Biapenem

Biapenem is a novel parenteral broad spectrum carbapenem primarily used for the treatment of complicated infections like sepsis, lower respiratory infections, urinary tract infections, intra-abdominal and genitourinary infections etc. in Japan, Thailand and China since two decades, has been recently approved in India. Biapenem shows good bactericidal activity against Gram-positive bacteria including streptococcus pneumoniae, pyogenes and methicillin-susceptible staphylococcus aureus (MSSA). It also shows antibacterial activities against Gram-negative bacteria including resistant Pseudomonas aeruginosa and Acinetobacter baumannii. Evidence from international studies confirmed that biapenem can be used as effectively and safely as meropenem or imipenem/ cilastatin in the treatment of various infectious diseases. This article summarizes the milestones, unique structure, mechanism of action, pharmacokinetics, special pharmacological properties and spectrum of in vitro activity of biapenem. The results of comparative clinical trials on Biapenem are also described, as is the patient safety and tolerability observed during these studies.

Environmental superbugs: The case study of Pedobacter spp

The environment is one of the main reservoirs of antibiotic resistance genes (ARGs) but multidrug resistant (MDR) environmental isolates are barely characterised. As suggested by the name, Pedobacter species have been predominantly isolated from soils, but are also recovered from water (including drinking water), chilled food, fish, compost, sludge, glaciers and other extreme environments. The susceptibility phenotype of Pedobacter lusitanus NL19 (isolated from a deactivated uranium mine), its closely related species and the genus type strain were investigated. All strains are MDR bacteria, resistant to β-lactams, colistin, aminoglycosides and ciprofloxacin. Therefore, Pedobacter spp. are likely intrinsically resistant to β-lactams (including ertapenem) and to other three classes of antibiotics. 6%-8% of their total protein-encoding genes encode a diverse collection of putative ARGs, including β-lactamases. These enzymes are highly abundant in all the other Pedobacter strains with sequenced genomes, especially class C, class B3 and class A. LUS-1 and PLN-1 were further characterised in E. coli. LUS-1 is a class A β-lactamase and it conferred an increase in the MIC of cefotaxime, albeit very low. PLN-1 is a class B3 β-lactamase with carbapenemase activity, conferring resistance to ertapenem and a 66x and 16x increase in the MIC of imipenem and meropenem, respectively. PLN-1 also hydrolyses ampicillin, 1st and 3rd generation cephalosporins, and at a lower extent cephamycins and 4th generation cephalosporins. Therefore, Pedobacter spp. encode a large and diverse arsenal of resistance mechanisms that make them environmental superbugs.

Therapeutic drug monitoring of beta-lactam antibiotics - Influence of sample stability on the analysis of piperacillin, meropenem, ceftazidime and flucloxacillin by HPLC-UV

INTRODUCTION

Therapeutic drug monitoring (TDM) is a useful tool to optimize antibiotic therapy. Increasing interest in alternative dosing strategies of beta-lactam antibiotics, e.g. continuous or prolonged infusion, require a feasible analytical method for quantification of these antimicrobial agents. However, pre-analytical issues including sample handling and stability are to be considered to provide valuable analytical results.

METHODS

For the simultaneous determination of piperacillin, meropenem, ceftazidime and flucloxacillin, a high performance liquid chromatography (HPLC) method including protein precipitation was established utilizing ertapenem as internal standard. Long-term stability of stock solutions and plasma samples were monitored. Furthermore, whole blood stability of the analytes in heparinized blood tubes was investigated comparing storage under ambient conditions and 2-8°C.

RESULTS

A calibration range of 5-200μg/ml (piperacillin, ceftazidime, flucloxacillin) and 2-200μg/ml (meropenem) was linear with r²>0.999, precision and inaccuracy were <9% and <11%, respectively. The successfully validated HPLC assay was applied to clinical samples and stability investigations. At -80°C, plasma samples were stable for 9 months (piperacillin, meropenem) or 13 months (ceftazidime, flucloxacillin). Concentrations of the four beta-lactam antibiotics in whole blood tubes were found to remain within specifications for 8h when stored at 2-8°C but not at room temperature.

CONCLUSIONS

The presented method is a rapid and simple option for routine TDM of piperacillin, meropenem, ceftazidime and flucloxacillin. Whereas long-term storage of beta-lactam samples at -80°C is possible for at least 9 months, whole blood tubes are recommended to be kept refrigerated until analysis.

[Analysis of the distribution characteristics and drug resistance of non-fermenting bacterial infection in intensive care unit from 2009 to 2015]

OBJECTIVE

To study the distribution characteristics and drug resistance of non-fermenting bacterial infection in intensive care unit (ICU) at a tertiary hospital during seven consecutive years, and to provide evidence for rational use of antibiotics in ICU.

METHODS

A retrospective analysis was conducted. The related data about non-fermentative bacteria obtained from clinical specimens, collected from lower respiratory tract, blood, urine, bile and other secretions of ICU patients admitted to Binzhou Medical University Hospital from January 2009 to December 2015 were retrospectively analyzed. The distribution characteristics and drug resistance of non-fermentative bacteria, and isolation rate of multiple drug resistance (MDR) strains were analyzed.

