A novel 2-step process for the management of inpatient beta-lactam allergy labels

BACKGROUND

Inpatient beta-lactam allergy labels may increase the unnecessary use of aztreonam and non-beta-lactam antibiotics, which can then lead to more adverse events and increased health care costs, OBJECTIVE: To assess the impact of a novel 2-step process (medication history review followed by risk stratification) on rates of beta-lactam delabeling, aztreonam use, and desensitizations on pediatric, adult, and obstetrics inpatients at a tertiary academic center.

METHODS

We prospectively collected data on 700 patients who received inpatient consultation from the Beta-Lactam Allergy Evaluation Service between August 2021 and July 2022. Patients were delabeled either by medication review alone, drug challenge alone if with a low-risk history, or penicillin skin test followed by drug challenge if with a high-risk history. Generalized linear regression modeling was used to compare aztreonam days of therapy in the intervention year with the 2 prior years. Drug desensitizations were assessed by electronic chart review.

RESULTS

Most of the patients (n = 656 of 700, 94%) had more than or equal to 1 beta-lactam allergy label removed, clarified, or both; 77.9% of these patients (n = 511 of 656) had 587 beta-lactam allergy labels removed. Nearly one-third (n = 149, 27.6%) had 162 allergy labels removed solely by medication history review. All 114 penicillin skin tests performed had negative results, and 98% (8 of 381) of the patients who underwent any drug challenge passed. Only 5.7% of the delabeled patients were relabeled. There was a 27% reduction in aztreonam use (P = .007). Beta-lactam desensitizations were reduced by 80%.

CONCLUSION

A full-time inpatient beta-lactam allergy service using medication history review and risk stratification can safely and effectively remove inpatient beta-lactam allergy labels, reduce aztreonam use, and decrease beta-lactam desensitizations.

ALPINE2: Efficacy and safety of 14-day vs 28-day inhaled aztreonam for Pa eradication in children with cystic fibrosis

BACKGROUND

Antibiotic eradication therapies recommended for newly isolated Pseudomonas aeruginosa (Pa) in people with cystic fibrosis (pwCF) can be burdensome. ALPINE2 compared the efficacy and safety of a shortened 14-day course of aztreonam for inhalation solution (AZLI) with 28-day AZLI in paediatric pwCF.

METHODS

ALPINE2 (a double-blind, phase 3b study) included children aged 3 months to <18 years with CF and new-onset Pa infection. Participants were randomized to receive 75 mg AZLI three times daily for either 28 or 14 days followed by 14 days' matched placebo. The primary endpoint was rate of primary Pa eradication (no Pa detected during the 4 weeks post AZLI treatment). Non-inferiority was achieved if the lower 95% CI bound of the treatment difference between the two arms was above -20%. Secondary endpoints included assessments of Pa recurrence during 108 weeks of follow-up after primary eradication. Safety endpoints included treatment-emergent adverse events (TEAEs).

RESULTS

In total, 149 participants were randomized (14-day AZLI, n = 74; 28-day AZLI, n = 75) and 142 (95.3%) completed treatment. Median age: 6.0 years (range: 0.3-17.0). Baseline characteristics were similar between treatment arms. Primary Pa eradication rates: 14-day AZLI, 55.9%; 28-day AZLI, 63.4%; treatment difference (CI), -8.0% (-24.6, 8.6%). Pa recurrence rates at follow-up end: 14-day AZLI, 54.1% (n = 20/37); 28-day AZLI, 41.9% (n = 18/43). TEAEs were similar between treatment arms. No new safety signals were observed.

CONCLUSIONS

Non-inferiority of 14-day AZLI versus 28-day AZLI was not demonstrated. Both courses were well tolerated, further supporting AZLI short-term safety in paediatric and adolescent pwCF.

CLINICALTRIALS

GOV: NCT03219164.

Ceftobiprole for Treatment of Complicated Staphylococcus aureus Bacteremia

BACKGROUND

Ceftobiprole is a cephalosporin that may be effective for treating complicated Staphylococcus aureus bacteremia, including methicillin-resistant S. aureus.

METHODS

In this phase 3, double-blind, double-dummy, noninferiority trial, adults with complicated S. aureus bacteremia were randomly assigned in a 1:1 ratio to receive ceftobiprole at a dose of 500 mg intravenously every 6 hours for 8 days and every 8 hours thereafter, or daptomycin at a dose of 6 to 10 mg per kilogram of body weight intravenously every 24 hours plus optional aztreonam (at the discretion of the trial-site investigators). The primary outcome, overall treatment success 70 days after randomization (defined as survival, bacteremia clearance, symptom improvement, no new S. aureus bacteremia-related complications, and no receipt of other potentially effective antibiotics), with a noninferiority margin of 15%, was adjudicated by a data review committee whose members were unaware of the trial-group assignments. Safety was also assessed.

RESULTS

Of 390 patients who underwent randomization, 387 (189 in the ceftobiprole group and 198 in the daptomycin group) had confirmed S. aureus bacteremia and received ceftobiprole or daptomycin (modified intention-to-treat population). A total of 132 of 189 patients (69.8%) in the ceftobiprole group and 136 of 198 patients (68.7%) in the daptomycin group had overall treatment success (adjusted difference, 2.0 percentage points; 95% confidence interval [CI], -7.1 to 11.1). Findings appeared to be consistent between the ceftobiprole and daptomycin groups in key subgroups and with respect to secondary outcomes, including mortality (9.0% and 9.1%, respectively; 95% CI, -6.2 to 5.2) and the percentage of patients with microbiologic eradication (82.0% and 77.3%; 95% CI, -2.9 to 13.0). Adverse events were reported in 121 of 191 patients (63.4%) who received ceftobiprole and 117 of 198 patients (59.1%) who received daptomycin; serious adverse events were reported in 36 patients (18.8%) and 45 patients (22.7%), respectively. Gastrointestinal adverse events (primarily mild nausea) were more frequent with ceftobiprole.

CONCLUSIONS

Ceftobiprole was noninferior to daptomycin with respect to overall treatment success in patients with complicated S. aureus bacteremia. (Funded by Basilea Pharmaceutica International and the U.S. Department of Health and Human Services; ERADICATE ClinicalTrials.gov number, NCT03138733.).

Safety of Ceftazidime-Avibactam in Combination with Aztreonam (COMBINE) in a Phase I, Open-Label Study in Healthy Adult Volunteers

This phase I study evaluated the safety of the optimal ceftazidime-avibactam (CZA) with aztreonam (ATM) regimens identified in hollow fiber infection models of MBL-producing Enterobacterales. Eligible healthy subjects aged 18 to 45 years were assigned to one of six cohorts: 2.5 g CZA over 2 h every 8 h (approved dose), CZA continuous infusion (CI) (7.5 g daily), 2 g ATM over 2 h every 6 h, ATM CI (8 g daily), CZA (approved dose) with 1.5 g ATM over 2 h every 6 h, and CZA (approved dose) with 2 g ATM over 2 h every 6 h. Study drug(s) were administered for 7 days. The most frequently observed adverse events (AEs) were hepatic aminotransferase (ALT/AST) elevations (n = 19 subjects). Seventeen of the 19 subjects with ALT/AST elevations received ATM alone or CZA-ATM. The incidence of ALT/AST elevations was comparable between the ATM-alone and CZA-ATM cohorts. Two subjects in the ATM CI cohort experienced severe ALT/AST elevation AEs. All subjects with ALT/AST elevations were asymptomatic with no other findings suggestive of liver injury. Most other AEs were of mild to moderate severity and were similar across cohorts, except for prolonged prothrombin time (more frequent in CZA-ATM cohorts). These results suggest that CZA-ATM administered as 2-h intermittent infusions is safe and that some caution should be exercised with the use of ATM CI at an ATM dose of 8 g daily. If CZA-ATM is prescribed, clinicians are advised to monitor liver function, hematologic, and coagulation parameters. Future controlled studies are required to better define the safety and efficacy of the CZA-ATM regimens evaluated in this phase I study.

