James A. Poupard

History of Biological Warfare: Catapults to Capsomeres

Claims that biologcal agents have been used as weapons of war can be found in both the written records and the art work of many early civilizations. In fact, warring factions have used, threatened to use, or accused their enemies of using various forms of biological warfare (BW) throughout recorded hstory. Nevertheless hstorical documentation proving the use of biological warfare has always been sparse, and such information has been clouded in h s century by governments that are unwilling to admit to using biological warfare or to lift the cloak of secrecy surroundmg these activities. The murkiness of the historical record may discourage academic pursuit of the subject but does add a certain mystique to attempts to chronicle the history of biological warfare. Another factor that has inhibited careful historical analysis of biological warfare is the value-laden nature of the subject itself: it is difficult to discuss h s means of warfare without eliciting emotional responses, and as the other papers in this section demonstrate, these responses often color reports of the use of biologcal warfare.’P2 The fact that moral or ethical judgments almost always accompany consideration of biological warfare issues has discouraged discussion withm the one group that should be most interested in the subject-microbiologists. T h s review chronicles the hstory of biologcal warfare from 300 B.C. to the present, using examples from many published sources. We have divided the chronology into s k historic periods on the basis of techca l innovations that changed the nature of biological weapons. One sgdicant feature of this survey is that it relates exclusively to the use of viable organisms in biological warfare.3We have omitted references to use of bacterial toxins or related chemical derivatives of microorganisms because we believe they can better be dealt with as examples of chemical warfare.

Molecular Evolution Perspectives on Intraspecific Lateral DNA Transfer of Topoisomerase and Gyrase Loci in Streptococcus pneumoniae, with Implications for Fluoroquinolone Resistance Development and Spread

ABSTRACT Fluoroquinolones are an important class of antibiotics for the treatment of infections arising from the gram-positive respiratory pathogen Streptococcus pneumoniae. Although there is evidence supporting interspecific lateral DNA transfer of fluoroquinolone target loci, no studies have specifically been designed to assess the role of intraspecific lateral transfer of these genes in the spread of fluoroquinolone resistance. This study involves a comparative evolutionary perspective, in which the evolutionary history of a diverse set of S. pneumoniae clinical isolates is reconstructed from an expanded multilocus sequence typing data set, with putative recombinants excluded. This control history is then assessed against networks of each of the four fluoroquinolone target loci from the same isolates. The results indicate that although the majority of fluoroquinolone target loci from this set of 60 isolates are consistent with a clonal dissemination hypothesis, 3 to 10% of the sequences are consistent with an intraspecific lateral transfer hypothesis. Also evident were examples of interspecific transfer, with two isolates possessing a parE-parC gene region arising from viridans group streptococci. The Spain 23F-1 clone is the most dominant fluoroquinolone-nonsusceptible clone in this set of isolates, and the analysis suggests that its members act as frequent donors of fluoroquinolone-nonsusceptible loci. Although the majority of fluoroquinolone target gene sequences in this set of isolates can be explained on the basis of clonal dissemination, a significant number are more parsimoniously explained by intraspecific lateral DNA transfer, and in situations of high S. pneumoniae population density, such events could be an important means of resistance spread.

A survey of β-lactamase-producing Haemophilus influenzae an evaluation of 5750 isolates

Previous studies have reported that 15%-34% of Haemophilus influenzae produce beta-lactamase. A surveillance program was developed by SmithKline Beecham Clinical Laboratories to determine the current percentage of beta-lactamase-producing H. influenzae from five selected geographic locations in the United States. In 1993, results of 5750 isolates from specimens submitted to five reference clinical laboratories were evaluated. Data were collected from 29 states and the District of Columbia. The percentages of beta-lactamase-producing H. influenzae was 33% and ranged from 22%-40% for the individual states.

