INTRODUCTION: The high prevalence of Klebsiella pneumoniae infections is related to the ability of K. pneumoniae to acquire and disseminate exogenous genes associated with mobile elements, such as R plasmids, transposons and integrons. This study investigated the presence of class 1 integrons in clinical and microbiota isolates of K. pneumoniae belonging to different phylogenetic groups and correlated these results with the antimicrobial resistance profiles of the studied isolates. METHODS: Of the 51 isolates of K. pneumoniae selected for this study, 29 were from multidrug-resistant clinical isolates, and 22 were from children's microbiota. The susceptibility profile was determined using the disk diffusion method, and class 1 integrons were detected through polymerase chain reaction (PCR). RESULTS: The results showed that none of the 22 microbiota isolates carried class 1 integrons. Among the 29 clinical isolates, 19 (65.5%) contained class 1 integrons, and resistance to sulfamethoxazole/trimethoprim was identified in 18 of these isolates (94.7%). Among the K. pneumoniae isolates with class 1 integrons, 47% belonged to the KpI phylogenetic group, and one isolate (14.3%) carrying these genetic elements belonged to the KpIII group. CONCLUSIONS: The wide variety of detected class 1 integrons supports the presence of high rates of antimicrobial resistance, genetic variability, and rapid dissemination of beta-lactamase genes among K. pneumoniae clinical isolates in recent years in hospitals in Recife-PE, Brazil. The findings of this study indicate that the surveillance of K. pneumoniae integrons in clinical isolates could be useful for monitoring the spread of antibiotic resistance genes in the hospital environment.