A comparison of ten USEPA approved total coliform/E. coli tests

Since 2002, the United States Environmental Protection Agency (USEPA) has approved ten enzyme-based total coliform and E. coli detection tests for examination of drinking water. These tests include: Colilert, Colilert-18, Colisure, m-Coli Blue 24, Readycult Coliforms 100, Chromocult, Coliscan, E * Colite, Colitag and MI Agar. The utility of the enzyme based test systems is based on both the ability of the test to detect the target organisms at low levels and the ability of the test system to suppress the growth of non-target organisms that might result in false positive results. Differences in the ability of some of these methods to detect total coliform and E. coli, as well as suppress Aeromonas spp., a common cause of "false positive" results, have been observed. As a result, this study was undertaken to elucidate the strengths and weaknesses of each method. Water samples were collected from three geographically and chemically diverse groundwaters in Wisconsin. One-hundred milliliter aliquots were individually spiked with both low concentrations (one to ten organisms) and high concentrations (fifty to one-hundred) of each of five different total coliform organisms (Serratia, Citrobacter, Enterobacter, E. coli, & Klebsiella). These spiked samples were used to test the capability of ten enzyme-based test systems to both detect and enumerate the spiked organisms. In addition, 100 ml samples were independently spiked with two different strains of Aeromonas spp. at six different levels, to assess the ability of each enzyme-based test to suppress Aeromonas spp. Analysis of the data indicated that wide variability exists among USEPA approved tests to detect and quantify total coliforms, as well as suppress Aeromonas spp.     

Prevalence of bacterial pathogens in biofilms of drinking water distribution systems

Water for human consumption is required to be free from any bacteria that might pose a health risk. The presence of biofilms in the drinking water distribution system may play a role in the presence of potential pathogens in the drinking water supply. Ninety-five biofilm samples from various parts of South Africa were tested for the presence of Escherichia coli, Aeromonas, Pseudomonas, Salmonella, Shigella and Vibrio spp. Members of these genera were quantified by the three-tube most probable number (MPN) approach using enrichment broths and plating on selective agars. The heterotrophic culturable counts were determined for both the planktonic and biofilm phases of the samples. Biofilm density varied between 10 and 1.9 × 10⁹ colony forming units cm^-2. The 16S rRNA identity of the putative pathogenic isolates revealed that high numbers of Aeromonas, Pseudomonas, Klebsiella and Enterobacter were present, but no putative Salmonella and Shigella could be confirmed. None of the Pseudomonas isolates belonged to the pathogenic Pseudomonas aeruginosa or Pseudomonas mendocina while the Aeromonas isolates showed relatedness to known pathogenic members of this group.     

Identification of culturable stream water bacteria from urban, agricultural, and forested watersheds using 16S rRNA gene sequencing

Bacteria present in water samples taken on a weekly basis, from June 2004 through June 2005, from three streams, were cultured on Coliscan^® Easygel^® agar plates. Colonies representative of a variety of colors and morphologies were subjected to amplification and sequencing of a 1000–1100 nt portion of the 16S rRNA gene. A total of 528 colonies were sequenced; these categorized into 26 genera and 78 species. Of 175 dark blue/purple colonies presumed to be E. coli, sequence analysis indicated that 45 (25%) were actually other genera. For the urban stream Gwynns Falls Gwynns Run, E. coli was the most common genus/species encountered, followed by Klebsiella and Aeromonas. For Pond Branch, a stream located in a forested watershed, it was Serratia, followed by Yersinia and Aeromonas. For McDonogh (MCDN), a stream associated with Zea mays (corn) row crop agriculture, E. coli was the most frequently isolated genus/species, followed by Aeromonas and Enterobacter. ERIC-PCR genotyping of isolates from the most prevalent genera/species, indicated a high degree of diversity within-stream for E. coli and K. pneumoniae. Conversely, genotyping of Y. enterocolitica isolates indicated that some were shared between different streams.     

