Interferons alpha/beta inhibit IL-7-induced proliferation of CD4- CD8- CD3- CD44+ CD25+ thymocytes, but do not inhibit that of CD4- CD8- CD3- CD44- CD25- thymocytes

We have determined partial sequences of the gyrA and parC genes of Enterobacter cloacae type strain including the regions analogous to the quinolone resistance-determining region of the Escherichia coli gyrA gene. The deduced 65- and 49-amino acid sequences of the determined regions of the E. cloacae gyrA and parC genes were identical to the corresponding regions of the E. coli GyrA and ParC proteins, respectively. We examined 40 clinical strains of E. cloacae isolated from patients with urinary tract infection for susceptibilities to nalidixic acid and ciprofloxacin. Based on the nalidixic acid and ciprofloxacin MICs, these isolates were divided into 19 quinolone-susceptible strains (MICs of nalidixic acid, 3.13-25 mg/L; MICs of ciprofloxacin, < or = 0.025 mg/L) and 21 quinolone-resistant strains (MICs of nalidixic acid, 400 to > 800 mg/L; MICs of ciprofloxacin, 0.39-100 mg/L). We analysed five quinolone-susceptible and 21 quinolone-resistant strains for alterations in GyrA and ParC. The five quinolone-susceptible strains had amino acid sequences in GyrA and ParC identical to those of type strain. Of the 21 quinolone-resistant isolates, three (MICs of nalidixic acid, 400 to > 800 mg/L; MICs of ciprofloxacin, 0.39-3.13 mg/L) had a single amino acid change at the position equivalent to Ser-83 in the E. coli GyrA protein and no alterations in ParC; one (MIC of nalidixic acid, > 800 mg/L; MIC of ciprofloxacin, 3.13 mg/L) had a single amino acid change at Ser-83 in GyrA and a single amino acid change at the position equivalent to Glu-84 in the E. coli ParC protein; two (MIC of nalidixic acid, > 800 mg/L; MIC of ciprofloxacin, 25 mg/L) had double amino acid changes at Ser-83 and Asp-87 in GyrA and no alterations in ParC; and 15 (MICs of nalidixic acid, > 800 mg/L; MICs of ciprofloxacin, 25-100 mg/L) had double amino acid changes at Ser-83 and Asp-87 in GyrA and a single amino acid change at Ser-80 or Glu-84 in ParC. This study suggests, that in clinical isolates of E. cloacae, DNA gyrase is a primary target of quinolones, that only a single amino acid change at Ser-83 in GyrA is sufficient to generate high-level resistance to nalidixic acid and to decrease susceptibility to ciprofloxacin, and that the accumulation of amino acid changes in GyrA and the simultaneous presence of the ParC alterations play a central role in developing high-level resistance to ciprofloxacin.     

Sparfloxacin resistance in clinical isolates of Streptococcus pneumoniae: involvement of multiple mutations in gyrA and parC genes

Antimicrobial susceptibility testing revealed among 150 clinical isolates of Streptococcus pneumoniae 4 pneumococcal isolates with resistance to fluoroquinolones (MIC of ciprofloxacin, >/=32 microgram/ml; MIC of sparfloxacin, >/=16 microgram/ml). Gene amplification and sequencing analysis of gyrA and parC revealed nucleotide changes leading to amino acid substitutions in both GyrA and ParC of all four fluoroquinolone-resistant isolates. In the case of strains 182 and 674 for which sparfloxacin MICs were 16 and 64 microgram/ml, respectively, nucleotide changes were detected at codon 81 in gyrA and codon 79 in parC; these changes led to an Ser-->Phe substitution in GyrA and an Ser-->Phe substitution in ParC. Strains 354 and 252, for which sparfloxacin MICs were 128 microgram/ml, revealed multiple mutations in both gyrA and parC. These strains exhibited nucleotide changes at codon 85 leading to a Glu-->Lys substitution in GyrA, in addition to Ser-79-->Tyr and Lys-137-->Asn substitutions in ParC. Moreover, strain 252 showed additional nucleotide changes at codon 93, which led to a Trp-->Arg substitution in GyrA. These results suggest that sparfloxacin resistance could be due to the multiple mutations in GyrA and ParC. However, it is possible that other yet unidentified mutations may also be involved in the high-level resistance to fluoroquinolones in S. pneumoniae.     

Targeting of DNA gyrase in Streptococcus pneumoniae by sparfloxacin: selective targeting of gyrase or topoisomerase IV by quinolones

gyrA and parC mutations have been identified inn Streptococcus pneumoniae mutants stepwise selected for resistance to sparfloxacin, an antipneumococcal fluoroquinolone. GyrA mutations (at the position equivalent to resistance hot spot Ser-83 in Escherichia coli GyrA) were found in all 17 first-step mutants examined and preceded DNA topoisomerase IV parC mutations (at Ser-79 or Glu-83), which appeared only in second-step mutants. The targeting of gyrase by sparfloxacin in S. pneumoniae but of topoisomerase IV by ciprofloxacin indicates that target preference can be altered by changes in quinolone structure.     

