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PubMed2000

[The experimental validation of the advantages of combined emergency (fluoroquinolones) and specific (EV Nalr) prevention of plague versus their sequential use].

Mice immunization with reference vaccine at the early stage of plague infection provided animals survival and prolonged mean survival period up to 2-5 days. Ciprofloxacin, ofloxacin and pefloxacin prevents development of post vaccine immunity at white mice, immunized by reference vaccine strain EV. Nalidixic acid and norfloxacin effect on post vaccine immunity was lower. Use of immunogenic strain EV Nafr (resistant to nalidixic acid and fluoroquinolones) provided antiplague immunity formation at the background of fluoroquinolones prophylaxis. Ciprofloxacin, ofloxacin and pefloxacin used for plague prophylaxis at white mice infected with Yersinia pestis (about 1000 LD50) inhibited postinfective immunity development. Nalidixic acid and norfloxacin didn't demonstrate such effect. Urgent (fluoroquinolones) and specific (EV Nalr) combined prophylaxis was evaluated as more effective for a 5-day period and provided the development of antiplague immunity.

Animals↗

PubMed1983

Evidence for an active role of donor cells in natural transformation of Pseudomonas stutzeri.

The transfer of chromosomal genes in a cell mat of Pseudomonas stutzeri was ca. 10(3) times more efficient per microgram of DNA if DNA was added as a constituent of intact donor cells rather than as a solution. Such intact cell-mediated transfer appears to depend on cell contact. It is independent of the presence of plasmids in donor strains and is DNase I sensitive, thus fitting the usual definition of transformation. It is bidirectional: cells of either strain in a transformation mixture served as the donor and recipients. The donor function in cell contact transformation was inhibited by nalidixic acid but was unaffected by rifampin and streptomycin at growth-inhibiting concentrations. Concentrations of nalidixic acid sufficient to inhibit donor function completely had no effect on the ability of nalidixic acid-resistant recipients to take up DNA from solution. These experiments suggest that certain cells donate DNA to others in the cell mat: they argue against the hypothesis that the function of donor cells is merely cell lysis.

Bacterial Proteins↗

PubMed1988

In vitro susceptibilities of Ehrlichia risticii to eight antibiotics.

Inhibition of the proliferation of Ehrlichia risticii cultured in murine macrophage P388D1 cells by eight antibiotics was evaluated by indirect fluorescent-antibody staining with an antiserum specific to E. risticii. There was a negative correlation between the percentage of infected cells and the log10 of the concentrations of all antibiotics examined. The ranks of the antibiotics in the order of 50% inhibitory concentrations (on a microgram-per-milliliter basis) after 48 h of exposure were as follows: demeclocycline, doxycycline, and oxytetracycline less than minocycline less than rifampin less than tetracycline less than erythromycin and nalidixic acid. When the antibiotics were removed after 48 h of incubation, continuous inhibition of proliferation was evident at 72 h. At 96 h regrowth of the organisms occurred in most of the cultures. The rate of regrowth was the highest with nalidixic acid, followed by erythromycin, at all concentrations of the antibiotic tested. Regrowth was observed with less than 0.1 microgram of minocycline per ml and less than 0.01 microgram of oxytetracycline, tetracycline, and doxycycline per ml. With more than 0.01 microgram of demeclocycline per ml, however, the inhibition persisted for up to 72 h after removal of the antibiotic. These results indicate that demeclocycline was slightly more effective than doxycycline, oxytetracycline, and minocycline in eliminating E. risticii in macrophages in vitro, whereas tetracycline and rifampin were less effective. Nalidixic acid and erythromycin were ineffective.

Anti-Bacterial Agents↗

PubMed2001

Genetics of thermotolerance in ciprofloxacin resistant mutant of Rhizobium leguminosarum bv phaseoli.

A ciprofloxacin resistant mutant (Cf(R)) of Rhizobium leguminossarum bv phaseoli USDA 2695 which nodulates common bean plants (Phaseolus vulgaris L) was isolated after nitrous acid mutagenesis. Another mutant resistant to nalidixic acid (Nal(R)) was isolated spontaneously. Both mutants showed thermotolerance as evident by their ability to grow at elevated (40 degrees C) temperature, although the wild type (USDA 2695) failed to grow at this temperature. Transformation and plasmid curing experiments suggested the gene(s) controlling thermotolerance (TrR) and resistance to nalidixic acid or ciprofloxacin were located on the main chromosome and not on the plasmids. High frequency of co-transfer of TrR-Cr(R) and Tr(R)-Nal(R) during transformation experiments indicated a close association of these gene(s). Role of DNA gyrase and supercoiling in these thermotolerant mutants has been discussed.