DNA-based real-time detection and quantification of aeromonads from fresh water beaches on Lake Ontario

The present study was designed to develop a novel, rapid, direct DNA-based protocol to enumerate aeromonads in recreational waters. An Aeromonas genus-specific real-time quantitative polymerase chain reaction (Q-PCR) protocol was developed and optimized using newly designed genus-specific oligonucleotide primers derived from the gyrase B subunit (GyrB) gene. A standard curve was developed based on the PCR protocol with a minimum quantification limit of 10 cell equivalents ml^-1 achieved using an autoclaved water sample from recreational water spiked with known quantities of an Aeromonas ATCC strain. The Q-PCR protocol was validated and applied to detect and quantify the total number of aeromonads in water samples collected from two fresh water beaches on Lake Ontario. The Q-PCR protocol revealed significantly higher numbers of aeromonads in all water samples than a culture-based assay at both beaches. Foreshore sand was found to serve as a reservoir of high concentrations of Aeromonas similar to this phenomenon noted for enteric bacteria like Eschershia coli. The new real-time Q-PCR protocol facilitated the rapid quantification of total numbers of Aeromonas cells present in recreational water samples in <3 hours without culturing.     

Analysis of Pyrethroid Insecticides in <Emphasis Type="Italic">Chironomus dilutus</Emphasis> Using Matrix Solid Phase Dispersion Extraction

A matrix solid phase dispersion method was developed to detect eight pyrethroid insecticides in the aquatic invertebrate, Chironomus dilutus. A mixture of silica gel, diatomaceous earth and primary/secondary amino solid absorbents were selected as the dispersion matrix, while 7% ethyl ether in hexane was used as the elution solvent. Method detection limits for the target pyrethroids ranged from 0.46 to 4.4 μg kg⁻¹, and recoveries were 63.5%–124.0%, 43.7%–116.0% and 53.1%–93.1% at spiked levels of 5, 20 and 50 μg kg⁻¹, respectively. The developed method was used to assess pyrethroid residues in laboratory-exposed and field-collected C. dilutus.     

Inactivation of Nitrosomonas europaea and pathogenic Escherichia coli by chlorine and monochloramine

The purpose of this study was to measure the chlorine and monochloramine inactivation kinetics of Nitrosomonas europaea at 21°C in the presence and absence of particles. The inactivation kinetics rates were compared with those obtained with Escherichia coli O157:H7. The results show that, in pure water, the use of free chlorine produced 4 log₁₀ of N. europaea inactivation at a CT value of 0.8 mg.min l^-1, whereas monochloramine yielded 4 log₁₀ of inactivation at CT values of approximately 9.9–16.4 mg.min l^-1. With E. coli, chlorine produced approximately 4 log₁₀ of inactivation at a CT of 0.13 mg.min l^-1, whereas monochloramine resulted in 4 log₁₀ of inactivation at a CT of approximately 9.2 mg.min l^-1. These results suggest that N. europaea is more resistant to monochloramine and chlorine than E. coli. Corrosion debris, soil material and wastewater had no statistically significant (p < 0.05) impact on the inactivation of N. europaea by either chlorine or monochloramine. It seems likely that the CT values present in distribution systems would be sufficient to control suspended cells of these two organisms, especially under conditions of breakpoint chlorination, which could be used to control nitrification. Adequate disinfection should prevent the growth of these organisms in a distribution system.     

Are the defined substrate-based methods adequate to determine the microbiological quality of natural recreational waters?

Monitoring the microbiological quality of water used for recreational activities is very important to human public health. Although the sanitary quality of recreational marine waters could be evaluated by standard methods, they are time-consuming and need confirmation. For these reasons, faster and more sensitive methods, such as the defined substrate-based technology, have been developed. In the present work, we have compared the standard method of membrane filtration using Tergitol-TTC agar for total coliforms and Escherichia coli, and Slanetz and Bartley agar for enterococci, and the IDEXX defined substrate technology for these faecal pollution indicators to determine the microbiological quality of natural recreational waters. ISO 17994:2004 standard was used to compare these methods. The IDEXX for total coliforms and E. coli, Colilert^®, showed higher values than those obtained by the standard method. Enterolert^® test, for the enumeration of enterococci, showed lower values when compared with the standard method. It may be concluded that more studies to evaluate the precision and accuracy of the rapid tests are required in order to apply them for routine monitoring of marine and freshwater recreational bathing areas. The main advantages of these methods are that they are more specific, feasible and simpler than the standard methodology.     