Expression patterns of proliferating cell nuclear antigen in the small intestine of mice infected with Metagonimus yokogawai and Metagonimus Miyata type

The in vitro antimicrobial activities of AM-1155, a new fluoroquinolone, tosufloxacin and fleroxacin were tested against 55 clinical isolates of Neisseria gonorrhoeae using the agar dilution method. In our previous study, all the strains had been examined for mutations in the region corresponding to the quinolone-resistance determining region of the Escherichia coli gyrA gene and the analogous region of the parC gene, and tested for susceptibility to ciprofloxacin. In this study, the 55 isolates of N. gonorrhoeae were assigned to one of three categories based on the presence or absence of alterations in GyrA and ParC. In each category, the antimicrobial activity of AM-1155 against the isolates was compared with those of tosufloxacin and fleroxacin. The MICs of AM-1155 for 11 highly fluoroquinolone-resistant isolates with alterations in both GyrA and ParC ranged from 0.06 to 1.0 microgram/ml. The MICs inhibiting 50% (MIC50) and 90% (MIC90) of these isolates were 0.125 and 1.0 microgram/ml, respectively. The MICs of AM-1155 for 20 moderately fluoroquinolone-resistant isolates with alterations only in GyrA ranged from 0.03 to 0.25 microgram/ml (MIC50, 0.06 microgram/ml; MIC90m, 0.125 microgram/ml). The MICs of AM-1155 for 24 of the quinolone-susceptible isolates without alterations in either GyrA or ParC ranged from 0.004 to 0.03 microgram/ml (MIC50, 0.008 microgram/ml. MIC90, 0.015 microgram/ml). There were significant differences between the MIC distribution of AM-1155 and each corresponding MIC distribution of tosufloxacin and fleroxacin in these three categories to which the 55 isolates were assigned (p < 0.05). Based on the MIC90S of the tested fluoroquinolones, AM-1155 was two- and eightfold more active against the highly fluoroquinolone-resistant isolates than tosufloxacin and fleroxacin, respectively. Against the moderately fluoroquinolone-resistant isolates, AM-1155 was four- and sixteenfold more active than tosufloxacin and fleroxacin, respectively. Against the quinolone-susceptible strains, AM-1155 was also two- to fourfold more active than the other fluoroquinolones. Overall, AM-1155 exhibited more potent in vitro activity against both quinolone-resistant and quinolone-susceptible isolates of N. gonorrhoeae than tosufloxacin and fleroxacin. In ciprofloxacin treatment failures of gonorrhea at single doses of 500 mg. MICs for the causative organisms have ranged from 1.0 to 16.0 micrograms/ml. The MICs of AM-1155 for the isolates harboring quinolone resistance-associated genetic alterations, including strains exhibiting ciprofloxacin MICs of 2.0 and 8.0 micrograms/ml, still ranged from 0.03 to 1.0 microgram/mL A single-dose study in humans has demonstrated higher peak serum concentrations and longer half-lives of AM-1155, resulting in the AUC0-00 values of AM-1155, which are threefold greater than those of ciprofloxacin at the single doses of 400 and 600 mg. Because of its potent in vitro antimicrobial activity and advantageous pharmacokinetic behavior, AM-1155 may be a clinically useful agent for treating gonorrhea including that caused by quinolone-resistant strains.     

Isolation and characterization of a dibenzofuran-degrading yeast: identification of oxidation and ring cleavage products