RESULTS

2 672 strains of nonfermentative bacteria were isolated during seven consecutive years, accounting for 57.9％ gram negative (G-) bacilli (2 672/4 613),and 35.2％ of all bacteria (2 672/7 587).The top five were Acinetobacter baumannii (38.4％),Pseudomonas aeruginosa (34.6％),Onion burkholderia cepacia (9.9％),Stenotrophomonas maltophilia (6.2％),and Pseudomonas fluorescens (5.6％).Non-fermentative bacteria were mainly isolated from the lower respiratory tract (60.9％).Isolation of the non-fermentative bacteria accounted for over 50％ of G-bacilli during seven consecutive years, and the isolation rate of the top five types of bacteria showed no obvious change, while positive rate of Acinetobacter baumannii showed a tendency to increase (obviously from 26.5％ in 2009 to 50.2％ in 2015),and a lowering trend of positive rate of Onion burkholderia cepacia,Stenotrophomonas maltophilia, and Pseudomonas fluorescens was obvious (from 15.6％,10.6％,13.0％ in 2009 to 5.6％,7.4％,1.4％ in 2015 respectively) was observed. The isolation rate of Pseudomonas aeruginosa was stable (about 30％) during seven consecutive years. The drug susceptibility results showed that the resistant rates of Acinetobacter baumannii against imipenem, meropenem, aminoglycosides and third-generation cephalmsporins were all higher than 70％,while its resistant rate to cefoperazone-sulbactam was relatively lower (40.2％-68.1％)with relatively higher sensitivity rate (23.6％-46.0％).In contrast, the resistant rates of Pseudomonas aeruginosa against antibiotics were low,while the sensitivity rate to fourth-generation cephalmsporins cefepime (58.3％-87.7％)and third-generation cephalmsporins was high (ceftazidime:55.6％-79.3％,piperacillin-tazobactam:62.5％-86.2％,cefoperazone-sulbactam:46.0％-89.8％).From 2009 to 2015,the incidence of MDR strains of Acinetobacter baumannii showed an obvious increasing tendency (from 68.0％ to 84.1％);in contrast, the incidence of MDR strains of Pseudomonas aeruginosa did not show an obviously increase in incidence from 2009 to 2012,on the other hand, it showed a decreasing tendency from a peak 68.6％ in 2012 to 23.5％ in 2015.

CONCLUSIONS

The isolation rate of non-fermentative bacteria was high and the drug resistance situation was serious. Therefore,it is important to grasp the knowledge regarding distribution characteristics, drug resistance and variation of non-fermentative bacteria in ICU. It is not only beneficial for both rational use of antibiotics, improve efficacy but also helpful in reducing the emergence of drug resistance stains.

Severe Bloodstream Infection due to KPC-Producer E coli in a Renal Transplant Recipient Treated With the Double-Carbapenem Regimen and Analysis of In Vitro Synergy Testing: A Case Report

Transplant recipients are at high risk of infections caused by multidrug resistant microorganisms. Due to the limited therapeutic options, innovative antimicrobial combinations against carbapenem-resistant Enterobacteriaceae causing severe infections are necessary.A 61-year-old woman with a history of congenital solitary kidney underwent renal transplantation. The postoperative course was complicated by nosocomial pneumonia due to Stenotrophomonas maltophilia and pan-sensitive Escherichia coli, successfully treated with antimicrobial therapy. On postoperative day 22, diagnosis of surgical site infection and nosocomial pneumonia with concomitant bacteremia due to a Klebisella pneumoniae carbapenemase-producer E coli was made. The patient was treated with the double-carbapenem regimen (high dose of meropenem plus ertapenem) and a potent synergistic and bactericidal activity of this un-conventional therapeutic strategy was observed in vitro. Despite a microbiological response with prompt negativity of blood cultures, the patient faced a worse outcome because of severe hemorrhagic shock.The double-carbapenem regimen might be considered as a rescue therapy in those subjects, including transplant recipients, in whom previous antimicrobial combinations failed or when colistin use might be discouraged. Performing in vitro synergy testing should be strongly encouraged in cases of infections caused by pan-drug resistant strains, especially in high-risk patients.

[Distribution and drug resistance of the pathogenic bacteria from sputum specimens of 1 125 children with tracheo bronchial foreign bodies]

OBJECTIVE

To analyze the distribution and drug susceptibility of the pathogenic bacteria in the airway secretions in children with tracheobronchial foreign bodies so as to assist physicians in clinical prescription.

METHODS

Sputum specimens of 1 125 children with tracheobronchial foreign bodies were collected in removal of the foreign bodies by rigid bronchoscope, and the drug susceptibility test was performed.

RESULTS

Pathogenic bacteria were detected in 218 (19.4%) of 1 125 sputum specimens. Among the pathogenic bacteria, 126 (57.79%) strains were gram-negative bacilli, consisting of 76 (34.86%) strains of Haemophilus influenzae, 10 (4.59%) strains of Escherichia coli, 7 (3.21%) strains of Sewer enterobacter, 7 (3.21%) strains of Pseudomonas aeruginosa, and 6 (2.75%) strains of Klebsiella bacillus; and 92 (42.21%) strains were gram-positive bacilli, consisting of 80 (36.69%) strains of Streptococcus pneumonia and 10 (4.59%) strains of Escherichia coli. Most of detected gram-negative bacilli were highly sensitive to cefepime, ceftazidine, imipenem and amikacin, no strains were resistant to meropenem and ciprofloxacin. None of the detected gram-positive bacilli were resistant to cefepime, vancomycin, levofloxacin and teicoplanin.

CONCLUSIONS

The Haemophilus influenzae of gram-negative bacilli and the Streptococcus pneumonia of gram-positive bacilli are the main pathogenic bacteria existing in the airway secretions of children with tracheobronchial foreign bodies. The Haemophilus influenzae were highly sensitive to cephalosporin, imipenem and amikacin, and the Streptococcus pneumonia to cefepime, vancomycin, levofloxacin and teicoplanin.