Bactericidal activity of Ag nanoparticle-impregnated fibreglass for water disinfection

A new bactericidal system composed of fibreglass impregnated with silver (Ag) nanoparticles was developed and tested. Silver content, particle size and distribution were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The antibacterial effectiveness was evaluated against Escherichia coli (E. coli, ATCC 29055). The minimum inhibitory loading was determined to be less than 1.8 wt% of silver nanoparticles per gram of fibreglass. In a 1 h immersion test, using a 0.1 mg fibreglass mat ml^-1, with 2.9 wt% loading of silver nanoparticles completely disinfected 100 ml of 10⁶ CFU ml^-1 of E. coli, dramatically outperforming activated carbon fibres impregnated with silver. Inactivation rate studies of 0.05 mg fibreglass mat ml^-1 (Ag 1.8 wt%) with 10¹² CFU E. coli displayed a 7 log reduction in 5 minutes. The activation and reuse of fibreglass (Ag 4.3 wt%) maintained its full effectiveness after two cycles of use and thermal regeneration at 350°C.     

Acute and Postexposure Effects of Ammonia Toxicity on Juvenile Barramundi (<Emphasis Type="Italic">Lates calcarifer</Emphasis> [Bloch])

Lethal and sublethal effects of ammonia toxicity to juvenile barramundi (Lates calcarifer) were investigated under laboratory conditions following the OECD guidelines for testing of chemicals. Acute toxicity was tested in a static nonrenewal system at pH 9.0 and temperature around 29°C. The 24-, 48-, and 96-h LC₅₀ values for barramundi were 3.89, 3.67, and 3.31 mg total ammonia N L⁻¹ and 1.59, 1.47, and 1.3 mg nonionized ammonia N L⁻¹, respectively. Estimated lethal concentrations indicated a relatively high sensitivity to acute ammonia toxicity for barramundi and equaled the 25th percentile most sensitive North American fish species with regard to the species mean acute value (USEPA 1999). A 3-week postexposure experiment on surviving individuals from the acute toxicity test, in clean water, indicated that exposure to acute concentrations up to 1.16 mg nonionized ammonia N L⁻¹ did not have any significant effects on growth.     

Fucus spp. as a Mercury Contamination Bioindicator in Costal Areas (Northwestern Portugal)

Mercury has been considered as one of the most important pollutants in coastal and estuarine areas. Efforts have been made to detect, as early as possible, the effects of this and other metals in several species. Macroalgae, particularly Fucus spp., have been widely used as biomonitors of metal pollution. In this study, three Fucus species (F. spiralis, F. vesiculosus and F. ceranoides) were collected from several sampling sites in Portugal. The concentrations of mercury were determined in three structural parts (holdfast, stipe and receptacles). Two different techniques were used to determine mercury concentrations. Almost all mercury concentrations (in sediments and in water) were below national and international standards. Mercury concentration in the specimens (0.012–0.061 μg g⁻¹ for receptacles, 0.028–0.221 μg g⁻¹ for stipe and 0.029–0.287 μg g⁻¹ for holdfast) was always higher that those obtained for the sediment (0.001–0.112 μg g⁻¹). With few exceptions the contrary was found for receptacles. In general, a good agreement between concentrations of mercury in sediment and Fucus was found. The results indicate that Fucus accumulate mercury and may be a suitable species for use in risk assessment for coast and estuarine areas, by providing valuable information regarding the levels of mercury that will be available for the consumers of Fucus spp.     