PURPOSE: To investigate the development of fluoroquinolone resistance among Neisseria gonorrhoeae isolates in Japan and the frequency and patterns of mutations involving the GyrA and ParC proteins, which confer quinolone resistance to the bacteria, in isolates. MATERIALS AND METHODS: Antimicrobial susceptibilities of 145 gonococcal isolates, including 79 isolated from February 1992 through February 1993 and 66 isolated from February 1995 through February 1996, to six fluoroquinolones and several other antibiotics were compared with those of 27 isolates obtained from 1981 through 1984. To identify mutations in gyrA and parC genes of the isolates, the quinolone resistance-determining regions of the gyrA and parC genes were PCR-amplified and the PCR products were directly sequenced. RESULTS: The minimum inhibitory concentration for 90% of strains (MIC90) values of norfloxacin for the isolates from 1992 to 93 (4 microg./ml.) and 1995 to 96 (8 microg./ml.) were 16- and 32-fold, respectively, higher than those for isolates from 1981 to 84 (0.25 microg./ml.). The MIC90 values of ciprofloxacin for isolates from 1992 to 93 (0.5 microg./ml.) and 1995 to 96 (1 microg./ml.) showed increase of 8- and 16-fold, respectively, in comparison with those from 1981 to 84 (0.063 microg./ml.). The isolates from 1992 to 93 and 1995 to 96 were also less susceptible to newer fluoroquinolones including levofloxacin, sparfloxacin, DU-6859a and AM-1155, as compared with those from 1981 to 84. In 46 (67.6%) and 16 (23.5%) of the 68 gonococcal strains sequenced, GyrA and ParC mutations were identified, respectively. No ParC substitutions were identified in any isolates without co-existence of the GyrA mutation. A Ser-91 to Phe mutation, which was detected in 30 (65.2%) of the 46 isolates with GyrA mutations, was the most common GyrA mutation. Mutants with the single Ser-91 to Phe substitution in GyrA were 12-fold and at least 13-fold, respectively, less susceptible to norfloxacin and ciprofloxacin than the wild type. CONCLUSIONS: The results obtained in this study suggest that a high prevalence of gonococcal isolates with the Ser-91 to Phe mutation in GyrA has reduced the susceptibility of this organism to fluoroquinolones in Japan.     

Development of a rapid assay for detecting gyrA mutations in Escherichia coli and determination of incidence of gyrA mutations in clinical strains isolated from patients with complicated urinary tract infections

The MICs of ofloxacin for 743 strains of Escherichia coli isolated from 1988 to 1994 were determined by testing. The strains were from patients with urinary tract infections complicated by functional or anatomical disorders of the urinary tract. Those determined to be ofloxacin resistant (MIC, > or =12.5 microg/ml) comprised 3 of 395 strains (1.3%) from the 1988 to 1990 group, 2 of 166 strains (1.2%) from the 1991 to 1992 group, and 7 of 182 strains (3.8%) from the 1993 to 1994 group. The incidence of resistant strains increased significantly during this period. The percentage of isolates with moderately decreased susceptibilities to ofloxacin (MIC, 0.39 to 3.13 microg/ml) also rose during the same period. To determine the incidence of gyrA mutations in urinary-tract-derived strains of E. coli, we developed a simple and rapid assay based on PCR amplification of the region of the gyrA gene containing the mutation sites followed by digestion of the PCR product with a restriction enzyme. Using this assay, we examined all 182 strains isolated in 1993 and 1994 for the presence of mutations at Ser-83 and Asp-87 in the gyrA gene. Of these strains, 33 (18.1%) had mutations in the gyrA gene. The incidences of mutations at Ser-83, at Asp-87, and at both codons were 10.4 (19 strains), 4.4 (8 strains), and 3.3% (6 strains), respectively. To determine the correlation of the mutations in the gyrA gene with susceptibilities to quinolones (nalidixic acid, ofloxacin, norfloxacin, and ciprofloxacin), we further examined 116 strains for which the MICs of ofloxacin were > or =0.2 microg/ml that were chosen from the isolates in the 1988 to 1992 group. The MICs of nalidixic acid for the strains without mutations at either Ser-83 or Asp-87 were < or =25 microg/ml, whereas those for the strains with single mutations or double mutations were from 50 to >800 microg/ml. For the fluoroquinolones, significant differences in the distributions of the MICs were observed among the strains without mutations, with single mutations, and with double mutations. The accumulation of mutations in the gyrA gene was associated with an increase in fluoroquinolone resistance. Ofloxacin MICs for the majority of the strains with single and double mutations were 0.39 to 3.13 and 6.25 to 100 microg/ml, respectively. This study demonstrates a chronological increase in the percentage of not only highly fluoroquinolone-resistant strains, corresponding to those with double mutations in the gyrA gene, but also strains with moderately decreased susceptibilities to fluoroquinolones, corresponding to those with single mutations. This increase in the incidence of strains with a single mutation in the gyrA gene portends a further increase in the incidence of strains with clinically significant resistance to fluoroquinolones.     

Efflux pump-mediated quinolone resistance in Staphylococcus aureus strains wild type for gyrA, gyrB, grlA, and norA

Fluoroquinolone efflux was studied in 47 Staphylococcus aureus clinical strains with MICs of ciprofloxacin (CFX) of < or = 2 micrograms/ml. Forty-three strains were wild type for gyrA, gyrB, and grlA quinolone resistance-determining regions and for norA and its promoter region. Forty of these strains (MICs of CFX, 0.1 to 0.2 microgram/ml) did not show efflux of fluoroquinolones. Three strains (MICs of CFX, 1 to 2 micrograms/ml) showed efflux. These results suggest that efflux can appear in S. aureus clinical strains in the absence of mutations in norA and its promoter.     

