Chemical composition and synergistic effect of three Moroccan lavender EOs with ciprofloxacin against foodborne bacteria: a promising approach to modulate antimicrobial resistance.

The aim of this study was to determine the chemical profile of the essential oils (EOs) of three Moroccan lavender species (Lavandula pedunculata, LP; Lavandula angustifolia, LA; and Lavandula maroccana, LM) and to investigate, for the first time, the synergistic effect of the optimal mixture of the EOs with conventional antibiotic ciprofloxacin against three pathogenic foodborne bacteria. Gas chromatography/mass spectrometry analysis showed that eucalyptol (39·05%), camphor (24·21%) and borneol (8·29%) were the dominant compounds of LA-EO. LP-EO was characterized by the abundance of camphor (74·51%) and fenchone (27·06%), whereas carvacrol (42·08%), camphor (17·95%) and fenchone (12·05%) were the main constituents of LM-EO. EOs alone or combined showed a remarkable antimicrobial activity against the tested bacteria with minimum inhibitory concentrations (MICs) ranging from 3·53 to 15·96 mg ml-1 . The optimal mixture, calculated using a mixture design, corresponded to 19% LA, 38% LP and 43% LM. All combination of the EOs and the best EO mixture with ciprofloxacin exhibited a total synergism with fractional inhibitory concentration index values ranging from 0·27 to 0·37. The best EO mixture showed the highest gain of 128-fold, especially against Salmonella spp., more than that found testing the EOs separately. These findings should be taken into consideration for a possible application in the pharmaceutical and food industries.

Predictors of Iranian women's intention to first papanicolaou test practice: An application of protection motivation theory.

BACKGROUND AND AIM: Given the importance of papanicolaou (Pap) test in the early detection and timely treatment of cervical cancer, present study was designed to determine predictors of a sample of Iranian women's intention to first Pap test practice based on the protection motivation theory (PMT) variables. MATERIALS AND METHODS: In this cross-sectional study, a total of 240 women referral to the 30 primary health care clinics were selected. They completed a developed scale based on PMT variables including intention, perceived vulnerability and severity, fear, response costs, response efficacy and self-efficacy. Path analysis was used to determine the association between predictive factors and intention. RESULTS: The results showed that PMT had goodness of fit with a χ2/df = 2.37, df = 28, P= 0.001 and RMSEA = 0.076. PMT explained 42% of the variance in women's intention to get first Pap smear test. Self-efficacy (b = 0.55, P< 0.001) and response efficacy (b = 0.19, P< 0.001) were found to be the predictors of intention. CONCLUSION: These findings may be used to develop tailored, theory-based educational interventions associated with Pap testing among women.

Study on chemical analysis, antioxidant and in vitro antifungal activities of essential oil from wild Vitex agnus-castus L. seeds growing in area of Argan Tree of Morocco against clinical strains of Candida responsible for nosocomial infections.

OBJECTIVE: To study the composition, the antioxidant activity and the in vitro antifungal action anti-Candida species of essential oils extracted from seeds of Vite xagnus-castus L. MATERIALS AND METHOD: The essential oils were extracted using Clevenger-type apparatus and analyzed by gas chromatography/mass spectrometry (GC/MS). The antioxidant activity was analyzed using the DPPH free radical-scavenging method. Susceptibility tests for Candida albicans (12), C. dubliniensis (1), C. glabrata (3), C. krusei (3), C. parapsilosis (6), C. lusitaniae (1), C. famata (1) and C. tropicalis (3) were expressed as inhibition zone by the disc-diffusion method and as minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) by the broth macrodilution method, compared to amphotricin B and fluconazol as standard drugs. RESULTS: Major components were: 1,8-cineole (19.61%), sabinene (14.57%), α-pinene (9.76%), ß-farnesene (6.04%), ß-caryophyllene oxide (5.83%) and ß-caryophyllene (5.02%). A low antioxidant activity was found (IC50=1.072mg/ml), but it can be exploited. V. agnus-castus seeds essential oils disosed a 35-58mm zone of inhibition (mean: 49mm) against all 30 isolates tested. In broth macrodilution method, all the tested Candida species were susceptible to the essential oils and this activity was concentration-dependent. MIC values varied from 0.13 to 2.13mg/ml V. agnus-castus seeds essential oils. CONCLUSION: Results of this study indicated that the oils of plant origin could be used as potential anti-Candida species causative agents of nosocomial infections. These oils exhibited a noticeable antifungal activity against the selected fungi. The natural antifungal substances are inexpensive and have fewer side effects, they may represent alternative therapies for candidiasis.

