Design, synthesis and biological evaluation of monobactams as antibacterial agents against gram-negative bacteria.

A series of monobactam derivatives were prepared and evaluated for their antibacterial activities against susceptible and resistant Gram-negative strains, taking Aztreonam and BAL30072 as the leads. Six conjugates (12a-f) bearing PIH-like siderophore moieties were created to enhance the bactericidal activities against Gram-negative bacteria based on Trojan Horse strategy, and all of them displayed potencies against susceptible Gram-negative strains with MIC ≤ 8 µg/mL. SAR revealed that the polar substituents on the oxime side chain were beneficial for activities against resistant Gram-negative bacteria. Compounds 19c and 33a-b exhibited the promising potencies against ESBLs-producing E. coli and Klebsiella pneumoniae with MICs ranging from 2 µg/mL to 8 µg/mL. These results offered powerful information for further strategic optimization in search of the antibacterial candidates against MDR Gram-negative bacteria.

Interspecies scaling of excretory amounts using allometry - retrospective analysis with rifapentine, aztreonam, carumonam, pefloxacin, miloxacin, trovafloxacin, doripenem, imipenem, cefozopran, ceftazidime, linezolid for urinary excretion and rifapentine, cabotegravir, and dolutegravir for fecal excretion.

1. Interspecies allometry scaling for prediction of human excretory amounts in urine or feces was performed for numerous antibacterials. Antibacterials used for urinary scaling were: rifapentine, pefloxacin, trovafloxacin (Gr1/low; <10%); miloxacin, linezolid, PNU-142300 (Gr2/medium; 10-40%); aztreonam, carumonam, cefozopran, doripenem, imipenem, and ceftazidime (Gr3/high; >50%). Rifapentine, cabotegravir, and dolutegravir was used for fecal scaling (high; >50%). 2. The employment of allometry equation: Y = aW(b) enabled scaling of urine/fecal amounts from animal species. Corresponding predicted amounts were converted into % recovery by considering the respective human dose. Comparison of predicted/observed values enabled fold difference and error calculations (mean absolute error [MAE] and root mean square error [RMSE]). Comparisons were made for urinary/fecal data; and qualitative assessment was made amongst Gr1/Gr2/Gr3 for urine. 3. Average correlation coefficient for the allometry scaling was >0.995. Excretory amount predictions were largely within 0.75- to 1.5-fold differences. Average MAE and RMSE were within ±22% and 23%, respectively. Although robust predictions were achieved for higher urinary/fecal excretion (>50%), interspecies scaling was applicable for low/medium excretory drugs. 4. Based on the data, interspecies scaling of urine or fecal excretory amounts may be potentially used as a tool to understand the significance of either urinary or fecal routes of elimination in humans in early development.

Aztreonam lysine: a novel inhalational antibiotic for cystic fibrosis.

Acquisition of Pseudomonas aeruginosa, the most prevalent organism isolated from cystic fibrosis (CF) airways, is associated with an accelerated clinical deterioration and reduced survival. Strategies to chronically suppress P. aeruginosa infections in individuals with CF have evolved over the last four decades and now largely focus on regular administration of aerosolized antibiotics. Aztreonam lysine (AZLI; Cayston, Gilead Pharmaceuticals [Foster City, CA, USA]), a novel formulation of the monobactam aztreonam suitable for aerosol delivery has recently been developed. AZLI is administered as 75 mg three-times daily for 28 days in 'on/off' cycles using the Altera/eFlow electronic nebulizer (PARI Innovative Manufacturers [Midlothian, VA, USA]). In individuals with CF chronically infected with P. aeruginosa, AZLI improved healthcare-associated quality-of-life scores, pulmonary function and weight, prolonged time to requirement of antibacterial therapy for symptoms of pulmonary exacerbation and reduced P. aeruginosa sputum burdens. These outcomes were durable over 18 months of cycled use. AZLI has been demonstrated to be safe and effective, and expands available chronic maintenance therapies in CF.

Comparison of the pharmacokinetics and pharmacodynamic profile of carumonam in cystic fibrosis patients and healthy volunteers.