[Pharmacokinetics study of injected doripenemin healthy volunteers]

OBJECTIVE

To study the pharmacokinetics of injected doripenem in Chinese healthy volunteers, in order to optimize dosages for patients.

METHODS

Twelve healthy volunteers were recruited in the threecross Latin square designed study. Participants received intravenous infusions of 0.25, 0.5 and 1.0 g doripenem sequentially in three periods at a random order. Plasma and urine doripenem were measured by HPLC-UV, using an internal standard method with meropenem for plasma samples and an external standard method for urine samples, respectively. Phoenix WinNonlin 6.1 pharmacokinetic software was used to calculate non-compartment pharmacokinetics parameters. SPSS 19.0 software was used for statistical analysis.

RESULTS

A single dose infusion of 0.25, 0.5 and 1.0 g doripenemin 60 min produced the following respective parameters: Cmax (11.81 +/- 1.52), (22.80 +/- 3.80) and (47.26 +/- 8.38) microg/mL, Tmax (60.42 +/- 1.44), (58.33 +/- 5.77) and (60.00 +/- 0) min, t(1/2) (63.48 +/- 10.51), (69.12 +/- 16.72) and (69.30 +/- 11.71) min, AUC(0-1), (1100.86 +/- 150.04), (2111.50 +/- 359.58) and (4359.50 +/- 789.38) microg/(mL x min). Linear Regression and Confidence Interval analyses suggested a linear kinetic characteristic. Doripenem was mainly excreted through kidneys, with 24 h cumulative urine excretion rates ranging from 70% to 75% for the three doses of infusions. It was safe to administer doripenem through infusion in healthy volunteers. Adverse reactions occurred in 19.44% cases of infusions, although all were mild reactions. Tinnitus happened in two cases (8.33%) of infusions, which required close observations.

CONCLUSION

Doripenem infusion possesses a linear kinetics. There is no need to adjust the regimenpatients.

Species distribution of clinical Acinetobacter isolates revealed by different identification techniques

A total of 2582 non-duplicate clinical Acinetobacter spp. isolates were collected to evaluate the performance of four identification methods because it is important to identify Acinetobacter spp. accurately and survey the species distribution to determine the appropriate antimicrobial treatment. Phenotyping (VITEK 2 and VITEK MS) and genotyping (16S rRNA and rpoB gene sequencing) methods were applied for species identification, and antimicrobial susceptibility test of imipenem and meropenem was performed with a disk diffusion assay. Generally, the phenotypic identification results were quite different from the genotyping results, and their discrimination ability was unsatisfactory, whereas 16S rRNA and rpoB gene sequencing showed consistent typing results, with different resolution. Additionally, A. pittii, A. calcoaceticus and A. nosocomialis, which were phylogenetically close to A. baumannii, accounted for 85.5% of the non-A. baumannii isolates. One group, which could not be clustered with any reference strains, consisted of 11 isolates and constituted a novel Acinetobacter species that was entitled genomic species 33YU. None of the non-A. baumannii isolates harbored a bla_OXA-51-like gene, and this gene was disrupted by ISAba19 in only one isolate; it continues to be appropriate as a genetic marker for A. baumannii identification. The resistance rate of non-A. baumannii isolates to imipenem and/or meropenem was only 2.6%, which was significantly lower than that of A. baumannii. Overall, rpoB gene sequencing was the most accurate identification method for Acinetobacter species. Except for A. baumannii, the most frequently isolated species from the nosocomial setting were A. pittii, A. calcoaceticus and A. nosocomialis.

[Effects of antibiotics plus efflux pump inhibitors on mutant selection window of Pseudomonas aeruginosa in vitro]

OBJECTIVE

To explore the effects of antibiotics plus efflux pump (EPI) inhibitors on mutant selection window of Pseudomonas aeruginosa in vitro.

METHODS

In standard strains, the minimum inhibitory concentrations (MICs) of meropenem, ceftazidime, amikacin and ciprofloxacin alone were measured. Then the MICs of four antibiotics respectively plus EPI, including reserpine, omeprazole, azithromycin, carbonyl cyanide m-chlorophenyl- hydrazone (CCCP) and Phe-Arg-β-naphtylamide (PAβN), were measured by checkerboard test. And the mutant prevention concentrations (MPC) of antibiotics alone and antibiotics plus different EPIs were also measured by agar dilution method. Selection indices (SI) were acquired through MPC divided by MIC. Similarly, the SI of meropenem, ceftazidime and ciprofloxacin which respectively plus amikacin and amikacin plus ciprofloxacin were measured. In clinical strains, MIC, MPC and SI of antibiotics alone and four antibiotics plus CCCP were measured.

RESULTS

In standard strains, the SI of meropenem, ceftazidime, amikacin and ciprofloxacin alone were >32, >32, 16 and 16. After adding EPI, the SI of four antibiotics were 16, 16, 16, 8 (reserpine), 16, 32, 16, 8 (omeprazole), 8, 16, 16, 8 (azithromycin), 8, 8, 16, 8 (CCCP) and 8, 16, 16, 8 (PAβN). The SI of meropenem, ceftazidime and ciprofloxacin plus amikacin were 4, 4, 8. And the SI of amikacin plus ciprofloxacin was 4. In clinical strains, the SI of ciprofloxacin significantly decreased after adding CCCP.

