Antimicrobial treatment of Morganella morganii invasive infections: Systematic review.

BACKGROUND: Morganella morganii is a Gram-negative, rod-shaped, facultative anaerobic bacillus divided into two subspecies, morganii and sibonii. Previously classified as Proteus morganii, it belongs to human gut commensal microbiota. Nevertheless, on rare occasions, especially in nosocomial and postoperative environment as well as in patients with the impaired immune system and young children, it may cause potentially fatal systemic infection.

OBJECTIVES: The aim of our systematic review was to determine whether and what invasive infections in humans were caused by Morganella morganii and to estimate outcomes of administered antibiotic management.

DATA SOURCES: This systematic review was registered at the PROSPERO database of systematic reviews and meta-analyses before initiation of the research (registration number CRD42020171919). Study eligibility criteria and participants. patients of any age and both sex harbouring Morganella morganii as the only microorganism in bodily fluids or tissues, from where it was isolated and identified by one or more of the following diagnostic methods: conventional techniques including colony morphology, Vitek 2, API or BD Phoenix biochemical systems, as well as more sophisticated methods, such as Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) and species-specific PCR for M. morganii.

METHODS AND INTERVENTIONS: We have systematically searched MEDLINE, EBSCO, SCOPUS, SCINDEX and GOOGLE SCHOLAR for case reports and case series with M. morganii invasive infections.

RESULTS: M. morganii can cause serious infections of different tissue in patients of any age. The most isolates were susceptible to ceftazidime, imipenem and amikacin. Majority of the patients completely recovered after antibiotic treatment. About 15% of the patients died despite of the therapy. Gentamicin was the most frequently used antibiotic in the treatment of infection caused by M. morganii.

CONCLUSION: M. morganii invasive infections should be taken into consideration by the clinicians, especially in hospital conditions, due to its high degree of mortality and high potential of this bacterium to develop multidrug resistance. Treatment of M. morganii infections should include gentamycin in combination with third generation cephalosporin or another antibiotic to which M. morganii is susceptible (after testing isolates for third cephalosporin generation for the production of AmpC β -lactamases).