Methods for Data Mining from Large Multinational Surveillance Studies

ABSTRACT Traditionally, large surveillance studies have been analyzed by the use of the MICs at which 90% of isolates tested are inhibited (MIC90s), MIC50s, frequency distributions, and percent susceptibility. In the past, these approaches have proved satisfactory for the monitoring of resistance. From these traditional uses, one can readily detect an increase in MICs for organism and drug combinations. Now that large surveillance studies have been conducted for a number of years and databases have grown to include a large number of datum points, new approaches to the extraction of useful information from these studies are needed. The present study proposes approaches, including the use of antibiotypes, principal components analysis, phylogenetics, and population genetic analysis, to the evaluation of data from large multinational surveillance studies. Application of these types of analyses can be used to describe genetic diversity, analyze changes in susceptibility patterns over time, and possibly, shed light on the origins and evolution of antimicrobial resistance. As global surveillance studies become more common and new questions concerning the evolution of resistance are raised, innovative approaches to analysis of the data will increase in importance.

Evaluation of 500 gram negative isolates to determine the number of major susceptibility interpretation discrepancies between the Vitek and MicroScan Walkaway for 9 antimicrobial agents.

Although the Vitek and MicroScan Walkaway are two of the most commonly used automated antimicrobial susceptibility test systems, few studies have been performed comparing discrepancies between these systems. In this study, 500 Gram negative clinical isolates were tested against ampicillin, ampicillin/sulbactam, ticarcillin, ticarcillin/clavulanate, imipenem, ciprofloxacin, norfloxacin, mezlocillin, and piperacillin to determine the number of major interpretation discrepancies between the two systems. The 500 isolates consisted of 100 isolates each of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus mirabilis and Enterobacter species. Each isolate was tested simultaneously in both systems using the same standardized inoculum. Eighty-four major discrepancies occurred, of which 48 were reproducible. The reproducible discrepancy rate, for the 4,500 isolate/antimicrobic combinations tested, was 48 of 4500 (1.06%). The rate for individual antimicrobics varied from 17 of 500 (3.4%) for ampicillin to no discrepancies for ticarcillin or ciprofloxacin. Of the 48 reproducible discrepancies, 44 (92%) were Vitek resistant, MicroScan susceptible. Fifteen (31%) of the Vitek and 21 (44%) of the MicroScan results were confirmed by broth microdilution. Disk diffusion results were in agreement with 15 (31%) of the Vitek and 21 (44%) of the MicroScan results. Twelve (25%) of the broth microdilution and 12 (25%) of the disk diffusion results were intermediate. The broth microdilution and disk diffusion results for the 48 isolates with reproducible discrepancies were in agreement more often with MicroScan. However, there was less very major error comparing the Vitek results for these isolates to the broth microdilution and disk diffusion. Overall, the result of this evaluation indicate that the number of major interpretation discrepancies between the two systems is minimal for the isolate/antimicrobic combinations tested.

Determination of moxifloxacin anaerobic susceptibility breakpoints according to the Clinical and Laboratory Standards Institute guidelines

A summary of the key data presented to Clinical and Laboratory Standards Institute (CLSI, formerly National Committee for Clinical and Laboratory Standards) in determination of moxifloxacin anaerobic breakpoints is presented. The breakpoint analysis required review of a variety of data, including bacteriologic and clinical outcomes by MIC of anaerobic isolates from prospective clinical trials in patients with complicated intra-abdominal infections, human and animal pharmacokinetic/pharmacodynamic (PK/PD) information and in vitro models, MIC distributions of indicated organisms, and animal model efficacy data for strains with MIC values around prospective breakpoints. The compilation of the various components of this breakpoint analysis supports the US Food and Drug Administration (FDA) and CLSI moxifloxacin anaerobic breakpoints of < or =2 mg/L (susceptible), 4 mg/L (intermediate), and > or =8 mg/L (resistant), and provides information to European investigators for interpretation of MICs prior to establishment of the European Committee on Antimicrobial Susceptibility Testing breakpoints.