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In vitro activity of ABT-773, a new ketolide, against recent clinical isolates of Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis.

The in vitro activity of ABT-773 was evaluated against Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis isolates. ABT-773 was the most active antimicrobial tested against S. pneumoniae. ABT-773 and azithromycin were equivalent in activity against H. influenzae and M. catarrhalis and more active than either clarithromycin or erythromycin.

Anti-Bacterial Agents↗

Activities and postantibiotic effects of gemifloxacin compared to those of 11 other agents against Haemophilus influenzae and Moraxella catarrhalis.

The activity of gemifloxacin against Haemophilus influenzae and Moraxella catarrhalis was compared to those of 11 other agents. All quinolones were very active (MICs, </=0.125 microgram/ml) against 248 quinolone-susceptible H. influenzae isolates (40.7% of which were beta-lactamase positive); cefixime (MICs, </=0.125 microgram/ml) and amoxicillin-clavulanate (MICs </=4.0 microgram/ml) were active, followed by cefuroxime (MICs, </=16.0 microgram/ml); azithromycin MICs were </=4.0 microg/ml. For nine H. influenzae isolates with reduced quinolone susceptibilities, the MICs at which 50% of isolates are inhibited (MIC(50)s) were 0.25 microgram/ml for gemifloxacin and 1.0 microgram/ml for the other quinolones tested. All strains had mutations in GyrA (Ser84, Asp88); most also had mutations in ParC (Asp83, Ser84, Glu88) and ParE (Asp420, Ser458), and only one had a mutation in GyrB (Gln468). All quinolones tested were equally active (MICs, </=0.06 microgram/ml) against 50 M. catarrhalis strains; amoxicillin-clavulanate, cefixime, cefuroxime, and azithromycin were very active. Against 10 H. influenzae strains gemifloxacin, levofloxacin, sparfloxacin, and trovafloxacin at 2x the MIC and ciprofloxacin at 4x the MIC were uniformly bactericidal after 24 h, and against 9 of 10 strains grepafloxacin at 2x the MIC was bactericidal after 24 h. After 24 h bactericidal activity was seen with amoxicillin-clavulanate at 2x the MIC for all strains, cefixime at 2x the MIC for 9 of 10 strains, cefuroxime at 4x the MIC for all strains, and azithromycin at 2x the MIC for all strains. All quinolones except grepafloxacin (which was bactericidal against four of five strains) and all ss-lactams at 2x to 4x the MIC were bactericidal against five M. catarrhalis strains after 24 h; azithromycin at the MIC was bactericidal against all strains after 24 h. The postantibiotic effects (PAEs) against four quinolone-susceptible H. influenzae strains were as follows: gemifloxacin, 0.3 to 2.3 h; ciprofloxacin, 1.3 to 4.2 h; levofloxacin, 2.8 to 6.2 h; sparfloxacin, 0.6 to 3.0 h; grepafloxacin, 0 to 2.1 h; trovafloxacin, 0.8 to 2.8 h. At 10x the MIC, no quinolone PAEs were found against the strain for which quinolone MICs were increased. Azithromycin PAEs were 3.7 to 7.3 h.

Anti-Bacterial Agents↗

Multicenter surveillance of antimicrobial resistance of Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis in Taiwan during the 1998-1999 respiratory season.

A susceptibility surveillance study of 276 isolates of Streptococcus pneumoniae, 301 of Haemophilus influenzae, and 110 of Moraxella catarrhalis was carried out from November 1998 to May 1999 in Taiwan. High rates of nonsusceptibility to penicillin (76%), extended-spectrum cephalosporins (56%), azithromycin (94%), clarithromycin (95%), and trimethoprim-sulfamethoxazole (TMP-SMX) (65%) for S. pneumoniae isolates and high rates of nonsusceptibility to amoxicillin (58%) and TMP-SMX (52%) for H. influenzae isolates were found. Higher percentages of S. pneumoniae isolates nonsusceptible to aminopenicillins, extended-spectrum cephalosporins, macrolides, and TMP-SMX were observed among penicillin-intermediate and -resistant isolates. All quinolones tested were active in vitro against these three organisms.

Drug Resistance, Microbial↗

Activities of BMS 284756 (T-3811) against Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae isolates from SENTRY antimicrobial surveillance program medical centers in Latin America (1999).

