Phenotypic and Molecular Characterization of AmpC ß-Lactamases among Escherichia coli a Prospective Study in Southeast Iran.

BACKGROUND: Escherichia coli (E. coli) causes serious health problems due to the high rate of its resistance to common antibiotics. AmpC ß-lactamases are important cephalosporinases, encoded by E. coli chromosome, that cause resistance to cefoxitin, cephalothin, most penicillins, cefazolin, and beta-lactamase inhibitor-beta-lactams. This study aimed to detect AmpC ß-lactamases among E. coli strains at three educational hospitals in Iran. METHODS: Two hundred and thirty samples were recovered from the three educational hospitals in Zahedan City in southeast Iran. Sixty E. coli strains were identified by biochemical and differential tests. E. coli strains with extended-spectrum ß-lactamases (ESBLs) were selected by disk-diffusion agar method and combined diffuse disc test. Finally, selected isolates were screened by polymerase chain reaction (PCR) for the common AmpC genotypes MOX, FOX, CIT, DHA, EBC, and ACC. RESULTS: Out of 60 E. coli strains, 13 isolates (21.7%) were ESBL positive and 7 strains (11.6%) were phenotypically AmpC beta-lactamase producers. Three isolates had CIT (23.1%), 5 had DHA (38.5%), 4 had EBC (30.8%), and 1 had ACC (7.7%) genotypes. CONCLUSIONS: The high prevalence of AmpC-producing E. coli strains in hospital settings is an important challenge for health care systems. Data about beta-lactamase producers that are crucial for controlling bacterial resistance should be upgraded.

Development and Characteristics of Novel PLGA-chitosan as a New Nanocarrier for Pentavalent Vaccine Delivery.

BACKGROUND: Lately, the employment of nano-carriers has been known as an optimistic means of drug and vaccine delivery. OBJECTIVE: Nano vaccines are a novel tier of vaccines that can develop humoral and cellular immune responses and can be introduced as a practical and secure nano vaccine candidate for the prevention of diseases. The purpose of this study was to accomplish and use biodegradable nano-carriers for the synthesis of pentavalent vaccine and immunogenicity evaluation in the animal models. The PLGA nanoparticle was prepared and modified with chitosan nanoparticles. Nano-carrier PLGA-chitosan was loaded by the DTP-HepB-Hib antigens and confirmed by DLS, SEM, TEM and FT-IR, then in vitro loading and release were evaluated. Toxicity was assessed by the MTT method in the Hec293 cells. Antigenicity evaluation and histopathological study were conducted by injection of new nano pentavalent vaccines in the BALB/c mice and the immune response was measured in the serum samples through an indirect ELISA method. RESULTS: Conclusions drawn from the current study exhibited the plausible ability of nano-carrier to deliver the vaccine. A notable increase was shown in total IgG and IgM antibodies examined in mice vaccinated with new nano vaccines. The histopathological study in the treated mice showed no toxicity in the vital organs of mice. CONCLUSION: The engineered vaccine delivery system showed the ability to induce robust immune responses and also suitability features of the PLGA-chitosan as a promising carrier to improve vaccine delivery.

Characterization of plant-growth-promoting traits of Acinetobacter species isolated from rhizosphere of Pennisetum glaucum.

A total of 31 Acinetobacter isolates were obtained from the rhizosphere of Pennisetum glaucum and evaluated for their plant-growth-promoting traits. Two isolates, namely Acinetobacter sp. PUCM1007 and A. baumannii PUCM1029, produced indole acetic acid (10-13 microgram/ml). A total of 26 and 27 isolates solubilized phosphates and zinc oxide, respectively. Among the mineral-solubilizing strains, A. calcoaceticus PUCM1006 solubilized phosphate most efficiently (84 mg/ml), whereas zinc oxide was solubilized by A. calcoaceticus PUCM1025 at the highest solubilization efficiency of 918%. All the Acinetobacter isolates, except PUCM1010, produced siderophores. The highest siderophore production (85.0 siderophore units) was exhibited by A. calcoaceticus PUCM1016. Strains PUCM1001 and PUCM1019 (both A. calcoaceticus) and PUCM1022 (Acinetobacter sp.) produced both hydroxamate- and catechol-type siderophores, whereas all the other strains only produced catechol-type siderophores. In vitro inhibition of Fusarium oxysporum under iron-limited conditions was demonstrated by the siderophore-producing Acinetobacter strains, where PUCM1018 was the most potent inhibitor of the fungal phytopathogen. Acinetobacter sp. PUCM1022 significantly enhanced the shoot height, root length, and root dry weights of pearl millet seedlings in pot experiments when compared with controls, underscoring the plant-growth-promoting potential of these isolates.