Piperacillin. A review of its antibacterial activity, pharmacokinetic properties and therapeutic use

Successful Clinical Avoidance of Colorectal Anastomotic Leakage through Local Decontamination

AIM

An anastomotic leak is an unpredictable postoperative complication during recovery from colorectal surgery that may require a re-operation. Potentially pathogenic bacteria like Pseudomonas (and Enterococcus) contribute to the pathogenesis of an anastomotic leak through their capacity to degrade collagen and to activate tissue matrix metalloprotease-9 in host intestinal tissues. The microbiome, therefore, is the key to preventing an anastomotic leak after colorectal surgery. The aim of this trial was to investigate whether perioperative selective decontamination with a new mixture of locally acting antibiotics specially designed against Pseudomonas aeruginosa and Enterococcus faecalis can reduce or even stop early symptomatic leakage.

METHOD

All hospitalized patients in our University Clinic undergoing colorectal surgery with a left-sided anastomosis were included as two groups; patients in the intervention group received polymyxin B, gentamicin and vancomycin every six hours for five postoperative days and those in the control group did not receive such an intervention. An anastomotic leak was defined as a clinically obvious defect of the intestinal wall integrity at the colorectal anastomosis site (including suture) that leads to a communication between the intra- and extraluminal compartments, requiring a re-do surgery within seven postoperative days.

RESULTS

Between February 2017 and May 2023, a total of 301 patients (median age of 63 years) were analyzed. An anastomotic leak was observed in 11 patients in the control group (n = 152), but in no patients in the intervention group (n = 149); this difference was highly significant.

CONCLUSION

The antibiotic mixture (with polymyxin B, gentamicin and vancomycin) used for local decontamination in our study stopped the occurrence of anastomotic leaks completely. According to the definition of anastomotic leak, no further surgery was required after local perioperative decontamination.

Transcriptomic analysis of multi-drug resistant Escherichia coli K-12 strain in response to Lavandula angustifolia essential oil

To better understand the synergistic antibacterial activity between piperacillin and Lavandula angustifolia essential oil (LEO) against multidrug-resistant Escherichia coli, we performed microarray transcriptomic analysis of LEO when used alone and in combination with piperacillin against the non-treated control. In total, 90 genes were differentially expressed after the combination of LEO and piperacillin treatment. Among the up-regulated genes, nfsB, nemA, fruA, nfsB, nemA are known to control microbial metabolism and nitrotoluene degradation, which were observed only in the LEO-piperacillin combinatory treatment. Four candidate genes from the microarray result, srIA, srID, waaR and nfsB, were validated by qRT-PCR as these genes showed differential expression consistently in the two methods. Biochemical pathway analysis showed that there was upregulation of genes involved in several biological processes including fructose and mannose metabolism, phosphotransferase system (PTS), lipopolysaccharide biosynthesis and nitrotoluene degradation. Genes involved in microbial metabolism in diverse environments were found both up- and down-regulated in LEO-piperacillin combinatory treatment. Our study provides new information concerning the transcriptional changes that occur during the LEO and piperacillin interaction against the multidrug-resistant bacteria and contributes to unravel the mechanisms underlying this synergism.

Contribution of β-lactamase and efflux pump overproduction to tazobactam-piperacillin resistance in clinical isolates of Escherichia coli

INTRODUCTION

Tazobactam-piperacillin (TZP) is a mixture of a broad-spectrum penicillin and an irreversible β-lactamase inhibitor. TZP is effective against Gram-negative bacteria that produce extended-spectrum β-lactamases, and it is used as a first-line or second-line drug to treat serious infections.

METHODS

This study identified three TZP-resistant and two TZP-intermediate strains among 514 clinical isolates of Escherichia coli.

RESULTS

These five isolates possessed one or more β-lactamase genes, bla_TEM-1, bla_CTX-M-2, bla_CTX-M-14, and/or bla_CMY-8. The expression levels of β-lactamase genes and acrAB genes in the strains were examined by using real-time reverse transcription PCR. The total enzymatic piperacillin-degrading activity in cells was determined. Two TZP-resistance mechanisms were identified: hyperproduction of TEM-1 in the two resistant strains; and simultaneous high production of β-lactamase and efflux pump AcrAB in the two TZP-intermediate isolates. The latter are an international high-risk clone O25b:H4-ST131-H30R.