CONCLUSIONS

Both MIC and MPC of meropenem, ceftazidime and ciprofloxacin decreased significantly after adding EPI. The mutant selection window decreased when ciprofloxacin was combined with CCCP.

Examination of cfiA-mediated carbapenem resistance in Bacteroides fragilis strains from a European antibiotic susceptibility survey

Of 1284 Bacteroides strains collected in Europe in 2000 for antibiotic susceptibility surveillance, 65 isolates displayed imipenem minimum inhibitory concentrations (MICs) > or =1 mg/L and were chosen for a thorough analysis of their resistance mechanism. Twenty-five of the isolates were positive for the cfiA carbapenem resistance gene. The resistance rates were 0.8% and 1.3% for imipenem and meropenem, respectively. In six of the strains, insertion sequence (IS) elements (IS613, IS614B, IS1186 and IS1187) activated the cfiA gene. However, other strains displayed at least elevated carbapenem MICs or were carbapenem resistant and produced measurable carbapenemase activities but did not harbour IS elements in the region upstream of the cfiA gene. The major determinant of carbapenem resistance in Bacteroides fragilis is production of CfiA metallo-beta-lactamase via activation of the cfiA gene by IS elements (higher level resistance) or by activation of its putative own promoter.

Colitic scid mice fed Lactobacillus spp. show an ameliorated gut histopathology and an altered cytokine profile by local T cells

BACKGROUND

Scid mice transplanted with CD4 T blast cells develop colitis. We investigated if the disease was influenced in colitic mice treated with antibiotic and fed Lactobacillus spp.

METHODS

Colitic scid mice were treated for 1 week with antibiotics (vancomycin/meropenem) followed or not followed by a 3-week administration of Lactobacillus reuteri DSM-12246 and Lactobacillus rhamnosus 19070-2 at 2x10 live bacteria/mouse/24 hours. After 12 weeks, the rectums were removed for histology, and CD4 T cells from the mesenteric lymph nodes (MLN) were polyclonally activated for cytokine measurements.

RESULTS

Irrespective of no treatment or treatments with antibiotics and probiotics, all mice transplanted with T cell blasts lost 10% of their body weight during the 12-week experimental period, whereas the nontransplanted mice had a 10% weight increase (P<0.001). All mice treated with antibiotics but not fed probiotics showed severe gut inflammation, whereas only 2 of the 7 mice fed probiotics showed signs of severe colitis (P<0.05). MLN-derived CD4 T cells from this latter group of mice showed lower levels of interleukin-4 secretion (P<0.05) and a tendency to higher interferon-gamma production than mice not fed probiotics.

CONCLUSIONS

Our data suggest that probiotics added to the drinking water may ameliorate local histopathological changes and influence local cytokine levels in colitic mice but not alter the colitis-associated weight loss.

Noncognitive symptoms and long-term treatment expectations for Alzheimer disease

Alzheimer disease (AD) is characterized by both cognitive and noncognitive symptoms that can lead to functional impairment, increased caregiver burden, and institutionalization. Pharmacologic therapies traditionally used to treat cognitive symptoms of AD may prevent and/or control many noncognitive symptoms as well. The acetylcholinesterase inhibitors (AChEIs) galantamine, rivastigmine, and donepezil have been shown to maintain or improve function for at least 1 year. They also have been shown to improve or delay the onset of neuropsychiatric and behavioral symptoms. These noncognitive benefits can impact greatly the lives of patients with AD as well as the persons who care for them.

Metallo-β-lactamase expressing multi-resistant Acinetobacter baumannii transmitted in the operation area

Outbreaks of Acinetobacter baumannii demonstrating multiple antibiotic resistance, including meropenem resistance, have been described as severe therapeutic problems. Here we describe a monoclonal outbreak of infection and colonization with multidrug-resistant A. baumannii over a two-month period. Resistance to meropenem was mediated by expression of a metallo-beta-lactamase enzyme. Four of 14 patients showed clinical signs of infection and two died. Contamination of the environment, water, or instruments were excluded as causes of the outbreak. All patients, except one, underwent surgery in a specific operation theatre where surgery of contamination class IV (infected, dirty) was performed. Although individual surgeon error was eliminated, analyses of the patients' histories suggested that bacterial transmission had occurred during surgery. Five patients showed signs of A. baumannii infection and two of these patients suffered from large abdominal wounds infected with a high density of A. baumannii requiring repeated revisions. Presumably, these revisions favoured the transmission of A. baumannii, which is remarkably resistant to various environmental stresses including soaps, disinfectants and dry conditions. No case of meropenem-resistant A. baumannii had been observed in the hospital before the outbreak. Interestingly, the resistant bacteria appear to have been imported by a patient returning from West Africa. This indicates that, similar to MRSA, multiresistant A. baumannii may be introduced by patients from foreign hospitals. The outbreak was stopped in the following months by reinforcing standard procedures and by taking all necessary precautions such as patient isolation, and finally only one new case was detected.

