Safety and efficacy of imipenem/cilastatin in treatment of complicated urinary tract infections

Phenotypic detection of Extended Spectrum β-Lactamases (ESBL) among gram negative uropathogens reveals highly susceptibility to imipenem

Objective:

We aimed to determine antibiotic susceptibility patterns of ESBL- and non-ESBL bacteria isolated from pregnant women with UTI in antenatal wards in Khartoum State, Sudan.

Methods:

This cross-sectional study was conducted during April-July 2016 at different hospitals in Khartoum State. Mid-stream urine samples were obtained from 150 hospitalized pregnant women and cultured on CLED (Cystine Lactose Electrolyte Deficient) agar. Microorganisms were identified using standard microbiological procedures. Isolated Gram-negative bacteria were tested for antibiotic susceptibility and ESBL screening using modified Kirby- Bauer method and Double Disc Synergy Test (DDST) respectively.

Results:

Urine culture revealed positive results in 33/150 (22%) and the most prevalent isolates were Gram negative bacteria (18/33, 54.5%). Among gram-negative bacteria, isolates of E. coli were the most prevalent accounting 66.6% (12/18) followed by K. pneumoniae (4/18, 22.2%) and K. oxytoca (2/18, 11.1%). ESBL was detected in 8/18 (44.4%) of the Gram-negative isolates. Of note, imipenem was the most susceptible antibiotic for ESBL-producer and non-ESBL producer Gram negative isolates, accounting 100% susceptibility for both bacterial groups. Overall susceptibility rates were also high for ciprofloxacin (13/18, 72.2%). In other hand, co-trimoxazole and amoxicillin showed high resistance pattern for ESBL-producer and non-ESBL producer isolates; 27.8%, 44.4% and 38.9%, 38.9% susceptibility rates of co-trimoxazole and amoxicillin for ESBL-producer and non-ESBL producer isolates, respectively.

Conclusions:

Imipenem remains the most powerful option for ESBL- and non-ESBL bacteria causing UTIs in pregnant women. However, due to tremendous increase of antibiotic-resistant, antibiotic-susceptibility testing is recommended as a routine investigation for admitted pregnant women.

Pharmacokinetics, Safety, and Tolerability of Single and Multiple Doses of Relebactam, a β-Lactamase Inhibitor, in Combination with Imipenem and Cilastatin in Healthy Participants

Relebactam is a novel class A and C β-lactamase inhibitor that is being developed in combination with imipenem-cilastatin for the treatment of serious infections with Gram-negative bacteria. Here we report on two phase 1 randomized, double-blind, placebo-controlled pharmacokinetics, safety, and tolerability studies of relebactam administered with or without imipenem-cilastatin to healthy participants: (i) a single-dose (25 to 1,150 mg) and multiple-dose (50 to 625 mg every 6 h [q6h] for 7 to 14 days) escalation study with men and (ii) a single-dose (125 mg) study with women and elderly individuals.

Relebactam is a novel class A and C β-lactamase inhibitor that is being developed in combination with imipenem-cilastatin for the treatment of serious infections with Gram-negative bacteria. Here we report on two phase 1 randomized, double-blind, placebo-controlled pharmacokinetics, safety, and tolerability studies of relebactam administered with or without imipenem-cilastatin to healthy participants: (i) a single-dose (25 to 1,150 mg) and multiple-dose (50 to 625 mg every 6 h [q6h] for 7 to 14 days) escalation study with men and (ii) a single-dose (125 mg) study with women and elderly individuals. Following single- or multiple-dose intravenous administration over 30 min, plasma relebactam concentrations declined biexponentially, with a terminal half-life (t_1/2) ranging from 1.35 to 1.85 h independently of the dose. Exposures increased in a dose-proportional manner across the dose range. No clinically significant differences in pharmacokinetics between men and women, or between adult and elderly participants, were observed. Urine pharmacokinetics demonstrated that urinary excretion is the major route of relebactam elimination. No drug-drug interaction between relebactam and imipenem-cilastatin was observed, and the observed t_1/2 values for relebactam, imipenem, and cilastatin were comparable, thus supporting coadministration. Relebactam administered alone or in combination with imipenem-cilastatin was well tolerated across the dose ranges studied. No serious adverse events or deaths were reported. The pharmacokinetic profile and favorable safety results supported q6h dosing of relebactam with imipenem-cilastatin in clinical treatment trials.

