No abstract

The prevalence of carbapenem-resistant Acinetobacter baumannii in Saudi Arabia and their resistance genetic mechanisms are yet to be identified. We studied the prevalence and genetic diversity of extended-spectrum beta-lactamase genes, particularly the PER-1 gene, among carbapenem-resistant A. baumannii strains from patients at a tertiary care hospital in Riyadh, Saudi Arabia between 2006 and 2014. Fresh subcultured samples were tested for antimicrobial susceptibility minimum inhibitory concentration (MIC). Total genomic DNA was extracted from each isolate and further used for polymerase chain reaction (PCR) genotyping, sequence-based typing (SBT) of PER-1 and OXA-51-like gene, and multilocus sequence typing (MLST) of positive isolates. Randomly selected clinical isolates (n = 100) were subjected to MLST. A total of 503 isolates were characterized as multidrug-resistant (MDR) using the MIC. Isolates were further PCR tested for bla and bla resistance genes (n = 503). The genotyping results showed that 68/503 (14 %) isolates were positive to bla TEM. The genotyping results of PER-1-like genes showed that 384/503 (76.3 %) were positive among MDR Acinetobacter isolates. Based on SBT, the majority of these isolates were clustered into three main groups including isolates harboring PER-1: AB11 (bla ), isolate AB16 (bla), and, finally, the plasmid pAB154 (bla ). Remarkably, many isolates were concealing the PER-1 gene and harboring the TEM resistance genes as well. MLST results for selected isolates (n = 100) identified four main sequence types (STs: 2, 19, 20, and 25) and four novel isolates (ST 486-489). We report 76.3 % prevalence of the PER-1 resistance gene among Acinetobacter clinical isolates from Riyadh, Saudi Arabia. Further work is needed to explore the clinical risks and patient outcome with such resistance related to healthcare-associated infections and investigate the genetic and molecular mechanisms that confer the MDR phenotype.

A retrospective cohort study was conducted among hospitalized children less than 12 years of age who had Acinetobacter spp. isolated from ≥1 cultures between October 2001 and December 2007 at King Abdulaziz Medical City in Riyadh, Saudi Arabia. Children with multidrug-resistant (MDR) Acinetobacter spp. healthcare-associated infections (HAIs) were compared to children with antimicrobial-susceptible Acinetobacter spp. HAIs and to children colonized with Acinetobacter. Children with MDR Acinetobacter spp. HAIs were older (p = 0.01), more likely to be admitted to an intensive care unit (ICU) (p = 0.06), and had a higher mortality rate (p = 0.02) than colonized children. Children with MDR Acinetobacter spp. HAIs were older than children with antimicrobial-susceptible Acinetobacter spp. HAIs (p = 0.0004), but their mortality rates were similar. Among children with MDR Acinetobacter spp. HAIs, burn injuries were the most common underlying illness. HAIs caused by MDR or susceptible Acinetobacter spp. occurred after prolonged hospitalization, suggesting nosocomial acquisition. Patients infected with MDR Acinetobacter spp. frequently received inappropriate empiric therapy (73.9 %). Further studies are needed in order to identify effective strategies to prevent nosocomial transmission and effective ways of improving patient outcomes.