CONCLUSION

TZP resistance is still rare in clinical isolates of E. coli. However, resistance can develop on high production and/or combinations of known antimicrobial resistance mechanisms in different ways.

Cefepime shows good efficacy and no antibiotic resistance in pneumonia caused by Serratia marcescens and Proteus mirabilis - an observational study

Background

Many antibiotics have no effect on Gram-positive and Gram-negative microbes, which necessitates the prescription of broad-spectrum antimicrobial agents that can lead to increased risk of antibiotic resistance. These pathogens constitute a further threat because they are also resistant to numerous beta-lactam antibiotics, as well as other antibiotic groups. This study retrospectively investigates antimicrobial resistance in hospitalized patients suffering from pneumonia triggered by Gram-negative Serratia marcescens or Proteus mirabilis.

Methods

The demographic and clinical data analyzed in this study were obtained from the clinical databank of the HELIOS Clinic, Witten/Herdecke University, Wuppertal, Germany, for inpatients presenting with pneumonia triggered by S. marcescens or P. mirabilis from 2004 to 2014. An antibiogram was conducted for the antibiotics utilized as part of the management of patients with pneumonia triggered by these two pathogens.

Results

Pneumonia was caused by Gram-negative bacteria in 115 patients during the study period from January 1, 2004, to August 12, 2014. Of these, 43 (37.4 %) hospitalized patients [26 males (60.5 %, 95 % CI 45.9 %–75.1 %) and 17 females (39.5 %, 95 % CI 24.9 %–54.1 %)] with mean age of 66.2 ± 13.4 years had pneumonia triggered by S. marcescens, while 20 (17.4 %) patients [14 males (70 %, 95 % CI 49.9 %–90.1 %) and 6 females (30 %, 95 % CI 9.9 %–50.1 %)] with a mean age of 64.6 ± 12.8 years had pneumonia caused by P. mirabilis. S. marcescens showed an increased antibiotic resistance to ampicillin (100 %), ampicillin-sulbactam (100 %), and cefuroxime (100 %). P. mirabilis had a high resistance to tetracycline (100 %) and ampicillin (55 %). S. marcescens (P < 0.0001) and P. mirabilis (P = 0.0003) demonstrated no resistance to cefepime in these patients with pneumonia.

Conclusions

S. marcescens and P. mirabilis were resistant to several commonly used antimicrobial agents, but showed no resistance to cefepime.

No Resistance to Penicillin, Cefuroxime, Cefotaxime, or Vancomycin in Pneumococcal Pneumonia

OBJECTIVES

Group B Streptococcus is a primary source of pneumonia, which is a leading cause of death worldwide. During the last few decades, there has been news of growing antibiotic resistance in group B streptococci to penicillin and different antibiotic agents. This clinical study retrospectively analyzes antimicrobial resistance in inpatients who were diagnosed with group B streptococcal pneumonia.

METHODS

All of the required information from inpatients who were identified to have group B streptococcal pneumonia was sourced from the database at the Department of Internal Medicine of HELIOS Clinic Wuppertal, Witten/Herdecke University, in Germany, from 2004-2014. Antimicrobial susceptibility testing was performed for the different antimicrobial agents that were regularly administered to these inpatients.

RESULTS

Sixty-six inpatients with a mean age of 63.3 ± 16.1 years (45 males [68.2%, 95% CI 60.0%-79.4%] and 21 females [31.8%, 95% CI 20.6%-43.0%]) were detected to have group B streptococcal pneumonia within the study period from January 1, 2004, to August 12, 2014. Group B Streptococcus had a high resistance rate to gentamicin (12.1%), erythromycin (12.1%), clindamycin (9.1%), and co-trimoxazole (3.0%), but it was not resistant to penicillin, cefuroxime, cefotaxime, or vancomycin (P < 0.0001).

CONCLUSION

No resistance to penicillin, cefuroxime, cefotaxime, or vancomycin was detected among inpatients with pneumonia caused by group B streptococci.

No Development of Imipenem Resistance in Pneumonia Caused by Escherichia coli

BACKGROUND

Antibiotic resistance continues to rise due to the increased number of antibiotic prescriptions and is now a major threat to public health. In particular, there is an increase in antibiotic resistance to Escherichia coli according to the latest reports.