Our objectives were to compare the pharmacokinetics (PK) of carumonam, a monobactam, between cystic fibrosis (CF) patients and healthy volunteers and assess its pharmacodynamic profile. We studied 10 adult CF patients and 18 healthy volunteers of similar body size (dose: 2.166 g of carumonam as 15-min intravenous infusion). High performance liquid chromatography with ultraviolet detection (HPLC-UV) was used for drug analysis and NONMEM (ICON, Ellicot City, MD) for population PK and Monte Carlo simulation with targets between > or =20% and 100% free time above MIC (fT > MIC). Unscaled renal clearance was 24% higher in CF patients. Lean body mass and creatinine clearance explained the difference in average clearance and volume of distribution between both subject groups. For a daily dose of 6 g per 70 kg of total body weight, 15-min infusions q8h achieved robust (>90%) probabilities of target attainment (PTAs) (target, 60% fT > MIC) for MICs < or =3 mg/L in CF patients and < or =6 mg/L in healthy volunteers. At the same dose, 4-h infusions q8h achieved robust PTAs up to markedly higher MICs < or =8 to 12 mg/L in CF patients and < or =16 mg/L in healthy volunteers.

[Comparative studies on activities of antimicrobial agents against causative organisms isolated from patients with urinary tract infections (2004). I. Susceptibility distribution].

The bacterial strains isolated from 490 patients diagnosed as having urinary tract infections (UTIs) in 14 institutions in Japan were collected between August 2004 and July 2005. The susceptibilities of them to many kinds of antimicrobial agents were measured. Of them, 577 strains were estimated as causative bacteria and used for the measurement. The strains consisted of 156 gram-positive bacterial strains (27.0%) and 421 gram-negative bacterial strains (73.0%). Against Staphylococcus aureus, arbekacin (ABK), vancomycin (VCM) showed the strongest activity and prevented the growth of all strains with 2 microg/mL. Against Enterococcus faecalis, ampicillin (ABPC) and VCM showed a strong antibacterial activity. The antibacterial activity of cephems to Escherichia coli was generally good, and especially cefozopran (CZOP) and cefpirome (CPR) showed the strongest activity (MIC90: < or = 125 microg/mL). Quinolone resistant E. coli [MIC of ciprofloxacin (CPFX): > or = 4 microg/mL] was detected at frequency of 18.8%, which was higher than that in the last year. Against Klebsiella pneumoniae, CZOP, meropenem (MEPM), and carumonam (CRMN) showed the strongest activity and prevented the growth of all strains with 0.125 microg/mL or less. The antibacterial activity of the other cephems was relatively good, and decrease in their activity observed in the last year study was not recognized. Against Serratia marcescens, imipenem (IPM) and gentamicin (GM) had the strongest antibacterial activity. Against Proteus mirabilis, CRMN showed the strongest activity and prevented the growth of all strains with 0.125 microg/mL or less. MEPM prevented the growth of all strains with 0.25 microg/mL. Next, cefmenoxime (CMX), ceftazidime (CAZ), CZOP, cefixime (CFIX), cefpodoxime (CPDX), and cefditoren (CDTR) showed a strong activity. The antibacterial activity of the drugs to Pseudomonas aeruginosa was generally low, and MIC90 of all the drugs was ranged from 32 to > 128 microg/mL except IPM and MEPM having 16 microg/mL. The antibacterial activities of CZOP and CAZ were considered to be relatively good on MIC50 comparison (MIC50: 2 microg/mL).

Susceptibility of Streptococcus mutans and Streptococcus sobrinus to cell wall inhibitors and development of a novel selective medium for S. sobrinus.