Resistance to fluoroquinolones in Escherichia coli isolated from poultry

Quinolone-resistant Escherichia coli strains were isolated from poultry clinical samples in Saudi Arabia. The poultry flocks had been treated with oxolinic acid or flumequine prophylaxis. The measure of the uptake of fluoroquinolones showed that none of the strains had a reduced accumulation of quinolones. The result of complementation with the wild-type E. coli gyrA gene, which restored fluoroquinolone susceptibility, and the isolation of DNA gyrase from six isolates indicated that the resistant strains had an altered DNA gyrase. The minimum effective dose of ciprofloxacin for inhibition of supercoiling catalyzed by the isolated gyrases varied from 0.085 microgram/ml for a susceptible isolate (MIC < 4 micrograms/ml) up to 96 micrograms/ml for the more resistant one (strain 215, MIC > 64 micrograms/ml). For the same two isolates, the minimum effective doses of sparfloxacin varied from 0.17 up to 380 micrograms/ml. The in vitro selection of spontaneous single-step fluoroquinolone-resistant mutants using ciprofloxacin suggested that the more resistant mutants are likely the result of several mutations. These results also show that, as in human medicine, cross-resistance between older quinolones and fluoroquinolones can exist in veterinary isolates and reiterate the need for the prudent use of these drugs.     

Role of mutations in DNA gyrase genes in ciprofloxacin resistance of Pseudomonas aeruginosa susceptible or resistant to imipenem

In Pseudomonas aeruginosa, resistance to imipenem is mainly related to a lack of protein OprD and resistance to fluoroquinolones is mainly related to alterations in DNA gyrase. However, strains cross resistant to fluoroquinolones and imipenem have been selected in vitro and in vivo with fluoroquinolones. We investigated the mechanisms of resistance to fluoroquinolones in 30 clinical strains of P. aeruginosa resistant to ciprofloxacin (mean MIC, >8 micrograms/ml), 20 of which were also resistant to imipenem (mean MIC, >16 micrograms/ml). By immunoblotting, OprD levels were markedly decreased in all of the imipenem-resistant strains. Plasmids carrying the wild-type gyrA gene (pPAW207) or gyrB gene (pPBW801) of Escherichia coli were introduced into each strain by transformation. MICs of imipenem did not change after transformation, whereas those of ciprofloxacin and sparfloxacin dramatically decreased (25- to 70-fold) for all of the strains. For 28 of them (8 susceptible and 20 resistant to imipenem), complementation was obtained with pPAW207 but not with pPBW801. After complementation, the geometric mean MICs of ciprofloxacin and sparfloxacin (MICs of 0.3 microgram/ml and 0.5 microgram/ml, respectively) were as low as those for wild-type strains. Complementation was obtained only with pPBW801 for one strain and with pPAW207 and pPBW801 for one strain highly resistant to fluoroquinolones. These results demonstrate that in clinical practice, gyrA mutations are the major mechanism of resistance to fluoroquinolones even in the strains of P. aeruginosa resistant to imipenem and lacking OprD, concomitant resistance to these drugs being the result of the addition of at least two independent mechanisms.     

In vitro activity of the new fluoroquinolone CP-99,219

The in vitro activity of the new fluoroquinolone CP-99,219 [7-(3-azabicyclo[3.1.0]hexyl)naphthyridone] was compared with those of four other quinolones against 541 gram-negative, 283 gram-positive, and 70 anaerobic bacterial isolates. CP-99,219 inhibited 90% of many isolates in the family Enterobacteriaceae at a concentration of < or = 0.25 micrograms/ml (range, < 0.008 to 1 microgram/ml), an activity comparable to those of tosufloxacin and sparfloxacin and two times greater than that of temafloxacin. Ninety percent of the Proteus vulgaris, Providencia rettgeri, Providencia stuartii, and Serratia marcescens isolates were inhibited by 0.5 to 2 micrograms of CP-99,219 per ml. CP-99,219 inhibited 90% of the Pseudomonas aeruginosa and Haemophilus influenzae isolates at 1 and 0.015 micrograms/ml, respectively. The compound inhibited methicillin-susceptible Staphylococcus aureus at 0.06 micrograms/ml, whereas a ciprofloxacin concentration of 1 microgram/ml was required to inhibit these organisms. CP-99,219 inhibited 90% of methicillin-resistant S. aureus isolates at a concentration of < or = 4 micrograms/ml, while ciprofloxacin and temafloxacin had MICs against these isolates of > 16 micrograms/ml. Streptococci were inhibited by < or = 0.25 micrograms/ml, an activity comparable to that of tosufloxacin. CP-99,219 was eight times more active than ciprofloxacin against Streptococcus pneumoniae. Bacteroides species were inhibited by CP-99,219 at a concentration of 2 micrograms/ml, whereas inhibition of these species required 4- and 16-microgram/ml concentrations of tosufloxacin and ciprofloxacin, respectively. The MBCs of CP-99,219 ranged from two to four times the MICs, and inoculum size had a minimal effect on MIC. CP-99,219 was active against P. aeruginosa at pH 5.5, with only a fourfold increase in MIC compared with values obtained at pH 7.5. The addition of up to 9 mM Mg(2+) increased the MIC range from 0.03 to 0.06 microgram/ml to 0.12 to 0.5 microgram/ml. In view of its excellent in vitro activity against both gram-positive and gram-negative bacteria, CP-99,219 merits further study to determine it's clinical pharmacologic properties and potential for therapeutic use.     