TRIAL DESIGN

This article examines, retrospectively, antibiotic resistance in patients with community- and nosocomial-acquired pneumonia caused by E coli.

METHODS

The data of all patients with community- and nosocomial-acquired pneumonia caused by E coli were collected from the hospital charts at the HELIOS Clinic, Witten/Herdecke University, Wuppertal, Germany, within the study period 2004 to 2014. An antibiogram was performed for the study patients with pneumonia caused by E coli. Antimicrobial susceptibility testing was performed for the different antibiotics that have been consistently used in the treatment of patients with pneumonia caused by E coli. All demographic, clinical, and laboratory data of all of the patients with pneumonia caused by E coli were collected from the patients' records.

RESULTS

During the study period of January 1, 2004 to August 12, 2014, 135 patients were identified with community- and nosocomial-acquired pneumonia affected by E coli. These patients had a mean age of 72.5 ± 11.6 (92 [68.1%, 95% CI 60.2%-76.0%] males and 43 [31.9%, 95% CI 24.0%-39.8%] females). E coli had a high resistance rate to ampicillin (60.7%), piperacillin (56.3%), ampicillin-sulbactam (44.4%), and co-trimoxazole (25.9%). No patients with pneumonia caused by E coli showed resistance to imipenem (P < 0.0001).

CONCLUSION

E coli was resistant to many of the typically used antibiotics. No resistance was detected toward imipenem in patients with pneumonia caused by E coli.

A novel antibiotic based long-term model of ovine smoke inhalation injury and septic shock

We modified our established and clinically relevant ARDS model of smoke inhalation injury and septic shock by administration of combined antibiotics (AB) such as piperacillin and ciprofloxacin, to more closely mimic the clinical intensive care setting. Twenty-three sheep were subjected to the injury, and allocated to four groups for a 96 h study period: sham (n=5 non-injured); control (n=6: injured); AB6h (n=6: injured, antibiotics started 6 h post-injury); AB12h (n=6: injured, antibiotics started 12 h post-injury). All sham animals survived 96 h. Control, AB6h, AB12h groups reached criteria of septic shock within 12 h post-injury. All controls died within 36 h. Eighty three percent of AB6h and fifty percent of AB12h survived 96 h. Median survival times were significantly improved in the treated groups compared with the control group: 24 h in control vs. 80.5 h in AB6h, and 65 h in AB12h animals. Combined ciprofloxacin and piperacillin therapy was effective, reduced nitric oxide production and mortality, and will allow future long-term studies in this model.

Determination of the biliary excretion of piperacillin in humans using a novel method

AIM

To evaluate the applicability of a novel method to determine the biliary excretion of piperacillin.

METHODS

Healthy volunteers were administered piperacillin i.v. Duodenal aspirates were collected via a custom-made oroenteric catheter; blood and urine also were collected. Gallbladder ejection fraction (EF) was determined by gamma scintigraphy and pharmacokinetic parameters were calculated using noncompartmental analysis.

RESULTS

The fraction of the piperacillin dose excreted unchanged into bile was 1.1 +/- 0.3% (biliary clearance corrected for EF was 0.032 +/- 0.008 ml min(-1) kg(-1)).

CONCLUSIONS

This methodology can be used to determine reliably the biliary clearance of drugs that are excreted only marginally into bile. Normalization of biliary clearance for EF significantly reduces intersubject variability of this parameter.

Pharmacodynamics of piperacillin in severely ill patients evaluated by using a PK/PD model

Penetration of antiinfective drugs into soft tissues is essential for antimicrobial killing at the target site, but is substantially lower in severely ill patients compared with healthy subjects. The present study was conducted to assess the antimicrobial effect of piperacillin in severely ill patients. Strains of Staphylococcus aureus and Pseudomonas aeruginosa were exposed in vitro to concentrations of piperacillin, simulating the pharmacokinetic profiles measured in soft tissue of patients and healthy subjects. The simulation for patients resulted in effective killing, whereas bacterial regrowth was detected for healthy subjects. Our in vitro simulation showed that bacterial killing may be effective in severely ill patients despite relatively low concentrations of piperacillin at the target site. This finding is due to impaired renal function and subsequently prolonged tissue and plasma half-lives of piperacillin in intensive care patients.