The Toxicity of Margosan-O, a Product of Neem Seeds, to Selected Target and Nontarget Aquatic Invertebrates

Margosan-O, an insecticide formulated from extracts of neem tree (Azadirachta indica) seed kernels, besides being toxic, also has feeding, oviposition-deterring, and growth-inhibitory effects on insects. This product, registered in the United States for ornamental plants, has been proposed for food crop use. However, little information exists on its effects on aquatic organisms. This study investigated toxicity of Margosan-O to the mosquito Culex spp., a possible target species, and to nontarget species—two crustaceans, Daphnia magna, Hyalella azteca, and a dipteran, Chironomus riparius. The 48-h EC50 value of 105 mg L⁻¹ for Culex spp. was significantly more toxic than for C. riparius (281 mg L⁻¹), not significantly different from D. magna (125 mg L⁻¹) but was significantly less toxic than for H. azteca (71 mg L⁻¹). A concentration of 20–30 mg L⁻¹ caused growth inhibitory effects in Culex spp. and C. riparius larvae and 40 and 84 mg L⁻¹ affected growth and reproduction in H. azteca and D. magna, respectively. Margosan-O may not be suitable for mosquito control since the concentrations required to control emergence may have some nontarget effects. Alternatively, the agricultural application of Margosan-O is also not expected to reduce the survival or produce growth and reproductive effects in nontarget aquatic organisms. However, based on estimated concentrations of less than 10 mg L⁻¹ in adjacent shallow bodies of water and recommendations for repeated applications, there should be concern that the threshold for chronic toxicity is too narrow. Received: 9 April 1997/Accepted: 7 April 1998     

After the flood: an evaluation of in-home drinking water treatment with combined flocculent-disinfectant following Tropical Storm Jeanne - Gonaives, Haiti, 2004

Tropical Storm Jeanne struck Haiti in September 2004, causing widespread flooding which contaminated water sources, displaced thousands of families and killed approximately 2,800 people. Local leaders distributed PūR^®, a flocculent-disinfectant product for household water treatment, to affected populations. We evaluated knowledge, attitudes, practices, and drinking water quality among a sample of PūR^® recipients.     

Boron Concentration in Water, Sediment and Different Organisms around Large Borate Deposits of Turkey

Boron is an essential nutrient for plants and an essential element for many organisms, but can be toxic to aquatic and terrestrial organisms above certain concentrations. The aim of this research was to determine boron concentrations in water, sediment and biotic samples (Gammaridae spp.-Crustacea, Helix sp.-Gastropoda, Donax sp.-Bivalvia, Helobdella sp.-Hirudinae, Ephemeroptera nymph, Chrinomidae larvae, Tipulidae larvae-Insecta, Rana sp.-Amphibia, Natrix sp.-Serpentes, fish sample Leiscus cephalus (Linnaeus, 1758) and leaves of Salix sp.-Salicacea from Seydi Stream (Kırka-Eskişehir). Our results have shown that boron concentrations of the Seydi Stream water is higher than the Turkish Environmental Guidelines standard (>1 mg L⁻¹) and in Europe (mean values typically below 0.6 mg L⁻¹).     

Toxicity of Metal Pyrithione Photodegradation Products to Marine Organisms with Indirect Evidence for Their Presence in Seawater

We evaluated the acute toxicities of the metal pyrithiones (MePTs)—copper pyrithione (CuPT) and zinc pyrithione (ZnPT)—to four species of marine algae and a marine crustacean (Tigriopus japonicus). We also performed acute toxicity tests using six of the main MePT photodegradation products: pyridine-N-oxide (PO); 2-mercaptopyridine (HPS); pyridine-2-sulfonic-acid (PSA); 2-mercaptopyridine-N-oxide (HPT); 2,2′-dithio-bis-pyridine ([PS]₂); and 2,2′-dithio-bis-pyridine-N-oxide ([PT]₂)—and three marine organisms representing three trophic levels: an alga (Skeletonema costatum), a crustacean (T. japonicus), and a fish (Pagrus major). The acute toxicity values (72-h EC₅₀) of CuPT, ZnPT, HPT, (PT)₂, (PS)₂, HPS, PO, and PSA for S. costatum, which was the most sensitive of the test organisms to the chemicals tested, were 1.5, 1.6, 1.1, 3.4, 65, 730, >100,000, and >100,000 μg l⁻¹, respectively. CuPT was detected in the growth media used for S. costatum tests and in seawater containing HPT or (PT)₂; the concentration of CuPT in seawater containing HPT was highly dependent on the Cu²⁺ concentration. These results indicate that in the presence of sufficient Cu²⁺, the toxicities of HPT and (PT)₂ should be assessed as CuPT because in Japan MePTs are most frequently used as antifouling booster biocides in conjunction with cuprous oxide.     