Susceptibilities of bacteria isolated from patients with lower respiratory infectious diseases to antibiotics (1996)

The bacteria isolated from the patients with lower respiratory tract infections were collected by institutions located throughout Japan, since 1981. Ikemoto et al. have been investigating susceptibilities of these isolates to various antibacterial agents and antibiotics, and characteristics of the patients and isolates from them each year. Results obtained from these investigations are discussed. In 16 institutions around the entire Japan, 557 strains of presumably etiological bacteria were isolated mainly from the sputa of 449 patients with lower respiratory tract infections during the period from October 1996 to September 1997. MICs of various antibacterial agents and antibiotics were determined against 98 strains of Staphylococcus aureus, 93 strains of Streptococcus pneumoniae, 84 strains of Haemophilus influenzae, 84 strains of Pseudomonas aeruginosa (non-mucoid strains), 17 strains of Pseudomonas aeruginosa (mucoid strains), 31 strains of Moraxella subgenus Branhamella catarrhalis, 21 strains of Klebsiella pneumoniae etc., and the drug susceptibilities of these strains were assessed except for those strains that died during transportation. 1) S. aureus S. aureus strains for which MICs of oxacillin (MPIPC) were higher than 4 micrograms/ml (methicillin-resistant S. aureus) accounted for 67.3%. The frequency of the drug resistant bacteria increased comparing to the previous year's 52.7%. Arbekacin (ABK) and vancomycin (VCM) showed the highest activities against both S. aureus and MRSA with MIC80s of 1 microgram/ml. 2) S. pneumoniae Imipenem (IPM) and panipenem (PAPM) of carbapenems showed the most potent activities with MIC80s of 0.063 microgram/ml. Faropenem (FRPM) showed the next potent activity with MIC80 of 0.125 microgram/ml. The other drugs except erythromycin (EM), clindamycin (CLDM) and tetracycline (TC) were active against S. pneumoniae tested with MIC80s of 8 micrograms/ml or below. 3) H. influenzae The activities of all drugs were potent against H. influenzae tested with MIC80s of 4 micrograms/ml or below. Cefotiam (CTM), cefmenoxime (CMX), cefditoren (CDTR) and ofloxacin (OFLX) showed the most potent activities with MIC80s of 0.063 microgram/ml. 4) P. aeruginosa (mucoid strains) Tobramycin (TOB) showed the most potent activity against P. aeruginosa (mucoid strains) with MIC80 of 1 microgram/ml. Ceftazidime (CAZ), cefsulodin (CFS), IPM, gentamicin (GM), ABK and ciprofloxacin (CPFX) showed the next potent activities, with MIC80s of 2 micrograms/ml. The MIC80s of the other drugs ranged from 4 micrograms/ml to 16 micrograms/ml. 5) P. aeruginosa (non-mucoid strains) TOB and CPFX showed the most potent activities against P. aeruginosa (non-mucoid strains) with MIC80s of 1 microgram/ml. The MIC80s of piperacillin (PIPC) and cefoperazone (CPZ) were 16 micrograms/ml in 1995, and they were 64 micrograms/ml in 1996. 6) K. pneumoniae All drugs except ampicillin (ABPC) were active against K. pneumoniae. CMX, cefpirome (CPR), cefozopran (CZOP) and carumonam (CRMN) showed the most potent activities against K. pneumoniae with MIC80s of 0.125 microgram/ml. The MIC80s of the other drugs ranged from 0.25 microgram/ml to 2 micrograms/ml. 7) M.(B) catarrhalis Against M.(B.) catarrhalis, all drugs showed good activities with MICs of 4 micrograms/ml or below. IPM and minocycline (MINO) showed the most potent activities with MICs of 0.063 microgram/ml. Also, we investigated year to year changes in the characteristics of patients, their respiratory infectious diseases, and the etiology. Patients' backgrounds were examined for 557 isolates from 449 cases. The examination of age distribution indicated that the proportion of patients with ages over 60 years was 71.0% of all the patients showing a slight increase over that in 1994. Proportions of diagnosed diseases were as follows: Bacterial pneumonia and chronic bronchitis were the most frequent with 35.9% and 30.3% respectively. They were followed by bronchiectasis with a proportion of 10.     