New onset of multiple organ dysfunction after receiving long-term high-dose piperacillin for outpatient treatment of osteomyelitis

Toxic side effects of piperacillin occur in many organ systems and may be cumulative dose related. We report a patient receiving long-term high-dose piperacillin to accommodate convenient outpatient intravenous therapy of osteomyelitis. He developed life-threatening multiorgan dysfunction on day 20 of piperacillin administration after 49 days of antibiotics, suggesting a likely adverse drug reaction. Piperacillin should be administered according to the manufacturer's recommendations of dosage, frequency and duration, and suggested monitoring. Unorthodox treatment regimens are discouraged.

An observational study on the epidemiology of respiratory tract bacterial pathogens and their susceptibility to four injectable beta-lactam antibiotics: piperacillin, piperacillin/tazobactam, ceftazidime and ceftriaxone

Bacterial infections of the respiratory tract account for a large proportion of total medical consultations in general practice. In recent years, antibiotic resistance has increased alarmingly in a number of bacterial species that are common causes of these infections. The aim of this observational study was to determine the antibiotic resistance of microbial agents isolated from patients with acute or acutely exacerbated respiratory infections. Subjects recruited as potential sources of bacteria were either outpatients seen in a number of specialized clinics and hospital practices, or hospitalized patients. Overall, 648 consecutive patients (67% male, mean age 48.1+/-27.0 years) with infection of the upper or lower respiratory tract were observed during a 13-month period. A total of 551 pathogenic microbial strains were isolated and tested for their in vitro susceptibility to piperacillin, piperacillin/tazobactam, ceftazidime, and ceftriaxone. Among all isolates, the four most frequent pathogens were Pseudomonas aeruginosa (132 isolates, 24%), Streptococcus pyogenes (99 isolates, 18%), Staphylococcus aureus (93 isolates, 17%), and Klebsiella pneumoniae (46 isolates, 8%). The susceptibility of gram-positive isolates ranged from 97.5% to 95.1%, and no remarkable difference was found in the antibacterial activity of tested b-lactam antibiotics. The susceptibility of gram-negative isolates to piperacillin and piperacillin/tazobactam was also similar: 96.5% and 97.1%, respectively. In contrast, differences were found between piperacillin (or piperacillin/tazobactam) and either ceftazidime (p=0.003) or ceftriaxone (p<0.0003) in gram-negative isolates. We conclude that, despite the extensive use of beta-lactam antibiotics (piperacillin, ceftazidime, and ceftriaxone) in medical practice during the past three decades, the susceptibility of the most common pathogens involved in the etiology of upper and lower respiratory tract infections to these antibiotics is still high. In particular, bacterial resistance developed by gram-positive organisms against piperacillin is negligible and not alarming.

Comparative in vitro evaluation of piperacillin/tazobactam in a tertiary care hospital

Bacterial resistance is usually a serious problem in tertiary care hospitals. The aim of this in vitro study was to evaluate the beta-lactamase inhibitor combination piperacillin/tazobactam in a hospital environment with high bacterial resistance rates and compare it with other beta-lactam agents. Three hundred and sixty-two isolates from various clinical materials were studied during the period March-August 1996. Material for culture was collected from patients of all the wards of our hospital, with the majority being from the Intensive Care Unit (45%). Pathogenic Gram-positive and Gram-negative bacteria with high resistance rates and beta-lactamase production were studied (staphylococci, enterococci, Enterobacteriaceae, Pseudomonas). Significant bacterial resistance rates were identified for ceftazidime (50% for Klebsiellae, 60% for Enterobacter spp, 60% for Proteus spp, 33% for Pseudomonas spp, 75% for Acinetobacter spp) and ciprofloxacin (33% for both Klebsiellae and Enterobacter spp, 67% for Pseudomonas spp, 50% Acinetobacter spp). Fifty percent of Enterococcus isolates were resistance to ciprofloxacin but all of them were susceptible to piperacillin/tazobactam, amoxicillin/clavulanate and imipenem. The antibacterial activity of piperacillin/tazobactam (susceptibility rates 83 to 100% for Enterobacteriaceae, 83% for Pseudomonas spp and 75% for Acinetobacter spp) was higher than that of ceftazidime, piperacillin and ciprofloxacin. Imipenem, being mostly a reserve product, showed higher activity against Acinetobacter, Klebsiella and Enterobacter species.