Accumulation of Organotin Compounds in the Deep-Sea Environment of Nankai Trough, Japan

The concentration of butyltin (BT) and phenyltin (PT) compounds was measured in sediment, gastropods (Colliloconcha nankaiensis), sea cucumbers (Psychropotes verrucosa), galatheid crabs (Munidopsis albatrossae and Munidopsis subsquamosa), and bivalves (Clyptogena tsubasa and Clyptogena nautilei) collected from the Nankai Trough (water depth about 3000 m). Sediment at depths of up to 1 cm was taken by a core sampler and at depths of up to 15 cm was taken by rake. The concentration of BTs in sediment core from a depth of 0–1 cm (0.041 mg kg⁻¹ dry) was higher than in sediment core from 0–15 cm (0.021 mg kg⁻¹ dry). The relative proportion of different BTs in the 0–1-cm sediment core was similar to that in the 0–15-cm sediment core, but the concentration of PTs in the former (0.028 mg kg⁻¹ dry) was lower than in the latter 0–15 cm (0.052 mg kg⁻¹ dry). Organotin (OT) compounds were also detected in deep-sea organisms. The means of BT concentrations in C. nankaiensis, P. verrucosa, M. albatrossae, M. subsquamosa, Cl. tsubasa, and Cl. nautilei were, respectively, 0.089, 0.057, 0.018, 0.016, 0.019, and 0.026 mg kg⁻¹. The corresponding concentrations of PTs were 0.212, 0.363, 0.166, 0.186, 0.030, and 0.025 mg kg⁻¹. High concentrations of BTs and PTs were observed in gastropods and sea cucumbers. The species of deep-sea organism can be classified by δ¹³C value into two groups (A and B). The organisms in group A use organic matter chemosynthesized by symbiotic bacteria while those in group B depend on photosynthesis carried out near the surface by phytoplankton. No difference in BT or TBT concentration is observed between the two groups, but PT and TPT concentrations are higher in group B. Trophic levels in the food chain are often estimated using δ¹⁵N values. Group B showed a higher trophic level than group A. Although no change in BT and TBT concentration was observed to accompany increases of δ¹⁵N values, PT and TPT concentrations generally increased with increasing δ¹⁵N values. The compositions of BTs in deep-sea organisms were calculated. An increasing proportion of MBT and a declining proportion of DBT were observed at higher trophic levels. No correlation between the shell length of Cl. nautilei and BT or PT concentration was observed. The average partition coefficients of TBT for C. nankaiensis, P. verrucosa, M. albatrossae, M. subsquamosa, Cl. Tsubasa, and Cl. nautilei were 2.6, 0.72, 0.63, 0.19, 0.43, 0.30, and 0.46.     

Body Residues and Responses of the Midge Chironomus riparius to Sediment-Associated 2,4,5-Trichlorophenol in Subchronic and Chronic Exposures