[Study of the usefulness of a kit containing imipenem/cilastatin powder with diluent for injection: accuracy of reconstitution]

The usefulness of a kit consisting of non-glass packaging was evaluated in terms of accuracy of reconstitution. The newly developed imipenem/cilastatin powder-and-diluent kit consists of a polyolefin bag with two chambers that contain impenem/cilastatin powder and diluent (0.9% saline, 100 ml), respectively. The accuracy of reconstitution was determined by nurse and pharmacists at the Kitasato University East Hospital by measuring the amount of materials remaining in vials after reconstitution using the syringe dilution method and the transfer-needle dilution method. The mean percent amounts of imipenem and cilastatin remaining after preparation by the syringe dilution method were 5.58 +/- 2.60% and 4.08 +/- 1.77%, respectively. The mean percent amounts of imipenem and cilastatin remaining after preparation by the transfer-needle dilution method were 3.99 +/- 2.28% and 3.71 +/- 2.09%, respectively. The amount of imipenem/cilastatin remaining in the newly developed kit should be negligible, because the kit serves as both a vial and a dosing package. Therefore, greater accuracy in terms of reconstitution is expected with the newly developed kit than with the traditional syringe dilution or transfer-needle dilution methods.

[Study of the usefulness of a kit containing imipenem/cilastatin powder with diluent for injection: convenience of use and preparation]

The usefulness of a newly developed imipenem/cilastatin powder-and-diluent kit packed in non-glass container was compared to that packed in commercially available glass vials. The imipenem/cilastatin powder-and-diluent kit container is made of a polyolefin bag with two chambers that contain imipenem/cilastatin powder and diluent (0.9% saline, 100 ml), respectively. The convenience of use of the kit and the time required for the preparation of the dosing solution were evaluated by nurses and pharmacists at the Kitasato University East Hospital. The newly developed kit received higher scores with regard to convenience of use and led to a 46 approximately 59% reduction in the time required for preparation as compared to the commercially available glass vials.

In vitro activity and beta-lactamase stability of LJC 10,627

The in vitro activity of LJC 10,627, a new carbapenem, was compared with those of imipenem, cefotaxime, ceftazidime, and gentamicin. LJC 10,627 inhibited 90% of Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Enterobacter aerogenes, Enterobacter agglomerans, Enterobacter cloacae, Hafnia alvei, Citrobacter freundii, Citrobacter diversus, Proteus mirabilis, Morganella morganii, Proteus rettgeri, Serratia marcescens, Pseudomonas cepacia, salmonellae, shigellae, aeromonas, and yersiniae at less than or equal to 2 micrograms/ml. Haemophilus influenzae was inhibited by 0.5 microgram/ml, and moraxellae were inhibited by 0.12 microgram/ml. LJC 10,627 was twofold more active than imipenem against aerobic gram-negative organisms and inhibited ceftazidime-, cefotaxime-, and gentamicin-resistant members of the genera Klebsiella, Enterobacter, Citrobacter, and Serratia at less than or equal to 2 micrograms/ml. Xanthomonas maltophilia strains were resistant to the drug. Imipenem was two- to fourfold more active than LJC 10,627 against Staphylococcus aureus and Staphylococcus epidermidis. LJC 10,627 did not inhibit most methicillin-resistant Staphylococcus aureus or methicillin-resistant Staphylococcus epidermidis strains. LJC 10,627 inhibited Streptococcus pyogenes and Streptococcus pneumoniae at 0.06 and 0.12 microgram/ml, respectively. Bacteroides fragilis and other Bacteroides spp. were inhibited by 0.5 microgram of LJC 10,627 per ml. Serum (50%) did not affect the MICs. LJC 10,627 was not hydrolyzed by plasmid-mediated beta-lactamases of Bush types 2b, 2b', TEM-1, TEM-2, TEM-3, TEM-5, TEM-7, TEM-9, and SHV-1; the chromosomal beta-lactamases of Bush type 1; P-99; a Morganella enzyme; or a Citrobacter freundii enzyme. The Bush type 2c and 2d enzymes OXA-1, OXA-2, PSE-1, PSE-2, and PSE-4 did not hydrolyze LJC 10,627, nor did the beta-lactamases of Staphylococcus aureus, Moraxella spp., Bacteroides fragilis, and Proteus vulgaris. The beta-lactamase of Xanthomonas hydrolyzed LJC 10,627, albeit at approximately one-third the rate that imipenem was hydrolyzed.

Renal dehydropeptidase-I stability of LJC 10,627, a new carbapenem antibiotic

LJC 10,627 is a new parenteral carbapenem antibiotic. LJC 10,627 stability against human renal dehydropeptidase-I was compared with that of imipenem. Hydrolysis of this compound was not detectable by spectrophotometrical assay. Even after a 2-h incubation of antibiotics with this enzyme at 30 degrees C, the concentration of LJC 10,627 remained at 92.3% of the initial concentration, whereas imipenem completely disappeared. Thus, it was found that this compound was highly stable against human renal dehydropeptidase-I. Furthermore, LJC 10,627 had a low affinity for this enzyme, as indicated by the high Ki value (0.38 mM).

Comparative study of certain antibiotics on epileptogenic property, including (1Rpi, 5S, 6S)-2-[(6,7-dihydro-5H-pyrazolo[1,2-a][1,2,4]triazolium-6-yl)] thio-6-[(R)-1-hydroxyethyl]-1-methyl-carbapenem-3-carboxylate (LJC10627), a carbapenem antibiotic with broad antimicrobial spectrum