Natural extracts stimulate membrane-associated mechanisms of resistance in Gram-negative bacteria.

UNLABELLED: Several mechanisms are involved in the bacterial resistance towards antimicrobial agents. The membrane-associated mechanisms of resistance were studied in Escherichia coli strains after incubation with Thymus maroccanus essential oil, its major components (carvacrol and thymol) or with certain antibiotics. The minimum inhibitory concentration (MIC) and the expression of membrane proteins, porins and efflux pumps were determined in wild type and derivative strains. Derivative strains adapted to different compounds displayed a high level of resistance to all tested antibiotics. The MIC increase is associated with an overexpression of an efflux pump immunorelated to AcrAB-TolC in various variants. Interestingly, the expression of outer membrane proteins slightly decreases in these strains. We demonstrate that the increase in antibiotic resistance correlates with membrane changes observed in the variants. This type of bacterial adaptation to natural compounds can occur in vivo providing the emergence/selection of bacteria less susceptible to clinically used antibiotics. SIGNIFICANCE AND IMPACT OF THE STUDY: Thymus maroccanus essential oil and some major components are able to select variants that modify the expression of transporters involved in the influx (porins) and in the efflux (AcrAB family) of various drugs. Importantly, these membrane proteins are involved in the transport of natural compounds and several antibiotic families. This special 'membrane adaptation' can explain the persistence of less susceptible/tolerant bacteria in the environment where natural compounds are present and the continuous stimulation of efflux systems in these bacteria.

Thymus maroccanus essential oil, a membranotropic compound active on Gram-negative bacteria and resistant isolates.

AIMS: The effects of Thymus maroccanus essential oil (EO) on the integrity of the cell membranes and the permeability of the outer membrane (OM) and inner membrane (IM) of Escherichia coli, Enterobacter aerogenes and Salmonella enterica Typhimurium were investigated. METHODS AND RESULTS: The bacterial release of intracellular proteins, cytoplasmic ß-galactosidase and periplasmic ß-lactamase induced by T. maroccanus EO was compared to the membranotropic activity of polymyxin B (PB) known as an effective permeabilizer of the membrane of Gram-negative bacteria. Results showed that T. maroccanus EO increased the permeability of the OM and IM of studied bacteria and induced the release of intracellular proteins into the external medium. CONCLUSIONS: The effect of T. maroccanus EO on the outer membrane was comparable to that of PB, and both T. maroccanus EO and PB induce similar levels of ß-lactamase release. In addition, it also promoted the release of the cytoplasmic ß-galactosidase. Moreover, the lipopolysaccharide molecules and the overexpression of efflux pumps seem to play a crucial role in the level of susceptibility of studied bacteria to the permeabilizing effect of T. maroccanus EO. SIGNIFICANCE AND IMPACT OF STUDY: These results demonstrate that T. maroccanus EO can restore antibiotic activity by targeting the two bacterial membranes and would be attractive candidates for developing new adjuvants for combating resistant Gram-negative bacteria.

GEMOX regimen in the treatment of metastatic differentiated refractory thyroid carcinoma.

Treatment options for radioiodine resistant metastatic thyroid cancer patients are limited, and chemotherapy is considered an outdated therapeutic method for differentiated thyroid carcinoma. In this study, we evaluated the activity and safety of gemcitabine and oxaliplatin combination which is considered an out of label therapeutic method in patients with differentiated metastatic thyroid cancer refractory to 131-I treatment. Fourteen refractory patients (8 papillary, 6 follicular), six men/eight women with median age of 63 years and performance status (0-3) were included. Patients received gemcitabine (1,000 mg/m(2)) plus oxaliplatin (100 mg/m(2)) every 2 weeks until 12-cycles and each cycle correspond to 2 weeks treatment. This protocol was approved by the local Institutional Review Boards. Response rate was assessed every four cycles. Progression-free and overall survivals were calculated. Median treatment was 9.5 cycles (range 2-17) with 22 weeks duration. Overall response rate was 57%, with 7% achieving a complete response (1/14), 50% a partial response (7/14), and 28% with a stable disease. All patients with follicular subtype showed objective responses. Eleven patients progressed at a median time of 10.1 months; 10 of 14 patients still alive and the median survival was not reached (median follow-up of 19.8 months). The combination was generally well tolerated. No deaths occurred due to therapy and no grade IV toxicity was recorded. The most common treatment-related adverse events grade 1/3 includes asthenia, peripheral neuropathy, diarrhea, anemia, thrombocytopenia, and neutropenia. In conclusion, the GEMOX regimen is well tolerated and effective in advanced differentiated thyroid cancer. However, this retrospective data on a small sample size are considered preliminary and needs to be evaluated prospectively in a higher number of patients in a clinical trial.