Subchronic and chronic toxicity of sediment-associated 2,4,5-trichlorophenol to the midge Chironomus riparius was determined by conducting a 10-day growth and a 50-day emergence tests with spiked lake sediment (nominal initial TCP concentrations were 25, 51, 101, 203, 304 and 405 μmol kg⁻¹ dry weight in the growth test and 25, 76, 152 and 304 μmol kg⁻¹ dry weight the emergence test). In addition, we measured the residue of chlorophenol in larval tissue and made an attempt to relate it with the observed adverse biological responses. The larvae were exposed individually to avoid density-dependent effects of mortality on food ration and growth of the surviving larvae. In the growth test, mortality was low at sediment concentrations ≤193 μmol TCP kg⁻¹, but it increased sharply at the higher concentrations being 37 and 94% at 334 and 441 μmol kg⁻¹ DW, respectively. The effect of sediment TCP concentration on larval mortality was highly significant (10-day LC50 337 μmol TCP kg⁻¹ dry sediment) in the growth test. In the emergence test, however, mortality was low (3–13%) at all concentrations. TCP did not affect larval growth at the concentrations used. The concentration of TCP in the whole larvae after the 10-day exposure was proportional to sediment concentration, being at highest 160 μmol kg⁻¹ fresh weight. When the average body residues of TCP were below 80 μmol kg⁻¹, mortality was low, but it increased when the body residue approached 100 μmol kg⁻¹. After the 10-day exposure, the body residue, at which 50% of the larvae survived (CBR50) was 113 μmol g⁻¹. TCP exposure accelerated larval development and the midges exposed to 171 and 324 μmol TCP kg⁻¹ emerged earlier than those in the other concentrations or in the control sediment. In natural environments, sediment-associated chlorophenolics are probably not a major environmental problem to benthic fauna because concentrations similar to that which we observed to cause adverse effects to C. riparius (>60 mg kg⁻¹ dry sediment) are rare. Received: 15 June 1998/Accepted: 5 January 1999     

Pesticide and Pathogen Contamination of Vegetables in Ghana’s Urban Markets

The objective of the study was to determine and compare the current level of exposure of the Ghanaian urban population to hazardous pesticide and fecal coliform contamination through the consumption of fresh vegetables produced in intensive urban and periurban smallholder agriculture with informal wastewater irrigation. A total of 180 vegetable samples (lettuce, cabbage, and spring onion) were randomly collected under normal purchase conditions from 9 major markets and 12 specialized selling points in 3 major Ghanaian cities: Accra, Kumasi and Tamale. The samples were analyzed for pesticide residue on lettuce leaves, total and fecal coliforms, and helminth egg counts on all three vegetables. Chlopyrifos (Dursban) was detected on 78% of the lettuce, lindane (Gamalin 20) on 31%, endosulfan (Thiodan) on 36%, lambda-cyhalothrin (Karate) on 11%, and dichloro-diphenyl-trichloroethane on 33%. Most of the residues recorded exceeded the maximum residue limit for consumption. Vegetables from all 3 cities were fecally contaminated and carried fecal coliform populations with geometric mean values ranging from 4.0 × 10³ to 9.3 × 10⁸ g^–1 wet weight and exceeded recommended standards. Lettuce, cabbage, and spring onion also carried an average of 1.1, 0.4, and 2.7 helminth eggs g^–1, respectively. The eggs were identified as those of Ascaris lumbricoides, Ancylostoma duodenale, Schistosoma heamatobium, and Trichuris trichiura. Because many vegetables are consumed fresh or only slightly cooked, the study shows that intensive vegetable production, common in Ghana and its neighboring countries, threatens public health from the microbiologic and pesticide dimensions. Standard recommendations to address this situation (better legislations, law enforcement, or integrated pest management) often do not match the capabilities of farmers and authorities. The most appropriate entry point for risk decrease that also addresses postharvest contamination is washing vegetables before food preparation at the household or “chop” bar (street restaurant).     

Carba NP test for the detection of carbapenemase-producing Pseudomonas aeruginosa

IntroductionThe Carba NP test is a biochemical chromogenic assay developed to detect carbapenemase activity. Variable performance has been reported according to the type of carbapenemase and bacterial species involved. We aimed to describe the benefit of the Carba NP test and its commercial version, the RAPIDEC® CARBA NP, to detect carbapenemase-producing Pseudomonas aeruginosa.MethodsPubMed and ScienceDirect databases were searched. The following data was collected from each included study: research protocol, molecular profile of the tested strains, and sensitivity and specificity of the test used to detect carbapenemase-producing P. aeruginosa.ResultsThirty-four studies were included. The most frequently tested strains were metallo-beta-lactamase producers. The pooled sensitivity to detect carbapenemase-producing P. aeruginosa with the original Carba NP test, the Clinical and Laboratory Standards Institute (CLSI) Carba NP test, and the RAPIDEC® CARBA NP was 92%, 95%, and 96%, respectively. The pooled specificity was 99% with the original and the CLSI Carba NP tests, and 92% with the RAPIDEC® CARBA NP. Several studies evaluated modified versions of the Carba NP test to detect carbapenemase-producing P. aeruginosa, with reported sensitivity and specificity exceeding 90% in most cases.ConclusionThe Carba NP test allows for fast screening and easy handling as well as optimal performance to detect carbapenemase-producing P. aeruginosa. These findings should be confirmed by further studies including a larger cohort of isolates and various types of carbapenemases, mainly non-metallo-beta-lactamases.     