Kinetics of piperacillin and tazobactam in ventricular cerebrospinal fluid of hydrocephalic patients

Its broad antibacterial spectrum qualifies the combination of piperacillin and tazobactam for therapy of nosocomial bacterial central nervous system (CNS) infections. Since these infections sometimes are accompanied by only minor dysfunction of the blood-cerebrospinal fluid (CSF) barrier, patients with noninflammatory occlusive hydrocephalus who had undergone external ventriculostomy were studied (n = 9; age range, 48 to 75 years). After administration of the first dose of piperacillin (6 g)-tazobactam (0.5 g) over 30 min intravenously, serum and CSF were drawn repeatedly and analyzed by high-performance liquid chromatography. Pharmacokinetics were determined by noncompartmental analysis. Maximum concentrations of piperacillin in CSF ranged from 8.67 to <0.37 mg/liter (median, 3.42 mg/liter), and those of tazobactam ranged from 1.37 to 0.11 mg/liter (median, 0.45 mg/liter). CSF maxima were observed, in median, 1.5 and 2 h after the end of the infusion. Elimination in CSF was considerably slower than in serum (median half-life at beta phase for piperacillin, 5.9 h in CSF versus 1.47 h in serum; for tazobactam, 6.1 h versus 1.34 h). For tazobactam, the ratio of the area under the concentration-time curve (AUC) in CSF to the AUC in serum was approximately three times as high as that for piperacillin (medians, 0.106 versus 0.034). In view of the tazobactam concentrations in CSF observed in this study, the practice of using a constant concentration of 4 mg of tazobactam per liter for MIC determination is inadequate for intracranial infections. Larger amounts of tazobactam than the standard dose of 0.5 g three times daily may be necessary for CNS infections.

Significant Role of Chemotherapy in the Treatment of Multiloculated Liver Abscesses Evaluated with CT and Angiographic Examinations

The role of chemotherapy was evaluated in 2 cases of solitary multiloculated liver abscesses. Both patients were free of biliary tract diseases, liver trauma, iatrogenic causes and colorectal diseases. Angiography revealed a hypervascular abscess wall and increased flow of the hepatic artery. In the first case, pyelonephritis was accompanied by left renalstones, and Escherichia coli was isolated from the urine. Since a laboratory examination revealed liver dysfunction, a CT was performed which disclosed a liver abscess. A percutaneous nephrostomy and chemotherapy were performed. Pus from the abscess yielded Streptococcus sanguis, along with unidentified gram-positive rods and anaerobic gram-negative cocci. The liver abscess did not resolve in spite of percutaneous drainage and administration of imipenem, which may have been due to the presence of multiple septa. After the administration of piperacillin, the body temperature normalized, and fistulography revealed adequate drainage of the liver abscess which subsequently resolved. In the other case, the patient had pyorrhea with an accompanying right subphrenic abscess. Fusobacterium sp. were recovered from the pus of liver abscess. Flomoxef was administered for 17 days prior to percutaneous drainage. Serial CT examinations revealed the disappearance of septa in the liver abscess cavity, and the patient made an uneventful recovery after percutaneous drainage. Piperacillin and flomoxef are excreted into bile fairly well in the absence of biliary obstruction, which may indicate that the high biliary concentrations of these antimicrobial agents is responsible for the elimination of multiple septa and the favorable response of multiloculated liver abscesses to percutaneous drainage.

Single-dose pharmacokinetics of piperacillin and tazobactam in infants and children