Adaptation, Physiological↗

PubMed1990

A procedure for recording electroretinogram and visual evoked potential in freely moving cats.

A procedure for recording the electroretinogram (ERG) and the visual evoked potential (VEP) in freely moving cats was developed and used to test the visual toxicity of nalidixic acid. The electrodes for recording the ERG and VEP were implanted chronically in the sclera of the eye and on the surface of the visual cortex, respectively. Both the ERG and VEP were simultaneously recorded in freely moving cats using a slip ring that allows the cat to move freely without twisting the cables. After a 15-min dark-adaptation period, 20 responses to repetitive photic stimulation with an intensity of 2 joules and a 10-sec interstimulus interval were averaged by means of a minicomputer. The waveform of the ERG consisted of a negative wave (a-wave) followed by a positive wave (b-wave) with 2 to 3 oscillatory potentials on the rising slope. The VEP consisted of initial positive wave (P1 wave) followed by a negative wave (N1 wave) and late positive and negative deflections. The amplitude of the components of the ERG and VEP varied considerably from animal to animal, whereas within the same animal they were very stable. Using this technique, the effects of nalidixic acid, a retinotoxic compound, on the ERG and VEP were studied. Nalidixic acid produced a marked, but transient, decrease in the amplitude of the ERG b-wave after a single intravenous injection at a dose of 10 mg/kg. After repeated doses at 40 mg/kg/day for 2 weeks, the reduction in the amplitude of the b-wave was stronger, but remained transient. Upon ophthalmologic and histopathologic examination of the retina, no abnormalities indicating visual toxicity were observed. These results indicate that this procedure for recording the ERG and VEP is useful for evaluating the visual toxicity of drugs in freely moving cats.

Animals↗

PubMed1981

[Relationship between bacterial sensitivity to antimicrobial agents and their consumption (author's transl)].

Computerized data on the sensitivity of 20,006 strains of Gram-negative bacilli to ampicillin, cephalothin, gentamicin, tobramycin, nalidixic acid and co-trimoxazole were collected and evaluated in relation to drug consumption and hospital activity. Despite species-related differences, global sensitivity increased from 1975 to 1978 by 44.8% for cephalotin, 14.4% for ampicillin, 7.1% for gentamicin and 4.8% for tobramycin. There was no change in sensitivity to nalidixic acid and co-trimoxazole. During the same period the consumption of cephalosporins and aminoglycosides decreased by 28% and 21% respectively. Following a decrease between 1975 and 1977, the consumption of ampicillin and of nalidixic acid (and related compounds) went up again to reach in 1978 the same level as in 1975. Co-trimoxazole consumption remained unchanged. Since hospital activity remained the same throughout the period under study, it seems justified to correlate the increase in bacterial sensitivity observed to the decrease in consumption of antimicrobial agents.

Ampicillin↗

PubMed1995

Development of a direct viable count procedure for some gram-positive bacteria.

The direct viable count (DVC) is a procedure for enumerating viable-nonculturable cells. It should be noted, however, that bacteria demonstrating the viable but nonculturable phase have to date included only Gram-negative species, mainly because the DVC procedure does not lend itself to the analysis of Gram-positive bacteria since the DVC procedure is dependent on the bacterium being sensitive to nalidixic acid. The authors report here concerning studies on an analogous procedure for the direct enumeration of viable-nonculturable Gram-positive bacteria. To facilitate a differential DVC for Gram-positive bacteria, ciprofloxacin, enoxacin, norfloxacin or isopropyl cinodine were substituted for nalidixic acid. These antibiotics were chosen because, like nalidixic acid, they are DNA gyrase inhibitors. The concentrations used for each antibiotic were 1000 micrograms ml-1, 100 micrograms ml-1. Pure cultures of Staphylococcus aureus, Enterococcus faecalis, Streptococcus agalactiae, Listeria monocytogenes and Bacillus subtilis were obtained from the culture collection at the University of Wyoming and a faecal streptococcus was isolated from the Laramie wastewater treatment plant. An antibiotic and optimal concentration thereof was found which gave enlarged cells for all the organisms except the faecal streptococcus isolated from the wastewater plant for which no enlarged cells were ever seen. The antibiotic and concentration thereof which gave the optimal percent enlarged cells in the DVC procedure varied between organisms.

