Negative correlation between virulence and multidrug resistance in intrahospital and community acquired infections by Proteus mirabilis, in Eastern Venezuela

This is thefirst report for Venezuela of virulence/pathogenicity and resistance factors in intrahospital (HCAI) and community-acquired infec-tions (CAI) by P. mirabilis in two main hospitals from Eastern Venezuela. Viru-lence factors such as motility, biofilms, and resistance to serum killing (RSK) were determined. Antimicrobial susceptibility allowed classifying the isolates into resistant, multidrug resistant (MDR) and extensively drug-resistant (XDR). P. mirabilis was identified in HCAI in both hospitals mostly from secretions, while some CAI were identified from urine and secretions. Twitching, swarm-ing, biofilm and RSK were identified in many isolates. Eleven antimicrobials showed resistance frequencies from 22-54% in one or both hospitals. A high frequency of MDR isolates was found in these hospitals (60.6 to 56.5%). Strains carrying both blaCTX-M and blaTEM genes were found in one hospital in a frequency of 27.0%. We also found that the frequency of MDR was lower in strains with three or more virulence factors compared to those with fewer factors. Bacteria with swarming showed 5.85 times lower probability of being MDR, and those with twitching, 7.52 times lower probability. Infections by MDR/XDR P. mira-bilis strains in HCAI and CAI represent a public health problem that requires effective control and prevention measures to reduce their potential spread and persistence in the population