Imipenem/Cilastatin: The First Carbapenem Antibiotic

Imipenem/cilastatin is the first of a new class of β-lactam antibiotics called carbapenems. The antibacterial spectrum of imipenem exceeds any antibiotic investigated to date and includes gram-positive, gram-negative, and anaerobic organisms. Only methicillin-resistant organisms, Strep. faecium, Pseudomonas cepacia, and Pseudomonas maltophilia have been shown to be resistant. Imipenem is administered in a 1:1 ratio with cilastatin, which inhibits a renal enzyme (dehydropeptidase) and improves urinary recovery of imipenem. The elimination half-life of both compounds is 1.0 hours and recommended doses are 0.25–0.5 g iv q6h. Adverse events are similar in nature and incidence to β-lactam antibiotics, with phlebitis/thrombophlebitis, diarrhea, nausea, skin rash, and elevations of hepatic enzymes most common.

Clinical studies in phase II and III trials have shown imipenem/cilastatin to be effective in soft tissue infections, endocarditis, obstetrics and gynecology, complicated urinary tract infections, mixed anaerobic-aerobic infections, osteomyelitis, bacteremias, and pneumonias. Several comparative clinical trials have shown imipenem/cilastatin to be equal in efficacy to combination therapy. Imipenem/cilastatin may prove to be an alternative to combination antibiotic therapy because of its extremely broad spectrum of activity.

Statins decrease mortality in Lebanese patients with sepsis: A multicenter study

BACKGROUND

Sepsis is a significant public health concern. The clinical response to statins is variable among sepsis patients.

OBJECTIVE

The aim of the study was to determinate the effect of statin-treatment on mortality in Lebanese patients with sepsis.

METHODS

A retrospective multicenter study on Lebanese patients with sepsis between January 2008 and March 2012 was conducted. Patients with a primary diagnosis of sepsis admitted to the intensive care unit of two tertiary care hospitals in Beirut were included. Patients who continued to receive statin therapy for dyslipidemia during the hospital course were included in the statin treatment group. The control group consisted of patients not taking statin. Demographic characteristics, clinical signs, standard laboratory test and treatment received were compared between these two groups using univariate analysis. Logistic regression and survival analysis were performed by SPSS.

RESULTS

THREE HUNDRED FIFTY ONE LEBANESE PATIENTS WERE INCLUDED (AGE: 71.33 SD=14.97 years; Male: 56%). Among them, 30% took a statin at the doses recommended for dyslipidemia. The comparison of the two groups showed that in the statin treatment group: The mean serum level of C-reactive protein at the time of sepsis was significantly decreased (P=0.050), the length-stay at ICU significantly increased (P=0.047) and mortality significantly reduced (P<0.001). Results were confirmed by logistic regression, particularly for mortality. In the Cox regression analysis, hypothermia and shock were significantly associated with high mortality while statin treatment decreased mortality (hazard ratio = 0.540; 95% CI: 0.302-0.964; P=0.037).

CONCLUSIONS

At usual doses for dyslipidemia, statin treatment decreased incidence of mortality related to sepsis and improved the survival in this Lebanese septic population. Large randomized controlled clinical trials must be realized to give conclusive results about the potential beneficial effect of statins in sepsis.

