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PubMed1995

Antistaphylococcal activity of cefdinir, a new oral third-generation cephalosporin, alone and in combination with other antibiotics, at supra- and sub-MIC levels.

Cefdinir is one of the few oral third generation cephalosporins that shows useful activity against nosocomial Gram-positive pathogens. For this reason the anti-staphylococcal potency of the new drug, alone or in combination with other drugs was further characterized. Against penicillin-resistant, oxacillin-susceptible Staphylococcus isolates, cefdinir demonstrated useful in-vitro activity. MIC90 values (in mg/L) were 0.25 for Staphylococcus aureus (30 strains), 0.06 for Staphylococcus epidermidis (24), 0.125 for Staphylococcus hominis (10), 0.5 for both Staphylococcus xylosus (15) and Staphylococcus capitis (11) and 4 for Staphylococcus saprophyticus (10), while Staphylococcus haemolyticus (12) was less susceptible with a MIC90 value of 32. Cefdinir activity was not adversely affected by several variables such as pH, inoculum size or the presence of serum or urine. The new cephem induced a PAE on all isolates studied: with S. aureus the extent of regrowth suppression ranged from 0.8 to 1 h, and with the other species from 0.5 (S. epidermidis) to 4.1 h (S. haemolyticus). Development of resistant strains was rare. At the highest level used (10 x MIC) mutants arose with a frequency of 6 x 10(-8) with S. haemolyticus and 2 x 10(-9) with S. epidermidis. The absence of a paradoxical effect of increasing concentrations of cefdinir on its bactericidal activity was confirmed up to a value of 500-fold the MICs. When cefdinir activity was assessed in association with ciprofloxacin, netilmicin, clarithromycin, fosfomycin, rifampicin, teicoplanin and vancomycin using the chequerboard and time-kill techniques, indifference predominated with all strains and in all combinations. Synergism was detected only in 11 out of a total of 175 tests performed by the chequerboard method. Using the time-kill technique cefdinir reacted synergically in 25 of 126 tests. Antagonism was never observed. S. aureus exposed to sub-inhibitory concentrations of cefdinir failed to grow on mannitol-salt agar and to produce haemolysins, but retained coagulase activity. Penicillinase production was also lost in about 17% of the survivors. Hydrophobicity changes were detected in all species tested with the exception of S. saprophyticus.

Anti-Bacterial Agents↗
PubMed1996

Comparative distribution of resistance patterns and serotypes in Pseudomonas aeruginosa isolates from intensive care units and other wards.

The resistance patterns and O-serotypes of 2952 Pseudomonas aeruginosa isolates were studied and the relationship between patterns and serotypes was investigated. The penicillinase-producing and cephalosporinase-overproducing phenotypes were significantly more frequent in intensive care units than other wards, but there was no difference for the intrinsic resistance phenotype. The predominant serotypes were O6, O11 and O1. The incidence of serotype O12 was low. O11 isolates were more common in intensive care units and more resistant to all antibiotics than other isolates. Most O12 isolates had a penicillinase-producing phenotype and were resistant to aminoglycosides and ciprofloxacin, but susceptible to fosfomycin.

Aminoglycosides↗
PubMed1997

Isolation from clinical sources of Burkholderia cepacia possessing characteristics of Burkholderia gladioli.

Further characterization of 32 clinical isolates originally identified as Burkholderia cepacia by biochemical and fatty acid profiling revealed the presence of 12 strains bearing partial resemblance to the closely related species Burkholderia gladioli. These strains were highly resistant to a wide range of antibiotics including ticarcillin (with or without clavulanic acid), cefsulodin, imipenem, the aminoglycosides, colistin and fosfomycin. They typically produced a red-brown pigment and possessed distinct, although quite diverse biochemical profiles. This reinforces the previous opinion that hybrids between B. cepacia and B. gladioli exist and may possess a significant pathogenic role. It also suggests that further taxonomic clarification is required in the genus Burkholderia.