The epileptogenic effects of (1R, 5S, 6S)-2-[(6,7-dihydro-5H-pyrazolo[1,2-a][1,2,4]triazolium-6- yl)]thio-6-[(R)-1-hydroxyethyl]-1-methyl-carbapenem-3-carboxylate (LJC10627), a new derivative of carbapenem were studied in comparison with those of imipenem (imipenem/cilastatin), cefazolin and penicillin G. In intraventricular injection in rats, LJC10627 caused no epileptogenic activity at a dose of 32 micrograms. In contrast, imipenem, cefazolin and penicillin G showed dose-related seizure signs, continuous rhythmic spikes or high voltage spike-wave complexes and convulsive behaviors at doses higher than 10 micrograms. After intravenous injection of LJC10627, no epileptogenic signs on the electroencephalogram (EEGs) or in behavioral symptoms were observed, even at a dose of 500 mg/kg in rats and 300 mg/kg in rabbits, respectively. By contrast, imipenem/cilastatin provoked severe seizure patterns characterized by high voltage spikes-wave complex and convulsive behavior, both in rats and rabbits, using the same doses of LJC10627. Cefazolin and penicillin G also induced obvious epileptogenic signs in both rats and rabbits after intravenous injection. From these results, it was concluded that LJC10627, unlike imipenem (imipenem/cilastatin) and cefazolin, dose not elicit epileptogenic activity, and may therefore be safely used for clinical purpose.

In vitro and in vivo activities of LJC10,627, a new carbapenem with stability to dehydropeptidase I

The activity of LJC10,627 was compared with the activities of imipenem and other antibiotics. LJC10,627 was more active against most members of the family Enterobacteriaceae, Pseudomonas spp., and Acinetobacter spp. but slightly less active than imipenem against staphylococci and streptococci. LJC10,627 showed stability to mouse dehydropeptidase I and was more effective in vivo than imipenem plus cilastatin against gram-negative bacterial infections and as effective against staphylococcal infections.

In vitro antibacterial activity and beta-lactamase stability of the new carbapenem LJC10,627

In in vitro susceptibility tests the new carbapenem LJC10,627 showed potent antibacterial activity against gram-positive and gram-negative bacteria, except that most methicillin-resistant Staphylococcus aureus strains tested were found to be resistant to LJC10,627. LJC10,627 showed high activity against Pseudomonas aeruginosa and was active against Enterobacter cloacae and Citrobacter freundii strains which were resistant to ceftazidime and cefpirome. The Ki values of LJC10,627 for penicillinase Type I, cephalosporinase and oxyiminocephalosporinase were low, whereas the Ki value for L-1 enzyme from Xanthomonas maltophilia was high.

In vitro activity of LJC10,627, a new carbapenem antibiotic with high stability to dehydropeptidase I

The in vitro activity of LJC10,627, a new carbapenem, was compared with those of imipenem and ceftazidime. LJC10,627 had broad-spectrum activity against gram-positive and gram-negative clinical isolates. The MICs of this compound for 90% of members of the family Enterobacteriaceae tested (MIC90s), including strains resistant to ceftazidime, ranged from 0.1 to 25 micrograms/ml. LJC10,627 inhibited Pseudomonas aeruginosa at an MIC90 of 3.13 micrograms/ml; it thus was twofold more active than imipenem. This compound inhibited Haemophilus, Neisseria, and Branhamella species at MIC90s of 3.13, 0.1, and 0.1 micrograms/ml, respectively. LJC10,627 was two- to fourfold less active than imipenem against methicillin-susceptible Staphylococcus aureus and Staphylococcus epidermidis at MIC90s of 0.1 and 0.39 microgram/ml. However, the compound was found to be twofold more active than imipenem against Bacteroides fragilis at an MIC90 of 1.56 microgram/ml. LJC10,627 was very stable to various beta-lactamases except for Xanthomonas maltophilia oxyiminocephalosporinase type II. LJC10,627 was minimally hydrolyzed by swine renal dehydropeptidase I; its residual activity was 93.0% after 2 h. Killing kinetics of this compound for Escherichia coli and Pseudomonas aeruginosa showed that bactericidal action occurred at concentrations above the MIC (0.05 and 0.39 microgram/ml, respectively). LJC10,627 had a high affinity for penicillin-binding proteins 2, 4, and 1B(s) of Escherichia coli and Pseudomonas aeruginosa and penicillin-binding proteins 1 and 4 of Staphylococcus aureus.

Decreases of the susceptibility to low molecular weight beta-lactam antibiotics in imipenem-resistant Pseudomonas aeruginosa mutants: role of outer membrane protein D2 in their diffusion

Decreased susceptibilities to two low Mr beta-lactam antibiotics, CS-533 (a carbapenem; Mr, 339) and CGP31608 (a penem; Mr, 262), were found in imipenem-resistant mutants of Pseudomonas aeruginosa PAO. The diffusion rates of several beta-lactam antibiotics including imipenem, CS-533 and CGP31608 across the proteoliposome membrane reconstituted from the outer membrane of the wild type strain or its imipenem-resistant mutants were determined by the liposome swelling technique. Diffusion rates of imipenem, CS-533 and CGP31608 in the proteoliposomes from outer membranes of the imipenem-resistant strain were found to be 27, 20 and 47%, respectively, of the diffusion rates in proteoliposomes reconstituted from outer membranes of the sensitive parent strain. The SDS-polyacrylamide gel electrophoretogram of outer membrane proteins of the imipenem-resistant strains indicated deletion of protein D2. These results suggested that decreased susceptibilities to imipenem, CS-533 and CGP31608 were due to decreased outer membrane permeability, and that D2 is a protein fraction constituting pores for diffusion of these antibiotics through the P. aeruginosa outer membrane.