Representative strains of Streptococcus mutans and Streptococcus sobrinus showed differences in susceptibility to members of the monobactam group of beta-lactam antibiotics: S. sobrinus was less sensitive than S. mutans. The minimum inhibitory concentrations of aztreonam (AZT) and carumonam, both of which belong to this group, were 2,000 microg/ml for S. sobrinus and 125 microg/ml for S. mutans. Further addition of fosfomycin, bacitracin and sodium chloride to Mitis Salivarius agar (MS) supplemented with AZT resulted in growth inhibition of S. mutans and oral streptococci other than S. sobrinus, and was therefore used as a selective medium for S. sobrinus (MS-SOB medium). The average growth recovery of laboratory and clinically isolated strains of S. sobrinus on MS-SOB medium was 74.1% compared to that on MS medium. Seventy-eight percent of clinical samples in which S. sobrinus was detected yielded pure growth of S. sobrinus on MS-SOB medium.

Comparative epileptogenic properties of two monobactam derivatives in C57, Swiss and DBA/2 mice.

The behavioural and electrocortical effects of two monobactam derivatives were studied after intraperitoneal (ip) administration in DBA/2 mice, a strain genetically susceptible to sound-induced seizures, and in C57 and Swiss mice, two strains not prone to seizure. DBA/2 mice were more susceptible than Swiss and C57 mice to seizures induced by aztreonam or carumonam. No significant differences were observed between seizures elicited by aztreonam and carumonam in animals (DBA/2 only) administered intracerebroventricularly or ip. Although the main mechanism for seizure-like activity of monobactams cannot be easily determined, we believe that several mechanisms may be involved. An increased excitation of the central nervous system (CNS) by inhibition of GABA binding to receptors and a slow clearance of aztreonam and carumonam from the CNS may be postulated.

Estudo comparativo do aztreonam com um regime terapêutico incluindo um aminoglicosídeo no tratamento da pneumonia Gram-negativa / Comparative study of aztreonam in Gram-negative pneumonia versus a therapeutic regimen that includes an aminoglycoside

A pneumonia Gram-negativa é uma complicaçäo frequente em pacientes hospitalizados, particularmente quando suas defesas estäo diminuídas. A severidade dessas infecçöes exige que seja iniciada imediatamente uma terapia antimicrobiana empírica, que geralmente utiliza uma combinaçäo de um antibiótico beta-lactâmico de amplo espectro com um aminoglicosídeo (AMG), apesar da toxicidade potencial desse regime. Comparamos a eficácia de um novo antibiótico beta-lactâmico, o aztreonam, que apresenta um espectro específico de atividade contra bactérias Gram-negativas e uma excelente difusäo no tecido pulmonar, com a de outro regime antibiótico que incluía um AMG. De um total de 69 pacientes, 43 foram tratados com aztreonam e os restantes com um AMG. Ambos os grupos eram equivalentes com relaçäo à severidade da infecçäo e à patologia subjacente. A eficácia clínica foi semelhante nos dois regimes (81 por cento com aztreonam, 62 por cento com AMG). A eficácia antimicrobiana porém, foi superior no grupo de aztreonam (88 por cento com aztreonam, 65 por cento com AMG), embora essas diferenças tenham desaparecido nos pacientes do grupo de AMG tratados com uma combinaçäo de amicacina e cefoxima ou ticarcilina. Os índices de colonizaçäo/superinfecçäo também foram semelhantes em ambos os grupos, embora a seleçäo de bactérias Gram-negativas tenha sido mais frequente no grupo de AMG. Nossos resultados sugerem que a monoterapia com aztreonam é uma alternativa útil no tratamento da pneumonia Gram-negativa

Ensaio comparativo milticêntrico do aztreonam no tratamento de infecçöes Gram-negativas em pacientes comprometidos sob tratamento intensivo / A multicenter comparative trial of aztreonam in the treatment of Gram-negative infections in compromised intensive-care patients