Enterococcus faecium: in vitro activity of antimicrobial drugs, singly and combined, with and without defibrinated human blood, against multiple-antibiotic-resistant strains

The minimal inhibitory (MICs) and bactericidal concentrations of 14 antimicrobial drugs were determined against 17 clinical isolates of Enterococcus faecium, including 4 glycopeptide-resistant strains. Both teicoplanin and vancomycin lacked bactericidal activity against all 13 susceptible isolates. Time-kill experiments served to test various antibiotic combinations chiefly against glycopeptide-resistant strains in Mueller-Hinton broth (MHB) and in MHB supplemented with 65% (v/v) fresh defibrinated human blood. Co-trimoxazole, fusidic acid, and novobiocin yielded bacteriostatic effects. Rifampin was bactericidally active against rifampin-susceptible strains (MICs = 0.125 micrograms/ml), but less so against low-level-rifampin-resistant (MICs = 2-8 micrograms/ml) strains in MHB. However, in the presence of human blood, rifampin (2 micrograms/ml) combined with co-trimoxazole (0.25/4.75 micrograms/ml) killed rifampin-susceptible and low-level-rifampin-resistant, but not moderate-level-rifampin-resistant (MICs = 16-32 micrograms/ml) strains of E. faecium. Of two topical drugs examined, mupirocin merely inhibited strains of E. faecium; conversely, taurolidine at 2,000 micrograms/ml was efficacious against all strains examined, although the kinetics of bactericidal activity were retarded somewhat in the presence of 65 vol% human blood.     

Anomalous patterns of callosal connections develop in visual cortex of monocularly enucleated hamsters

Six multiply resistant isolates of Salmonella typhimurium var. copenhagen with high-level resistance to fluoroquinolones (e.g., MIC of ciprofloxacin: 32 micrograms/ml) were isolated from human patients (n = 3) and from cattle (n = 3). The isolates were examined by complementation tests using a set of broad-host-range plasmids, which carry either the gyrA+ or the gyrB+ genes or a combination of both from Escherichia coli K-12. The results indicated a combination of gyrA and gyrB mutations in all isolates. Subsequent direct sequencing of PCR-generated internal DNA fragments of gyrA revealed an identical double mutation in all six isolates (Ser-83-->Ala and Asp-87-->Asn). In addition, the results of phenotypic (i.e., phagetype, biotype, serotype) and genotypic characterization [i.e., ribotyping and polymerase chain reaction fingerprinting (PCR-fingerprinting)] were identical for all six isolates and were distinguishable from a quinolone-susceptible strain of the same serovar and an unrelated isolate of S. typhimurium. These data indicate the clonal identity of the fluoroquinolone-resistant strains of S. typhimurium isolated from men and cattle in Germany.     

Increased activity of a new chlorofluoroquinolone, BAY y 3118, compared with activities of ciprofloxacin, sparfloxacin, and other antimicrobial agents against anaerobic bacteria

A total of 435 clinical isolates of anaerobes were tested with a broth microdilution method to determine the activity of BAY y 3118 compared with those of other agents against anaerobic bacteria. All strains of Bacteroides capillosus, Prevotella spp., Porphyromonas spp., Fusobacterium spp., Clostridium spp., Eubacterium spp., Peptostreptococcus spp., and Veillonella parvula were susceptible (MICs of < or = 2 micrograms/ml) to BAY y 3118. Against the 315 strains of the Bacteroides fragilis group, five strains required elevated MICs (> or = 4 micrograms/ml) of BAY y 3118. Only imipenem and metronidazole were active against all anaerobes. Overall, BAY y 3118 was more active than ciprofloxacin, sparfloxacin, piperacillin, cefotaxime, and clindamycin against the test isolates.     

Glycopeptide susceptibility among Danish Enterococcus faecium and Enterococcus faecalis isolates of animal and human origin and PCR identification of genes within the VanA cluster

The MICs of vancomycin and avoparcin were determined for isolates of Enterococcus faecium and isolates of Enterococcus faecalis recovered from the feces of humans and animals in Denmark. Two hundred twenty-one of 376 (59%) isolates of E. faecium and 2 of 133 (1.5%) isolates of E. faecalis were resistant to vancomycin (MICs, 128 to > or = 256 micrograms/ml), and all vancomycin-resistant isolates were resistant to avoparcin (MICs, 64 to > or = 256 micrograms/ml). All vancomycin-resistant isolates examined carried the vanA, vanX, and vanR genes, suggesting that a gene cluster similar to that of the transposon Tn1546 was responsible for the resistance.     