Burkholderia↗
PubMed2000

Antimicrobial resistance of mesophilic Aeromonas spp. isolated from two European rivers.

The activity of 19 antibiotics and four antiseptics and/or disinfectants was studied against 138 non-redundant strains of Aeromonas spp. (104 Aeromonas caviae, 22 Aeromonas sobria and 12 Aeromonas hydrophila) isolated from two European rivers. Antibiotic resistance frequencies were: nalidixic acid, 59%; tetracycline, 14%; fosfomycin, 8%; tobramycin and cotrimoxazole, 7%; cefotaxime, 4%; chloramphenicol, 2%; gentamicin, 1%. Most of the nalidixic acid-resistant strains were susceptible to fluoroquinolones (54-98%). Antibiotic resistance rates varied according to the source of the strains. All Aeromonas spp. strains were killed by 50 ppm of chlorine, cetylpyridinium chloride and peracetic acid, and by 1600 ppm of glutaraldehyde.

Aeromonas↗
PubMed2001

Natural antimicrobial susceptibilities of Plesiomonas shigelloides strains.

The natural susceptibility of 74 Plesiomonas shigelloides strains isolated from humans (n = 50), water (n = 22) and animals (n = 2) to 71 antibiotics was examined. MICs were performed using a microdilution procedure with Mueller-Hinton broth and an inoculum of 1 x 10(6) cfu/mL. Plesiomonas strains were naturally susceptible or naturally susceptible and intermediate to tetracyclines, several aminoglycosides, aminopenicillins in combination with beta-lactamase inhibitors, all cephalosporins except cefoperazone, ceftazidime and cefepime, carbapenems, aztreonam, quinolones, trimethoprim, sulfamethoxazole, azithromycin, chloramphenicol, nitrofurantoin and fosfomycin. Uniform natural resistance was found to all penicillins tested, roxithromycin, clarithromycin, lincosamides, streptogramins, glycopeptides and fusidic acid. Plesiomonas strains were naturally resistant and intermediate to streptomycin, erythromycin and rifampicin. There were two susceptibility patterns to piperacillin/tazobactam, several cephalosporins and aztreonam. In contrast to a previous study with beta-lactam antibiotics, susceptibility testing of non-beta-lactams revealed no alterations of the MICs of most antibiotics, using different inocula and media. A database is described of the natural susceptibility of P. shigelloides strains to a wide range of antibiotics. It can be used for the validation of susceptibility test results of these bacteria.

Animals↗
PubMed2003

Non-hospital antimicrobial usage and resistance in community-acquired Escherichia coli urinary tract infection.

OBJECTIVES: To investigate the correlation between non-hospital antimicrobial consumption and resistance. METHODS: Information on the non-hospital sales of antimicrobials from 14 European countries in 1997 and 2000 was compared with the antimicrobial resistance profiles of Escherichia coli isolated from women with community-acquired urinary tract infection in the same countries in 1999/2000. RESULTS: There was no statistically significant correlation between the consumption of and resistance to co-amoxiclav, cefadroxil, fosfomycin, mecillinam, sulfamethoxazole, trimethoprim or trimethoprim-sulfamethoxazole. On the other hand, there were statistically significant correlations between consumption of broad-spectrum penicillins and quinolones in 1997 and 2000 and resistance to ciprofloxacin (P range 0.0005-0.0045) and nalidixic acid (P range 0.0013-0.0049). Total antimicrobial consumption in 1997 was significantly correlated to ciprofloxacin (P=0.0009) and nalidixic acid (P=0.0018) resistance, and there were significant relationships between quinolone consumption in both years and resistance to gentamicin (P range 0.0029-0.0043) and nitrofurantoin (P range 0.0003-0.0007). E. coli with multiple antimicrobial resistance were significantly more common in countries with high total antimicrobial consumption. CONCLUSIONS: Owing to the frequent presence of many possible confounding factors, antimicrobial resistance to one drug does not always correlate well to the consumption of the same drug or closely related drugs. This study showed that the degree of antimicrobial consumption was significantly correlated to the incidence of multidrug-resistant E. coli.