Antibiotic regimens for late-onset neonatal sepsis

BACKGROUND

Neonatal sepsis is a major cause of morbidity and mortality. It is the third leading cause of neonatal mortality globally constituting 13% of overall neonatal mortality. Despite the high burden of neonatal sepsis, high-quality evidence in diagnosis and treatment is scarce. Due to the diagnostic challenges of sepsis and the relative immunosuppression of the newborn, many neonates receive antibiotics for suspected sepsis. Antibiotics have become the most used therapeutics in neonatal intensive care units, and observational studies in high-income countries suggest that 83% to 94% of newborns treated with antibiotics for suspected sepsis have negative blood cultures. The last Cochrane Review was updated in 2005. There is a need for an updated systematic review assessing the effects of different antibiotic regimens for late-onset neonatal sepsis.

OBJECTIVES

To assess the beneficial and harmful effects of different antibiotic regimens for late-onset neonatal sepsis.

SEARCH METHODS

We searched the following electronic databases: CENTRAL (2021, Issue 3); Ovid MEDLINE; Embase Ovid; CINAHL; LILACS; Science Citation Index EXPANDED and Conference Proceedings Citation Index - Science on 12 March 2021. We also searched clinical trials databases and the reference lists of retrieved articles for randomised controlled trials (RCTs) and quasi-RCTs.

SELECTION CRITERIA

We included RCTs comparing different antibiotic regimens for late-onset neonatal sepsis. We included participants older than 72 hours of life at randomisation, suspected or diagnosed with neonatal sepsis, meningitis, osteomyelitis, endocarditis, or necrotising enterocolitis. We excluded trials that assessed treatment of fungal infections.

DATA COLLECTION AND ANALYSIS

Three review authors independently assessed studies for inclusion, extracted data, and assessed risk of bias. We used the GRADE approach to assess the certainty of evidence. Our primary outcome was all-cause mortality, and our secondary outcomes were: serious adverse events, respiratory support, circulatory support, nephrotoxicity, neurological developmental impairment, necrotising enterocolitis, and ototoxicity. Our primary time point of interest was at maximum follow-up.

MAIN RESULTS

We included five RCTs (580 participants). All trials were at high risk of bias, and had very low-certainty evidence. The five included trials assessed five different comparisons of antibiotics. We did not conduct a meta-analysis due to lack of relevant data. Of the five included trials one trial compared cefazolin plus amikacin with vancomycin plus amikacin; one trial compared ticarcillin plus clavulanic acid with flucloxacillin plus gentamicin; one trial compared cloxacillin plus amikacin with cefotaxime plus gentamicin; one trial compared meropenem with standard care (ampicillin plus gentamicin or cefotaxime plus gentamicin); and one trial compared vancomycin plus gentamicin with vancomycin plus aztreonam. None of the five comparisons found any evidence of a difference when assessing all-cause mortality, serious adverse events, circulatory support, nephrotoxicity, neurological developmental impairment, or necrotising enterocolitis; however, none of the trials were near an information size that could contribute significantly to the evidence of the comparative benefits and risks of any particular antibiotic regimen. None of the trials assessed respiratory support or ototoxicity. The benefits and harms of different antibiotic regimens remain unclear due to the lack of well-powered trials and the high risk of systematic errors.

AUTHORS' CONCLUSIONS

Current evidence is insufficient to support any antibiotic regimen being superior to another. RCTs assessing different antibiotic regimens in late-onset neonatal sepsis with low risks of bias are warranted.

A Phase III, randomized, controlled, non-inferiority trial of ceftaroline fosamil 600 mg every 8 h versus vancomycin plus aztreonam in patients with complicated skin and soft tissue infection with systemic inflammatory response or underlying comorbidities

OBJECTIVES

Increasing the ceftaroline fosamil dose beyond 600 mg every 12 h may provide additional benefit for patients with complicated skin and soft tissue infections (cSSTIs) with severe inflammation and/or reduced pathogen susceptibility. A Phase III multicentre, randomized trial evaluated the safety and efficacy of ceftaroline fosamil 600 mg every 8 h in this setting.

METHODS

Adult patients with cSSTI and systemic inflammation or comorbidities were randomized 2:1 to intravenous ceftaroline fosamil (600 mg every 8 h) or vancomycin (15 mg/kg every 12 h) plus aztreonam (1 g every 8 h) for 5-14 days. Clinical cure was assessed at the test of cure (TOC) visit (8-15 days after the final dose) in the modified ITT (MITT) and clinically evaluable (CE) populations. Non-inferiority was defined as a lower limit of the 95% CI around the treatment difference greater than -10%. An MRSA-focused expansion period was initiated after completion of the main study. Clinicaltrials.gov registration numbers NCT01499277 and NCT02202135.

RESULTS

Clinical cure rates at TOC demonstrated non-inferiority of ceftaroline fosamil 600 mg every 8 h versus vancomycin plus aztreonam in the MITT and CE populations: 396/506 (78.3%) versus 202/255 (79.2%) patients (difference -1.0%, 95% CI -6.9, 5.4) and 342/395 (86.6%) versus 180/211 (85.3%) patients (difference 1.3%, 95% CI -4.3, 7.5), respectively. In the expansion period, 3/4 (75%) patients treated with ceftaroline fosamil were cured at TOC. The frequency of adverse events was similar between groups.

CONCLUSIONS

Ceftaroline fosamil 600 mg every 8 h was effective for cSSTI patients with evidence of systemic inflammation and/or comorbidities. No new safety signals were identified.

Tolerability of aztreonam and carbapenems in patients with IgE-mediated hypersensitivity to penicillins

BACKGROUND

Studies performed on samples larger than 100 subjects with a documented IgE-mediated hypersensitivity to penicillins have demonstrated a cross-reactivity rate of approximately 1% between penicillins and both imipenem and meropenem, whereas a single study found a cross-reactivity rate of 6.2% with aztreonam in 16 such subjects.

OBJECTIVE

To assess the cross-reactivity and tolerability of aztreonam and 3 carbapenems (imipenem-cilastatin, meropenem, and ertapenem) in patients with documented IgE-mediated hypersensitivity to penicillins.

METHODS

A total of 212 consecutive subjects with immediate reactions to penicillins and positive results on skin tests to at least 1 penicillin reagent underwent skin tests with aztreonam and carbapenems; subjects with negative results were challenged with escalating doses of aztreonam and carbapenems.

RESULTS

All subjects displayed negative skin test results to both aztreonam and carbapenems; 211 accepted challenges and tolerated them. Challenges were not followed by full therapeutic courses.