Anticandidal activity of the essential oils of Thymus maroccanus and Thymus broussonetii and their synergism with amphotericin B and fluconazol.

The discovery of antifungal drugs had eradicated some infections that ravaged the humankind. But their indiscriminate use has led to the development of multidrug resistant pathogens. One strategy employed to overcome these resistance mechanisms is the use of combination of the essential oils (EOs) of medicinal plants and conventional drugs. In this study, we investigated a possible synergistic effect of the EOs of two Moroccan endemic thymes (Thymus broussonetii and T. maroccanus) with amphotericin B (Amp B) and fluconazol against Candida albicans. The fractional inhibitory concentration indices (FICI) of T. maroccanus and T. broussonetii EOs combined with Amp B and fluconazol, calculated from the checkerboard titer assay, were 0.49, 0.27, 0.37 and 0.3, respectively. Also, our results indicate that the synergistic effect of EOs with fluconazol was stronger than the combination with Amp B. All these data highlight that the EOs tested potentiate the antifungal action of Amp B and fluconazol, suggesting a possible utilization of these EOs in addition to antifungal drugs for the treatment of some candidiasis due to C. albicans. The use of these combinations is likely to reduce the minimum effective dose of the drugs, thus minimizing their toxic side effects and the treatment cost.

[Treatment of olive mill wastewater by a process combining an intensive treatment (Jet-Loop reactor) followed by an extensive treatment (stabilization ponds)]. / Traitement des effluents d'huileries par un procédé combinant un traitement intensif (Jet-Loop reactor) suivi d'un traitement extensif (bassins de stabilisation).

Olive oil mill wastewater (OMW) is generally recognized as an environmentally troublesome by-product of the olive oil industry as its disposal without any treatment is known to cause serious environmental problems. However, this effluent has a high fertilizing power and constitutes, with urban wastewater, an important low-cost source. Biological treatment of OMW, with a process combining an aerobic reactor, 'Jet-Loop', and waste stabilization ponds, was investigated for possible agricultural reuse. The focus of the present study was to evaluate the contribution and the complementarity of the two systems in the total OMW treatment. Bio-treatment was performed using a 100-litre Jet-Loop reactor working volume achieving a chemical oxygen demand (COD) and phenolic compounds maximum removal rate of 72% and 68%, respectively, at a hydraulic retention time of 10 days. Co-treatment of OMW and domestic wastewater in waste stabilization ponds, with a hydraulic retention time of 22 days, reached a global removal rate of 66% for COD while no trace of phenolic compounds was detected on this level during the entire treatment period. Dynamics of faecal coliforms in stabilization ponds showed a total removal rate of 99.9% (3 logarithmic units (Log.U)). Preliminary results of agronomic tests on the ray-grass have evaluated the fertilizing effect of the final effluent resulting from the co-treatment.

Co-treatment of olive-mill and urban wastewaters by experimental stabilization ponds.

Olive oil mill wastewater (OMW) constitutes a source of environmental problems in Morocco due to its significantly high organic load, its phytotoxic properties and its relatively low biodegradability. An effective option for its disposal is its agricultural use after co-treatment with urban wastewater (UWW). The main objective of this investigation was to evaluate the potential of this co-treatment, using experimental waste stabilization ponds, in removing OMW phytotoxicity. We examined the influence of the organic load, at the entry of the treatment system, on the evolution of some physicochemical (chemical oxygen demand and polyphenols) and microbiological (fecal coliforms and fecal streptococci) parameters. The results showed a removal of the organic, phenolic and microbial load throughout the treatment which differed from one system to another according to the OMW load applied to each system. The results concerning the germination assays of Zea mays and Solanum lycopersicum suggested that the co-treatment of OMW with UWW would decrease the phytotoxicity of this waste.

