Bioterrorism alleging use of anthrax and interim guidelines for management--United States, 1998.
From October 30 through December 23, 1998, CDC received reports of a series of bioterroristic threats of anthrax exposure. Letters alleged to contain anthrax were sent to health clinics on October 30, 1998, in Indiana, Kentucky, and Tennessee. During December 17-23 in California, a letter alleged to contain anthrax was sent to a private business, and three telephone threats of anthrax contamination of ventilation systems were made to private and public buildings. All threats were hoaxes and are under investigation by the Federal Bureau of Investigation (FBI) and local law enforcement officials. The public health implications of these threats were investigated to assist in developing national public health guidelines for responding to bioterrorism. This report summarizes the findings of these investigations and provides interim guidance for public health authorities on bioterrorism related to anthrax. (+info)
Ciprofloxacin decreases the rate of ethanol elimination in humans.
BACKGROUND: Extrahepatic ethanol metabolism is postulated to take place via microbial oxidation in the colon, mediated by aerobic and facultative anaerobic bacteria. AIMS: To evaluate the role of microbial ethanol oxidation in the total elimination rate of ethanol in humans by reducing gut flora with ciprofloxacin. METHODS: Ethanol was administered intravenously at the beginning and end of a one week period to eight male volunteers. Between ethanol doses volunteers received 750 mg ciprofloxacin twice daily. RESULTS: A highly significant (p=0.001) reduction in the ethanol elimination rate (EER) was detected after ciprofloxacin medication. Mean (SEM) EER was 107.0 (5.3) and 96.9 (4.8) mg/kg/h before and after ciprofloxacin, respectively. Faecal Enterobacteriaceae and Enterococcus sp. were totally absent after medication, and faecal acetaldehyde production capacity was significantly (p<0.05) decreased from 0.91 (0.15) to 0.39 (0.08) nmol/min/mg protein. Mean faecal alcohol dehydrogenase (ADH) activity was significantly (p<0. 05) decreased after medication, but ciprofloxacin did not inhibit human hepatic ADH activity in vitro. CONCLUSIONS: Ciprofloxacin treatment decreased the ethanol elimination rate by 9.4%, with a concomitant decrease in intestinal aerobic and facultative anaerobic bacteria, faecal ADH activity, and acetaldehyde production. As ciprofloxacin has no effect on liver blood flow, hepatic ADH activity, or cytochrome CYP2E1 activity, these effects are probably caused by the reduction in intestinal flora. (+info)
Infectious complications in 126 patients treated with high-dose chemotherapy and autologous peripheral blood stem cell transplantation.
The effect of an extensive prophylactic antimicrobial regimen was prospectively assessed in 126 patients after high-dose chemotherapy and autologous PBSC. They received ciprofloxacin (500 mg/12 h), acyclovir (200 mg/6 h), and itraconazole (200 mg/12 h) orally until neutrophil recovery. Febrile patients received i.v. imipenem (500 mg/6 h) to which vancomycin and amikacin were added if fever persisted for 2-3 and 5 days, respectively. Amphotericin B lipid complex was further given on day 7 or 8 of fever. Median times for a neutrophil count of >0.5 x 10(9)/l and a platelet count of >20 x 10(9)/l were 9 and 11 days. Severe neutropenia (<0.1 x 10(9)/l) lasted for a median of 5 days in which 72% of febrile episodes and 50% of cases of bacteremia occurred. Gram-positive bacteria were isolated in 30 of 40 episodes of bacteremia, 25 of which were caused by Staphylococcus epidermidis. Clinical foci were the intravascular catheter in 35 cases, respiratory infection in 11, cellulitis in two, anal abscess in one, and neutropenic enterocolitis in one. The high incidence of febrile episodes (94%) and bacteremias (31%) may be due to the lack of efficacy of antimicrobial prophylaxis and the persistence of a 5-day period of severe neutropenia. (+info)
Inhibition of human immunodeficiency virus type 1 replication by combination of transcription inhibitor K-12 and other antiretroviral agents in acutely and chronically infected cells.