CONCLUSIONS

These data indicate the tolerability of both aztreonam and carbapenems in penicillin-allergic subjects. In those who especially require these alternative β-lactams, however, we recommend pretreatment skin tests, both because rare cases of cross-reactivity have been reported and because negative results indicate tolerability.

[Revival of selected well-tried antibiotics. Special features of the antiinfective agents penicillin G, fosfomycin, aztreonam and colistin]

Although a worldwide increasing incidence of bacterial infections with panresistant pathogens may need innovative antiinfective agents, no breakthrough developments can be expected in the near future. As a consequence, well-tried antibiotics like aztreonam, fosfomycin and colistin, are experiencing a clinical revival, particularly if they are used in an improved manner. Even penicillin G with its narrow spectrum of antimicrobial activity remains an important considerable agent of first choice in special indications compared to broad spectrum antiinfectives.

An 18-month study of the safety and efficacy of repeated courses of inhaled aztreonam lysine in cystic fibrosis

Chronic airway infection with Pseudomonas aeruginosa (PA) causes morbidity and mortality in patients with cystic fibrosis (CF). Additional anti-PA therapies are needed to improve health status and health-related quality of life. AIR-CF3 was an international 18-month, open-label study to evaluate the safety and efficacy of repeated courses of aztreonam for inhalation solution (AZLI, now marketed as Cayston®) in patients aged ≥ 6 years with CF and PA infection who previously participated in one of two Phase 3 studies: AIR-CF1 or AIR-CF2. Patients received up to nine courses (28 days on/28 days off) of 75 mg AZLI two (BID) or three times daily (TID) based on randomization in the previous trials. 274 patients, mean age 28.5 years (range: 8-74 years), participated. Mean treatment adherence was high (92.0% BID group, 88.0% TID group). Hospitalization rates were low and adverse events were consistent with CF. With each course of AZLI, FEV(1) and scores on the Cystic Fibrosis Questionnaire-Revised Respiratory Symptom scale improved and bacterial density in sputum was reduced. Benefits waned in the 28 days off therapy, but weight gain was sustained over the 18 months. There were no sustained decreases in PA susceptibility. A dose response was observed; AZLI TID-treated patients demonstrated greater improvements in lung function and respiratory symptoms over 18 months. Repeated intermittent 28-day courses of AZLI treatment were well tolerated. Clinical benefits in pulmonary function, health-related quality of life, and weight were observed with each course of therapy. AZLI is a safe and effective new therapy in patients with CF and PA airway infection.

Integrated safety summary of CANVAS 1 and 2 trials: Phase III, randomized, double-blind studies evaluating ceftaroline fosamil for the treatment of patients with complicated skin and skin structure infections

OBJECTIVES

Treatment of complicated skin and skin structure infections (cSSSIs) requires therapy that is effective against a range of Gram-positive and Gram-negative bacteria, including resistant pathogens such as methicillin-resistant Staphylococcus aureus. Equally important is the need to provide therapy that is safe and well tolerated. Ceftaroline fosamil is a new-generation, parenteral cephalosporin that was developed for the treatment of moderate to severe bacterial infections, including cSSSIs. This report provides an integrated safety summary of the CeftAroliNe Versus VAncomycin in Skin and Skin Structure Infections (CANVAS) 1 and 2 studies (registration numbers NCT00424190 and NCT00423657).

METHODS

Adult patients with cSSSIs requiring intravenous therapy received 600 mg of ceftaroline fosamil every 12 h or 1 g of vancomycin plus 1 g of aztreonam every 12 h for 5-14 days (randomized 1 : 1). All patients were followed for treatment-emergent adverse events (TEAEs) occurring from the start of the initial study drug infusion up to the test-of-cure visit, ∼1 week following the last dose of study medication; serious adverse events (SAEs) that occurred within 30 days after the last dose were recorded.

RESULTS

A total of 1378 patients received any amount of study drug and were included in the safety analysis. The percentage of patients with an SAE was similar between the ceftaroline fosamil and the vancomycin plus aztreonam groups (4.3% versus 4.1%). The majority of patients (>75%) had either no or mild TEAEs and the distribution of TEAEs based on severity was comparable between the groups. The most commonly reported TEAEs in patients treated with ceftaroline fosamil included nausea (5.9%), headache (5.2%), diarrhoea (4.9%) and pruritus (3.5%).

CONCLUSIONS

Ceftaroline fosamil was well tolerated and did not result in any unexpected safety concerns. The data from the CANVAS trials suggest that ceftaroline fosamil has the expected safety and tolerability profile common to the cephalosporin class.

CANVAS 1: the first Phase III, randomized, double-blind study evaluating ceftaroline fosamil for the treatment of patients with complicated skin and skin structure infections

OBJECTIVES

Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a common cause of complicated skin and skin structure infections (cSSSIs). Increasing antibiotic resistance and significant morbidity in cSSSIs have led to a need for new effective and safe therapies. Ceftaroline fosamil, a novel parenteral cephalosporin with excellent in vitro activity against Gram-positive pathogens, including MRSA, and many Gram-negative pathogens, was evaluated as therapy for cSSSIs in a large multicentre study. The primary study objective was to determine non-inferiority [lower limit of 95% confidence interval (CI), -10%] in the clinical cure rate achieved with ceftaroline fosamil monotherapy compared with that achieved with vancomycin plus aztreonam in the clinically evaluable (CE) and modified intent-to-treat (MITT) patient populations.

METHODS

Adult patients with cSSSIs requiring intravenous therapy received 600 mg of ceftaroline fosamil every 12 h or 1 g of vancomycin plus 1 g of aztreonam every 12 h for 5-14 days (randomized 1 : 1). Clinical and microbiological response, adverse events (AEs) and laboratory tests were assessed. Registration number NCT00424190 (http://clinicaltrials.gov/ct2/show/NCT00424190).

RESULTS

Of 702 enrolled patients, 353 received ceftaroline fosamil and 349 received vancomycin plus aztreonam. Baseline characteristics of treatment groups were comparable. Clinical cure rates were similar for ceftaroline fosamil and vancomycin plus aztreonam in the CE (91.1%, 288/316 versus 93.3%, 280/300; 95% CI, -6.6, 2.1) and MITT (86.6%, 304/351 versus 85.6%, 297/347; 95% CI, -4.2, 6.2) populations, respectively. The clinical cure rate for MRSA cSSSIs was 95.1% (78/82) for ceftaroline fosamil and 95.2% (59/62) for vancomycin plus aztreonam. The microbiological success rate was also similar for ceftaroline fosamil and vancomycin overall, and for MRSA. The rates of AEs, serious AEs, deaths and discontinuations because of an AE were similar for ceftaroline fosamil and vancomycin plus aztreonam. The most common AEs for ceftaroline fosamil and vancomycin plus aztreonam were diarrhoea (3.4% versus 3.2%), nausea (5.7% versus 4.6%), headache (5.1% versus 3.7%) and pruritus (3.1% versus 8.4%), respectively.

CONCLUSIONS

Ceftaroline fosamil achieved high clinical cure and microbiological success rates, was efficacious for cSSSIs caused by MRSA and other common cSSSI pathogens and was generally well tolerated. Ceftaroline fosamil has the potential to provide a monotherapy alternative for treatment of cSSSIs.