The antimicrobial activity of BMS 284756, a novel des-F(6)-quinolone, was comparatively evaluated against 257 Streptococcus pneumoniae, 198 Haemophilus influenzae, and 88 Moraxella catarrhalis strains isolated in Latin America between July and September of 1999 as part of the SENTRY Antimicrobial Surveillance Program. Nearly 28.0% of S. pneumoniae strains were nonsusceptible to penicillin. The rank order of quinolone potency versus S. pneumoniae was BMS 284756 (MIC at which 90% of isolates were inhibited [MIC(90)], 0.12 microg/ml) > trovafloxacin (MIC(90), 0.25 microg/ml) > gatifloxacin (MIC(90), 0.5 microg/ml) > levofloxacin and ciprofloxacin (MIC(90), 1 to 2 microg/ml). All S. pneumoniae strains that were not susceptible to other quinolones were inhibited by BMS 284756 at < or = 2 microg/ml. The overall prevalence of beta-lactamase production was 15.2% in H. influenzae and 98.9% in M. catarrhalis. BMS 284756 showed excellent potency and spectrum against this group of pathogens, inhibiting all isolates at < or = 0.12 microg/ml. BMS 284756 exhibited activity similar to those displayed by the new fluoroquinolones, such as levofloxacin, trovafloxacin, or gatifloxacin, and could be a therapeutic option for empirical treatment of community-acquired respiratory tract infections.

Anti-Infective Agents↗

Activities of faropenem, an oral beta-lactam, against recent U.S. isolates of Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis.

The in vitro activities of faropenem and other antimicrobial agents were determined against 4,725 Streptococcus pneumoniae isolates, 2,614 Haemophilus influenzae isolates, and 1,193 Moraxella catarrhalis isolates collected from 273 U.S. laboratories during 1999. Faropenem MICs at which 90% of isolates are inhibited were 0.008, 0.25, and 1 microg/ml for penicillin-susceptible, -intermediate, and -resistant S. pneumoniae strains, respectively; 0.5 and 1 microg/ml for beta-lactamase-positive and -negative H. influenzae strains, respectively; and 0.12 and 0.5 microg/ml for beta-lactamase-negative and -positive M. catarrhalis strains, respectively. Faropenem holds promise as an oral therapy for community-acquired respiratory tract infections.

Anti-Bacterial Agents↗

Susceptibilities to levofloxacin in Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis clinical isolates from children: results from 2000-2001 and 2001-2002 TRUST studies in the United States.

Among respiratory tract isolates of Streptococcus pneumoniae from children, resistance to penicillins, cephalosporins, macrolides, and trimethoprim-sulfamethoxazole (SXT) increases on an annual basis. Pediatric patients who do not respond to conventional therapy for respiratory tract infections someday may be treated with fluoroquinolones. In this study, MICs of beta-lactams, azithromycin, SXT, and levofloxacin were determined and interpreted by using NCCLS guidelines for isolates of S. pneumoniae (2,834 from children and 10,966 from adults), Haemophilus influenzae (629 from children and 2,281 from adults), and Moraxella catarrhalis (389 from children and 1,357 from adults) collected during the 2000-2001 and 2001-2002 respiratory illness seasons in the United States as part of the ongoing TRUST surveillance studies. Rates of resistance to penicillin, azithromycin, and SXT were > or = 7.5% higher among patients < or = 4 years old than among patients 5 to 10, 11 to 17, and > or = 18 years old in both the 2000-2001 and the 2001-2002 respiratory illness seasons. Levofloxacin resistance was detected in 2 of 2,834 isolates (0.07%) from patients <18 years old. Levofloxacin MICs of 0.25 to 1 micro g/ml accounted for 99.6, 99.5, 99.3, 99.7, 98.4, and 98.0% of isolates from patients < 2, 2 to 4, 5 to 10, 11 to 17, 18 to 64, and > 64 years old. Multidrug resistance was twice as common among patients < or = 4 years old (25.3%) as among patients 5 to 10 years old (13.7%), 11 to 17 years old (11.9%), 18 to 64 years old (12.1%), and > 64 years old (12.4%). The most common multidrug resistance phenotype in S. pneumoniae isolates for all age groups was resistance to penicillin, azithromycin, and SXT (70.3 to 76.6%). For H. influenzae and M. catarrhalis isolates from patients < 2, 2 to 4, 5 to 10, 11 to 17, 18 to 64, and > 64 years old, levofloxacin MICs at which 90% of the isolates were inhibited were 0.015 and 0.03 to 0.06 microg/ml, respectively, in the 2000-2001 and 2001-2002 respiratory illness seasons. In the 2000-2001 and 2001-2002 respiratory illness season surveillance studies in the United States, 99.9% of pediatric isolates of S. pneumoniae were susceptible to levofloxacin. If fluoroquinolones become a treatment option for pediatric patients, careful monitoring of fluoroquinolone susceptibilities will be increasingly important in future surveillance studies.

