Pseudomonas aeruginosa has been identified as an opportunistic pathogen that causes pulmonary infections in individuals with cystic fibrosis (CF), according to a study published in Current Microbiology.

Because P. aeruginosa has a high adaptive capacity that favors the selection of antibiotic-resistant strains, the researchers sought to explore the rate and distribution of multidrug-resistant and extensively drug-resistant P. aeruginosa among pediatric patients with CF who experienced recurrent infections. They also sought to distinguish the current efficacy of the antibiotics that are commonly used as eradication therapy at a Mexican child-focused institute.

One hundred eighteen bacterial isolates from 57 respiratory secretion samples from 25 children with CF, who were treated at the department of pneumology and thoracic surgery at the National Institute of Pediatrics between
April 2015 and July 2019, were identified as P. aeruginosa. The samples underwent molecular identification, antimicrobial sensitivity tests, and random amplified polymorphic DNA (RAPD) genotyping by polymerase chain reaction.

The bacterial isolates were grouped in 84 RAPD profiles and 46 RAPD clusters with a 80% or more similarity. All of the isolates revealed a similarity to the reference strains of less than 40%. Overall, 97.4% (115 of 118) of the isolates were distributed in unique patient-specific clusters; however, 3 of the isolates from cluster 5 (Pa33ra, Ra78r, and Pa119r) exhibited cross-infectivity between 2 sisters, whose resistance profile remained unchanged for more than 2 years.

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Throughout the study period, 8 patients who experienced recurrent infections presented with coinfections with isolates from different clusters, with 5 of them presenting with momentary coinfections at the same time.

In all, 81 isolates from 8 patients with recurrent infections were distributed in 13 clusters, with it being notable that
17 initial bacterial isolates from such clusters exhibited diverse adaptive directions in antibiotic resistance over time.  

In addition, 77.1% (91 of 118) of the isolates and 51.7% (61 of 118) of the isolates demonstrated in vitro susceptibility to ceftazidime and amikacin, respectively—both of which are known to be used as eradication therapy at
the National Institute of Pediatrics.  

Further, 42.4% (50 of 118) of the isolates were classified as multidrug-resistant and 12.7 as extensively drug-resistant. Of these resistant isolates, 84.6% (55 of 65) were identified among patients with recurrent infections.

The high frequency of extensively drug-resistant strains detected among children with CF should be considered a “caution mark,” with such resistance patterns more commonly observed among adult patients. In addition, amikacin may soon prove to be ineffective as an antibiotic.

The authors concluded that “Careful use of available antibiotics is crucial before therapeutic possibilities are reduced and [the] ‘antibiotic resistance crisis’ worsens among children with CF.”

Reference

Gutiérrez-Santana JC, Gerónimo-Gallegoa A, Martínez-Corona MB, et al. High rates of extensively drug-resistant Pseudomonas aeruginosa in children with cystic fibrosis. Curr Microbiol. 2022;79(11):353. doi:10.1007/s00284-022-03048-4