health professionals in malaria control planning. The course described here was organized jointly by the World Health Organization, the Ministry of Health and Medical Education and the School of Public Health in Iran. The first course was held in 1997 and the fifth WHO-approved course is now in progress. The course focuses on dynamic, interactive, practical and problem-solving learning methods. It provides the participants with the knowledge, skills, competence and confidence to be able to analyse the malaria problem. The course fulfils the requirements of the Roll Back Malaria campaign. In the 8-week training period subjects such as basic bio-statistics and epidemiology, microcomputing, malaria parasitology, malaria entomology, vector control, case management, epidemiological approach to malaria control, field work and planning for malaria control are taught. Each participant is evaluated in each subject. A total of 71 participants from 17 countries in the WHO African and Eastern Mediterranean Regions, mainly those with a malaria problem, have graduated.