Adolescent↗

Antimicrobial resistance in Haemophilus influenzae and Moraxella catarrhalis respiratory tract isolates: results of the Canadian Respiratory Organism Susceptibility Study, 1997 to 2002.

A total of 7,566 unique patient isolates of Haemophilus influenzae and 2,314 unique patient isolates of Moraxella catarrhalis were collected between October 1997 and June 2002 from 25 medical centers in 9 of the 10 Canadian provinces. Among the 7,566 H. influenzae isolates, 22.5% produced beta-lactamase, while 92.4% of the 2,314 M. catarrhalis isolates produced beta-lactamase. The incidence of beta-lactamase-producing H. influenzae isolates decreased significantly over the 5-year study period, from 24.2% in 1997-1998 to 18.6% in 2001-2002 (P < 0.01). The incidence of beta-lactamase-producing M. catarrhalis isolates did not change over the study period. The overall rates of resistance to amoxicillin and amoxicillin-clavulanate for H. influenzae were 19.3 and 0.1%, respectively. The rank order of cephalosporin activity based on the MICs at which 90% of isolates were inhibited (MIC(90)s) was cefotaxime > cefixime > cefuroxime > cefprozil > cefaclor. On the basis of the MICs, azithromycin was more active than clarithromycin (14-OH clarithromycin was not tested); however, on the basis of the NCCLS breakpoints, resistance rates were 2.1 and 1.6%, respectively. Rates of resistance to other agents were as follows: doxycycline, 1.5%; trimethoprim-sulfamethoxazole, 14.2%; and chloramphenicol, 0.2%. All fluoroquinolones tested, including the investigational fluoroquinolones BMS284756 (garenoxacin) and ABT-492, displayed potent activities against H. influenzae, with MIC(90)s of < or = 0.03 microg/ml. The MIC(90)s of the investigational ketolides telithromycin and ABT-773 were 2 and 4 microg/ml, respectively, and the MIC(90) of the investigational glycylcycline GAR-936 (tigecycline) was 4 microg/ml. Among the M. catarrhalis isolates tested, the resistance rates derived by using the NCCLS breakpoint criteria for H. influenzae were <1% for all antibiotics tested except trimethoprim-sulfamethoxazole (1.5%). In summary, the incidence of beta-lactamase-positive H. influenzae strains in Canada is decreasing (18.6% in 2001-2002), while the incidence of beta-lactamase-positive M. catarrhalis strains has remained constant (90.0% in 2001-2002).

Adolescent↗

In vitro pharmacodynamic activities of ABT-492, a novel quinolone, compared to those of levofloxacin against Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis.

ABT-492 is a novel quinolone with potent activity against gram-positive, gram-negative, and atypical pathogens, making this compound an ideal candidate for the treatment of community-acquired pneumonia. We therefore compared the in vitro pharmacodynamic activity of ABT-492 to that of levofloxacin, an antibiotic commonly used for the treatment of pneumonia, through MIC determination and time-kill kinetic analysis. ABT-492 demonstrated potent activity against penicillin-sensitive, penicillin-resistant, and levofloxacin-resistant Streptococcus pneumoniae strains (MICs ranging from 0.0078 to 0.125 micro g/ml); beta-lactamase-positive and beta-lactamase-negative Haemophilus influenzae strains (MICs ranging from 0.000313 to 0.00125 micro g/ml); and beta-lactamase-positive and beta-lactamase-negative Moraxella catarrhalis strains (MICs ranging from 0.001 to 0.0025 micro g/ml), with MICs being much lower than those of levofloxacin. Both ABT-492 and levofloxacin demonstrated concentration-dependent bactericidal activities in time-kill kinetics studies at four and eight times the MIC with 10 of 12 bacterial isolates exposed to ABT-492 and with 12 of 12 bacterial isolates exposed to levofloxacin. Sigmoidal maximal-effect models support concentration-dependent bactericidal activity. The model predicts that 50% of maximal activity can be achieved with concentrations ranging from one to two times the MIC for both ABT-492 and levofloxacin and that near-maximal activity (90% effective concentration) can be achieved at concentrations ranging from two to five times the MIC for ABT-492 and one to six times the MIC for levofloxacin.

