Aly E. Abo-Amer

Role of wild birds as carriers of multi-drug resistant Escherichia coli and Escherichia vulneris

Emergence and distribution of multi-drug resistant (MDR) bacteria in environments pose a risk to human and animal health. A total of 82 isolates of Escherichia spp. were recovered from cloacal swabs of migrating and non-migrating wild birds. All bacterial isolates were identified and characterized morphologically and biochemically. 72% and 50% of isolates recovered from non-migrating and migrating birds, respectively, showed positive congo red dye binding (a virulence factor). Also, hemolysin production (a virulence factor) was showed in 8% of isolates recovered from non-migrating birds and 75% of isolates recovered from migrating birds. All isolates recovered from non-migrating birds were found resistant to Oxacillin while all isolates recovered from migrating birds demonstrated resistance to Oxacillin, Chloramphenicol, Oxytetracycline and Lincomycin. Some bacterial isolates recovered from non-migrating birds and migrating birds exhibited MDR phenotype. The MDR isolates were further characterized by API 20E and 16S rRNA as E. coli and E. vulneris. MDR Escherichia isolates contain ~1–5 plasmids of high-molecular weights. Accordingly, wild birds could create a potential threat to human and animal health by transmitting MDR bacteria to water streams and other environmental sources through their faecal residues, and to remote regions by migration.

Biosorption of aluminum, cobalt, and copper ions by Providencia rettgeri isolated from wastewater

Twenty‐three bacterial isolates from polluted water and soil were screened for heavy metals resistance (i.e., Al3+, Co2+, and Cu2+). The most potent isolate was identified by morphological characteristics, biochemical tests and confirmed by API20E kits as Providencia rettgeri MAM‐4. Removal of Al3+ from aqueous solution by P. rettgeri is more efficient (∼fourfold) than that by B. cereus ATCC 11778 (a comparison strain) at concentration of 200 mg L−1 Al3+. P. rettgeri was able to remove Co2+ more than B. cereus ATCC 11778 at concentration of 50 mg L−1 Co2+. Inoculation of P. rettgeri into clay enhanced significantly the removal of Al3+, Co2+, and Cu2+. P. rettegri MI (mutant strain) was able to tolerate more Al3+ than that of the parent strain. P. rettgeri was resistant to 7 out of 15 antibiotics tested. P. rettgeri MAM‐4 isolated from wastewater had ability to remove Al3+, Co2+, and Cu2+ efficiently from aqueous media; and enhanced significantly metal biosporption by clay. This study has revealed that P. rettgeri could be employed as an effective and economic technology for the removal such metal elements from polluted environment.

Molecular approach and bacterial quality of drinking water of urban and rural communities in Egypt

Water is necessary to life so when supplied as drinking water to consumers, a satisfactory quality must be maintained. In Egypt, infectious intestinal diseases are the major cause of hospitalization in almost all regions. The purpose of this study was to evaluate the microbiological quality of treated and untreated water samples from urban and rural communities. Thirty-five samples of treated (chlorinated) water from taps, 25 samples of bottled water and 15 samples of hand pump (untreated) water collected from different cities alongside the River Nile during the winter of 2007 were bacteriologically tested for safety as drinking water. This study indicated good quality of tap water and bottled water. The untreated water samples (hand pumps) were, however, slightly contaminated by faecal coliforms, faecal enterococci, Clostridium perfringens, Salmonella and Shigella. Consequently, the consumers in the villages receiving water through hand pumps are often exposed to the risk of water-borne diseases due to inadequate treatment of the raw water. Therefore, there are guidelines necessary to protect groundwater quality. Moreover, PCR-amplified by some functional gene fragments such as dctA, dcuB, frdA, dcuS and dcuR genes of the E. coli was adapted for use as a non-cultivation-based molecular approach for detection of E. coli populations from water samples without the need for pure and identified cultures.

Isolation and Molecular Characterization of Heavy Metal-Resistant Alcaligenes faecalis from Sewage Wastewater and Synthesis of Silver Nanoparticles

Environmental pollution with toxic heavy metals is increasing throughout the world alongside industrial development. Microorganisms and microbial products can be highly efficient bioaccumulators of soluble and particulate forms of metals, especially dilute external solutions. Microbe related technologies (Biotechnology) may provide an alternative or additive conventional method for metal removal or metal recovery. This study dealt with isolation, identification and characterization of heavy metal-resistant (Pb2+, Cd2+, Al3+, Cu2+, Ag2+ and Sn2+) bacteria from sewage wastewater at Taif Province, Saudi Arabia. Nine bacterial isolates were selected by using an enrichment isolation procedure based on high level of heavy metal resistance. All the isolates showed high resistance to heavy metals with Minimum Inhibitor Concentration (MIC) ranging from 800 μg/ml to 1400 μg/ml. All nine resistant isolates showed multiple tolerances to heavy metals. On the basis of morphological, biochemical and 16S rRNA characterization, the most potent isolates (Cd1-1, Ag1-1, Ag1-3 and Sn1-1) were identified as Alcaligenes faecalis. Scanning electron microscope analysis showed that the morphology of Alcaligenes faecalis Ag1-1 was unchanged after growth in medium without and with addition of Ag2+ indicative Ag2+ is not toxic to the isolate under the conditions tested. The ability of Alcaligenes faecalis Ag1-1 to synthesize sliver nanoparticles was examined. The heavy metal-resistant bacteria obtained could be useful for the bioremediation of heavy metal-contaminated environment.