Um ensaio comparativo multicêntrico foi realizado em 4 hospitais universitários para avaliar a eficácia do aztreonam, um novo antibiótico monobactâmico. Todos os pacientes incluídos no estudo haviam sido admitidos à unidade de tratamento intensivo hospitalar com distúrbios subjacentes severos. No total, foram documentadas 167 infecçöes em 157 pacientes (78 pneumonias, 26 infecçöes do trato urinário, 23 peritonites e 40 septicemias). O estudo foi realizado em duas fases. Na fase 1, 49 pacientes que receberam aztreonam foram comparados a 26 que receberam amicacina. Ambas as drogas foram administradas como cobertura única contra bacilos Gram-negativos. Na fase 2, 48 pacientes tratados com aztreonam foram comparados a 34 que receberam uma combinaçäo sinérgica de amicacina e um beta-lactâmico de amplo espectro. Os resultados sugerem que o aztreonam pode ser adotado como monoterapia no tratamento de infecçöes Gram-negativas sistêmicas, com uma eficácia comparável à do tratamento antimicrobiano convencional. O aztreonam provavelmente é mais eficaz que a amicacina no tratamento de infecçöes do trato respiratório e pelo menos täo eficaz quanto à combinaçäo de beta-lactâmicos e aminoglicosídeos. Pode-se estabelecer uma dose-padräo adequada de 3-4 g/dia de aztreonam em pacientes comprometidos, devendo ser combinada a uma cobertura Gram-positiva quando o tratamento for prescrito empiricamente

Interactions between active-site serine beta-lactamases and so-called beta-lactamase-stable antibiotics. Kinetic and molecular modelling studies.

The interactions between imipenem and four monobactams and three class A beta-lactamases have been studied in detail. Despite their reputation as being beta-lactamase-stable, some of these compounds were significantly hydrolysed by the enzymes. The results obtained with the Streptomyces albus G beta-lactamase have been analysed in the light of molecular modelling studies. The discussion is extended to include other so-called beta-lactamase-stable antibiotics to demonstrate that this appellation can often be misleading.

[Recombinant human granulocyte-colony stimulating factor (rhG-CSF) treatment for spleen abscess and periostitis in a patient with chronic granulomatous disease].

A 9-year-old boy with chronic granulomatous disease was hospitalized on May, 1991, because of continued fever and pain in the right elbow. Increased bone intensity at the distal end of right humerus on x-ray and a 33 x 36 mm space-occupying lesion in the spleen on abdominal CT scan were recognized. Under a diagnosis of periosteitis and spleen abscess, intravenous infusion of rhG-CSF at a dose of 200 micrograms/m2/day was started in combination with antimicrobial therapy. Fever, tenderness, swelling in the right elbow and inflammatory indices improved three weeks after the institution of therapy. Hydrogen peroxide (H2O2) formation by neutrophil increased significantly, although intermittently, during the therapy. The spleen abscess had completely vanished on CT scan on February, 1992. The therapy was well tolerated and no significant side effects were observed. The use of rhG-CSF in combination with potent antibiotics is recommended for patients with serious infections in chronic granulomatous disease to avoid a fatal course.

Effects of quinolones on nucleoid segregation in Escherichia coli.

The effects of quinolone antibiotics on nucleoid segregation in growing Escherichia coli were examined by using fleroxacin (Ro 23-6240, AM 833) as a prototype compound. At levels that were close to its MIC and induced growth arrest and filamentation, fleroxacin caused large nucleoids to appear in midcell, suggesting inhibition of nucleoid segregation. With increasing fleroxacin concentrations, nucleoids became progressively smaller, suggesting inhibition of DNA replication. Removal of fleroxacin restored normal cell and nucleoid morphology in filaments with large nucleoids but not in filaments with small nucleoids. The results are consistent with inhibition of chromosome decatenation at low quinolone concentrations (bacteriostatic effect) and DNA supercoiling at high concentrations (bactericidal effect).

Pharmacokinetics of carumonam (AMA-1080) in patients with impaired renal function and in those undergoing hemodialysis.