Anti-Bacterial Agents↗

PubMed1992

Quantitative in vitro assessment of phototoxicity by a fibroblast-neutral red assay.

We have adapted the neutral red uptake assay for quantitative assessment of injury to fibroblast cultures by potential phototoxins. Tetracycline derivatives, quinolone derivatives, and chlorpromazine were used as model compounds for development of the assay. Human fibroblasts were incubated with potential phototoxins, the cell cultures irradiated with UV, and the capacity for neutral red uptake determined. Demeclocycline and doxycycline, two known photosensitizers, showed a 94% and 95% decrease of neutral red uptake, respectively, indicating photo-induced cytotoxicity. Minocycline, a non-photosensitizing tetracycline derivative, showed no decrease in uptake. Tetracycline, a weak phototoxin, showed minor (10%) decrease at equivalent concentrations (20 micrograms/ml). Microscopic observation of neutral red uptake and cell damage paralleled the spectrophotometric findings. Chlorpromazine, a non-tetracycline phototoxin, showed 91% decrease. An additional group of phototoxic drugs, quinolone antibacterials, were studied. Nalidixic acid, ofloxacin, ciprofloxacin, and norfloxacin all demonstrated phototoxicity, with nalidixic acid showing the greatest decrease in neutral red uptake. This methodology may provide a useful rapid method to quantify phototoxic potential of new drugs or suspected phototoxins.

Cells, Cultured↗

PubMed2004

Suboptimal clinical response to ciprofloxacin in patients with enteric fever due to Salmonella spp. with reduced fluoroquinolone susceptibility: a case series.

BACKGROUND: Salmonella spp. with reduced susceptibility to fluoroquinolones have higher than usual MICs to these agents but are still considered "susceptible" by NCCLS criteria. Delayed treatment response to fluoroquinolones has been noted, especially in cases of enteric fever due to such strains. We reviewed the ciprofloxacin susceptibility and clinical outcome of our recent enteric fever cases. METHODS: Salmonella enterica Serotype Typhi (S. Typhi) and Serotype Paratyphi (S. Paratyphi) blood culture isolates (1998-2002) were tested against nalidixic acid by disk diffusion (DD) and agar dilution (AD) and to ciprofloxacin by AD using NCCLS methods and interpretive criteria. Reduced fluoroquinolone susceptibility was defined as a ciprofloxacin MIC of 0.125-1.0 mg/L. The clinical records of patients treated with ciprofloxacin for isolates with reduced fluoroquinolone susceptibility were reviewed. RESULTS: Seven of 21 (33%) S. Typhi and S. Paratyphi isolates had reduced susceptibility to fluoroquinolones (MIC range 0.125-0.5 mg/L). All 7 were nalidixic acid resistant by DD (no zone) and by AD (MIC 128- >512 mg/L). The other 14 isolates were nalidixic acid susceptible and fully susceptible to ciprofloxacin (MIC range 0.015-0.03 mg/L). Five of the 7 cases were treated initially with oral ciprofloxacin. One patient remained febrile on IV ciprofloxacin until cefotaxime was added, with fever recurrence when cefotaxime was discontinued. Two continued on oral or IV ciprofloxacin alone but had prolonged fevers of 9-10 days duration, one was switched to IV beta-lactam therapy after remaining febrile for 3 days on oral/IV ciprofloxacin and one was treated successfully with oral ciprofloxacin. Four of the 5 required hospitalization. CONCLUSIONS: Our cases provide further evidence that reduced fluoroquinolone susceptibility of S. Typhi and S. Paratyphi is clinically significant. Laboratories should test extra-intestinal Salmonella spp. for reduced fluoroquinolone susceptibility.

Anti-Infective Agents↗

PubMed1985

Further characterization of SOS system induction in recBC mutants of Escherichia coli.