8-Difluoromethoxy-1-ethyl-6-fluoro-1,4-dihydro-7-[4-(2-methoxyp hen yl)-1- piperazinyl]-4-oxoquinoline-3-carboxylic acid (K-12) has recently been identified as a potent and selective inhibitor of human immunodeficiency virus type 1 (HIV-1) transcription. In this study, we examined several combinations of K-12 and other antiretroviral agents for their inhibitory effects on HIV-1 replication in acutely and chronically infected cell cultures. Combinations of K-12 and a reverse transcriptase (RT) inhibitor, either zidovudine, lamivudine, or nevirapine, synergistically inhibited HIV-1 replication in acutely infected MT-4 cells. The combination of K-12 and the protease inhibitor nelfinavir (NFV) also synergistically inhibited HIV-1, whereas the synergism of this combination was weaker than that of the combinations with the RT inhibitors. K-12 did not enhance the cytotoxicities of RT and protease inhibitors. Synergism of the combinations was also observed in acutely infected peripheral blood mononuclear cells. The combination of K-12 and cepharanthine, a nuclear factor kappa B inhibitor, synergistically inhibited HIV-1 production in tumor necrosis factor alpha-stimulated U1 cells, a promonocytic cell line chronically infected with the virus. In contrast, additive inhibition was observed for the combination of K-12 and NFV. These results indicate that the combinations of K-12 and clinically available antiretroviral agents may have potential as chemotherapeutic modalities for the treatment of HIV-1 infection. (+info)
Prediction of the effects of inoculum size on the antimicrobial action of trovafloxacin and ciprofloxacin against Staphylococcus aureus and Escherichia coli in an in vitro dynamic model.
The effect of inoculum size (N0) on antimicrobial action has not been extensively studied in in vitro dynamic models. To investigate this effect and its predictability, killing and regrowth kinetics of Staphylococcus aureus and Escherichia coli exposed to monoexponentially decreasing concentrations of trovafloxacin (as a single dose) and ciprofloxacin (two doses at a 12-h interval) were compared at N0 = 10(6) and 10(9) CFU/ml (S. aureus) and at N0 = 10(6), 10(7), and 10(9) CFU/ml (E. coli). A series of pharmacokinetic profiles of trovafloxacin and ciprofloxacin with respective half-lives of 9.2 and 4 h were simulated at different ratios of area under the concentration-time curve (AUC) to MIC (in [micrograms x hours/milliliter]/[micrograms/milliliter]): 58 to 466 with trovafloxacin and 116 to 932 with ciprofloxacin for S. aureus and 58 to 233 and 116 to 466 for E. coli, respectively. Although the effect of N0 was more pronounced for E. coli than for S. aureus, only a minor increase in minimum numbers of surviving bacteria and an almost negligible delay in their regrowth were associated with an increase of the N0 for both organisms. The N0-induced reductions of the intensity of the antimicrobial effect (IE, area between control growth and the killing-regrowth curves) were also relatively small. However, the N0 effect could not be eliminated either by simple shifting of the time-kill curves obtained at higher N0s by the difference between the higher and lowest N0 or by operating with IEs determined within the N0-adopted upper limits of bacterial numbers (IE's). By using multivariate correlation and regression analyses, linear relationships between IE and log AUC/MIC and log N0 related to the respective mean values [(log AUC/MIC)average and (log N0)average] were established for both trovafloxacin and ciprofloxacin against each of the strains (r2 = 0.97 to 0.99). The antimicrobial effect may be accurately predicted at a given AUC/MIC of trovafloxacin or ciprofloxacin and at a given N0 based on the relationship IE = a + b [(log AUC/MIC)/(log AUC/MIC)average] - c [(log N0)/(log N0)average]. Moreover, the relative impacts of AUC/MIC and N0 on IE may be evaluated. Since the c/b ratios for trovafloxacin and ciprofloxacin against E. coli were much lower (0.3 to 0.4) than that for ampicillin-sulbactam as examined previously (1.9), the inoculum effect with the quinolones may be much less pronounced than with the beta-lactams. The described approach to the analysis of the inoculum effect in in vitro dynamic models might be useful in studies with other antibiotic classes. (+info)
In vitro activities of cephalosporins and quinolones against Escherichia coli strains isolated from diarrheic dairy calves.