Adolescent↗
PubMed2004

In vitro susceptibility of recent antibiotic-resistant urinary pathogens to ertapenem and 12 other antibiotics.

BACKGROUND: The treatment of complicated urinary tract infections may require the use of a parenteral antibiotic with potent activity against the most common urinary pathogens. Ertapenem is a broad-spectrum 1beta-methyl carbapenem with a long plasma half-life that allows administration of a single daily dose. METHODS: The purpose of this work was to test the in vitro susceptibility to ertapenem, ampicillin, cefazolin, cefuroxime, cefotaxime, co-amoxiclav, piperacillin/tazobactam, imipenem, gentamicin, amikacin, fosfomycin, ciprofloxacin and co-trimoxazole of 482 strains of urinary pathogens of the family Enterobacteriaceae isolated from patients in the community of Madrid (40% from males). The distribution was as follows: Escherichia coli (n = 315), Proteus mirabilis (n = 42), Klebsiella spp. (n = 14) and AmpC-producing Enterobacteriaceae (n = 111). The strains studied were selected based on their resistance to quinolones and aminoglycosides, and their production of extended-spectrum beta-lactamases (ESBLs) or AmpC-type beta-lactamases. RESULTS: All the strains were susceptible to ertapenem, imipenem and amikacin. The MIC(90) of ertapenem ranged from a minimum of 0.03 mg/L for Proteus vulgaris and a maximum of 1 mg/L for Enterobacter spp. Ertapenem was the most active of all drugs tested in all cases. On comparing antibiotic resistance among ESBL-producing strains of E. coli (n = 35) and E. coli strains not producing ESBLs (n = 280), statistically significant differences were obtained for ciprofloxacin (P = 0.002) and gentamicin (P = 0.011). Regarding ertapenem, only a slight increase in MIC(50) was seen, the value being 0.015 mg/L for strains not producing ESBLs versus 0.03 mg/L for ESBL-producing strains. CONCLUSIONS: In view of its significant antibiotic potency against antibiotic-resistant Enterobacteriaceae, ertapenem may constitute a good therapeutic alternative in urinary infections caused by these pathogens.

Anti-Bacterial Agents↗
PubMed2004

In vitro activities of cefotaxime, vancomycin, quinupristin/dalfopristin, linezolid and other antibiotics alone and in combination against Propionibacterium acnes isolates from central nervous system infections.

OBJECTIVES: To evaluate the antibiotic susceptibilities of Propionibacterium acnes isolates from central nervous system (CNS) infections to agents used in current treatment regimens. METHODS: MICs of 16 reference antibiotics were determined by an agar dilution method for 24 consecutive strains of P. acnes isolated from individual patients with intracranial empyema or brain abscess. Bactericidal activities of antibiotics against P. acnes PAN14 were studied at 0.25-2 x MIC using a time-kill method. RESULTS: All of the isolates were resistant to fosfomycin, intermediate or resistant to metronidazole and susceptible to all the other antibiotics tested, except for nine strains, which were intermediate to ofloxacin. Among antibiotics tested alone in time-kill experiments, vancomycin was the most effective drug and exhibited bactericidal activity after 24 h at 1x and 2 x MIC, whereas cefotaxime and ciprofloxacin were bactericidal after 48 h at 2 x MIC. No significant bactericidal activity could be demonstrated with the other antibiotics tested alone. The addition of cefotaxime to vancomycin resulted in bactericidal activity at lower concentrations (0.5 x MIC), whereas synergy was observed between quinupristin/dalfopristin and cefotaxime at 2 x MIC. In contrast, antagonism was observed between cefotaxime and linezolid, and ciprofloxacin and clindamycin. CONCLUSION: Our data suggest that P. acnes isolates causing CNS infections remain highly susceptible to most antibiotics used for the treatment of such infections. Moreover, we showed that cefotaxime, vancomycin and ciprofloxacin possess good bactericidal activities against P. acnes, and that these activities may be enhanced when vancomycin is combined with cefotaxime or when cefotaxime is combined with quinupristin/dalfopristin.