Carbapenems and monobactams: imipenem, meropenem, and aztreonam

Imipenem and meropenem, members of the carbapenem class of beta-lactam antibiotics, are among the most broadly active antibiotics available for systemic use in humans. They are active against streptococci, methicillin-sensitive staphylococci, Neisseria, Haemophilus, anaerobes, and the common aerobic gram-negative nosocomial pathogens including Pseudomonas. Resistance to imipenem and meropenem may emerge during treatment of P. aeruginosa infections, as has occurred with other beta-lactam agents; Stenotrophomonas maltophilia is typically resistant to both imipenem and meropenem. Like the penicillins, the carbapenems have inhibitory activity against enterococci. In general, the in vitro activity of imipenem against aerobic gram-positive cocci is somewhat greater than that of meropenem, whereas the in vitro activity of meropenem against aerobic gram-negative bacilli is somewhat greater than that of imipenem. Daily dosages may range from 0.5 to 1 g every 6 to 8 hours in patients with normal renal function; the daily dose of meropenem, however, can be safely increased to 6 g. Infusion-related nausea and vomiting, as well as seizures, which have been the main toxic effects of imipenem, occur no more frequently during treatment with meropenem than during treatment with other beta-lactam antibiotics. The carbapenems should be considered for treatment of mixed bacterial infections and aerobic gram-negative bacteria that are not susceptible to other beta-lactam agents. Indiscriminate use of these drugs will promote resistance to them. Aztreonam, the first marketed monobactam, has activity against most aerobic gram-negative bacilli including P. aeruginosa. The drug is not nephrotoxic, is weakly immunogenic, and has not been associated with disorders of coagulation. Aztreonam may be administered intramuscularly or intravenously; the primary route of elimination is urinary excretion. In patients with normal renal function, the recommended dosing interval is every 8 hours. Patients with renal impairment require dosage adjustment. Aztreonam is used primarily as an alternative to aminoglycosides and for the treatment of aerobic gram-negative infections. It is often used in combination therapy for mixed aerobic and anaerobic infections. Approved indications for its use include infections of the urinary tract or lower respiratory tract, intra-abdominal and gynecologic infections, septicemia, and cutaneous infections caused by susceptible organisms. Concurrent initial therapy with other antimicrobial agents is recommended before the causative organism has been determined in patients who are seriously ill or at risk for gram-positive or anaerobic infection.

Imipenem

Imipenem is the first of a new class of beta-lactam antibiotics, the carbapenems, to be released for clinical use. It has the broadest antibacterial activity of all antibiotics available for systemic use in humans. It is active against streptococci, methicillin-sensitive staphylococci, Neisseria, Haemophilus, anaerobes, and the common aerobic gram-negative nosocomial pathogens including Pseudomonas. Resistance to imipenem may emerge during treatment of P. aeruginosa infections, as has occurred with other beta-lactam agents; P. maltophilia and P. cepacia are typically resistant to it. Like the penicillins, imipenem has inhibitory activity against enterococci. Daily doses may range from 500 mg to 1 g, every 6 to 8 hours, in patients with normal renal function. The principal toxic effects have been nausea and vomiting, which occur during intravenous infusion, and seizures, which develop in 1 to 3% of treated patients and are likely to occur in the setting of renal insufficiency and underlying disease of the central nervous system. Imipenem should be considered for treatment of mixed bacterial infections and treatment of resistant aerobic gram-negative bacteria that are not susceptible to other beta-lactam agents. In addition to provoking unnecessary toxicity, indiscriminate use of this agent will promote dissemination of resistance against it.

Treatment of gram-negative infections in patients with renal impairment: new alternatives to aminoglycosides

Aminoglycosides have become an indispensable component in the armamentarium against serious gram-negative infections. In spite of the availability of effective guidelines for prevention, the frequency of toxic side effects associated with aminoglycoside therapy is an impetus for the substitution of safer and equally efficacious alternatives, particularly in the setting of renal impairment. Recently, three new classes of antibiotics with potent gram-negative activity have become available. These are the monobactams, the carbapenems, and the fluorinated 4-quinolones. The antimicrobial spectrum of aztreonam, a monobactam, closely resembles that of aminoglycosides. Imipenem, a carbapenem, is a broad spectrum antibiotic with activity against gram-negative aerobes as well as gram-positive aerobes and many anaerobes. Ciprofloxacin, an orally active quinolone, has gram-positive and gram-negative coverage against aerobes but not anaerobes. These agents offer an alternative therapeutic option to aminoglycosides and, in the setting of pre-existing renal impairment, are particularly attractive in view of their safety.