Susceptibility of naturally occurring carbapenem antibiotics to renal dehydropeptidase-I. An easy assay using a plate technique based on a novel chromogenic beta-lactamase substrate

A general screening procedure is described which allows the rapid determination of the susceptibility of naturally occurring carbapenem antibiotics to renal dehydropeptidase-I at the broth level. The procedure is based on the incubation of carbapenem-containing solutions with dehydropeptidase-I and the subsequent assay of residual beta-lactamase-inhibiting/inactivating activity of carbapenems by means of a plate technique using the chromogenic beta-lactamase substrate PADAC.

Antimicrobial and beta-lactamase inhibitory activities of carpetimycins A and B, new carbapenem antibiotics

Carpetimycins A and B showed widely broad spectra and potent activity against gram-positive and gram-negative bacteria, including various species of anaerobic bacteria. The antimicrobial activity of carpetimycin A was 8 to 64 times greater than that of carpetimycin B and 4 to 128 times greater than that of cefoxitin. The inhibitory concentration of carpetimycin A required to inhibit more than 90% of clinical isolates was 0.39 micrograms/ml for Escherichia coli and klebsiella and 1.56 microgram/ml for Proteus and Staphylococcus aureus. At a concentration of 3.13 micrograms/ml, carpetimycin A inhibited almost all clinical isolates of Enterobacter and Citrobacter, which showed resistance to many clinically used beta-lactam antibiotics. Carpetimycins A and B furthermore were shown to have potent inhibitory activities against several kinds of beta-lactamases produced by beta-lactam-resistant strains; they inhibited not only penicillinase-type beta-lactamases but also cephalosporinase-type beta-lactamases, which were insensitive to clavulanic acid. In combination with beta-lactam antibiotics such as ampicillin, carbenicillin, and cefazolin, carpetimycins A and B showed synergistic activities against beta-lactam-resistant bacteria.

Quaternary heterocyclylamino beta-lactams: a generic alternative to the classical acylamino side chain

6 beta-[(1-Substituted-4-pyridinio)amino]penam-3-carboxylates and 7 beta-[(1-substituted-4-pyridinio)amino]ceph-3-em-4-carboxylates have been found to be interesting new classes of antibacterial beta-lactams, readily available by SN2 Ar coupling of fluoro-substituted quaternized pyridines and appropriate amino lactam carboxylic acids. Compared to penicillin G, the penam 12c exhibited a spectrum extended to Gram-negative species, such as Escherichia, Shigella, Klebsiella and Enterobacter, offset by a loss of potency against Gram-positive species. Excluding Pseudomonas, many examples of the cephems showed excellent activity against the above Gram-negative organisms, and in some cases, such as 15i, the spectrum included good performance against the staphylococci and streptococci. With Serratia and many Proteus species, there was an adverse inoculum and medium effect which was not observed in the good Gram-positive reach of the cephem series.

A comparative in vitro study of thienamycin

The in vitro activity of thienamycin was compared to that of other antibiotics against a large panel of bacteria obtained in blood cultures from cancer patients. This compound was the most active against gram-positive cocci and also proved to be extremely active against the gram-negative bacteria. It was also very active against multi-resistant gram-negative bacilli. Because of its broad spectrum of activity including Pseudomonas spp., thienamycin deserves clinical testing in the future.

Asparenomycins A, B and C, new carbapenem antibiotics. I. Taxonomic studies on the producing microorganisms

Two streptomycete isolates, PA-31088 and PA-39504, were found to produce new carbapenem antibiotics, asparenomycins A, B and C. Strain PA-31088 was identified as a new species of Streptomyces and the name Streptomyces tokunonensis sp. nov. proposed. Strain PA-39504 was identified as Streptomyces argenteolus.

In vitro activity of thienamycin

The in vitro activity of thienamycin was determined simultaneously in Müller-Hinton broth and peptone broth. Minimum inhibitory and bactericidal concentrations were compared to those of 4 aminoglycosides and 3 cefalosporins. The activity of thienamycin against gram-negative aerobic bacterial was influenced by the media. Peptone broth gave the lowest MICs and MBCs. Concentrations less than or equal to 8 mcg thienamycin/ml peptone broth inhibited 354 out of 382 strains tested.

Interaction of beta-lactamase of Streptomyces cacaoi. I. Clavulanic acid and PS-5

Inactivation of a beta-lactamase of Streptomyces cacaoi by clavulanic acid and PS-5 was investigated and compared with that of a beta-lactamase of Bacillus cereus. Inhibition of the enzymes induced by clavulanic acid and the beta-lactam antibiotic PS-5 was found to be progressive with time. However, the degree of inhibition of the beta-lactamase from S. cacaoi increased more progressively with time than that of the enzyme from B. cereus. Conformative response constants were determined. As compared with clavulanic acid, over ten times higher concentrations of PS-5 were necessary to give a similar degree of inhibition. At lower concentrations, both clavulanic acid and PS-5 behaved as competitive inhibitors. Ki values calculated from the integrated form of the LINEWEAVER-BURK type were 1.1 X 10(-7) M and 7.6 X 10(-6) M for clavulanic acid and PS-5, respectively.