Acetamides↗
PubMed2005

Risk factors for ciprofloxacin resistance among Escherichia coli strains isolated from community-acquired urinary tract infections in Turkey.

OBJECTIVES: To determine the risk factors for community-acquired ciprofloxacin-resistant Escherichia coli urinary tract infection (UTI). METHODS: The study was performed with isolates from community-acquired UTIs collected from 15 centres representing six different geographic regions of Turkey. All microbiological procedures were carried out in a central laboratory. Multivariate analysis was performed for detection of risk factors for resistance. Use of quinolones more than once within the last year, living in a rural area, having a urinary catheter, age >50 and complicated infections were included in the model as variables and logistic regression was performed. RESULTS: A total of 611 gram-negative isolates were studied: 321 were isolated from uncomplicated UTI and 290 were isolated from complicated UTI. E. coli was the causative agent in 90% of the uncomplicated UTIs and in 78% of the complicated UTIs (P < 0.001). Seventeen percent of E. coli strains isolated from uncomplicated cases and 38% of E. coli strains isolated from complicated UTI were found to be resistant to ciprofloxacin. In multivariate analysis, age over 50 [odds ratio (OR): 1.6; confidence interval (CI): 1.08-2.47; P = 0.020], ciprofloxacin use more than once in the last year (OR: 2.8; CI: 1.38-5.47; P = 0.004) and the presence of complicated UTI (OR: 2.4; CI: 1.54-3.61; P < 0.001) were found to be associated with ciprofloxacin resistance. Detection of strains of E. coli producing extended-spectrum beta-lactamase (ESBL) enzymes was two times more common in the patients who received ciprofloxacin than those who did not (15% versus 7.4%). CONCLUSIONS: The increasing prevalence of infections caused by antibiotic-resistant bacteria makes the empirical treatment of UTIs more difficult. One of the important factors contributing to these high resistance rates might be high antibiotic use. Urine culture and antimicrobial susceptibility testing are essential in Turkey for patients with UTI who have risk factors for resistance, such as previous ciprofloxacin use. Fluoroquinolone-sparing agents such as nitrofurantoin and fosfomycin should be evaluated as alternative therapies by further clinical efficacy and safety studies.

Adolescent↗
PubMed2006

Characterization of acquired beta-lactamases and their genetic support in multidrug-resistant Pseudomonas aeruginosa isolates in Taiwan: the prevalence of unusual integrons.

OBJECTIVES: The present study was conducted to investigate acquired beta-lactamases and their genetic support in 26 Pseudomonas aeruginosa isolates that were resistant to nearly all antipseudomonal drugs from six medical centres in Taiwan. METHODS: Acquired beta-lactamases and their genetic support were determined by PCR-based strategies. RESULTS: Four and 16 of the 26 isolates were found to produce VIM-2 and VIM-3 metallo-beta-lactamases (MBLs), respectively, and 1, 1 and 2 isolates produced OXA-17, OXA-10 and PSE-1, respectively. These bla genes are all in class 1 integrons that are probably chromosomally located. The bla(VIM-3)-containing integron, with a deletion between int1 and the bla(VIM-3) structural gene, has six gene cassettes, bla(VIM-3), a probable fosfomycin resistance determinant, aacA4, aacA4, aadB and aacA4. The bla(VIM-2)-containing integron, without detectable 5'-conserved segment, contains four genes cassettes (aacA7-bla(VIM-2)-dhfr-aacA5) and is ended by tniC. The bla(OXA-10)-containing integron includes a catB3 cassette and a fused gene cassette, which is made up of bla(OXA-17) and a novel streptomycin-spectinomycin gene, designated aadA15. The bla(OXA-17)-containing integron has three gene cassettes (aacA4-catB2-bla(OXA-17)) but the 59-base element of the bla(OXA-17) cassette is interrupted by a putative transposase gene. The bla(PSE-1)-containing integron has three gene cassettes, aacA4, an aadA3-related gene designated aadA3b and bla(PSE-1). PFGE revealed genetic diversity among the multidrug-resistant isolates from different hospitals. CONCLUSIONS: This study demonstrated the high prevalence of VIM-type MBLs and the presence of unusual bla-encoding integrons in multidrug-resistant P. aeruginosa isolates in Taiwan. The spread of bla(VIM-2)-related genes by horizontal transfer might have occurred.