Application of lime and calcium hypochlorite in the dephenolisation and discolouration of olive mill wastewater.

The application of hypochlorite for the removal of soluble COD, phenolic and polyphenolic like compounds, and other organic compounds responsible for the olive mill wastewater (OOWW) colour has been experimentally studied. After the OOWW filtration on a sand column, the effluent was subjected to a fast liming under optimal conditions. Lime application reduced polyphenols, COD and SS contents to half of their initial values but an important blackening of the treated OOWW was observed, especially when adding high concentrations of lime (10% (W/V) and 15% (W/V)). A second stage of treatment was applied using calcium hypochlorite. In this stage, removal of the studied compounds reached as much as 95% at higher concentrations, and particularly the colouring of OOWW which is generally difficult to eliminate was greatly reduced. The OOWW hypochloration acted through coagulation-flocculation and a rapid oxidation of the organic matter proceeded from the first 5min. The kinetic study of the degradation of the waste polluting compounds from liming showed that Ca(ClO)(2) reacts similarly in the elimination of organic compounds, polyphenols, SS and colouration. The analysis of the organochloride compounds generated by the reaction between hypochlorite and the organic compounds showed that DDD, DDT and the heptachlor contents exceeded the values recommended by the International and European drinking water standards.

[Impact of olive oil wastewater on the physicochemical and biological quality of groundwater in the Haouz plain, south of Marrakesh (Morocco)]. / Impact des effluents des huileries d'olive sur la qualité physico-chimique et biologique des eaux souterraines dans la plaine du Haouz au sud de Marrakech (Maroc).

Olive Oil Waste Water (OOWW) is acidic water known for its antibacterial and phytotoxic effects. In Morocco, these effluents are generally drained into the surrounding environment without any treatment or are collected and retained in large evaporation basins, which can constitute a source of potential pollution of groundwater. The analysis of water from 14 wells, in an agricultural zone, where there are four storage basins of OOWW coming from various types of oil mills, showed that their physicochemical and biological quality is largely influenced by the presence of these basins. Indeed, high values of COD (400 mg O2 L(-1)), polyphenols (180 mg l(-1)) and electrical conductivity (1.89 mS cm-') were recorded in P5 water. This well is located only 5 m from a storage basin of OOWW coming from the H4 oil mill which rejects OOWW charged with organic matter (more than 290 g of O2 L(-1) of COD, on average). However, the settlement of a basin, dug close to a modern oil mill (H3), which produces large OOWW volumes but is loaded with low organic pollutant concentration (100 g of O2L(-1) of COD), reduced notably the effect of the OOWW infiltration on groundwater. This resulted in the improvement of the groundwater physicochemical quality near this basin (P7 and P8); the organic matter contents expressed by COD vary from 26.7 mg l(-1) to 30 mg l(-1) and the polyphenol contents are on average between 41 mg l(-1) and 47.6 mg l(-1). The analysis of the total well water fauna showed a great taxonomic richness with variations in time and space. The biodiversity decreases in groundwater polluted by the oil mill waste and the underground fauna disappears completely if the degree of contamination of groundwater is high.

[Disseminated erythematous lupus with bilateral diaphragmatic involvement]. / Lupus érythémateux disséminé avec atteinte diaphragmatique bilatérale.

The diaphragm is an unusual localization for disseminated erythematous lupus and is generally not recognized. We present the case of a 34-year-old woman who developed bilateral pain in the base of the thorax 15 days before hospitalization without any bronchial signs and NYHA stage II dyspnea. The patient's general health status remained satisfactory and the physical examination was normal except for diffuse inflammatory joint pain and cutaneous photosensitivization. The chest x-ray disclosed ascension of both hemidiaphragms with retracted lungs associated with bilateral basal atalectasia. The diagnosis of lupus with diaphragmatic involvement was retained due to the clinical presentation with diffuse joint pain, photosensitization with facial erythema, pericardial effusion and elevated antinuclear antibody and lymphopenia (1 100/mm3). Lung function tests revealed a restrictive syndrome. Oral corticosteroids 1 mg/kg/d enabled clinical and functional improvement. In light of this observation we discuss the pathogenic mechanisms of this uncommon localization of lupus and the difficulty of establishing a sure diagnosis.