In vitro activities of meropenem, PD 127391, PD 131628, ceftazidime, chloramphenicol, co-trimoxazole, and ciprofloxacin against Pseudomonas cepacia

In a study of 110 Pseudomonas cepacia isolates from patients without cystic fibrosis, the in vitro potencies of three new compounds, meropenem, PD 127391, and PD 131628, were comparable to those of ceftazidime and ciprofloxacin and exceeded those of chloramphenicol and co-trimoxazole. The MICs of ceftazidime, ciprofloxacin, meropenem, and the PD compounds for 90% of strains tested were < or = 4 micrograms/ml, whereas they were 32 micrograms/ml for chloramphenicol and co-trimoxazole. Data for 20 isolates from patients with cystic fibrosis indicated that the isolates were less susceptible to all seven antibiotics tested, with the most active compounds being meropenem and PD 127391.     

In vitro activity of RP59500, an injectable streptogramin antibiotic, against vancomycin-resistant gram-positive organisms

The in vitro activity of RP59500, a streptogramin antibiotic, against 146 clinical isolates of vancomycin-resistant gram-positive bacteria was examined. Five strains of the species Enterococcus casseliflavus and Enterococcus gallinarum, for which the MIC of vancomycin was 8 micrograms/ml, were also studied. Twenty-eight vancomycin-susceptible strains of Enterococcus faecalis and Enterococcus faecium were included for comparison. The drug was highly active against Leuconostoc spp., Lactobacillus spp., and Pediococcus spp. (MICs, < or = 2 micrograms/ml). RP59500 was more active against vancomycin-susceptible strains of E. faecium than E. faecalis (MICs for 90% of the strains [MIC90s], 1.0 versus 32 micrograms/ml). Vancomycin-resistant strains of E. faecalis were as resistant to RP59500 as vancomycin-susceptible strains (MIC90, 32 micrograms/ml), but some vancomycin-resistant E. faecium strains were relatively more resistant to the new agent (MIC90, 16; MIC range, 0.5 to 32 micrograms/ml) than were vancomycin-susceptible organisms of this species.     

Comparative studies on activities of antimicrobial agents against causative organisms isolated from patients with urinary tract infections (1996). I. Susceptibility distribution

The frequencies of isolation and susceptibilities to antimicrobial agents were investigated on 680 bacterial strains isolated from patients with urinary tract infections (UTIs) in 10 hospitals during the period of June 1996 to May 1997. Of the above bacterial isolates, Gram-positive bacteria accounted for 30.4% and a majority of them were Enterococcus faecalis. Gram-negative bacteria accounted for 69.6% and most of them were Escherichia coli. Susceptabilities of several isolated bacteria to antimicrobial agents were as followed; 1. Enterococcus faecalis Ampicillin (ABPC) showed the highest activity against E. faecalis isolated from patients with UTIs. Its MIC90 was 1 microgram/ml. Imipenem (IPM) and vancomycin (VCM) were also active with the MIC90S of 2 micrograms/ml. The others had low activities with the MIC90S of 16 micrograms/ml or above. 2. Staphylococcus aureus including MRSA Arbekacin (ABK) and VCM showed the highest activities against both S. aureus and MRSA isolated from patients with UTIs. The MIC90S of them were 1 or 2 micrograms/ml. The others except minocycline (MINO) had low activities with the MIC90S of 32 micrograms/ml or above. 3. Staphylococcus epidermidis ABK and VCM showed the strongest activities against S. epidermis isolated from patients with UTIs. The MICs for all strains were equal to or lower than 2 micrograms/ml. Cefazolin (CEZ), cefotiam (CTM) and cefozopran (CZOP) were also active with the MIC90S of 4 micrograms/ml. Compared with antimicrobial activities of cephems is 1995, the MIC90S of them had changed into a better state. They ranged from 4 micrograms/ml 16 micrograms/ml in 1996. 4. Streptococcus agalactiae All drugs except MINO were active against S. agalactiae. ABPC, CZOP, IPM, and clarithromycin (CAM) showed the highest activities. The MICs for all strains were equal to or lower than 0.125 micromilligrams. Tosufloxacin (TFLX) and VCM were also active with the MIC90S of 0.5 micromilligrams. 5. Citrobacter freundii Gentamicin (GM) showed the highest activity against C. freundii isolated from patients with UTIs. Its MIC90 was 0.5 micrograms/ml. IPM and amikacin (AMK) were also active with the MIC90S of 1 microgram/ml and 2 micrograms/ml, respectively. Cefpirome (CPR) and CZOP were also active with the MIC90S of 8 micrograms/ml. The MIC90S of the others were 16 micrograms/ml or above. 6. Enterobacter cloacae IPM showed the highest activity against E. cloacae. The MICs for all strains were equal to or lower than 0.5 microgram/ml. The MIC90S of ciprofloxacin (CPFX) and TFLX were 1 microgram/ml, the MIC90 of AMK was 2 micrograms/ml, the MIC90S of CZOP, GM and ofloxacin (OFLX) were 4 micrograms/ml. The MIC50S of cephems except CEZ, cefmetazole (CMZ) and cefaclor (CCL) had changed into a better state in 1996, compared with those in 1995. 7. Escherichia coli All drugs except penicillins and MINO were active against E. coli. Particularly CPR, CZOP and IPM showed the highest activities against E. coli. The MIC90S of them were 0.125 microgram/ml or below. Among E. coli strains, those with low susceptibilities to cephems except CEZ, cefoperazone (CPZ), latamoxef (LMOX) and CCL have increased in 1996, compared with those in 1995. 8. Klebsiella pneumoniae K. pneumoniae was susceptible to all drugs except penicillins, with the MIC90S of 2 micrograms/ml or below. CPR had the strongest activity, the MICs for all strains were equal to or lower than 0.25 microgram/ml. Flomoxef (FMOX), cefixime (CFIX), CZOP and carumonam (CRMN) were also active with the MIC90S of 0.125 microgram/ml or below. 9. Pseudomonas aeruginosa All drugs except quinolones were not so active against P. aeruginosa with the MIC90S were 32 micrograms/ml or above. Quinolones were more active in 1996 than 1995. The MIC90S of them were between 4 micrograms/ml and 8 micrograms/ml, and the MIC50S of them were between 1 microgram/ml and 2 micrograms/ml. 10. Serratia marcescens GM showed the highest activity against S. marcescens. Its MIC90 was 1 micro     