The pharmacokinetics of carumonam (AMA-1080) were studied after a single intravenous 1.0-g dose was given to 26 subjects grouped according to their renal functions. Creatinine clearance (CLCR) was above 85, 50 to 84, 10 to 49, and below 10 ml/min/1.73 m2 in groups 1, 2, 3, and 4, respectively. All of the six patients in groups 4 were receiving maintenance hemodialysis, and they were studied both during and between hemodialysis sessions. Carumonam obeyed two-compartment model kinetics in all four group. The volume of distribution based on the area under serum concentration-time curve (Varea) did not differ significantly among the four groups, the mean value being 0.309 +/- 0.084 liter/kg. The elimination-phase (beta) half-lives were 1.53 +/- 0.36, 2.00 +/- 0.64, 5.08 +/- 1.85, and 12.8 +/- 4.1 h in groups 1, 2, 3, and 4, respectively. The 0- to 24-h cumulative urinary recoveries of carumonam were 83 +/- 11, 76 +/- 20, 58 +/- 25, and 12 +/- 9% of the administered dose in groups 1, 2, 3, and 4, respectively. The systemic and the renal clearances of carumonam decreased according to the severity of renal dysfunction, and the nonrenal clearance, which was calculated as the difference between renal and systemic clearances also decreased as CLCR decreased. A significant positive correlation existed between beta and CLCR (r = 0.847, P less than 0.01), and the beta of carumonam could be predicted by the following equation: beta (h-1) = 0.00460 X CLCR (ml/min/1.73 m2) + 0.049. Hemodialysis shortened the elimination-phase half-lives from 12.8 +/- 4.1 to 2.66 +/- 1.49 h in the six subjects in group 4. A 5-h hemodialysis in a hypothetical anephric subject weighing 60 kg was estimated to remove 51.4% of the drug present in the body at the start of hemodialysis.

Preferential hydrolysis of cis configuration compounds at the 3,4 position of monobactams by beta-lactamase from Morganella morganii.

Carumonam and BO-1166 (cis configuration) were inactivated by beta-lactamase of Morganella morganii more rapidly than were aztreonam and BO-1165 (trans configuration), as demonstrated by spectrophotometric analysis and microbiological assay. An active enzyme was recovered more rapidly from the inactivated enzyme-monobactam complex derived from the cis form of monobactams than from the complex derived from the trans form of monobactams. This result suggests that the configuration at the 3,4 position on the azetidinone ring of monobactams, together with the chemical structure of the side chains attached to the azetidinone ring, may play an important role in the stability of monobactams to the beta-lactamase of M. morganii.

[Clinical evaluation of the combination of carumonam and cefotiam in the treatment of complicated urinary tract infection].

The combination of carumonam (CRMN) and cefotiam (CTM), expected to have a broader spectrum of coverage in connection with urinary tract infections, was evaluated for its effectiveness and safety at the Department of Urology, Osaka University Hospital and 17 affiliated hospitals. CRMN and CTM were given together to 109 patients with complicated urinary tract infections (UTI), of whom 65 cases satisfied the "Criteria of UTI Committee for the Evaluation of Drug Efficacy in the UTI (3rd Ed.)", which was modified by adopting the midstream urine data for women. CRMN and CTM were administered by drip or one-shot infusion at a total daily dose of 4 g (equally mixed 1 g plus 1 g each, twice a day) for 5 consecutive days or longer. The overall clinical efficacy rate in the 65 cases of complicated UTI was 72%, estimated by the criteria cited above. The efficacy rate according to the infection type groupings was 72% for the 29 patients in the 1st group, 100% for the 1 patient in the 2nd group, 100% for the 7 patients in the 3rd group, 83% for the 6 patients in the 4th group, 50% for the 14 patients in the 5th group and 75% for the 8 patients in the 6th group. The disappearance rate of both urinary Gram positive cocci and Gram negative bacilli was 83.3%. Fifteen strains appeared after the treatment, only 4 of which were Gram positive cocci. Among the 109 patients treated with CRMN+CTM, no subjective side effects were recorded and the abnormalized laboratory findings observed were: eosinophilia in one patient, increases in both GPT and GOT in one patient, and lowered creatinine clearance in one patient. With a broader spectrum and safe regimen, the combination of CRMN/CTM is recommended as the first choice against complicated UTI.

Immunization of mice with antibiotic-treated Escherichia coli results in enhanced protection against challenge with homologous and heterologous bacteria.