Anti-Bacterial Agents↗
PubMed2006

Antimicrobial resistance among uropathogens that cause community-acquired urinary tract infections in Antananarivo, Madagascar.

BACKGROUND: Urinary tract pathogens obtained from patients in Madagascar are becoming increasingly resistant to commonly used antibiotics that are readily available at a low price. This poses a real problem for the treatment of community-acquired urinary tract infections (UTIs) in Madagascar. OBJECTIVES: To obtain data on the pathogens responsible for community-acquired UTIs in Antananarivo and on their susceptibility patterns to the antimicrobial agents that are currently used to treat UTIs. METHODS: We conducted a retrospective study on bacteria isolated from the urine of patients at the Institut Pasteur of Madagascar between January 2004 and April 2006. RESULTS: We isolated 903 pathogens from 673 women and 213 men. The most commonly isolated bacteria were Escherichia coli (607 strains), Klebsiella pneumoniae (87 strains), Staphylococcus aureus (35 strains) and Proteus mirabilis (32 strains). Seventy-seven per cent of Gram-negative bacilli were resistant to amoxicillin, 65.7% were resistant to trimethoprim/sulfamethoxazole and more than 15% were resistant to ciprofloxacin. Strains were rarely resistant to more expensive antibiotics (ceftriaxone 5.9%, fosfomycin 4.6%). Most bacteria showed intermediate susceptibility to nitroxolin. Resistance rates of E. coli to ceftriaxone and gentamicin increased significantly between 2005 and 2006, due to the increase in strains harbouring an extended-spectrum beta-lactamase. Gram-positive bacteria, Streptococcaceae and Staphylococcus spp. were rarely resistant, but 9.5% of streptococci were resistant to penicillin A and 8% of staphylococci were resistant to oxacillin. CONCLUSIONS: The rate of amoxicillin- and trimethoprim/sulfamethoxazole-resistant Enterobacteriaceae implies that another antibiotic should be used for empirical treatment and that there is a need for new generic drugs in developing countries, especially in Madagascar.

Adolescent↗
PubMed1999

Short-term therapy of acute uncomplicated cystitis.

Short-term therapy, including single-dose treatment and up to 3-day courses, can be considered the treatment of choice in premenopausal women with acute uncomplicated cystitis, because of similar effectiveness, better tolerance and compliance, and lower cost as compared with conventional therapy. Several studies with trimethoprim alone or in combination with a sulfonamide, usually sulphamethoxazole, and with fluoroquinolones with moderately long half-lives, such as ciprofloxacin, enoxacin, lomefloxacin and ofloxacin, suggested that results obtained with a single dose may be inferior to those with a 3-day course, and therefore that the latter may be better. Longer therapy was not considered to be necessary. On the other hand, fluoroquinolones with longer half-lives, such as fleroxacin, pefloxacin and rufloxacin, as single-dose therapy may be as effective as other standard regimens. Fosfomycin trometamol may also be suitable for single-dose therapy. Agents that have not been shown effective in any of these short-term regimens should no longer be used for the treatment of acute cystitis.

Acute Disease↗
PubMed1996

Treponema maltophilum sp. nov., a small oral spirochete isolated from human periodontal lesions.