Expression of several SOS functions such as induction of lambda prophage, inhibition of cell division and induction of both umuC and recA genes after UV-irradiation, nalidixic acid or mitomycin C addition was studied in an RecBC- mutant. UV-irradiation and mitomycin C induced all SOS functions studied in the RecBC- cells but at a lower level and delayed with respect to the wild-type strain. On the contrary, nalidixic acid was unable to trigger any of these SOS functions. In the RecBC- mutant, adenine only had a stimulating effect on the amplification of RecA protein synthesis following UV-irradiation. Nevertheless, in the wild-type strain the stimulating effect occurred in all SOS functions studied following UV-irradiation as well as in the amplification of RecA protein synthesis by nalidixic acid but not in the other SOS functions triggered by this compound. Furthermore, adenine produced a decrease in the mitomycin C-mediated induction of all SOS functions studied in both RecBC- and wild-type strains.

Adenine↗

PubMed1994

[Microbial drug resistance and the presence of plasmids in Salmonella strains isolated from different sources].

BACKGROUND: To establish the relationship between the presence of plasmid and their antimicrobial resistance of Salmonella strains. METHODS: We tested 171 strains of Salmonella isolated from different sources: natural waters (73 strains), food (23 strains), and from clinical samples (75 strains). The disk diffusion method was used to test the antimicrobial susceptibility of the strains to 13 drugs. Plasmid analysis were performed by agarose gel electrophoresis technique. RESULTS: Antimicrobial resistances of the strains significantly varies according to their primary isolation sources. Strains isolated from the water environment exhibited a full susceptibility to cephalothin and colistin, whilst all the strains isolated from food were sensitive to ampicillin, gentamicin, kanamycin, neomycin, tobramycin and trimethoprim-sulphamethoxazole. On the other hand, resistances to colistin, gentamicin and trimethoprim-sulphamethoxazole were not found in clinical isolates. From the 171 Salmonella strains tested, only 12.2% were sensitive to all the antimicrobials. The most frequently antibiotic resistances detected were to streptomycin (49.3%), tetracycline (33.1%) and nalidixic acid (30.7%). The percentage of strains that harboured plasmids was different depending on the source of isolation, ranging from 41.4% for water isolated, 76% for clinical isolates and 86.9% for food isolates. The relationship between antimicrobial resistance and plasmid presence is very close, since higher percentages of resistance to chloramphenicol, carbenicillin, cephalothin, kanamycin, neomycin, nalidixic acid and trimethoprim-sulphamethoxazole were obtained in strains containing plasmids. CONCLUSIONS: (a) The most frequently resistance detected in strains of Salmonella was to streptomycin (49.3% of the strains). On the other hand, only 0.6% of the strains were resistant to gentamicin. (b) Percentages of resistance to some antibiotics was higher in strains harbouring plasmids, that implies a relationship between the plasmid presence and the antibiotic resistance in Salmonella. (c) Curing of extrachromosomic elements by acridine orange showed a percentage of resistance lost greater than 70% for cephalothin, kanamycin, neomycin, and nalidixic acid. This indicates that the resistance to those antibiotics is mainly linked to plasmids. In the case of the unusual nalidixic acid-resistance, previously described in Shigella strains, suggests that are needed more studies to demonstrate the direct association between antimicrobial resistance and presence of plasmids.

Anti-Bacterial Agents↗

PubMed2001

Single or double mutational alterations of gyrA associated with fluoroquinolone resistance in Campylobacter jejuni and Campylobacter coli.