Anti-Infective Agents↗

Defined medium for Moraxella (Branhamella) catarrhalis.

A defined medium for growth of 24 strains of Moraxella (Branhamella) catarrhalis was devised. This medium (medium B4) contains sodium lactate as a partial carbon source, proline as both a partial carbon source and a partial nitrogen source, aspartate as a partial nitrogen source, and the growth factors arginine, glycine, and methionine. Either aspartate, glutamate, or proline could serve as sole nitrogen source, but growth occurred at a significantly better rate if proline was present together with either aspartate or glutamate, or with both aspartate and glutamate. With the exception of strain ATCC 23246, all the strains had an absolute requirement for arginine and either a partial or absolute requirement for glycine. The concentration of glycine required for optimal growth was found to be relatively high for an amino acid growth factor. Heart infusion broth was found to be growth inhibitory for spontaneous mutants of one strain able to grow in the absence of arginine, and such mutants reverted readily to arginine dependence accompanied by the ability to grow faster on the complex medium. Growth rates in the defined medium B4 were enhanced by the simultaneous addition of asparagine, glutamate, glutamine, leucine, lysine, histidine, and phenylalanine.

Amino Acids↗

Defined medium for Moraxella bovis.

A defined medium (medium MB) for Moraxella bovis was formulated. Nineteen strains grew well on medium MB. One strain was auxotrophic for asparagine, and another was auxotrophic for methionine. Strains of M. equi and M. lacunata also grew on medium MB. All strains had an absolute requirement for thiamine and were stimulated by or actually required the other growth factors in the medium.

Amino Acids↗

Degradation of naphthalene-2,6- and naphthalene-1,6-disulfonic acid by a Moraxella sp.

A naphthalene-2,6-disulfonic acid (2,6NDS)-degrading Moraxella strain was isolated from an industrial sewage plant. This culture could also be adapted to naphthalene-1,6-disulfonic acid as growth substrate. Regioselective 1,2-dioxygenation effected desulfonation and catabolism to 5-sulfosalicylic acid (5SS), which also could be used as the sole carbon source. 5SS-grown cells exhibited high gentisate 1,2-dioxygenase activity. Neither 5SS- nor gentisate-grown cells oxidized 2,6NDS; therefore, 2,6NDS or an early metabolite must serve as an inducer of the initial catabolic enzyme(s).

Benzenesulfonates↗

Occurrence of two different forms of protocatechuate 3,4-dioxygenase in a Moraxella sp.

Two alternative forms of protocatechuate 3,4-dioxygenase (PCase) have been purified from Moraxella sp. strain GU2, a bacterium that is able to grow on guaiacol or various other phenolic compounds as the sole source of carbon and energy. One of these forms (PCase-P) was induced by protocatechuate and had an apparent molecular weight of 220,000. The second form (PCase-G) was induced by guaiacol or other phenolic compounds, such as 2-ethoxyphenol or 4-hydroxybenzoate. It appeared to be smaller (Mr 158,000), and its turnover number was about double that of the former enzyme. Both dioxygenases had similar properties and were built from the association of equal amounts of nonidentical subunits, alpha and beta, which were estimated to have molecular weights of 29,500 and 25,500, respectively. The (alpha beta)3 and (alpha beta)4 structures were suggested for PCases G and P, respectively. On the basis of two-dimensional gel electrophoresis, the alpha and beta polypeptides of PCase-G differed from those of PCase-P. Amino acid analysis supported this conclusion. Both PCases, however, had several other properties in common. It is proposed that both isoenzymes were generated from different sets of alpha and beta subunits, and the significance of these data is discussed.

Amino Acids↗

Pathogenicity of Moraxella osloensis, a bacterium associated with the nematode Phasmarhabditis hermaphrodita, to the slug Deroceras reticulatum.