Isolation and Molecular Characterization of Heavy Metal-Resistant Azotobacter chroococcum from Agricultural Soil and Their Potential Application in Bioremediation

Pollution of soil with heavy metals, herbicides, antibiotics and other chemicals is known to have a negative effect on microbial activities. Therefore, the aim of this study was to isolate cultures of Azotobacter sp. from polluted and unpolluted soils and to study the effect of these pollutants on their growth. A total of 120 Azotobacter sp. were isolated from soils irrigated with wastewater (contaminated soils) and groundwater (uncontaminated soils). These isolates were screened for resistance to heavy metals, herbicide and antibiotics. Also, the soils from which the cultures were isolated were analyzed for the concentrations of Zn2+, Cd2+, Cu2+, Pb2+ and Mn2+ they contained. Contaminated soil showed high levels of heavy metals as compared to uncontaminated soil. The size of the Azotobacter population in contaminated soil was lower than that in uncontaminated soil. Of the Azotobacter isolates, 64 that were recovered from contaminated soil exhibited high resistance to heavy metals (Hg2+, Cd2+, Cu2+, Cr3+, Co2+, Ni2+, Zn2+ and Pb2+) and herbicide 2,4-D compared to 56 isolates from uncontaminated soil. Also, isolates from contaminated soil showed high resistance to chloramphenicol, nitrofurantoin and co-trimoxazole compared to those isolated from uncontaminated soil. The majority of Azotobacter isolates from contaminated soil showed multiple-resistance to different metal ions and antibiotics. All isolates failed to grow at pH less than 6. Salt concentration (5%) was found to be inhibitory to all isolates. The most potent isolates from contaminated soil that showed multiresistance to all substances tested were identified on the basis of morphological and biochemical characteristics, and 16S rRNA as A. chroococcum. These resistant isolates could be employed in contaminated soils and/or bioremediation.

Isolation of Bdellovibrio sp. from Wastewater and Their Potential Application in Control of Salmonella paratyphi in Water

ABSTRACT The problem of the increasing resistance of bacteria to conventional antibiotics gives the bacteria Bdellovibrio a great utility as a potential alternative source of antibiotics. Therefore, the preliminary goal of the present study was isolation and identification of antibiotic-resistant bacteria used as prey organisms for isolated Bdellovibrio sp., by xylose lysine desoxycholate (XLD) agar from different types of water in the Taif area, Saudi Arabia, and also to investigate water quality. Four antibiotic-resistant isolates of Salmonella sp. which were susceptible to Bdellovibrio were identified by morphological, biochemical and 16S rRNA characterization as Salmonella paratyphi. Seventeen strains of Bdellovibrio sp. were isolated from sewage wastewater using isolated S. paratyphi as prey bacteria by a double-layer plate. Only one of them causing a large plaque after 48 h of incubation at 37°C was designated Bdellovibrio AOA12. The shape of Bdellovibrio was confirmed by morphological characterization and electron microscopy. Bdellovibrio could lyse four antibiotic-resistant Gram-negative bacterial strains of Salmonella paratyphi but could not lyse Gram-positive bacteria such as Staphylococcus aureus and Bacillus cereus. The kinetic lysis of the Bdellovibrio as predator to four isolates of antibiotic-resistant Salmonella paratyphi as prey organisms was demonstrated. The results suggest that it may be possible to utilize Bdellovibrio to control antibiotic-resistant S. paratyphi in water.

Isolation and antimicrobial resistance of Escherichia coli isolated from farm chickens in Taif, Saudi Arabia

OBJECTIVES Poultry is one of the main sources of food in the world. Antimicrobial-resistant Escherichia coli can be transmitted to humans by contact with poultry waste or by contaminated poultry products, contributing to the increasing crisis of antimicrobial resistance. This study aimed to determine the incidence of antimicrobial resistance in E. coli isolated from chickens in Taif province, Saudi Arabia, and to identify the genes responsible for any resistance observed. METHODS A total of 150 cloacal swabs were aseptically obtained from chickens from different farms, from which 180 colonies of E. coli were identified using standard microbiology procedures. Antimicrobial susceptibility testing was performed by the Kirby-Bauer disk diffusion method. The genes blaSHV, aac(3)-IV, tet(A), tet(B), aadA1, catA1, cmlA, ere(A) and sul1 were detected by PCR. RESULTS Most of the E. coli isolates showed resistance to oxacillin (99%), lincomycin (98%) and oxytetracycline (97%). The prevalence of resistance to chloramphenicol (73%), ciprofloxacin (59%) and ampicillin (51%) was lower. Genes conferring resistance to β-lactams (blaSHV) and tetracyclines [tet(A) and tet(B)] were observed at prevalences of 96% and 95%, respectively, among the E. coli isolates. Chloramphenicol (catA1 and cmlA) and erythromycin [ere(A)] resistance genes showed prevalences of 72% and 15%, respectively, whereas gentamicin [aac(3)-IV], streptomycin (aadA1) and sulfonamide (sul1) resistance genes were detected in 20%, 20% and 10% of the studied isolates, respectively. CONCLUSION A significant prevalence of antimicrobial resistance genes was observed among E. coli isolates from farm chickens, supporting strict regulatory procedures for the use of antimicrobial agents.