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The authors discuss the move of the U.S. National Science Advisory Board for Biosecurity to explain its recommendations on the communication of experimental work on H5N1 influenza. They mentions that highly pathogenic avian influenza A infection has been a serious public health concern since its identification in Asia. The state that to date, no human pandemic has occurred.

Presents an introduction to the August 16, 2005 issue of the journal "Clinical Infectious Diseases."

Editorial. Comments on the concern on the proliferation of antibacterial containing consumer products worldwide. Evidence of the potential negative consequences; Guidelines on the use of surface chemicals; Maintenance of a high concentration of ingredients on surfaces for the antimicrobial job.

Presents a correspondence on infectious diseases. Carriage of antibiotic-resistant fecal bacteria; Detection of antibiotic resistance in the fecal flora; Diagnosis of tuberculosis.

Editorial. Focuses on bacterial resistance to multiple antibiotics. Factors that contribute to antimicrobial resistance; Acquisition of survival mechanism; Need to examine the ecology of the commensal or non-clinical bacteria.

Discusses a study by Telenti, et al, in the March 13, 1993 issue of `Lancet.' Detection of a specific mutation site in Mycobacterium tuberculosis that is associated with resistance to rifampicin; Details.

Looks at antimicrobial resistance, focussing on the behavior of bacterial agents. Introduction of resistant bacteria from hospital; Results of studies of emerging resistant bacteria; Results of studies concerning resistance in bacteria.

Focuses on triclosan. Use as an anti-bacterial and anti-fungal agent; Experiments with five independent triclosan-resistant mutants of E. coli K12 strain; Results; Effect of ethanol and diazaborine; Use in inhibiting E. coli and Salmonella typhimurium; The most resistant triclosan mutant.

The MarA protein of Escherichia coli can both activate and repress the initiation of transcription, depending on the position and orientation of its degenerate 20-bp binding site ("marbox") at the promoter. For all three known repressed genes, the marbox overlaps the promoter. It has been reported that MarA represses the rob promoter via an RNA polymerase (RNAP)-DNA-MarA ternary complex. Under similar conditions, we found a ternary complex for the repressed purA promoter also. These findings, together with the backwards orientation of repressed marboxes, suggested a unique interaction of MarA with RNAP in repression. However, no repression-specific residues of MarA could be found among 38 single-alanine replacement mutations previously shown to retain activation function or among mutants from random mutagenesis. Mutations Thr12Ala, Arg36Ala, Thr95Ile, and Pro106Ala were more damaging for activation than for repression, some up to 10-fold, so these residues may play a specific role in activation. We found that nonspecific binding of RNAP to promoterless regions of DNA was presumably responsible for the ternary complexes seen previously. When RNAP binding was promoter specific, MarA reduced RNAP access to the rob promoter; there was little or no ternary complex. These findings strongly implicate steric hindrance as the mechanism of repression of rob by MarA. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article "Sampling the Antibiotic Resistome," by V.M. D'Costa in the January 20, 2006 issue.

A letter to the editor is presented in response to a study on the prevalence and outcome of bacteremia among rural children in Kenya by researcher James A. Berkley and associates in the January 6, 2005 issue.

This editorial asserts that resistance to antibiotics is a problem that confronts all of us, thwarting treatment of inpatients and outpatients and compromising therapy for animals, fish, and agricultural crops. A discussion is presented about a strain of Salmonella enterica serotype typhimurium, known as definitive type 104 (DT104), in the United States that is resistant to five drugs. the strain's presence in Europe and the United States is mentioned.

Knowledge of the genetic basis for bacterial survival and persistence in soil is a critical component in the development of successful biological control strategies and for understanding the ecological success of bacteria. We found a locus specifying polyphosphate kinase (ppk) and a nonpredicted antisense RNA (iiv8) in Pseudomonasfluorescens Pf0-1 to be necessary for optimal competitive fitness in LB broth culture and sterile loam soil. Pf0-1 lacking ppk and iiv8 was more than 10-fold less competitive against wild-type Pf0-1 in sterile loam soil low in inorganic phosphate. Studies indicated that ppk, and not iiv8, was required for competitive fitness. No role for iiv8 was identified. While a ppk and iiv8 mutant of Pf0-1 did not have increased sensitivity to osmotic, oxidative, and acid stress, it was more sensitive to elevated temperatures in laboratory medium and during growth in sterile soil. ppk was shown to be part of the Pho regulon in P. fluorescens, being upregulated in response to a low external Pi concentration, Of importance, overproduction of polyphosphate in the soil environment appears to be more deleterious than production of none at all. Our findings reveal a new role for polyphosphate (and the need for proper regulation of its production) in competitive fitness of P. fluorescens in laboratory and soil environments. [ABSTRACT FROM AUTHOR]