CANVAS 2: the second Phase III, randomized, double-blind study evaluating ceftaroline fosamil for the treatment of patients with complicated skin and skin structure infections

OBJECTIVES

New therapies for complicated skin and skin structure infections (cSSSIs) are needed because of significant morbidity and increasing antimicrobial resistance. Methicillin-resistant Staphylococcus aureus (MRSA) is a common cause of cSSSIs. Ceftaroline fosamil, a novel parenteral cephalosporin with excellent in vitro activity against Gram-positive pathogens, including MRSA, and many Gram-negative pathogens, was evaluated as therapy for cSSSIs in a multinational Phase III study. The primary study objective was to determine non-inferiority [lower limit of 95% confidence interval (CI), -10%] in the clinical cure rate of ceftaroline fosamil monotherapy to that achieved with vancomycin plus aztreonam combination therapy in the clinically evaluable (CE) and modified intent-to-treat (MITT) analysis populations.

METHODS

Adult patients with cSSSIs requiring intravenous therapy received 600 mg of ceftaroline fosamil every 12 h or 1 g of vancomycin plus 1 g of aztreonam every 12 h for 5-14 days (randomized 1 : 1). Clinical and microbiological response, adverse events (AEs) and laboratory tests were assessed. Registration number NCT00423657 (http://clinicaltrials.gov/ct2/show/NCT00423657).

RESULTS

The study enrolled 694 patients, 348 of whom received ceftaroline fosamil and 346 of whom received vancomycin plus aztreonam. The treatment groups had comparable baseline characteristics. Clinical cure rates for the ceftaroline fosamil and vancomycin plus aztreonam groups were similar in the CE (92.2%, 271/294 versus 92.1%, 269/292; 95% CI, -4.4, 4.5) and MITT (85.1%, 291/342 versus 85.5%, 289/338; 95% CI, -5.8, 5.0) populations, respectively. MRSA cSSSIs were cured in 91.4% (64/70) of patients in the ceftaroline fosamil group and 93.3% (56/60) of patients in the vancomycin plus aztreonam group. The microbiological success rate in the microbiologically evaluable population was 92.9% and 95.0% for ceftaroline fosamil and vancomycin plus aztreonam, respectively. Ceftaroline fosamil and vancomycin plus aztreonam had similar rates of AEs, serious AEs and discontinuations because of an AE. The most common AEs for ceftaroline fosamil and vancomycin plus aztreonam included diarrhoea (6.5% versus 4.4%), nausea (6.2% versus 5.6%), headache (5.3% versus 5.3%) and pruritus (3.8% versus 8.3%), respectively.

CONCLUSIONS

Ceftaroline fosamil demonstrated high clinical cure and microbiological success rates, was efficacious against cSSSIs caused by MRSA and other common cSSSI pathogens and was generally well tolerated. Monotherapy with ceftaroline fosamil has the potential to provide an alternative treatment for cSSSIs.

Integrated analysis of CANVAS 1 and 2: phase 3, multicenter, randomized, double-blind studies to evaluate the safety and efficacy of ceftaroline versus vancomycin plus aztreonam in complicated skin and skin-structure infection

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) is a common cause of complicated skin and skin-structure infection (cSSSI). Increasing antimicrobial resistance in cSSSI has led to a need for new safe and effective therapies. Ceftaroline was evaluated as treatment for cSSSI in 2 identical phase 3 clinical trials, the pooled analysis of which is presented here. The primary objective of each trial was to determine the noninferiority of the clinical cure rate achieved with ceftaroline monotherapy, compared with that achieved with vancomycin plus aztreonam combination therapy, in the clinically evaluable (CE) and modified intent-to-treat (MITT) patient populations.

METHODS

Adult patients with cSSSI requiring intravenous therapy received ceftaroline (600 mg every 12 h) or vancomycin plus aztreonam (1 g each every 12 h) for 5-14 days.

RESULTS

Of 1378 patients enrolled in both trials, 693 received ceftaroline and 685 received vancomycin plus aztreonam. Baseline characteristics of the treatment groups were comparable. Clinical cure rates were similar for ceftaroline and vancomycin plus aztreonam in the CE (91.6% vs 92.7%) and MITT (85.9% vs 85.5%) populations, respectively, as well as in patients infected with MRSA (93.4% vs 94.3%). The rates of adverse events, discontinuations because of an adverse event, serious adverse events, and death also were similar between treatment groups.

CONCLUSIONS

Ceftaroline achieved high clinical cure rates, was efficacious against cSSSI caused by MRSA and other common cSSSI pathogens, and was well tolerated, with a safety profile consistent with the cephalosporin class. Ceftaroline has the potential to provide a monotherapy alternative for the treatment of cSSSI.

TRIAL REGISTRATION

ClinicalTrials.gov identifiers: NCT00424190 for CANVAS 1 and NCT00423657 for CANVAS 2.

[Tolerance and efficacy of ceftazidime in combination with aztreonam for exacerbations of cystic fibrosis]

BACKGROUND

Antibiotic therapy for acute pulmonary exacerbations in patients with cystic fibrosis is usually chosen based on the results of antimicrobial susceptibility. This can be difficult when bacteria are multiresistant. The objective of this retrospective study was to evaluate the tolerance and efficiency of ceftazidime and aztreonam combination (+/-tobramycin, +/-ciprofloxacin) in the treatment of acute exacerbations in cystic fibrosis patients who were chronically colonized with multiresistant P. aeruginosa.

PATIENTS

Seventeen severe patients, with FEV(1)=1070+/-66 mL and BMI=18+/-0.6 kg/m(2), who had chronic colonisation with P. aeruginosa with intermediate sensitivity or resistance to ceftazidime and aztreonam, were studied between June 2003 and March 2007. Oxygen saturation, dyspnoea, weight, FEV(1), FVC, and tolerance were evaluated before and after antibiotic courses.

RESULTS

Forty-two courses of treatment, administered between June 2003 and March 2007 were studied: Patients increased their FEV(1) and FVC (p=0.01). One antibiotic course was stopped after four days because of cutaneous side effects. The median delay until the next exacerbation was 101+/-10 days. These courses were compared with other combinations of antibiotics that the patients had received before. The combination of ceftazidime and aztreonam was more effective in patients receiving less than four courses per year for acute pulmonary exacerbation.

CONCLUSION

In chronically P. aeruginosa colonised cystic fibrosis patients, ceftazidime and aztreonam combination (+/-tobramycin, +/-ciprofloxacin) is well tolerated and efficient. This treatment suggests a clinical and functional benefit is possible, even in patients with severe disease.