A novel culture medium for cultivation of fastidious oral anaerobes is described. This medium, OMIZ-Pat, consists of a rich chemically defined basal medium supplemented with asialofetuin, as well as yeast extract and Neopeptone fractions. Addition of 1 mg of rifampin per liter and 100 mg of fosfomycin per liter allowed routine isolation of spirochetes by a limit dilution method in 96-well plates containing liquid OMIZ-Pat. In addition to members of the four previously recognized species of oral treponemes (Treponema denticola, Treponema pectinovorum, Treponema socranskii, and Treponema vincentii), 26 previously undescribed spirochete strains belonging to one group were isolated. We propose the name Treponema maltophilum sp. nov. for these small spirochetes, which have two endoflagella; one endoflagellum is attached at each cell pole, and the endoflagella overlap in the middle of the cell. Growth of these organisms was dependent on a carbohydrate like D-arabinose, L-fucose, D-maltose, L-rhamnose, D-ribose, D-sucrose, or D-trehalose and was inhibited by fetal bovine serum. T. Maltophilum is distinguished from other oral Treponema species by its 16S rRNA sequence, its protein and antigen patterns as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting, and its characteristic alpha-glucosidase activity. The strains included in the new species on the basis of their 16S rRNA sequences are heterogeneous with respect to their alpha-fucosidase, and beta-glucuronidase activities, their dependence on N-acetylglucosamine, and their antigens as detected with patient antibodies. Strain BR is designated the type strain, and strains HO2A and PNA1 are reference strains of the new species.

Antibodies, Bacterial↗
PubMed2001

Natural antibiotic susceptibility of Klebsiella pneumoniae, K. oxytoca, K. planticola, K. ornithinolytica and K. terrigena strains.

The natural susceptibility of 221 Klebsiella strains to 71 antibiotics was examined. The strains were isolated from clinical specimens and the environment, and belonged to K. pneumoniae subsp. pneumoniae (n = 40), K. pneumoniae subsp. ozaenae (37), K. pneumoniae subsp. rhinoscleromatis (10), K. oxytoca (44), K. planticola (40), K. ornithinolytica (25) and K. terrigena (25). MIC values were determined by a microdilution procedure in IsoSensitest broth according to the German standard (DIN). All Klebsiella spp. were naturally resistant or intermediate to amoxicillin, ticarcillin and to antibiotics to which other Enterobacteriaceae are also intrinsically resistant. Klebsiella spp. were naturally sensitive or intermediate to several penicillins, all tested cephalosporins, aminoglycosides, quinolones, tetracyclines, trimethoprim, cotrimoxazole, chloramphenicol and nitrofurantoin. K. pneumoniae subsp. ozaenae and subsp. rhinoscleromatis strains were generally more susceptible to antibiotics than strains of other Klebsiella taxa. K pneumoniae subsp. rhinoscleromatis was the most susceptible taxon, being highly susceptible to cefuroxime, anti-folates and naturally intermediate to erythromycin and clarithromycin. K. pneumoniae subsp. ozaenae was most susceptible to glycopeptides. K. oxytoca and K. terrigena strains were least susceptible to cefazoline, cefoperazone and fosfomycin, respectively. The results of the present study describe a database of the natural antimicrobial susceptibility of Klebsiella spp., which can be used for the validation of antibiotic susceptibility results of these bacteria. MIC patterns to beta-lactams indicate the expression of chromosomally encoded class A gamma-lactamases in all the species, including the subspecies of K. pneumoniae. Similar natural susceptibility patterns of K. planticola and K. ornithinolytica to all tested antibiotics support the status of K. ornithinolytica as a biovar of K. planticola.

Anti-Bacterial Agents↗
PubMed2005

Initiating a crystallographic analysis of recombinant (S)-2-hydroxypropylphosphonic acid epoxidase from Streptomyces wedmorensis.