Assessment of butyltin and phenyltin pollution in the sea mullet, Mugil cephalus, along the Moroccan and Spanish coasts (Mediterranean Sea).

Levels of three butyltin (BTs) compounds, monobutyltin (MBT), dibutyltin (DBT) and tributyltin (TBT), and three phenyltin (PTs) compounds, monophenyltin (MPhT), diphenyltin (DPhT), and triphenyltin (TPhT), were determined in the sea mullet, Mugil cephalus, collected along the northern Mediterranean coast of Morocco, and the south Mediterranean coast of Spain. Also, sediment samples from the Guadalquivir River (Spain) near to its mouth in the Mediterranean Sea were analysed. TBT and TPhT were the predominant compounds in the analyzed samples, and TBT concentrations were higher in liver than in muscle. In general, the total content of BTs in these samples was higher than PT levels. In the Moroccan coast, the highest value of BTs (18.00 mg/Kg wet weight) was found in the west harbour of the Tangier site, while the lowest concentration (0.01 mg/Kg wet weight) was detected in the Oued Laoue site. Concerning PTs compounds, the highest value (4.00 mg/Kg wet weight) was found in the harbour of the M'diq Site and the lowest value (0.01 mg/Kg wet weight) was detected in the Oued Laoue site. On the other hand, organotin (OT) residues were not detected in the water samples of the Spanish coast although TBT was identified in four of the nine sediment samples from the Guadalquivir River at concentrations between 15.45 and 245.07 mg/Kg wet weight.

Chemical composition and antifungal activity of essential oils of seven Moroccan Labiatae against Botrytis cinerea Pers: Fr.

Essential oils of seven Moroccan Labiatae were chemically analysed by GC-MS and evaluated for their in vitro antifungal activity against Botrytis cinerea. Among them, Origanum compactum and Thymus glandulosus greatly inhibited the growth of the mycelium. The inhibition of Botrytis cinerea was 100% for both oils at 100 ppm, while the IC(50)s were 35.1 and 79.2 ppm, respectively. Mentha pulegium exhibited moderate activity at 250 ppm since the inhibition of the mycelial growth was 58.5% and the IC(50) was 233.5 ppm. The main constituents of the studied oils were also examined. Thymol and carvacrol that are the two main constituents of Thymus glandulosus and Origanum compactum exhibited the strongest antifungal activity with 100% of inhibition at 100 ppm, respectively.

Solar inactivation of mesophilic Aeromonas by exogenous photooxidation in high-rate algal pond treating waste water.

AIMS: Investigations were carried out to observe the effect of sunlight on the survival of mesophilic Aeromonas (A. caviae, A. hydrophila and A. sobria) in high-rate algal pond. METHODS AND RESULTS: Light damage was estimated by loss of bacterial culturability, using simple beaker experiments. Survival of the strains studied under illuminated conditions was highly affected by the physico-chemical conditions within the microcosms. The inactivation of Aeromonas increased strongly as dissolved oxygen was increased, and was dependent on exogenous sensitizers. This process was enhanced by the high pH of water. Die-off of bacteria was prevented by adding catalase and pyruvate (H2O2 scavengers) into the microcosms. CONCLUSIONS: The damage of Aeromonas was mainly due to exogenous photooxidation. Hydrogen peroxide at least was involved in light-induced damage of bacteria. Aeromonas sobria appeared to be slightly less sensitive to photooxidation than A. hydrophila and A. caviae. SIGNIFICANCE AND IMPACT OF STUDY: The present study could explain the relative resistance of A. sobria to treatment in wastewater stabilization ponds.

Health effect of human wastes use in agriculture in El Azzouzia (the wastewater spreading area of Marrakesh city, Morocco).

The use of wastewater and excreta in agriculture constitutes an important source of spread Salmonella strains and protozoan infections into the environment. This practice has been used in El Azzouzia (the wastewater-spreading area of Marrakesh city, Morocco) for several years. The available circumstantial evidence gained from epidemiological and microbiological investigations suggests that the use of untreated wastewater causes an excess of protozoan infections among children living in El Azzouzia (72%) compared with those from a control area (45%). The pathogenic protozoan infections observed were giardiasis (39%) and amoebiasis (28%). For Salmonella infection, 21.34% of the exposed children were infected, while this rate did not exceed 1.14% in the control group. The serogroups B and C were the most commonly isolated. The sewage farming children are therefore more exposed to detectable risk from pathogenic micro-organisms than the control children.