Activities of new fluoroquinolones against fluoroquinolone-resistant pathogens of the lower respiratory tract

The activities of six new fluoroquinolones (moxifloxacin, grepafloxacin, gatifloxacin, trovafloxacin, clinafloxacin, and levofloxacin) compared with those of sparfloxacin and ciprofloxacin with or without reserpine (20 microg/ml) were determined for 19 Streptococcus pneumoniae isolates, 5 Haemophilus sp. isolates, and 10 Pseudomonas aeruginosa isolates with decreased susceptibility to ciprofloxacin from patients with clinically confirmed lower respiratory tract infections. Based upon the MICs at which 50% of isolates were inhibited (MIC50s) and MIC90s, the most active agent was clinafloxacin, followed by (in order of decreasing activity) trovafloxacin, moxifloxacin, gatifloxacin, sparfloxacin, and grepafloxacin. Except for clinafloxacin (and gatifloxacin and trovafloxacin for H. influenzae), none of the new agents had improved activities compared with that of ciprofloxacin for P. aeruginosa and H. influenzae. A variable reserpine effect was observed for ciprofloxacin and S. pneumoniae; however, for 9 of 19 (47%) isolates the MIC of ciprofloxacin was decreased by at least fourfold, suggesting the presence of an efflux pump contributing to the resistance phenotype. The laboratory parC (Ser79) mutant strain of S. pneumoniae required eightfold more ciprofloxacin for inhibition than the wild-type strain, but there was no change in the MIC of sparfloxacin and only a 1-dilution increase in the MICs of the other agents. For efflux pump mutant S. pneumoniae the activities of all the newer agents, except for levofloxacin, were reduced. Except for clinafloxacin, all second-step laboratory mutants required at least 2 microg of all fluoroquinolones per ml for inhibition.     

Evidence that ferritin is UV inducible in human skin: part of a putative defense mechanism

The low-affinity penicillin-binding protein (PBP) 5 is the main beta-lactam target and is responsible for resistance to this class of antibiotics in Enterococcus faecium. The PBP 5 variants of 15 clinical isolates (including 8 resistant to vancomycin) with different levels of beta-lactam resistance were analyzed. Most of the highly beta-lactam-resistant isolates produced small quantities of PBP 5 of low affinity. This was associated with particular amino acid substitutions: an Ala or Ile for Thr-499, a Glu for Val-629, and a Pro for Ser-667. A change of Met-485 to Thr or Ala (adjacent to the conserved SDN box) was observed in isolates with MICs of ampicillin of 64 or 128 microg/mL, respectively. In the 2 most resistant isolates, with MICs of ampicillin of 256 microg/mL, an additional Ser was present just after Ser-466. Thus, particular point mutations in PBP 5 and combinations thereof may lead to high-level beta-lactam resistance in E. faecium.