The oxirane (1R,2S)-1,2-epoxypropylphosphonic acid (fosfomycin) is a natural product antibiotic produced in Streptomyces wedmorensis by the metal-ion-dependent (S)-2-hydroxypropylphosphonic acid epoxidase. This epoxidase is highly unusual since it has no requirement for a haem prosthetic group. The gene encoding the enzyme, fom4, has been cloned and a highly efficient recombinant source of the enzyme established. Two different crystal forms, tetragonal and hexagonal, have been obtained. The hexagonal form displays symmetry consistent with space group P6(1/5)22 and unit-cell parameters a = 86.44, c = 221.56 A, gamma = 120 degrees. The Matthews coefficient, VM, of 2.7 A3 Da(-1) corresponds to two subunits, each of approximate weight 21.4 kDa, in the asymmetric unit with 55% solvent content. These crystals diffract to high resolution and experimental phases are being sought to determine the structure.

Base Sequence↗
PubMed1998

Analysis of genetic relationships and antimicrobial susceptibility of verotoxin-producing Escherichia coli strains isolated in Nagasaki Prefecture, Japan in 1996.

A total of 19 Escherichia coli O157 isolates were obtained in Nagasaki Prefecture, in the south-western part of Japan, between 1990 and 1996. Pulsed-field gel electrophoresis (PFGE) and computer-assisted analysis were applied to determine genetic relationships among these strains. Fragment patterns of the isolates in Nagasaki, as determined by PFGE, were compared with those of isolates in other areas where large outbreaks and sporadic cases of E. coli O157 infection occurred. Similarity values of all the strains isolated in Nagasaki Prefecture were over 0.65 except for E. coli O26. Some strains were identical to the strains isolated from the areas where large outbreaks occurred. All strains were susceptible to ampicillin, fosfomycin, minocycline, amikacin, ofloxacin and sulfamethoxazole-trimethoprim.

Anti-Bacterial Agents↗
PubMed1999

Antibacterial activities of new synthetic divalent cation chelators.

A series of new synthetic ligand compounds which chelate divalent cations was examined for the antibacterial activities of the compounds. Only 2 of 14 synthetic chelators, 9-trans-anthryl-1, 4, 8, 11-tetraaza-tetradecane (No. 6) and bis(2-pyridyl)methylamine (No. 13) showed antibacterial activities, whereas none of the diamines, hydrophilic triamines nor tetramines showed antibacterial activities. Chelators No. 6 and No. 13 inhibited the growth of both Gram-negative and -positive bacteria at doses of 25-200 microg/ml, comparable to those of common antibiotics such as polymixin B, fosfomycin and macrolides. Ethylenediaminetetraacetate (EDTA) potentiated these antibacterial activities, whereas an inhibitory effect of Mg2+ on the MICs of these chelators was observed. Moreover, these chelators enhanced the leakage of periplasmic beta-lactamase. It is therefore suggested that chelators No. 6 and No. 13 disrupt both the membranes and cytoplasmic functions of bacteria, resulting in cell death.

Anthracenes↗
PubMed2004

Release of Shiga toxin by membrane vesicles in Shigella dysenteriae serotype 1 strains and in vitro effects of antimicrobials on toxin production and release.

Effects of various antimicrobials on in vitro Shiga toxin production and release by Shigella dysenteriae serotype 1 was investigated in this study with particular reference to the role of outer membrane vesicles in toxin release by the organism. Five antimicrobials, namely nalidixic acid, ciprofloxacin, norfloxacin, fosfomycin and mitomycin C, were chosen for the study and the toxin titre was measured by the reverse passive latex agglutination (RPLA) method using an available kit. Only mitomycin C was found to induce production of Shiga toxin in the bacteria and its release by outer membrane vesicles. The highest titre of toxin was obtained in vesicle fraction suggesting that the vesicles play an important role in the release of Shiga toxin from periplasmic space by the organism.

Anti-Infective Agents↗