Effectiveness of empiric aztreonam compared to other beta-lactams for treatment of <em>Pseudomonas aeruginosa</em> infections

Abstract

PurposeTo evaluate the use of aztreonam as an active empiric therapy against subsequent culture of Pseudomonas aeruginosa (P. aeruginosa).MethodsThis was a retrospective cohort study conducted among patients who received either aztreonam or an antipseudomonal beta-lactam (BL) as an empiric therapy with subsequent culture with P. aeruginosa. All patients with at least one positive culture for P. aeruginosa between January 2014 and August 2016 were included in this analysis. The primary composite outcome was empiric therapy failure, defined as inappropriate empiric therapy, alteration of empiric antibiotic following culture results, or 30-day in-hospital mortality. Secondary outcomes included appropriate empiric therapy, alteration of empiric therapy, 30-day-in-hospital mortality, and post-culture hospital length of stay.ResultsThe primary outcome of empiric therapy failure was significantly higher in the aztreonam group than in the BL group (77.8% vs 41.9%; P=0.004). The aztreonam group had a lower rate of appropriate empiric therapy compared with the BL group (44.4% vs 66.1%; P=0.074) and higher alteration of empiric therapy once susceptibilities were known than when compared with the BL group (61.1%vs 28.2%; P=0.005). Although numerically higher, 30-day-in-hospital mortality and median hospital length of stay were not significantly different between the two groups.ConclusionEmpiric therapy failure occurred more often when initially using aztreonam vs a BL in a patient who subsequently had a P. aeruginosa infection. Only a third of patients within the aztreonam group had a documented BL allergy, demonstrating an inclination for clinicians to utilize this drug as an empiric therapy when there were more appropriate therapies available.

Prevalence of gram negative bacteria in infected burn wounds and antibiotic susceptibility pattern; a study conducted on stable burn patients reporting to out-patient department.

“…Aztreonam is a beta lactam antibiotic showed poor activity (10.5%) against p. aeruginosa in our study that is similar to the results of a study done by Hogan et al in USA, reporting 28% sensitivity of pseudomonas for aztreonam. 20 Piperacillin show great activity against P. aeruginosa but in our study its role was poor and showed just 21.1% activity. A study conducted in USA reported combined effect of piperacillin and tazobactam as 77.5% 21 , while some other studies reported high resistance of pseudomonas against piperacillin-tazobactam.…”

Acute care beta-lactam allergy pathways: approaches and outcomes

“…11 Although aztreonam is often used for inpatient gram-negative bacterial infections in patients with beta-lactam allergy histories because there is no risk of beta-lactam cross-reactivitydexcept in patients with ceftazidime allergydit is less effective against Pseudomonas Spp. 12 and is more costly (at least double the cost/day compared with the beta-lactams cefepime or ceftazidime). 13 The high cost of aztreonam explains some of the higher costs observed for inpatients with reported penicillin allergy.…”

<p>Selection between aztreonam and cephalosporins for treatment of infections with pseudomonads needs more caution</p>

“…In the recently published study1 to evaluate the use of aztreonam as an active empiric therapy against subsequent culture of Pseudomonas aeruginosa , empiric therapy failure using aztreonam is reported more common than on using β-lactam antibiotics in patients suffering P. aeruginosa infection. Though the study is interesting and revealing important findings regarding antibiotic use for treatment of P. aeruginosa infection, it should be accepted with caution as suggested by the authors1 repeatedly due to limited number of cases. In our observations on P. aeruginosa (95) and other pseudomonads (40) isolates from veterinary clinical cases we found that instead of generalizing the lesser efficacy of aztreonam in-depth studies are required.…”

“…However, on non-ESBL producing (37) strains aztreonam inhibited 42.1% isolates, much less than cefepime (68%), ceftriaxone (50%) and piperacillin + tazobactam (61.1%). Therefore, it is suggested to use the two classes of antibiotics (aztreonam and β-lactams) judiciously based on antibiotic stewardship principle1 instead of following some general rule for infections with pseudomonads.…”

“…The analysis on antibiotic sensitivity patterns of P. aeruginosa and NPA isolates from veterinary clinical cases indicated need of antibiotic sensitivity assay for judicious use of antibiotics in therapy ie, need to reinforce antimicrobial stewardship principles 1…”