We looked for the presence of gyrA mutations in seven fluoroquinolone-resistant French clinical isolates of Campylobacter jejuni and Campylobacter coli. Three of the five isolates of C. jejuni and the two isolates of C. coli had high-level resistance to nalidixic acid (MICs 128-256 microg/ml) and ciprofloxacin (MICs 32 microg/ml). A gyrA mutation was found in all these isolates leading to the following substitutions: Thr86-Ile in four cases and Asp90-Tyr for one C. coli strain. One isolate had high-level resistance to nalidixic acid (MIC 64 microg/ml) but low-level resistance to ciprofloxacin (MIC 2 microg/ml) and also carried a gyrA mutation leading to a Thr86-Ala substitution. The last isolate of C. jejuni studied displayed an atypical resistance phenotype: It was resistant to high levels of ciprofloxacin (MIC 64 microg/ml) but remained fully susceptible to nalidixic acid (MIC 2 microg/ml). This phenotype was not explained by the presence of peculiar mutations in gyrA or gyrB. It carried a gyrA mutation leading to a Thr86-Ile substitution and was devoid of gyrB mutation. Despite numerous attempts with various degenerate oligonucleotide primers deduced from conserved regions of known parC genes, we were unable to amplify a corresponding sequence in C. jejuni or C. coli. First-step and second-step in vitro mutants, derived from reference strain C. coli ATCC 33559 with ciprofloxacin or moxifloxacin as selecting agents, were found to carry one and two mutations in gyrA, respectively. In contrast with the results obtained with clinical isolates, a variety of gyrA mutations were obtained in vitro.

Anti-Infective Agents↗

PubMed1985

Norfloxacin. A review of its antibacterial activity, pharmacokinetic properties and therapeutic use.

Norfloxacin is one of the new 4-quinolone antibacterial agents. A fluorinated piperazinyl-substituted congener of nalidixic acid, it demonstrates a much wider in vitro antibacterial spectrum and greater potency than the parent compound. Its antibacterial activity against most Gram-negative pathogens is enhanced in comparison to nalidixic acid, but is similar to that of some of the other new 4-quinolones like enoxacin, and slightly less than that of ciprofloxacin. Unlike nalidixic acid, norfloxacin is also active against Pseudomonas aeruginosa and some Gram-positive organisms. In acute or uncomplicated urinary tract infections, norfloxacin has repeatedly been shown to be as effective as co-trimoxazole. Single studies have demonstrated a significantly better bacteriological cure rate with norfloxacin than with pipemidic acid, and similar cure rates with norfloxacin and both a nalidixic acid/sodium citrate mixture and amoxycillin. Similar results were found in a few studies comparing norfloxacin to pipemidic acid or amoxycillin in patients with chronic and/or complicated urinary tract infections. Norfloxacin is as effective as spectinomycin in gonorrhoea due to penicillin-resistant N. gonorrhoeae, and cures bacterial gastroenteritis caused by several gastrointestinal pathogens. Norfloxacin appears to be well tolerated and may have a low propensity to select for bacterial resistance during clinical use, although the latter needs further confirmation.

Antifungal Agents↗

PubMed1989

Survival of Vibrio anguillarum and Vibrio salmonicida at different salinities.

The fish pathogenic bacteria Vibrio anguillarum and V. salmonicida showed the capacity to survive for more than 50 and 14 months, respectively, in seawater microcosms. A salinity of 5% proved lethal to V. anguillarum harvested in the late-exponential growth phase, whereas a salinity of 9% was lethal to the bacterium after it had been starved at a salinity of 30% for 67 days. The lethal salinity for V. salmonicida harvested in the late-exponential growth phase was probably in the vicinity of 10%. V. anguillarum and V. salmonicida were very sensitive to nalidixic acid. Direct determination of viable cells after incubation with nalidixic acid was not possible, since the cells did not elongate. Samples of V. salmonicida were double stained with fluorescein isothiocyanate-labeled antibodies and 4',6-diamidino-2-phenylindole. After 3 or 4 days of starvation, there was a discrepancy between the total numbers of cells as determined by immunofluorescence versus by staining with 4',6-diamidino-2-phenylindole. The immunofluorescence counts remained high, which indicated the presence of intact cell envelopes but leakage of DNA and other cytoplasm components. After 2 weeks of starvation, for some of the cells, the region stained with 4',6-diamidino-2-phenylindole (i.e., DNA) was markedly smaller than the cell envelope. I attributed this to a shrinkage of the cytoplasm or a confined nucleoid or both. V. anguillarum lost its exoproteolytic activity before 11 days of starvation.

Animals↗

PubMed1997

Double-blind, randomized clinical trial for safety and efficacy of norfloxacin for shigellosis in children.