Diagnostic value of the ISAC® allergy chip in detecting latex sensitizations

Purpose

Latex allergy can be diagnosed by different test methods such as IgE quantification, Western blot, cellular antigen stimulation test (CAST), and in vivo methods [e.g. skin prick test (SPT)]. Phadia provides two modern methods using recombinant latex allergens: ImmunoCAP^® and the Immuno Solid-phase Allergen Chip (ISAC^®), which enables simultaneous determination of specific IgE against five latex allergens. We compared the diagnostic sensitivity of the ISAC^® test kit and the conventional Hev b 5—spiked ImmunoCAP^® latex extract.

Methods

Forty sera were sampled from subjects with suspected natural rubber latex (NRL) allergy. These patients had positive SPT to NRL extract, positive NRL Western blots, and positive results in the CAST. All sera were analysed using the ISAC^® and recombinant NRL ImmunoCAP^® allergens and compared to the results of 20 negative control sera.

Results

Only 22 of the 40 subjects (55 %) showed positivity to at least one latex allergen on the ISAC^® (sensitivity ISAC^® 55 %). The sensitivity of the ImmunoCAP^® latex extract was 70 %. The most frequently detected sensitization was against Hev b 6.01 (n = 12). When the serum samples were tested with all recombinant ImmunoCAP^® allergens, three additional sensitizations against latex could be detected compared to the ISAC^®.

Conclusions

Microarrays do offer many potential benefits such as elegant simultaneous determination of sensitizations against different NRL allergens with minimal amounts of serum. However, a negative NRL test result should be regarded with caution and at least be confirmed by other in vitro methods.     

The Bacteriological Safety and Antimicrobial Susceptibility of Bacteria Isolated from Street-Vended White Lupin (Lupinus Albus) in Bahir Dar,Ethiopia

Background

Whereas street vended foods are readily available sources of meals for many people across the world, the microbial safety of such food is always uncertain. In developing countries the major sources of food-borne illnesses are street vended foods. The aim of this study was thus to assess the prevalence and antibiogram of bacteria from white lupin in Bahir Dar Town.

Methods

A total of 40 samples were processed for detection of indicator bacteria and pathogens from December, 2011 to February, 2012 using standard bacteriological techniques. Antimicrobial susceptibility test was performed using the Kirby-Bauer disk diffusion method.

Results

The total coliform counts were 954.2±385 and 756.2±447.3 at the surface and the core of white lupin, respectively. On the other hand, the fecal coliform counts were 880.9±396.6 and 662.1±461.9 at surface and the core, respectively. There was a statistically significant difference in total colifoms and fecal coliform counts between the surface and core of white lupin (p <0.05). Escherichia coli 29 (72.5%), Salmonella spp. 23 (57.5%) and Shigella spp. 8 (20%) were the pathogens isolated. Most bacterial isolates were resistant to tetracycline, cotriamoxazole and erythromycin whereas many of them were sensitive to chloramphenicol, nalidixic acid, gentamicin and ciprofloxacin. The overall multiple antimicrobial resistances rate was 75%.

Conclusion

This study revealed contamination of white lupin and a potential health to consumers, and the bacteria isolated showed high rates of multiple drug resistance. Surveillance of antimicrobial resistance should be done on food borne pathogens. In addition, further studies should be conducted on the bacteriological quality of waters used for soaking white lupin.