The in vitro activities of several cephalosporins and quinolones against 195 strains of Escherichia coli isolated from diary calves affected by neonatal diarrhea were determined. One hundred thirty-seven of these strains produced one or more potential virulence factors (F5, F41, F17, cytotoxic necrotizing factor, verotoxin, and the eae gene), but the remaining 58 strains did not produce any of these factors. From 11 to 18% of the E. coli strains were resistant to cephalothin, nalidixic acid, enoxacin, and enrofloxacin. However, cefuroxime, cefotaxime, and cefquinome were highly effective against the E. coli isolates tested. Some significant differences (P < 0.05) in resistance to quinolones between the strains producing potential virulence factors and nonfimbriated, nontoxigenic, eae-negative strains were found. Thus, eae-positive, necrotoxigenic, and verotoxigenic (except for nalidixic acid) E. coli strains were significantly more sensitive to nalidixic acid, enoxacin, and enrofloxacin than nonfimbriated, nontoxigenic, eae-negative strains. Moreover, eae-positive strains were significantly more sensitive to enoxacin and enrofloxacin than F5-positive strains. Thus, the result of this study suggest that the bovine E. coli strains that produce some potential virulence factors are more sensitive to quinolones than those that do not express these factors. (+info)
Influences of urinary pH on ciprofloxacin pharmacokinetics in humans and antimicrobial activity in vitro versus those of sparfloxacin.
The impact of acidification and alkalinization of urine on the pharmacokinetics of ciprofloxacin was investigated after single 200-mg oral doses were administered to nine healthy male volunteers. In addition, the effect of human urine on the MICs of ciprofloxacin and sparfloxacin against some common urinary tract pathogens such as Escherichia coli and Pseudomonas aeruginosa was investigated. Acidic and alkaline conditions were achieved by repeated oral doses of ammonium chloride or sodium bicarbonate, respectively. Plasma ciprofloxacin levels in all subjects were adequately described in terms of two-compartment model kinetics with first-order absorption. Acidification and alkalinization treatments had no effect on ciprofloxacin absorption, distribution, or elimination. The total amount of unchanged ciprofloxacin excreted over 24 h under acidic conditions was 88.4 +/- 14.5 mg (mean +/- standard deviation) (44.2% of the oral dose) and 82.4 +/- 16.5 mg (41.2% of the oral dose) under alkaline conditions, while the total amount of unchanged drug excreted over 24 h in volunteers receiving neither sodium bicarbonate nor ammonium chloride was 90.53 +/- 9.8 mg (45.2% of the oral dose). The mean renal clearance of ciprofloxacin was 16.78 +/- 2.67, 16.08 +/- 3.2, and 16.31 +/- 2.67 liters/h with acidification, alkalinization, and control, respectively. Renal clearance and concentrations of ciprofloxacin in urine were not correlated with urinary pH. The antibacterial activity of ciprofloxacin and sparfloxacin against E. coli NIHJ JC-2 and P. aeruginosa ATCC 27853 was affected by human urine and in particular by its pH. The activities of both quinolones against E. coli NIHJ JC-2 were lower at lower urinary pH and rather uniform, while in the case of P. aeruginosa ATCC 27853 ciprofloxacin was more active than sparfloxacin. (+info)
Cloning, expression, and enzymatic characterization of Pseudomonas aeruginosa topoisomerase IV.
The topoisomerase IV subunit A gene, parC homolog, has been cloned and sequenced from Pseudomonas aeruginosa PAO1, with cDNA encoding the N-terminal region of Escherichia coli parC used as a probe. The homolog and its upstream gene were presumed to be parC and parE through sequence homology with the parC and parE genes of other organisms. The deduced amino acid sequence of ParC and ParE showed 33 and 32% identity with that of the P. aeruginosa DNA gyrase subunits, GyrA and GyrB, respectively, and 69 and 75% identity with that of E. coli ParC and ParE, respectively. The putative ParC and ParE proteins were overexpressed and separately purified by use of a fusion system with a maltose-binding protein, and their enzymatic properties were examined. The reconstituted enzyme had ATP-dependent decatenation activity, which is the main catalytic activity of bacterial topoisomerase IV, and relaxing activities but had no supercoiling activity. So, the cloned genes were identified as P. aeruginosa topoisomerase IV genes. The inhibitory effects of quinolones on the activities of topoisomerase IV and DNA gyrase were compared. The 50% inhibitory concentrations of quinolones for the decatenation activity of topoisomerase IV were from five to eight times higher than those for the supercoiling activities of P. aeruginosa DNA gyrase. These results confirmed that topoisomerase IV is less sensitive to fluoroquinolones than is DNA gyrase and may be a secondary target of new quinolones in wild-type P. aeruginosa. (+info)