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High-Level Resistance to Ceftazidime Conferred by a Novel Enzyme, CTX-M-32, Derived from CTX-M-1 through a Single Asp240-Gly Substitution. Monica Cartelle, 2004.A clinical strain of Escherichia coli isolated from pleural liquid with high levels of resistance to cefotaxime, ceftazidime, and aztreonam harbors a novel CTX-M gene (blaCTX-M-32) whose amino acid sequence differs from that of CTX-M-1 by a single Asp240-Gly substitution . Moreover, by site-directed mutagenesis we demonstrated that this replacement is a key event in ceftazidime hydrolysis Comparison of Ribotyping and Repetitive Extragenic Palindromic-PCR for Identification of Fecal Escherichia coli from Humans and Animals. C. Andrew Carson, 2003.This report compares the performances of two popular genotypic methods used for tracking the sources of fecal pollution in water, ribotyping and repetitive extragenic palindromic-PCR (rep-PCR) . The rep-PCR was more accurate, reproducible, and efficient in associating DNA fingerprints of fecal Escherichia coli with human and animal hosts of origin . Genetic Diversity and Temporal Variation in the Cyanophage Community Infecting Marine Synechococcus Species in Rhode Island's Coastal Waters. Marcia F. Marston, 2003.The cyanophage community in Rhode Island's coastal waters is genetically diverse and dynamic . Cyanophage abundance ranged from over 104 phage ml-1 in the summer months to less then 102 phage ml-1 during the winter months . Thirty-six distinct cyanomyovirus g20 genotypes were identified over a 3-year sampling period; however, only one to nine g20 genotypes were detected at any one sampling date . Phylogenetic analyses of g20 sequences revealed that the Rhode Island cyanomyoviral isolates fall into three main clades and are closely related to other known viral isolates of Synechococcus spp . Extinction dilution enrichment followed by host range tests and PCR restriction fragment length polymorphism analysis was used to detect changes in the relative abundance of cyanophage types in June, July, and August 2002 . Temporal changes in both the overall composition of the cyanophage community and the relative abundance of specific cyanophage g20 genotypes were observed . In some seawater samples, the g20 gene from over 50% of isolated cyanophages could not be amplified by using the PCR primer pairs specific for cyanomyoviruses, which suggested that cyanophages in other viral families (e.g., Podoviridae or Siphoviridae) may be important components of the Rhode Island cyanophage community .
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