Propionic acid fermentation of glycerol and glucose by Propionibacterium acidipropionici and Propionibacterium freudenreichii ssp. shermanii.

A comparative study was carried out in anaerobic batch cultures on 20 g/l of either glycerol or glucose using two propionibacteria strains, Propionibacterium acidipropionici and Propionibacterium freudenreichii ssp. shermanii. In all cases, fermentation end-products were the same and consisted of propionic acid as the major product, acetic acid as the main by-product and two minor metabolites, n-propanol and succinic acid. Evidence was provided that greater production of propionic acid by propionibacteria was obtained with glycerol as carbon and energy sources. P. acidipropionici showed higher efficiency in glycerol conversion to propionic acid with a faster substrate consumption (0.64 g l(-1) h(-1)) and a higher propionic acid production (0.42 g l(-1) h(-1) and 0.79 mol/mol). The almost exclusive production of propionic acid from glycerol by this bacterium suggested an homopropionic tendency of this fermentation. Acetic acid final concentration was two times lower on glycerol (2 g/l) than on glucose (4 g/l) for both micro-organisms. P. freudenreichii ssp. shermanii exhibited a glycerol fermentation pattern typical of non-associated glycerol-consumption-product formation. This could indicate a particular metabolism for P. freudenreichii ssp. shermanii oriented towards the production of other specific components. These results tend to show that glycerol could be an excellent alternative to conventional carbon sources such as carbohydrates for propionic acid production.

Salmonella infection in children from the wastewater-spreading zone of Marrakesh city (Morocco).

The available circumstantial evidence gained from epidemiological and microbiological investigations suggests that the use of untreated wastewater causes an excess of Salmonella infection among children living in El Azzouzia (the wastewater-spreading area of Marrakesh city, Morocco) compared with those from a control area that does not practice sewage irrigation (Sidi Moussa). The prevalence in the exposed group (32.56%) was significantly (P < 0. 001) higher than for the control group (1.14%). Serogroups B and C were the most commonly isolated. Boys were at greater risk (37.61%) of contracting Salmonella infection than girls (26.66%). Age-specified rates showed that children of less than 10 years old were infected at a higher rate than older children in the area (exposed group), with 40.32% and 19.72% rates of infection, respectively. Crop irrigation with untreated wastewater caused a significantly higher rate of infection with Salmonella in the children of agricultural workers (39.33%) than in the children of non-agriculturists (24.58%).

Pril-ampicillin-dextrin-ethanol agar for the isolation and quantification of Aeromonas spp. from polluted environmental waters.

Several selective media were evaluated for their suitability for the isolation and quantification of mesophilic Aeromonas species from naturally polluted samples. Satisfactory recoveries were obtained with most of them but only when densities of background microflora were low. When analysed samples were from highly polluted waters, results were inconsistent because they did not give quantitative recovery of mesophilic aeromonads or they did not permit ready differentiation of Aeromonas species from the competitive bacteria. A new medium was developed on the basis of the combination of some positive aspects of several published media, pril-ampicillin-dextrin-ethanol (PADE) agar. The medium employs dextrin (Merck 3006) as a fermentable carbohydrate and pril, ampicillin and ethanol as inhibitory substances. Recovery on PADE agar from suspensions of 15 tested strains of Aeromonas prepared from pure cultures was excellent. The confirmation rate of typical colonies designated Aeromonas spp. isolated from polluted samples exceeded 90%. Recoveries of stressed aeromonad strains on both PADE agar and a non-selective medium (TSA) did not show any significant difference (P > 0.05). PADE agar was more reliable for quantitative recovery of mesophilic aeromonads than the other selective media because of its characteristics: (i) inhibition of the swarming of Proteus, (ii) good reduction of the background, (iii) inhibition of the over growth of Klebsiella spp., (iv) absence of NaCl makes it unfavourable for the growth of halophilic vibrios, (v) combination of two pH indicators permitted a very easy differentiation between Aeromonas colonies and the competitive microflora. The medium can also be used for isolation of aeromonads from various sources by membrane filtration.