The efficacy and safety of tigecycline in the treatment of skin and skin-structure infections: results of 2 double-blind phase 3 comparison studies with vancomycin-aztreonam

Two phase 3, double-blind studies in hospitalized adults with complicated skin and skin-structure infections (cSSSI) determined the safety and efficacy of tigecycline versus that of vancomycin-aztreonam. Patients received tigecycline (100 mg, followed by 50 mg intravenously twice daily) or vancomycin (1 g intravenously twice daily) plus aztreonam (2 g intravenously twice daily) for up to 14 days. Populations were as follows: 1116 patients (566 treated with tigecycline, and 550 treated with vancomycin-aztreonam) constituted the modified intent-to-treat (mITT) population, 1057 patients (538 treated with tigecycline, and 519 treated with vancomycin-aztreonam) constituted the clinical mITT (c-mITT) population, and 833 patients (422 treated with tigecycline, and 411 treated with vancomycin-aztreonam) constituted the clinically evaluable population. Clinical responses to tigecycline and vancomycin-aztreonam at test-of-cure were similar: c-mITT, 79.7% (95% confidence interval [CI], 76.1%-83.1%) versus 81.9% (95% CI, 78.3%-85.1%) (P = .4183); and clinically evaluable, 86.5% (95% CI, 82.9%-89.6%) versus 88.6% (95% CI, 85.1%-91.5%) (P = .4233). Adverse events were similar, with increased nausea and vomiting in the tigecycline group and increased rash and elevated hepatic aminotransferase levels in the vancomycin-aztreonam group. Tigecycline monotherapy is as safe and efficacious as the vancomycin-aztreonam combination in treating patients with cSSSI.

Safety and efficacy of tigecycline in treatment of skin and skin structure infections: results of a double-blind phase 3 comparison study with vancomycin-aztreonam

In a randomized, double-blind, controlled trial, 546 patients with complicated skin and skin structure infections received tigecycline 100 mg/day (a 100-mg initial dose and then 50 mg intravenously twice daily) or the combination of vancomycin 2 g/day (1 g intravenously twice daily) and aztreonam 4 g/day (2 g intravenously twice daily) for up to 14 days. The primary end point was the clinical response in the clinical modified intent-to-treat (c-mITT) and clinically evaluable (CE) populations at the test-of-cure visit 12 to 92 days after the last dose. The microbiologic response at the test-of-cure visit was also assessed. Safety was assessed by physical examination, laboratory results, and adverse event reporting. Five hundred twenty patients were included in the c-mITT population (tigecycline group, n = 261; combination group, n = 259), and 436 were clinically evaluable (tigecycline group, n = 223; combination group, n = 213). The clinical responses in the tigecycline and the combination vancomycin and aztreonam groups were similar in the c-mITT population (84.3% versus 86.9%; difference, -2.6% [95% confidence interval, -9.0, 3.8]; P = 0.4755) and the CE population (89.7% versus 94.4%; difference, -4.7% [95% confidence interval, -10.2, 0.8]; P = 0.1015). Microbiologic eradication (documented or presumed) occurred in 84.8% of the patients receiving tigecycline and 93.2% of the patients receiving vancomycin and aztreonam (difference, -8.5 [95% confidence interval, -16.0, -1.0]; P = 0.0243). The numbers of patients reporting adverse events were similar in the two groups, with increased nausea and vomiting rates in the tigecycline group and an increased incidence of rash and increases in alanine aminotransferase and aspartate aminotransferase levels in the combination vancomycin and aztreonam group. Tigecycline was shown to be safe and effective for the treatment of complicated skin and skin structure infections.

Erythroderma due to aztreonam and clindamycin

A 73-year-old woman developed erythroderma with intense pruritus, malaise, and chills 7 days after treatment with intravenous clindamycin. Two years later she experienced a similar reaction with more rapid onset (48 hours) after treatment with aztreonam. Resolution followed withdrawal of treatment in both instances, and intradermal tests proved positive at delayed reading for both drugs.

Efficacy and safety of tigecycline monotherapy compared with vancomycin plus aztreonam in patients with complicated skin and skin structure infections: Results from a phase 3, randomized, double-blind trial

OBJECTIVES

To compare the effect of tigecycline monotherapy, a first-in-class, expanded broad spectrum glycylcycline, with the combination of vancomycin and aztreonam (V + A) in the treatment of complicated skin and skin structure infections (cSSSI).

METHODS

A phase 3, double-blind study conducted in 8 countries enrolled adults with cSSSI who required intravenous (IV) antibiotic therapy for > or =5 days. Patients were randomly assigned (1:1) to receive either tigecycline or V + A for up to 14 days. Primary endpoint was the clinical cure rate at the test-of-cure visit. Secondary endpoints included microbiologic efficacy and in vitro susceptibility to tigecycline of bacteria that cause cSSSI. Safety was assessed by physical examination, laboratory analyses, and adverse event reporting.

RESULTS

A total of 596 patients were screened for enrollment, 573 were analyzed for safety, 537 were included in the clinical modified intent-to-treat (c-mITT) population, 397 were clinically evaluable (CE), and 228 were microbiologically evaluable (ME). At test-of-cure, cure rates were similar between tigecycline and V + A groups in the CE population (82.9% versus 82.3%, respectively) and in the c-mITT population (75.5% versus 76.9%, respectively). Microbiologic eradication rates (subject level) at test-of-cure in the ME population were also similar between tigecycline and V + A. Frequency of adverse events was similar between groups, although patients receiving tigecycline had higher incidence of nausea, vomiting, dyspepsia, and anorexia, while increased ALT/SGPT, pruritus, and rash occurred significantly more often in V + A-treated patients.

CONCLUSIONS

This study demonstrates that the efficacy of tigecycline monotherapy for the treatment of patients with cSSSI is statistically noninferior to the combination of V + A.

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

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

Randomized comparison of aztreonam and chloramphenicol in treatment of typhoid fever

Patients with clinical typhoid fever plus a blood, bone marrow, or bile positive for Salmonella typhi or Salmonella paratyphi were included in an open clinical trial to compare the efficacy of aztreonam (6 g/day [2 g intravenously every 8 h]) given for 10 days with that of chloramphenicol (50 mg/kg of body weight per day [intravenously or orally]) administered for 14 days. A total of 44 patients, 22 in each group, were included in the study, and both groups were comparable in terms of baseline parameters. All patients randomized to receive chloramphenicol completed the 14 days of treatment, while two patients randomized to receive aztreonam developed an intestinal hemorrhage, and a third patient elected to withdraw from the trial. Defervescence occurred more quickly in the subjects receiving chloramphenicol than in those receiving aztreonam (P < 0.05). All patients in the chloramphenicol group were clinically cured during therapy, while four patients (21%) in the group receiving aztreonam were declared clinical treatment failures. None of the 19 patients receiving aztreonam, compared with 7 of 22 (32%) patients receiving chloramphenicol, had a positive blood culture after 24 h of therapy (P < 0.05). Adverse experiences were unusual and mild. In the study, aztreonam was less effective than chloramphenicol with regard to clinical effectiveness and time of defervescence but was more effective in the elimination of the infecting Salmonella organisms from the bloodstream.

Urticaria caused by sensitization to aztreonam

A 72-year-old woman presented with generalized urticaria after receiving an injection of aztreonam. After successive in vitro and in vivo studies, allergy to aztreonam with a good tolerance of the other beta-lactams was diagnosed.

Comparison of imipenem/cilastatin with the combination of aztreonam and clindamycin in the treatment of intra-abdominal infections

The clinical safety and efficacy of imipenem/cilastatin in the treatment of intra-abdominal infections was compared with the combination of aztreonam and clindamycin in a randomized prospective trial. The severity of illness was determined by means of the Apache II score and a fixed outcome reporting scheme was used. One hundred and four patients were entered into the study, of whom 80 were evaluable. Forty-two patients were treated with imipenem/cilastatin (500 + 500 mg qds) and 38 with aztreonam (600 tds) and clindamycin (1000 mg tds). The study groups were comparable for age and sex. The imipenem/cilastatin group differed from the aztreonam and clindamycin group in having significantly more patients with the diagnosis of acute appendicitis (P < 0.01) and a significantly lower mean Apache score (P < 0.05). The predominate microorganisms isolated in both groups were Escherichia coli and Bacteroides fragilis. Treatment with imipenem/cilastatin proved successful in 71% and failed in 24%, and initial success only was seen in 5%. The numbers in the group treated with aztreonam and clindamycin were 64%, 29% and 7% respectively. Severity of illness, as measured by Apache II score, had no influence on the study outcome. Imipenem/cilastatin as well as the combination of aztreonam and clindamycin were effective in the treatment of abdominal infections and no major adverse reactions were seen.

