Clinical Features and Outcomes of Raoultella Terrigena Infections. A Single-center Experience from Karachi, Pakistan: A Retrospective Study

Abstract

Objectives:Raoultella terrigena (formerly Klebsiella terrigena) is an environmental gram-negative rod. It may cause infections in humans, especially in the elderly and immunosuppressed patients. Moreover, this organism tends to be multi-drug resistant, limiting treatment options. Evidence on clinical presentation and outcomes of this infection is limited. We conducted this study to see its various clinical features, available treatment options, and associated clinical impacts of the R.terrigena infections. Methodology:We conducted a cross-sectional study on all adult patients with clinical specimens positive for Raoultella terrigena at a 700-bedded tertiary care hospital in Karachi, Pakistan, between January 2013 to December 2018. Results:There were 58 patients with R.terrigena in different cultures specimens identified. Amongst them n=12 (22.6%) were colonizers. The median age was 61.5 years (IQR=28), and most were male (60.9%). The most common infection site was the respiratory tract in 28.3%, followed by urinary tract infections, 26%, and central line-associated infections at 26.1%. Amongst infected cases, 37% were in septic shock, and of which 76.5% required vasopressors. 45.7% had respiratory failure requiring non-invasive ventilation in 47.6%, and mechanical ventilation in 52.4%. The previous history of multidrug-resistant organisms was present in 67.4% of patients and the history of prior antibiotics use within the last six months was present in 78.3%. 91.3% of isolates were resistant to piperacillin-tazobactam and meropenem, 65.2% were resistant to colistemethate. Eight patients lost to follow up. The majority of patients treated with combination therapy (n=31, 81.6%) and meropenem plus colistemethate was the most commonly used combination (n=11, 44%). The overall mortality rate was 44.7%. Conclusion: R.terrigena is a highly drug-resistant organism with a high mortality rate and causes hospital-acquired respiratory tract infections in most patients.