In a randomized, double-blind clinical trial, the efficacy and safety of norfloxacin were compared with nalidixic acid in the treatment of shigellosis in children. Out of 59 cases, Shigella spp. were isolated from 8 cases in the nalidixic acid group and 14 cases in the norfloxacin group. The norfloxacin group had significantly less duration of diarrhoea and presence of blood in stool as compared to the nalidixic acid group. No joint problem was encountered in this study at up to 4 months follow-up. Norfloxacin is safe and effective and showed no cartilage toxicity on short-term follow-up.

Anti-Infective Agents↗

PubMed2002

Comparison of aqueous commercial cleaners for effectiveness in removing Escherichia coli O157:H7 and Salmonella muenchen from the surface of apples.

Unpasteurized fruit juice and cider have been implicated in outbreaks of Escherichia coli O157:H7 and Salmonella infections, yet various processes used to clean and sanitize fruits before producing juice have not been thoroughly studied for their effectiveness in removing pathogens. The objective of this study was to evaluate cleaners used in the apple industry for their efficacy in removing E. coli O157:H7 and Salmonella from the surface of apples. E. coli O157:H7 was transformed with green fluorescent protein plasmid (pGFP). In addition to encoding for the production of GFP, the plasmid also encodes for ampicillin resistance. S. muenchen was adapted to grow in media containing 50 microg/ml nalidixic acid. The use of ampicillin and nalidixic acid resistant strains enabled enumeration of the pathogen without interference by microflora naturally present on apples. Unwaxed Red Delicious cv. apples were surface inoculated with 8.58 log10 cfu of E. coli O157:H7 and 8.11 log10 cfu of S. muenchen. Five commercial apple cleaners were applied at concentrations and exposure times recommended by manufacturers. Populations of E. coli O157:H7, S. muenchen, aerobic mesophiles, and yeasts and molds on apples treated with cleaners and water (control) were determined. Compared to washing with water, treatment with cleaners removed or killed up to 2.86, 3.11, 2.48, and 0.73 log10 cfu of E. coli O157:H7, S. muenchen, aerobic mesophiles, and yeasts and molds per apple, respectively. There were differences in the effectiveness of cleaners in removing pathogens, but pH (2.0 and 12.0) and concentration (1% and 5%) of cleaner, and time of exposure (0.5-2 min) were not correlated with magnitude of reduction in population. The use of some types of cleaners commercially formulated for apples may contribute significantly in attaining target 5-log10 reductions of pathogens on the fruit intended for unpasteurized juice production or the fresh produce market.

Colony Count, Microbial↗

PubMed1983

A hospital outbreak of multiresistant Salmonella typhimurium belonging to phage type 193.

An outbreak of nosocomial infection was caused by strains of Salmonella typhimurium phage type 193 that were resistant to ampicillin, chloramphenicol, neomycin-kanamycin, streptomycin, spectinomycin, sulfonamides, tetracyclines, trimethoprim, and nalidixic acid. Resistances to drugs other than nalidixic acid were specified by plasmids, and, on the basis of phage typing and plasmid characterization studies, the multiresistant phage type 193 strains were determined to be clonal. In a two-year period, 488 patients infected with these bacteria were identified. An investigation in a pediatric surgical ward, where the outbreak was particularly severe, showed that patients exposed to antibiotics were more likely to be colonized with the epidemic strain and that young debilitated patients were more liable to show clinical signs of infection. Epidemiologic studies suggested that cross infection via the hands of the ward staff was the likely means of propagation of the epidemic.

Anti-Bacterial Agents↗

PubMed1997

Shigella serogroups identified from adult diarrhoeal out-patients in Addis Ababa, Ethiopia: antibiotic resistance and plasmid profile analysis.

Fifty shigella strains were isolated from 700 diarrhoeal samples collected from adult diarrhoeal out-patients in Addis Ababa. Among the isolates, serogroup A comprised 28%, B 44%, C 18% and D 10%. Among all shigella serogroups, highest resistance was encountered to tetracycline (74%), ampicillin (70%), cephalothin (64%), trimethoprim-sulfamethoxazole (52%) and chloramphenicol (50%) while least resistance was observed to gentamicin (0%), polymyxin B (10%) and nalidixic acid (14%). Gentamicin, polymyxin B and nalidixic acid were found to be the drugs of choice for cases of shigellosis. All drug resistant isolates analysed for plasmids contained multiple plasmids ranging from 1.8 to greater than 21 Kilobases.

Adolescent↗