The pharmacokinetics of piperacillin and tazobactam were assessed after single-dose administration to 47 infants and children. Study subjects ranging in age from 2 months to 12 years were randomized to receive one of two different doses of a piperacillin-tazobactam combination (8:1): a low dose (n = 23) of 50 and 6.25 mg of piperacillin and tazobactam per kg of body weight, respectively, or a high dose (n = 24) of 100 and 12.5 mg, respectively. The pharmacokinetic behavior of tazobactam was very similar to that observed for piperacillin, supporting the use of these two agents in a fixed-dose combination. No differences in the pharmacokinetics of piperacillin or tazobactam were observed between the two doses administered. The elimination parameters half-life and total body clearance decreased and increased, respectively, with increasing age, whereas volume parameters (volume of distribution and steady-state volume of distribution) remained relatively constant for both compounds. The primary metabolite of tazobactam, metabolite M1, was measurable in the plasma of 18 of the 47 study subjects; 17 of these 18 subjects received the high doses. More than 70% of the administered piperacillin and tazobactam doses were excreted unchanged in the urine over a 6-h collection period. These data combined with the known in vitro susceptibilities of a broad range of pediatric bacterial pathogens indicate that a dose of 100 mg of piperacillin and 12.5 of mg tazobactam per kg of body weight administered as a fixed-dose combination every 6 to 8 h would be appropriate to initiate clinical efficacy studies in infants and children for the treatment of systemic infections arising outside of the central nervous system.

Pharmacokinetic characteristics of piperacillin/tazobactam

Piperacillin/tazobactam is a new combination of a broad-spectrum penicillin and a beta-lactamase inhibitor. In studies in healthy volunteers, the pharmacokinetics of piperacillin combined with tazobactam were similar to those of piperacillin alone. In contrast, tazobactam administered with piperacillin achieved higher plasma concentrations and had a longer half-life than tazobactam administered alone. Intravenous infusion of 4.0 g piperacillin with 0.5 g tazobactam over 5 min resulted in mean maximum plasma concentrations of 380 micrograms piperacillin/ml and 35.3 micrograms tazobactam/ml; half-lives were 1.14 h for piperacillin and 0.92 h for tazobactam. Within 30 min of infusion, piperacillin/tazobactam achieves 16-85% of plasma concentrations in skin, muscle, lung, gallbladder, and intestinal mucosa. Plasma and tissue levels remain above the MIC90s of major pathogens for 2 h post administration. These findings show that piperacillin/tazobactam is truly synergistic combination which can be expected to be effective in treating a wide variety of infections in the clinical setting.

Piperacillin/tazobactam. A review of its antibacterial activity, pharmacokinetic properties and therapeutic potential

Combining tazobactam, a beta-lactamase inhibitor, with the ureidopenicillin, piperacillin, successfully restores the activity of piperacillin against beta-lactamase-producing bacteria. Tazobactam has inhibitory activity, and therefore protects piperacillin against Richmond and Sykes types II, III, IV and V beta-lactamases, staphylococcal penicillinase and extended-spectrum beta-lactamases. However, tazobactam has only species-specific activity against class I chromosomally-mediated enzymes. Resistant organisms include some Citrobacter spp., Enterobacter spp., Serratia spp., Xanthomonas maltophilia and Enterococcus faecium. Consistent with its in vitro activity, preliminary clinical data indicate that the fixed combination of piperacillin/tazobactam (dose ratio 8:1) is effective in the treatment of moderate to severe polymicrobial infections, including intra-abdominal, skin and soft-tissue and lower respiratory tract infections. In limited comparative trials, piperacillin/tazobactam demonstrated equivalent or better efficacy than standard comparator regimens in these infections. Piperacillin/tazobactam in combination with an aminoglycoside was effective in the empirical treatment of fever in patients with neutropenia and compared favourably with ceftazidime in combination with an aminoglycoside, although second-line therapy with a glycopeptide antibiotic may be indicated in unresponsive episodes. Data from phase III trials indicate that piperacillin/tazobactam has a tolerability profile typical of a penicillin agent. Piperacillin/tazobactam provides a broad spectrum of antibacterial activity in a convenient single formulation suitable for use in the treatment of polymicrobial infections. Possible limitations concern its restricted activity against class I beta-lactamases, enzymes that are becoming increasingly important in the nosocomial environment. Combined therapy with an aminoglycoside may be necessary in more serious infections.

A randomized prospective study of cefoxitin versus piperacillin in appendicectomy

A randomized prospective study of antibiotic prophylaxis using a single dose of either cefoxitin or piperacillin is presented. The trial was carried out in Al Ain Hospital in the period 1989-1992 on 250 adult patients with non-perforated appendicitis. One group (124 patients) received 2 g cefoxitin, the other group (126 patients) 2 g piperacillin. Antibiotics were administered intravenously in the operating theatre immediately before surgery. Wound infection occurred in three patients, 2.4% of the cefoxitin group and in five patients (4%) of the second group (with no significant difference). The commonest infecting organisms were Escherichia coli (5 out of 8). Mean hospital stay for patients with wound infection was 15 days (range 12-21) compared with 6 days, (range 4-8) for non-infected cases. Prophylactic cefoxitin or piperacillin were each therefore similarly effective in minimizing the rate of wound infections in patients with non-perforated appendicitis.

