Outbreak of Multidrug-resistant Pseudomonas aeruginosa in a Tertiary Healthcare System in Detroit

ABSTRACT

Background. Pseudomonas aeruginosa is one of the most common causes of healthcare-associated infections in critically ill patients and those with suboptimal immunity. However, the development of multidrug resistant Pseudomonas aeruginosa (MDR Pa) creates an even great disease burden and threat to both the hospital and local community health. The purpose of this study is to illustrate a descriptive analysis of a cluster of MDR Pseudomonas, during a local surge of SARS-CoV-2 (COVID 19) pandemic. The goal is to shed more light on the troublesome parallel during outbreaks, such as COVID-19 and consequential secondary outcomes. Methods. From November 2020 through February 2021, 16 patients exposed to the intensive care units of a tertiary healthcare system were infected or colonized with a multidrug-resistant strain of P. aeruginosa (Figure 1). Outbreak investigation was conducted via retrospective chart review of the first eight cases and prospective analysis of the latter eight cases. The isolates collected prospectively were analyzed for taxonomic identification, antimicrobial resistance profile, and phylogenetic analysis. Clinical characteristics of all patients were collected, and epidemiological investigation was carried out. MDR is defined as resistance to at least four classes of antibiotics third-generation cephalosporins, fluoroquinolones, aminoglycosides, and carbapenems. Results. Of the 16 cases of MDR Pa infections, seven died within five months (Table 1). Antimicrobial resistance gene profiling detected blaOXA and blaPAO betalactamase genes in all the samples. One sample contained an additional blaVIM resistance gene, although this patient was colonized and not actively infected. The analysis suggests existence of two clusters demonstrating relatedness and possible horizontal transmission. Timing of this cluster of cases coincides with surge of COVID-19 cases. This highlights the importance of infection control measures and antimicrobial stewardship. Conclusion. Since early 2017 studies show there is a growing prevalence worldwide in transferable resistance, particularly for β-lactamases and carbapenemases, MDR Pseudomonas. This study emphasizes an irony paralleled during a pandemic, the needed efforts to prevent unintentional lapses in patient safety.