An Outbreak of Pan-drug Resistant Providencia Species in an Intensive Care Unit: A Case-Series

Background: Providencia species are opportunistic pathogens that can rarely cause nosocomial infections. They possess numerous virulence characteristics, such as intrinsic antibiotic resistance, which enable them to cause lethal outbreaks. The emergence of pan-drug resistant (PDR) isolates amplifies the threat of Providencia spp. to human health. Objectives: We described an outbreak caused by PDR Providencia spp. in the intensive care unit (ICU) of our medical center. Methods: This outbreak occurred at Imam Hossein Hospital in Tehran, Iran, between 20 June and 28 July 2023. The majority of the 14 patients experienced ventilator-associated pneumonia (VAP); however, two others had surgical site infections (SSI) and peritoneal abscesses. Samples were subcultured on Blood agar, Chocolate agar, and MacConkey agar, as well as differential gallery mediums. Additionally, susceptibility to antimicrobial agents was determined by the disk diffusion protocol using Mueller-Hinton (MH) agar. Results: The rapid diagnosis of the outbreak and practical measures recommended by the infection prevention and control (IPC) committee (e.g., sampling from other patients, hands of healthcare workers, and the environment to identify further cases and the source of the infection, contact isolation, disinfection of the ICU with 1% chlorine solution, and combined antibiotic therapy) assisted us in managing it. Nevertheless, the outbreak resulted in the mortality of eight patients, despite these preventive and therapeutic measures. Conclusions: Clinicians should be aware of nosocomial infections caused by opportunistic pathogens such as Providencia spp., especially in ICU-admitted patients with prolonged hospitalizations and broad-spectrum antibiotic administration. Strong clinical suspicion and timely detection of outbreaks, investigation of further cases, contact isolation of infected patients, disinfection of the environment, treatment with combined antibiotic regimens, and re-sampling of patients and the environment are the cornerstones of managing outbreaks caused by Providencia spp.