[Aztreonam as monotherapy in urinary tract infections with a systemic repercussion in patients with a relative contraindication for the use of aminoglycosides]

A comparative study has been performed to evaluate the clinical efficacy and safety of aztreonam in the treatment of urinary tract infections with systemic affectation, in a group of patients who showed a relative contraindication to be treated with aminoglycosides. The group studied was formed by 30 patients (21 females and 9 males). Mean age of said group was 78 years and percentage of patients over 65 years was 93%. Moreover, 53.3% of patients showed nephropathy, 30% diabetes mellitus and 16.6% hearing disorders. Responsible germ of the infection was identified through blood and urine culture in 24 patients (80%) being the most frequent isolated E. Coli (60%). The cure rate was of 76.6% and improvement rate was 13.3%. Three deaths happened on the studied group (10%). In a patient superinfection due to Enterococcus was detected. There were no significative adverse effects (hypersensibility reactions, hematological disorders, nephrotoxicity or hepatotoxicity). Aztreonam could be an efficacious alternative in the treatment of urinary infection with systemic affectation, caused by gram-negative germs, showing low toxicity.

Aztreonam

Aztreonam is the first monobactam and is unique among beta-lactam antibiotics for its spectrum of activity that is exclusively active against gram-negative aerobic bacteria. Broad clinical experience with this agent supports its use in the treatment of adults with severe or complicated urologic infections. Aztreonam may be safely used in patients with penicillin allergy. With a spectrum of activity that is comparable to the aminoglycosides but without the potential for ototoxicity or nephrotoxicity, aztreonam represents a rational choice of therapy for treatment of systemic urinary tract infections due to susceptible organisms.

Aztreonam

Aztreonam is a synthetic monobactam antibiotic that has excellent activity against aerobic gram-negative bacilli. It can be used as a single agent for the treatment of upper urinary tract infections caused by organisms resistant to the cephalosporins and ampicillin. It also can be administered in combination with a drug such as clindamycin for treatment of pelvic inflammatory disease or postoperative pelvic infections.

An open, comparative trial of aztreonam with vancomycin and gentamicin with piperacillin in patients with fulminant hepatic failure

Fifty patients admitted with fulminant hepatic failure and clinically suspected infection were allocated to receive either aztreonam and vancomycin or piperacillin and gentamicin as first line treatment. Fourteen patients died within 48 h of admission and were excluded from the analysis. Of the remaining 36 patients, 16 received aztreonam/vancomycin and 20 piperacillin/gentamicin. There were 18 episodes of infection in the aztreonam/vancomycin group and 24 in the piperacillin/gentamicin group (P = not significant). The most frequent bacterial pathogen was Staphylococcus aureus. Fungal infection developed in 13 patients (nine in the aztreonam/vancomycin group and four in the piperacillin/gentamicin group; P = not significant). Death attributed to infection occurred in 4 (25%) of 16 patients receiving aztreonam/vancomycin and 4 (20%) of 20 receiving piperacillin/gentamicin (P = not significant). Thirteen patients (three in the aztreonam/vancomycin group and ten in the piperacillin/gentamicin group) had clinical and microbiological improvement without addition or substitution of other antibiotics. No side-effects attributed to the study drugs were recorded.

A comparative trial of aztreonam versus gentamicin in the treatment of urinary tract infections

A prospective, randomized trial was conducted to compare the efficacy of aztreonam, a monobactam antibiotic, and gentamicin in the treatment of serious urinary tract infections. Fifty-five patients with a suspected or confirmed infection were randomized, 28 received aztreonam and 27 received gentamicin. Both antibiotics had a high clinical response rate (aztreonam 92%, gentamicin 85%). However, the duration of treatment was significantly shorter (p = 0.037, Wilcoxon Rank Sum Test) when aztreonam was used. There were no cases of toxicity with either antibiotic but 5 patients who received gentamicin required dose alteration. Aztreonam is well tolerated and is no less effective than gentamicin in the treatment of urinary tract infections and has advantages in convenience of use and duration of treatment.

Nephrotoxicity and ototoxicity of aztreonam versus aminoglycoside therapy in seriously ill nonneutropenic patients

A randomized double-blind clinical trial was done of aztreonam versus aminoglycoside therapy for the empiric treatment of seriously ill nonneutropenic patients suspected of aerobic gram-negative bacterial infection. Each patient was treated for greater than or equal to 72 h with the study drug. Nephrotoxicity, defined by greater than or equal to 50% increase in baseline serum creatinine, occurred in 12 (15%) of 92 patients receiving aminoglycoside therapy and 1 (1%) of 92 patients receiving aztreonam (P less than .004). More severe nephrotoxicity, defined by greater than or equal to 100% increase in baseline serum creatinine, occurred in 6 (6.5%) of 92 patients receiving aminoglycoside therapy and in 1 of 92 receiving aztreonam (P less than .11). Patients with an elevated baseline total bilirubin level were most likely to develop nephrotoxicity. Auditory toxicity occurred in 2 (7%) of 28 evaluatable patients receiving aminoglycoside therapy and in 1 (3%) of 33 receiving aztreonam (P less than .58). One patient, who received aminoglycoside, developed vestibular toxicity. In nonneutropenic patients believed to be at increased risk for renal dysfunction, aztreonam is a less toxic alternative to aminoglycoside therapy for treatment of suspected aerobic gram-negative infection.

Allergy to amoxicillin in patients who tolerated benzylpenicillin, aztreonam, and ceftazidime

The usual battery of skin tests employed for determining penicillin allergy may fail to detect allergic reactions to side chain-specific beta-lactam agents. We report the cases of six patients who experienced anaphylactic reactions after treatment and challenge with amoxicillin but who tolerated parenteral challenges with benzylpenicillin, aztreonam, and ceftazidime. Results of skin tests for amoxicillin (10 mg/mL) were positive for four of the six patients.

Toxic epidermal necrolysis possibly linked to aztreonam in bone marrow transplant patients

OBJECTIVE AND SETTING

After instituting aztreonam as part of antibiotic prophylaxis in bone marrow transplant (BMT) patients at the Seattle Department of Veterans Affairs Medical Center, the first two cases of toxic epidermal necrolysis (TEN) occurred in more than 250 BMT patients at this center. We have examined the possible cause-and-effect relationship between aztreonam and TEN.

PATIENTS

The first patient was a 23-year-old man with acute lymphocytic leukemia receiving a BMT from a related mismatched donor. He experienced profound conjunctivitis and superficial bulla covering 60 percent of his body surface area (BSA). The second patient, a 32-year-old man with lymphoma, received a BMT from a matched unrelated donor. He exhibited lymphocytosis, acute conjunctivitis, and bullous lesions covering 60 percent of his BSA.