The murine immune response to Escherichia coli exposed to subminimal inhibitory concentrations of four antibiotics was investigated. Groups of mice were injected for 8 weeks with formalin-killed bacteria and subsequently challenged with 10 x LD50 of viable E. coli. Mice receiving saline only (controls) died within 24 h. The mortality of mice immunized with ciprofloxacin-treated E. coli was significantly lower than that of mice immunized with E. coli untreated or treated with other antibiotics. Sera from mice immunized with ciprofloxacin-treated bacteria showed better bacteriostatic capacity and enhanced production of antibodies that bound to homologous and heterologous lipopolysaccharide isolated from several smooth and rough gram-negative strains. The better protection observed in mice immunized with ciprofloxacin-treated E. coli was probably due to an enhanced production of antibodies to epitopes on lipopolysaccharide that became better exposed and so more accessible after treatment with ciprofloxacin.

[Bacterial combination effect between carumonam and eight other antibiotics].

In vitro interactions between carumonam (CRMN) and 8 other antibiotics were studied using the agar dilution checkerboard technique against 88 clinical isolates of Escherichia coli, Proteus vulgaris, Serratia marcescens and Pseudomonas aeruginosa. Combinations of CRMN with 8 other antibiotics were generally additive or indifferent. Synergism was found against S. marcescens or P. aeruginosa with CRMN plus fosfomycin, gentamicin (GM) or dibekacin. Antagonism was not observed with CRMN plus any of the 8 other antibiotics tested. In a phase-contrast microscopic study, the synergism of CRMN in combination with GM were confirmed against P. aeruginosa 15846. CRMN in combination with GM demonstrated a in vivo synergy against experimental urinary tract infection caused by P. aeruginosa 15846 in mice. We think that combinations of several antibiotics with CRMN should be appropriate for initial therapy of infections because no antagonism appeared to occur with other antibiotic agents.

[Effect of combination therapy with carumonam and clindamycin on severe infections in patients with hematologic malignancies].

We evaluated the efficacy of a combination therapy with carumonam (CRMN) and clindamycin (CLDM) on severe infections in patients with hematologic malignancies. Fifty three patients were included in this study. The efficacy of the combination therapy was evaluated according to the criteria by TAKAKU et al. Fourteen cases were evaluated as excellent, and 24 cases were as good, with a total rate of effectiveness of 71.7% (38/53). It should be noted that the rate of effectiveness in patients having less than 100/microliters neutrophils was 77.3% (17/22). Adverse effects were observed in 2 patients (3.7%). One case was hepatotoxicity and the other was nephrotoxicity. Both were mild and transient, however. These observations suggested that the combination therapy with CRMN and CLDM was effective and safe for the treatment of severe infections in patients with hematologic malignancies.

[Clinical evaluation of the combination of carumonam and fosfomycin in the treatment of complicated urinary tract infection].

Carumonam (CRMN), the first monobactam antibiotic in Japan, has excellent activity against gram-negative bacteria and is useful in the treatment of urinary tract infections. However, it may be insufficient in the treatment of complicated urinary tract infections because of the increase in isolation of gram-positive bacteria, and it may be necessary to co-administer antibiotics active against gram-positive organisms to achieve a broader spectrum of coverage in connection with severe infections. The combination of CRMN and fosfomycin (FOM) was evaluated for its effectiveness and safety at the Department of Urology, Yamagata University Hospital and 7 affiliated hospitals. Clinical efficacy was assessed on 64 patients with complicated urinary tract infection according to the Criteria for Clinical Evaluation of Antimicrobial Agents in UTI (3rd. ed.) recommended by the Japan UTI Committee. Clinical efficacy was evaluated as excellent in 16, moderate in 32, poor in 16, with an overall clinical effectiveness rate of 75.0%, which is superior compared with CRMN alone. Of the total of 92 bacterial strains isolated, 66 (71.7%) were eradicated. Subjective adverse reaction was seen in 1 patient (1.4%), as nausea and anorexia. Slight increases in serum GOT and GPT ware recorded in 5 patients (7.1%). These findings disappeared after the termination of administration without treatment. The combination of CRMN and FOM might therefore be useful in the treatment of complicated urinary tract infections.