Moraxella osloensis, a gram-negative bacterium, is associated with Phasmarhabditis hermaphrodita, a nematode parasite of slugs. This bacterium-feeding nematode has potential for the biological control of slugs, especially the grey garden slug, Deroceras reticulatum. Infective juveniles of P. hermaphrodita invade the shell cavity of the slug, develop into self-fertilizing hermaphrodites, and produce progeny, resulting in host death. However, the role of the associated bacterium in the pathogenicity of the nematode to the slug is unknown. We discovered that M. osloensis alone is pathogenic to D. reticulatum after injection into the shell cavity or hemocoel of the slug. The bacteria from 60-h cultures were more pathogenic than the bacteria from 40-h cultures, as indicated by the higher and more rapid mortality of the slugs injected with the former. Coinjection of penicillin and streptomycin with the 60-h bacterial culture reduced its pathogenicity to the slug. Further work suggested that the reduction and loss of pathogenicity of the aged infective juveniles of P. hermaphrodita to D. reticulatum result from the loss of M. osloensis from the aged nematodes. Also, axenic J1/J2 nematodes were nonpathogenic after injection into the shell cavity. Therefore, we conclude that the bacterium is the sole killing agent of D. reticulatum in the nematode-bacterium complex and that P. hermaphrodita acts only as a vector to transport the bacterium into the shell cavity of the slug. The identification of the toxic metabolites produced by M. osloensis is being pursued.

Animals↗

Endotoxin activity of Moraxella osloensis against the grey garden slug, Deroceras reticulatum.

Moraxella osloensis is a gram-negative bacterium associated with Phasmarhabditis hermaphrodita, a slug-parasitic nematode that has prospects for biological control of mollusk pests, especially the grey garden slug, Deroceras reticulatum. This bacterium-feeding nematode acts as a vector that transports M. osloensis into the shell cavity of the slug, and the bacterium is the killing agent in the nematode-bacterium complex. We discovered that M. osloensis produces an endotoxin(s), which is tolerant to heat and protease treatments and kills the slug after injection into the shell cavity. Washed or broken cells treated with penicillin and streptomycin from 3-day M. osloensis cultures were more pathogenic than similar cells from 2-day M. osloensis cultures. However, heat and protease treatments and 2 days of storage at 22 degrees C increased the endotoxin activity of the young broken cells but not the endotoxin activity of the young washed cells treated with the antibiotics. This suggests that there may be a proteinaceous substance(s) that is structurally associated with the endotoxin(s) and masks its toxicity in the young bacterial cells. Moreover, 2 days of storage of the young washed bacterial cells at 22 degrees C enhanced their endotoxin activity if they were not treated with the antibiotics. Furthermore, purified lipopolysaccharide (LPS) from the 3-day M. osloensis cultures was toxic to slugs, with an estimated 50% lethal dose of 48 microg per slug, thus demonstrating that the LPS of M. osloensis is an endotoxin that is active against D. reticulatum. This appears to be the first report of a biological toxin that is active against mollusks.

Animals↗

Characterization of the first molluscicidal lipopolysaccharide from Moraxella osloensis.

Moraxella osloensis is a bacterium that is mutualistically associated with Phasmarhabditis hermaphrodita, a nematode that has potential for the biocontrol of mollusk pests, especially the slug Deroceras reticulatum. We discovered that purified M. osloensis lipopolysaccharide (LPS) possesses a lethal toxicity to D. reticulatum when administered by injection but no contact or oral toxicity to this slug. The toxicity of the LPS resides in the lipid A moiety. M. osloensis LPS was semiquantitated at 6 x 10(7) endotoxin units per mg. The LPS is a rough-type LPS with an estimated molecular weight of 5,300. Coinjection of galactosamine with the LPS increased the LPS's toxicity to the slug two- to four-fold. The galactosamine-induced sensitization of the slug to the LPS was reversed completely by uridine.

Animals↗

Selective medium for Moraxella nonliquefaciens.

A medium is described which selectively inhibits most bacteria from the normal flora of the conjunctiva, the lid-margin, and the upper respiratory tract but permits growth of Moraxella nonliquefaciens, M. liquefaciens, and the less fastidious strains of M. lacunata. The selective conditions are obtained with thiostrepton, tyrothricin, and sodium nalidixinate as inhibitors. Incubation under increased CO(2) pressure increased the number of primary isolations. M. nonliquefaciens was isolated on the selective medium twice as many times as on other media.

Anti-Bacterial Agents↗