INTERVENTIONS

Aztreonam was discontinued in both patients. The first patient was treated with pigskin grafting and the second was treated with topical silver sulfadiazine.

RESULTS

Despite stabilization of symptoms, both patients eventually died of infectious complications.

CONCLUSIONS

Histological data in both patients were more consistent with TEN than graft-versus-host disease (GVHD) in that dermal infiltrates were sparse or absent. The onset of cutaneous symptoms was of more acute onset than acute GVHD, and ocular complaints are uncommon in acute GVHD. Furthermore, the onset of TEN bore a closer temporal relationship to aztreonam than to other drugs administered.

A comparative study on aztreonam, ceftazidime and amikacin in the treatment of complicated urinary tract infections

In a prospective, randomized trial, aztreonam (1 g intravenously or intramuscularly, twice daily) was compared with ceftazidime (1 g intravenously or intramuscularly, twice daily) and amikacin (500 mg intravenously or intramuscularly, twice daily) in 76 patients aged 24 to 84 years (mean, 59.7 years) with complicated urinary tract infections. Initial pathogens included Escherichia coli (47.5%), Pseudomonas aeruginosa (22.5%), Klebsiella spp. (9%), Proteus spp. (7.5%) and Enterobacter spp (6%). In four patients initial urine cultures yielded more than one organism. All pathogens were sensitive to the three study drugs. Including performance of 4- to 6-week follow-up cultures, eradication of the pathogens occurred in 72% of patients treated with aztreonam, in 74% of those treated with ceftazidime and in 71% treated with amikacin (p greater than 0.05). Clinical success was observed in 84% of patients treated with aztreonam, in 82% of those treated with ceftazidime and in 85% treated with amikacin (p greater than 0.05). All drugs were well tolerated. It is concluded that aztreonam, ceftazidime and amikacin are equally effective and safe for the treatment of complicated urinary tract infections due to susceptible organisms.

Aztreonam-induced myelosuppression during treatment of Pseudomonas aeruginosa pneumonia

Aztreonam is a synthetic, monobactam antibiotic structurally related to the beta-lactam class of drugs. It has inhibitory activity against many aerobic gram-negative bacteria, although it does not inhibit gram-positive or anaerobic bacteria. Administration of aztreonam occasionally is associated with minimal and transient adverse effects. This case report describes a patient we believe experienced bone marrow suppression approximately ten days after aztreonam was given for treatment of pneumonia caused by Pseudomonas aeruginosa. This untoward effect primarily was manifested as neutropenia, although normochromic, normocytic anemia and thrombocytopenia were noted as well. One week after aztreonam was discontinued, the patient's bone marrow suppression resolved spontaneously. Although the mechanism responsible for myelosuppression is unclear, aztreonam may be implicated as the offending agent based on the temporal relationship between the development of neutropenia and its administration, and the resolution of neutropenia upon its discontinuation.

Efficacy of aztreonam in the treatment of neonatal sepsis

In Greece the majority of infections that affect the neonatal population are caused by gram-negative bacteria rather than by group B streptococci as in the United States. The present study investigated the efficacy of aztreonam, a beta-lactam antibiotic that is effective against gram-negative organisms, in this population. Fifty-five neonates aged 2 hours to 36 days who had sepsis were enrolled in this open study. Laboratory tests were extensive, and follow-ups were detailed. Aztreonam (90-125 mg/[kg.d]) administered in two or three doses was given in combination with penicillin (100,000 U/[kg.d]) for 6-15 days. Fifty-two infants were cured, one improved, and two did not improve and received other, more effective regimens. Adverse effects were minimal, and tolerance of aztreonam was excellent.

Aztreonam plus clindamycin versus tobramycin plus clindamycin in the treatment of intraabdominal infections

In a multicenter, randomized clinical trial, aztreonam and tobramycin were compared for efficacy and safety in the treatment of intraabdominal infections. Patients were randomly assigned to one of the drug regimens, and all but two patients were treated concomitantly with clindamycin. Efficacy of treatment could not be evaluated for 107 of the 316 patients enrolled in the study. Among the 209 patients who could be evaluated (104 treated with aztreonam and 105 with tobramycin), microbiologic cure was achieved in 93% and 86%, respectively, and a favorable clinical response was noted in 85% of the patients in both groups. The frequency of adverse drug reactions in the two groups was similar. In this study, the efficacy and safety profiles of aztreonam plus clindamycin were comparable to those of tobramycin plus clindamycin.

Infections in patients in intensive care units: can the combination of a monobactam and a penicillin replace the classic combination of a beta-lactam agent and an aminoglycoside?

An open, comparative, randomized study was performed in two medical intensive care units to compare the efficacy of the combination of aztreonam and either cloxacillin or oxacillin [(cl)oxacillin] with that of the combination of tobramycin and a cephalosporin. Of the 92 patients who were included in the study, 76 were evaluable. All patients suffered from severe, mostly pulmonary, infections and received ventilatory support. The aztreonam combination yielded an 80% rate of clinical cure; mortality was 15%. Use of the aminoglycoside combination resulted in a 51% rate of clinical cure; mortality was 23%. The difference in cure rate between the two combinations was statistically significant. Adverse effects were negligible in patients who received the aztreonam combination, and superinfection was seen in only 2%. Of the patients who received the aminoglycoside combination, 20% developed a superinfection and 11% developed a new renal insufficiency. Therefore, the combination of aztreonam and (cl)oxacillin is a valuable alternative to the combination of an aminoglycoside and a cephalosporin.

Efficacy and safety of low-dose aztreonam in the treatment of moderate to severe infections due to gram-negative bacilli

One hundred fifty-three patients with moderate to severe infections due to gram-negative bacilli, including septicemia (60 cases), lower respiratory tract infection (32 cases), intraabdominal infection (40 cases), and urinary tract infection (21 cases), were treated with aztreonam (1 g every 12 h). This dosage is lower than usual. Criteria for inclusion in the study included documented infection due to gram-negative bacilli and a measurement of severity of disease of less than 12 (as defined by a Simplified Acute Physiology Score for the 115 cases of community-acquired infection). Other than aztreonam, no antibiotic active against gram-negative bacilli was allowed to be used for treatment. Seventy-one patients in whom gram-positive or anaerobic organisms were detected or suspected were given additional agents effective against the organisms. One hundred forty-one patients (92.2%) were cured; the mean duration of treatment was 10.9 +/- 4.0 days. None of the gram-negative bacilli initially isolated became resistant to aztreonam. Colonization, generally by a gram-positive organism, was observed in 27 patients and superinfection was observed in five. Aztreonam was well tolerated. This study suggests that a dosage of 2 g daily of aztreonam should be appropriate in the treatment of moderate to severe infections due to susceptible gram-negative bacilli.