Pharmacokinetics and tissue penetration of tazobactam and piperacillin in patients undergoing colorectal surgery

The pharmacokinetics of tazobactam and piperacillin in plasma and different tissues after a 30-min intravenous infusion of 4 g of piperacillin and 0.5 g of tazobactam were investigated in 18 patients who underwent elective colorectal surgery. Serial blood samples were collected for up to 6 h after the initiation of the infusion. The types of tissue collected were fatty tissue, muscle, skin, appendix, and intestinal mucosa (proximal and distal). On the basis of concentrations in plasma, the following pharmacokinetic parameter values were obtained (values are means +/- standard deviations): maximum concentration of drug in serum, tazobactam, 27.9 +/- 7.67 micrograms/ml; piperacillin, 259 +/- 81.8 micrograms/ml; time to maximum concentration of drug in serum, tazobactam, 0.51 +/- 0.03 h; piperacillin, 0.51 +/- 0.03 h; area under the concentration-time curve, tazobactam, 47.6 +/- 13.3 micrograms.h/ml; piperacillin, 361 +/- 80.3 micrograms.h/ml; clearance, tazobactam, 188 +/- 52.3 ml/min; piperacillin, 194 +/- 42.9 ml/min; half-life, tazobactam, 1.42 +/- 0.32 h; piperacillin, 1.27 +/- 0.24 h; apparent volume of distribution, tazobactam, 0.31 +/- 0.07 liter/kg of body weight; piperacillin, 0.29 +/- 0.06 liter/kg; volume of distribution at steady state, tazobactam, 0.28 +/- 0.04 liter/kg; piperacillin, 0.25 +/- 0.05 liter/kg. The concentrations of tazobactam and piperacillin in fatty tissue and muscle tissue were 10 to 13 and 18 to 30% of the levels in plasma, respectively. In skin, the concentrations of piperacillin were 60 to 95% of the levels in plasma, whereas the concentrations of tazobactam in plasma were 49 to 93% of the levels in skin tissue. The mean concentration of tazobactam in the investigated gastrointestinal tissues (appendix, proximal and distal mucosa) exceeded levels in plasma after 1 h, while piperacillin showed a mean penetration into these tissues of 43 and 53%. The mechanisms that can be used to explain the extent of penetration of piperacillin and tazobactam are discussed. Simple diffusion may take place in fatty and muscle tissue, while penetration into skin and gastrointestinal tissue is governed by more complex mechanisms which lead to differences in penetration between piperacillin and tazobactam. For all tissues investigated (except fatty tissue), the time course of the concentrations of both compounds was similar, with a peak in concentration at between 1 and 2 h after the start of infusion followed by a decline of concentrations that were almost parallel to the curves of the drug concentrations in plasma. In plasma and in all investigated tissues, piperacillin as well as tazobactam reached or exceeded the concentrations found to be effective in vitro.

Pharmacokinetics and ascitic fluid penetration of piperacillin in cirrhosis

The pharmacokinetics of piperacillin were evaluated in seven healthy volunteers, eight cirrhotic patients without ascites and 11 cirrhotic patients with sterile ascites after a single 15-min intravenous infusion of 4 g of the drug. In ascitic patients, piperacillin rapidly entered the peritoneal fluid. Peritoneal concentrations were higher than 10 mg/l from 0.5 to 8 h after the infusion. Disappearance rate of piperacillin was slower in the ascitic fluid than in plasma. The plasma half life of piperacillin was more prolonged in cirrhotic patients that in control subjects. This difference was more marked in ascitic patients for whom half life was twice as high as in volunteers (1.95 versus 0.91 h; P less than 0.01).