Nosocomial urinary tract infections

Hospital-acquired urinary tract infections, which account for approximately 40 percent of all nosocomial infections, often result in serious complications and ultimately lead to rising hospital costs. To combat the high incidence of nosocomial urinary tract infections, surveillance and control programs must be developed and carefully maintained by hospitals. When urinary tract infections cannot be prevented, empiric therapy with broad-spectrum antibiotics effective against beta-lactamase-producing bacteria should begin immediately.

Imipenem: a new carbapenem antibiotic

Imipenem is a new carbapenem antibiotic that has an extremely broad spectrum of antibacterial activity. It has been used to treat a variety of serious infections and an increasing volume of literature documents its value in infections due to multiresistant bacteria. This article reviews the antibacterial activity, pharmacology, and clinical uses of imipenem.

Review of imipenem

Imipenem, a new carbapenem beta-lactam broad-spectrum antibiotic, is highly active in vitro against most aerobic and anaerobic gram-positive and gram-negative bacteria isolated from infectious diseases of human beings. Except for enterococci and methicillin-resistant staphylococci most gram-positive cocci are inhibited by less than 2 micrograms/ml. Although the MIC-90 of methicillin-resistant staphylococci may be less than 4 micrograms/ml, these bacteria are usually resistant to imipenem by modified testing methods. The enterococcus, S. faecalis, has an MIC-90 of less than 8 micrograms/ml but bactericidal concentration may be much higher. Most Enterobacteriaceae are highly susceptible to imipenem with MIC-90 of 0.5 to 2.0 micrograms/ml. Proteus species are less susceptible with MICs of 4 to 8 micrograms/ml. Isolates of P. aeruginosa have variable susceptibility with MICs ranging from 0.25 to 16 micrograms/ml. Pseudomonas maltophilia and P. cepacia are usually resistant to imipenem. Except for Clostridium species, most strict anaerobes are susceptible to less than 1.0 micrograms/ml of imipenem. When combined with cilastatin (1:1 ratio), the renal elimination of the active form is increased. The serum halflife in normal renal function is about 1 hour and increases to 3.4 hours in anuria. Major adverse effects are similar to those of cephalosporins except for seizures in some patients. Colonization with fungi and drug-resistant bacteria occurs in about 5% of imipenem-treated patients. Clinical studies have demonstrated efficacy in 79% to 96% of patients treated.

[Imipenem/cilastatin: in vitro activity, concentrations in plasma and prostatic adenoma and therapeutic results in patients with complicated urinary tract infections]

Minimal inhibitory concentrations (MICs) of imipenem, ceftazidime, piperacillin, tobramycin, azthreonam and carumonam were assessed for 400 urinary isolates from hospitalized patients with complicated and/or nosocomial urinary tract infections yielding greater than or equal to 10(5) colony forming units (cfu). More than 90% of the gram-negative pathogens were sensitive to all the antibiotics tested. However, only imipenem and piperacillin exhibited MIC90 values in the therapeutic range for gram-positive pathogens (approximately half of which were staphylococci and enterococci). Perioperative prophylaxis with 0.5 g imipenem/cilastatin administered at different time intervals before the operation (up to six hours) was performed in patients undergoing resection (n = 31), respectively enucleation (n = 1) of a prostatic adenoma or lithotriptic treatment (n = 4). Imipenem yielded peak plasma concentrations of 12.2 to 134.8 mg/l (mean 49.4 mg/l). The estimated half life time in these patients was approximately three hours. Considerable intra as well as interindividual variations were found for imipenem concentrations in prostatic adenoma. However, they were sufficiently high to reach sensitive pathogens (MICs up to 1 mg/l) for up to two-and-a-half hours. Up to six hours after dosing the concentrations in prostatic secretions ranged between 1 and 2 mg/l. A total of 20 urological patients suffering from complicated urinary tract infections (15 men, five women) received a short-term i.v. infusion of 0.5 mg imipenem/cilastatin t.i.d. for seven to 16 days (median seven days). In all these patients urines were sterile during therapy as well as one to two days after therapy. Follow-up examinations performed seven to ten days after the end of treatment in 19 of these patients showed ten patients to be free of infection (55%); these patients were classified as success. Seven patients (37%) presented a relapse (same pathogen) and two patients (10%) a re-infection (different pathogen). Imipenem/cilastatin was well tolerated locally and systemically.