Evaluation of the immunologic cross-reactivity of aztreonam in patients with cystic fibrosis who are allergic to penicillin and/or cephalosporin antibiotics

The immunogenicity, allergenicity, and cross-reactivity of aztreonam were investigated in 19 patients with cystic fibrosis (CF) who are allergic to beta-lactam antibiotics. Skin tests with benzyl-penicilloyl polylysine (BPO), minor determinant mixture, and the drug responsible for the previous allergic reaction were positive for 26%, 53%, and 79% of the patients, respectively. Serum IgG, but not IgE, antibodies to BPO were detected in nine of 14 patients. Eighteen patients whose skin tests with aztreonam were negative were treated. One developed bronchospasm. The others tolerated aztreonam, with an improvement in clinical score greater than or equal to 1 month after treatment (P less than .001). One patient without previous exposure had positive aztreonam skin tests and was later treated uneventfully after iv desensitization. Treatment with aztreonam did not result in IgG or IgE antibody responses in vitro. However, two patients had anaphylactic reactions on reexposure. In patients with CF, allergy to beta-lactam antibiotics is primarily drug-specific. But despite reduced immunogenicity and cross-reactivity, aztreonam should be administered cautiously to patients with CF who are allergic to other beta-lactam antibiotics because it is potentially allergenic with repeated use.

Treatment of gram-negative peritonitis with aztreonam in patients undergoing continuous ambulatory peritoneal dialysis

In a multicenter open study, intraperitoneal aztreonam was used together with vancomycin, cloxacillin, or flucloxacillin for initial empiric treatment of peritonitis associated with continuous ambulatory peritoneal dialysis (CAPD). Monotherapy with aztreonam was continued in 34 episodes of gram-negative peritonitis in 28 patients. The microorganisms isolated included Escherichia coli, Acinetobacter species, Pseudomonas species, and Klebsiella species. In three episodes, two organisms were cultured. Microbiologic assessment revealed cure in 27 episodes, cure with relapse in two, cure with superinfection in one, and treatment failure in four (with resistance to aztreonam in three). As assessed by clinical criteria, 27 episodes were cured, five failed to respond, and two responded partially. No adverse reactions to aztreonam were observed. Comparison of these 34 episodes with 35 episodes in historical controls (treated mainly with aminoglycosides and/or trimethoprim-sulfamethoxazole) showed significantly higher rates of cure (84% vs. 51%) and of survival (97% vs. 86%) as well as lower rates of catheter removal (65% vs. 87%) with aztreonam. Thus aztreonam is a safe and efficient agent for the treatment of peritonitis caused by gram-negative organisms in patients undergoing CAPD.

Clinical experience with aztreonam for treatment of infections in children

The in vitro activity, pharmacokinetics, bactericidal activity, and tissue penetration of aztreonam suggest that it may play a role in therapy for serious gram-negative bacterial infections in children. Several thousand children throughout the world received aztreonam during open or comparative clinical trials for treatment of infections including pyelonephritis, bacteremia, meningitis, skeletal infection, pneumonia, and peritonitis. Cure rates have ranged from 92% to 100%, with relapses seen mainly in children with obstructive renal lesions and those with infections caused by Salmonella. A comparative trial of aztreonam for treatment of neonatal sepsis showed it to be at least as effective as amikacin for this infection. Aztreonam yielded clinical results comparable to those of conventional combined therapy for pulmonary infection in patients with cystic fibrosis. Adverse effects in pediatric trials have been uncommon; fever, diarrhea, or rash occurred in less than 2% of treated children. Reversible laboratory abnormalities have occasionally been noted. On the basis of these data, aztreonam is considered an appropriate alternative agent for the treatment of serious gram-negative bacterial infections in neonates and children. Further comparative clinical trials will delineate specific indications.

Aztreonam in the treatment of gram-negative bacterial meningitis

Aztreonam was administered to 122 patients with presumptive or confirmed gram-negative bacillary meningitis in an open, multinational study. The antibiotic was administered at a dosage of 1-2 g to adults, 50 mg/kg to children greater than 2 years old, and 30 mg/kg to infants three or four times daily. Seventy-seven patients had microbiologically confirmed gram-negative meningitis due to an aztreonam-susceptible organism and received aztreonam for at least 48 hours. Haemophilus influenzae was the most frequently recovered pathogen (40 patients), followed by Enterobacteriaceae (16 patients), Neisseria meningitidis (15 patients), and Pseudomonas species (six patients). All but four patients were microbiologically cured. Microbiologic failure was associated with either a persistent intracerebral abscess (one patient) or a foreshortened course of therapy before microbiologic reevaluation and death (at 48 hours, 48 hours, and 72 hours after initiation of treatment, respectively). These data suggest that aztreonam is effective in the treatment of gram-negative bacillary meningitis caused by susceptible organisms.

Retrospective clinical study of hypersensitivity reactions to aztreonam and six other beta-lactam antibiotics in cystic fibrosis patients receiving multiple treatment courses

A total of 2,793 courses of treatment with seven beta-lactam antibiotics were administered to 121 cystic fibrosis patients chronically infected with Pseudomonas aeruginosa, and the patients were evaluated with respect to clinical hypersensitivity reactions. Seventy-five patients (62%) experienced 125 reactions, for an overall frequency (based on the number of courses) of 4.5%. Immediate reactions occurred in 34 patients (28.1%) during 53 courses (1.9%). The highest rate of reactions involved piperacillin (50.9% of patients), and the lowest rate involved imipenem and aztreonam (4.0% and 6.5% of patients, respectively); intermediate reaction rates were noted for carbenicillin (23.6% of patients), azlocillin (20.8%), cefsulodin (17.1%), and ceftazidime (13.0%). Cross-reactivity did not appear to be a major problem. Reactions to aztreonam seemed to be restricted to a small group of patients with a high propensity for beta-lactam hypersensitivity.

Efficacy of aztreonam in the treatment of skeletal infections due to Pseudomonas aeruginosa

Twenty-eight patients with skeletal infections due to Pseudomonas aeruginosa were treated with aztreonam during two open, noncomparative, multicenter clinical trials. Ten patients with septic arthritis received 2 g of aztreonam three times a day (modal) for 30 days (mean). The mean follow-up period was 4 weeks. Microbiologic cure was achieved in all 10 patients; complete clinical cure, in eight; and partial clinical cure, in two. Eighteen cases of osteomyelitis were treated with 2 g of aztreonam three times a day (modal) for 40 days (mean), with a mean follow-up period of 6 months. Microbiologic cure was achieved in 17 patients. Relapse occurred 1 month after therapy in one patient. Complete clinical cure was achieved in 13 and partial clinical cure was achieved in five patients. The most common adverse reactions to aztreonam were a transient elevation in levels of hepatic enzymes and transient eosinophilia. Three superinfections and one subsequent infection occurred. These results support use of aztreonam for the treatment of skeletal infections due to P. aeruginosa.

Safety of aztreonam in patients with cystic fibrosis and allergy to beta-lactam antibiotics

In an open clinical trial, aztreonam was administered repeatedly to 15 cystic fibrosis patients who were chronically infected with Pseudomonas aeruginosa and had previously had severe hypersensitivity reactions to other beta-lactam antibiotics, including anaphylactic shock, generalized urticaria, and drug-associated fever. After negative results in a skin-prick test and a lack of reaction to an intravenous test dose of aztreonam, the patients were treated with aztreonam (150 mg/[kg.d]) in combination with tobramycin (10-20 mg/[kg.d]) for 14-day periods at 3- to 4-month intervals. To date, a total of 56 course of aztreonam have been administered to these patients (three to six courses per patient), and no type 1 hypersensitivity reactions have occurred. However, as a result of drug-associated fever, the administration of aztreonam had to be discontinued in two of 15 cases. The remaining 13 patients have tolerated treatment well.