Effects of beta-lactam antibiotics on peptidoglycan synthesis in growing Neisseria gonorrhoeae, including changes in the degree of O-acetylation

Low concentrations of beta-lactam antibiotics caused an increased uptake of radioactive glucosamine into the sodium dodecyl sulfate-insoluble peptidoglycan of growing Neisseria gonorrhoeae. There was no appreciable change in the (small) amount of sodium dodecyl sulfate-soluble polymer present in the cultures. The sodium dodecyl sulfate-insoluble product in control cells was only partially dissolved by egg-white lysozyme (about 40%), but could all be released by the Chalaropsis B muramidase. In cells exposed to beta-lactams the proportion of labeled peptidoglycan susceptible to lysozyme increased to 60%. Examination of the Chalaropsis B digests by thin-layer chromatography showed that they contained disaccharide-peptide monomers with and without O-acetylation and bis-disaccharide-peptide dimers with one or two O-acetyl groups, or with none. beta-Lactam antibiotics caused a decrease in the degree of O-acetylation but did not greatly affect the amount of peptidoglycan cross-linking. They also had the effect of enlarging the bacteria and conserving and thickening the septa that could be observed in thin sections under the electron microscope. The relationship between these results and the effects of beta-lactams on in vitro synthesis of peptidoglycan by ether-treated N. gonorrhoeae is discussed.

Isolation and structure assignment

At least six distinct beta-lactam antibiotics of the epithienamycin family are produced by a strain of Streptomyces flavogriseus MB 4638. Each of the six can be isolated in substantially pure form by column chromatography using Dowex 1, Amberlite XAD-2 and Biogel packings. The structures were established by comparison of the ultraviolet, proton magnetic resonance and mass spectral characteristics with those of thienamycin and its derivatives. All six compounds contain the carbapenem ring system which is also found in thienamycin. They differ from each other and from thienamycin by chemical modifications and/or stereoisomerism. Enzymatically deacetylated epithienamycin A has the properties of an isomer of thienamycin.

Production and antibacterial activity

The epithienamycins are cell wall active antibiotics structurally related to N-acetylthienamycin. We have found forty-three isolated of Streptomyces flavogriseus which are capable of producing members of the epithienamycin family. Six major epithienamycin components, and xanthomycin, have been isolated from fermentation broth. Fermentation conditions can be varied to enrich for certain members of the epithienamycin family. All six components show activity in vitro versus a broad spectrum of bacterial species. The weight potencies vary 27 fold from the most active to least active.

Preparation and antibacterial activity of delta 1-thienamycin

delta 1-Thienamycin (2), a double-bond isomer of thienamycin, was prepared by isomerizing N-[[(p-nitrobenzyl)oxy]-carbonyl]thienamycin p-nitrobenzyl ester (5b) with DBU in Me2SO followed by hydrogenolysis of the protecting groups. When evaluated in a disc-diffusion antibacterial assay, delta 1-thienamycin was found to be essentially devoid of activity. The lack of antibacterial activity was ascribed to a chemically less reactive beta-lactam amide bond than that found in thienamycin.

C-19393 S2 and H2, new carbapenem antibiotics. III. Mode of action

Biochemical activities of new carbapenem antibiotics, C-19393 H2(H2) and C-19393 S2(S2), were examined in comparison with those of mecillinam using Escherichia coli. H2 showed remarkably high affinity for penicillin-binding protein (PBP) 2, and high affinity for PBPs 1 and 3. S2 showed high affinity for PBP 2, moderate affinity for PBP 1 and low affinity for PBP 3. They induced ovoid cells at lower concentrations and cell lysis at higher concentrations. The inhibitory potency of H2 for peptidoglycan synthesis was similar to that of mecillinam at lower concentrations up to 0.1 micrograms/ml. At concentrations higher than 0.1 micrograms/ml, the inhibition rate by H2 gradually increased up to 100%, whereas that by mecillinam remained at 60% level. The MICs of H2, S2 and mecillinam corresponded to the lowest concentrations giving 60% of inhibition of peptidoglycan synthesis at which concentrations the function of PBP 2 seemed to be prevented completely. These findings indicate that the primary targets of H2 and S2 are PBP 2 involved in cell shape determination in E. coli.

C-19393 S2 and H2, new carbapenem antibiotics. IV. Inhibitory activity against beta-lactamases

New carbapenem antibiotics, C-19393 S2 and H2, have been found to be potent and broad-spectrum inhibitors of beta-lactamases. Among 11 types of beta-lactamases tested, those from Escherichia coli (plasmid-bearing), Klebsiella pneumoniae, Proteus vulgaris, Serratia marcescens and Bacteroides fragilis were especially sensitive. They also inhibited cephalosporinases insensitive to clavulanic acid. The inhibition by C-19393 S2 and H2 was of progressive type, except for the inhibition of E. coli enzyme (plasmid-mediated type I) by C-19393 H2. The inhibition of E. coli beta-lactamase by C-19393 S2 was irreversible, while that by C-19393 H2 was reversible.

C-19393 S2 and H2, new carbapenem antibiotics. II. isolation and structures

Two new beta-lactam antibiotics, C-19393 S2 (1) and H2 (2), were isolated from the culture filtrate of Streptomyces griseus subsp. cryophilus nov. subsp. The structures were determined by spectral analysis as shown in Fig. 2. The antibiotics have broad antimicrobial activity and strongly inhibit beta-lactamases. The minor product (2) is more stable than cephalosporin C in aqueous solution.

C-19393 S2 and H2, new carbapenem antibiotics. I. Taxonomy of the producing strain, fermentation and antibacterial properties

C-19393 S2 and H2 are new carbapenem antibiotics produced by a streptomycete. The producing strain was taxonomically studied and named Streptomyces griseus subsp. cryophilus. Cobaltous compounds were necessary for production of the antibiotics. C-19393 S2 and H2 showed a broad spectrum of antibacterial activities with C-19393 H2 being 8 approximately 120 times more active than C-19393 S2. They also exhibited beta-lactamase-inhibiting activities and acted synergistically with ampicillin and cefotiam against clinical isolates resistant to beta-lactam antibiotics.