The Escherichia coli marRAB operon specifies two regulatory proteins, MarR (which represses) and MarA (which activates expression of the operon). The latter controls expression of multiple other chromosomal genes implicated in cell physiology, multiple drug resistance and virulence. Using randomly cloned E. coli DNA fragments in the bacterial adenylate cyclase two-hybrid system, we found that transketolase A (TktA) interacts with MarR. Purified (6H)-TktA immobilized on NiNTA resin-bound MarR. Overexpression or deletion of tktA showed that TktA interfered with MarR repression of the marRAB operon. Deletion of tktA increased antibiotic and oxidative stress susceptibilities, while its overexpression decreased them. Hydrogen peroxide induced tktA at 1 h treatment, while an increase in marRAB expression occurred only after 3 h exposure. This increase was dependent on the presence of tktA. Two MarR mutations which eliminated MarR binding to the marRAB operator and one which decreased dimerization of MarR had no effect on MarR interaction with TktA in the two-hybrid system. However, the interaction was disrupted by one of the three tested superrepressor mutant MarR proteins known to increase MarR binding to DNA. TktA inhibition of repression by MarR demonstrates a previously unrecognized level of control of the expression of marRAB operon. [ABSTRACT FROM AUTHOR]

Background. Much has been written recently about the potential hazards versus benefits of antibacterial (biocide)—containing soaps. The purpose of this systematic literature review was to assess the studies that have examined the efficacy of products containing triclosan, compared with that of plain soap, in the community setting, as well as to evaluate findings that address potential hazards of this use—namely, the emergence of antibiotic-resistant bacteria. Methods. The PubMed database was searched for English-language articles, using relevant keyword combinations for articles published between 1980 and 2006. Twenty-seven studies were eventually identified as being relevant to the review. Results. Soaps containing triclosan within the range of concentrations commonly used in the community setting (0.1%–0.45% wt/vol) were no more effective than plain soap at preventing infectious illness symptoms and reducing bacterial levels on the hands. Several laboratory studies demonstrated evidence of triclosan-adapted cross-resistance to antibiotics among different species of bacteria. Conclusions. The lack of an additional health benefit associated with the use of triclosan-containing consumer soaps over regular soap, coupled with laboratory data demonstrating a potential risk of selecting for drug resistance, warrants further evaluation by governmental regulators regarding antibacterial product claims and advertising. Further studies of this issue are encouraged. [ABSTRACT FROM AUTHOR]

We examined whether household use of antibacterial cleaning and hygiene products is an emerging risk factor for carriage of antimicrobial drug-resistant bacteria on hands of household members. Households (N = 224) were randomized to use of antibacterial or nonantibacterial cleaning and hygiene products for 1 year. Logistic regression was used to assess the influence of antibacterial product use in homes. Antibacterial product use did not lead to a significant increase in antimicrobial drug resistance after 1 year (odds ratio 1.33, 95% confidence interval 0.74-2.41), nor did it have an effect on bacterial susceptibility to triclosan. However, more extensive and longer term use of triclosan might provide a suitable environment for emergence of resistant species. Further research on this issue is needed. [ABSTRACT FROM AUTHOR]

Escherichia coli strain TP985, which has an insertional mutation in the gene for the periplasmic murein tripeptide binding protein MppA, was previously reported to overproduce MarA and exhibit a multipleantibiotic resistance (Mar) phenotype (H. Li and J. T. Park, J. Bacteriol. 181:4842-4847, 1999). We found that TP985 contained a previously unrecognized marR mutation which was responsible for the Mar phenotype. Transduction of the mppA mutation from TP985 to another wild-type strain did not affect antibiotic susceptibility. Overproduction of MppA repressed marA transcription in TP985 but not in other mppA or marR mutants. Therefore, TP985 contains an additional unknown mutation(s) that facilitates the repression of marA expression by MppA. [ABSTRACT FROM AUTHOR]