Cytoprotection against neutrophil-delivered oxidant attack by antibiotics

In the present study we have investigated the effect of six antibiotics (penicillin G, ceftazidime, cephotaxime, cephoperazon, ampicillin and piperacillin) on the neutrophil cytolytic activity by using a system constituted of phorbol-12-myristate-13-acetate-triggered neutrophils and 51Cr-labelled lymphoblastoid Daudi target cells. The results demonstrate that five of these drugs (ceftazidime, cephotaxime, cephoperazon, ampicillin and piperacillin) are capable of inhibiting the neutrophil cytolytic activity by inactivating the hypochlorous acid (HOCl) generated extracellularly by the myeloperoxidase pathway and crucial to the target cell lysis. Penicillin G had no effect on neutrophil-mediated cytolysis. Thus, these data demonstrate that ceftazidime, cephotaxime, cephoperazon, ampicillin and piperacillin lower the neutrophil-mediated target cell damage by a HOCl-scavenging mechanism, suggesting a possible cytoprotective role for these drugs during infections.

Micro-method for the determination of piperacillin in plasma by high-performance liquid chromatography

A simple and sensitive high-performance liquid chromatographic method for the determination of piperacillin in plasma is described. A C8 reversed-phase column was used with a mobile phase consisting of methanol-water-triethylamine (550:450:4, v/v/v) adjusted to pH = 3 with orthophosphoric acid and UV detection at 270 nm. Cephalothin was used as internal standard. The method involves a plasma protein precipitation with acetonitrile followed by extraction of endogenous compound with chloroform and injection of the upper aqueous phase into the chromatograph. Within-day and between-day assays give relative standard deviations less than or equal to 5.7%. The detection limit is 0.2 microgram ml-1. Stability studies show that piperacillin degradation starts at -4 degrees C. Therefore, samples have to be processed promptly and stored at -20 degrees C. The method described is convenient for clinical monitoring and for pharmacokinetic studies.

Synthesis and antimicrobial activities of some new tetrahydro-2H-1,3,5-thiadiazine-2-thione derivatives of ampicillin

Compounds having alpha-[dihydro-5-substituted 6-thioxo-2H- 1,3,5-thiadiazine-3(4H)-yl]benzylpenicillin structure were synthesized by the reaction of ampicillin trihydrate, formaldehyde and dithiocarbamic acid salts. The structures were evident from chemical and spectral analysis. The antimicrobial activities of the compounds were investigated against some gram-positive (Staphylococcus aureus and Streptococcus faecalis) and gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria and some yeast-like fungi (Candida albicans, C. parapsilosis, C. stellatoidea and C. pseudotropicalis) and molds such as Trichophyton rubrum, T. mentagrophytes, Microsporum canis, M. gypseum, Penicillium and Aspergillus by the tube dilution method. In addition to MIC (minimal inhibitory concentration), MBC (minimal bactericidal concentration) and MFC (minimal fungicidal concentration) values were determined using ampicillin trihydrate as standard. The compounds synthesized were usually found as effective as ampicillin trihydrate against S. aureus and S. faecalis and less effective than ampicillin trihydrate against E. coli. Both the compounds synthesized and ampicillin trihydrate are ineffective in the concentrations studied against P. aeruginosa. Compound 10 and 11 are more effective against all the yeast-like fungi than the other compounds and ampicillin trihydrate.

A pharmacodynamic model for the activity of antibiotics against microorganisms under nonsaturable conditions

An exact mathematical solution was derived to a pharmacodynamic model which illustrates bacterial survival in the presence of antibiotics. In this report the survival of Pseudomonas aeruginosa in the medium of an initial concentration of 0.64 mM (320 mg/L) of piperacillin [(2S,5R,6R)-6-[(R)-2-(4-ethyl-2,3-dioxo-1- piperazinecarboxyamido)-2-phenylacetamido]-3,3-dimethyl-7- oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate] was well described by the derived model for up to 24 h. The bacterial killing by the antibiotic and apparent natural growth rate constants were 2955.3 h-1 X mol-1 and 0.5698 h-1, respectively. The functional equation was also fit to the data of ampicillin against Escherichia coli under simulated in vivo conditions. The optimal multiple dosing time and the minimum critical concentration to achieve antimicrobial action can be readily calculated from the developed model. Computer simulations were made to examine the effect on microbial survival of such factors as initial antibiotic concentration (Co), elimination half-life (t1/2), kill rate constant (K) of the antibiotic, and apparent growth rate constant (Kapp) of the test organism.