The objective of this study was to describe the microbiological characteristics of an extensively drug-resistant (XDR) isolate of Morganella morganii obtained from a patient with sepsis of urinary origin and to describe the patient's clinical characteristics. We further aimed to perform a literature review of the situation in Latin America regarding Gram-negative bacillus (GNB) carriers of New Delhi metallo-β-lactamase (NDM-1) and qnr genes and current reports on the treatment of infections caused by XDR enterobacteria, with particular attention to colistin-resistant isolates. The patient's clinical data were obtained from his medical history. Microbiological identification and susceptibility testing were done using the VITEK 2 Compact System. Resistance genes were detected by PCR and sequencing. Blood and urine cultures grew an M. morganii isolate (Mm4232) harboring NDM-1 and qnrD1. The patient was treated successfully with fosfomycin and double doses of meropenem. There are no previous reports of the use of fosfomycin and meropenem to treat infections by XDR enterobacteria harboring NDM-1 carbapenemase. This is the first report of qnrD1 in South America. We consider that this report could be helpful to physicians implementing treatments for infections caused by XDR GNB, including colistin-carbapenem-resistant GNB.

Carbapenem-resistant Acinetobacter baumannii (CRAB) infections are an increasing concern in intensive care units (ICUs) worldwide. The combination of carbapenemases and 16S rRNA-methyltransferases (16S-RMTases) further reduces the therapeutic options. OXA-carbapenemase/A. baumannii clone tandems in Latin America have already been described; however, no information exists in this region regarding the occurrence of 16S-RMTases in this microorganism. In addition, the epidemiology of A. baumannii in ICUs and its associated resistance profiles are poorly understood. Our objectives were as follows: to study the clonal relationship and antibiotic resistance profiles of clinical and digestive colonizing A. baumannii isolates in an ICU, to characterize the circulating carbapenemases, and to detect 16S-RMTases. Patients admitted between August 2010 and July 2011 with a clinically predicted hospital stay > 48 hr were included. Pharyngeal and rectal swabs were obtained during the first fortnight after hospitalization. Resistance profiles were determined with MicroScan^® and VITEK2 system. Carbapenemases and 16S-RMTases were identified by PCR and sequencing, and clonality was assessed by pulsed-field gel electrophoresis and multilocus sequence typing. Sixty-nine patients were studied and 63 were diagnosed with bacterial infections. Among these, 29 were CRAB isolates; 49 A. baumannii were isolated as digestive colonizers. These 78 isolates were clustered in 7 pulsetypes, mostly belonging to ST79. The only carbapenemase genes detected were bla_OXA-51 (n = 78), bla_OXA-23 (n = 62), and bla_OXA-58 (n = 3). Interestingly, two clinical isolates harbored the rmtC 16S-RMTase gene. To the best of our knowledge, this is the first description of the presence of rmtC in A. baumannii.

Pseudomonas aeruginosa is a leading cause of hospital-acquired infections worldwide. Biofilm production, antibiotic resistance, and a wide range of virulence factors contribute to their persistence in nosocomial environments. We describe an outbreak caused by a multidrug-resistant P. aeruginosa strain in an ICU. Antibiotic susceptibility was determined and bla_PER-1 and qnrVC were amplified via PCR. Clonality was determined using PFGE and biofilm formation was studied with a static model. A combination of antibiotics was assessed on both planktonic cells and biofilms. WGS was performed on five isolates. All isolates were clonally related, resistant to ceftazidime, cefepime, amikacin, and ceftolozane-tazobactam, and harbored bla_PER-1; 11/19 possessed qnrVC. Meropenem and ciprofloxacin reduced the biofilm biomass; however, the response to antibiotic combinations with rifampicin was different between planktonic cells and biofilms. WGS revealed that the isolates belonged to ST309 and serotype O11. bla_PER-1 and qnrVC6 were associated with a tandem of ISCR1 as part of a complex class one integron, with aac(6′)-Il and ltrA as gene cassettes. The structure was associated upstream and downstream with Tn4662 and flanked by direct repeats, suggesting its horizontal mobilization capability as a composite transposon. ST309 is considered an emerging high-risk clone that should be monitored in the Americas.

Introduction: To characterize extended-spectrum β-lactamases (ESBLs) and plasmid-mediated quinolone resistance (PMQR) genes in Escherichia coli isolates obtained from extra-intestinal samples in three Uruguayan hospitals. Methodology: Fifty-five ESBL-producing E. coli isolates were studied. Virulence genes, ESBLs, and PMQR genes were detected by polymerase chain reaction. ESBL-producing isolates were compared by pulsed-field gel electrophoresis. Multi-locus sequence typing was also performed on 13 selected isolates. Results: Thirty-seven isolates harbored blaCTX-M-15 (67.3%), eight blaCTX-M-2 (14.6%), five blaCTX-M-14 (9.1%), three carried both blaCTX-M-2 and blaCTX-M-14, one blaCTX-M-9, and one blaCTX-M-8. Among the CTX-M-15 producers, 92% belonged to sequence types ST131 and ST405, and carried aac(6’)Ib-cr as well. Isolates harboring blaCTX-M-2, blaCTX-M-14, blaCTX-M-9, or blaCTX-M-8 were found to be genetically unrelated. Conclusions: The successful dissemination of CTX-M-15-producing E.coli isolates seems to be linked to the spreading of high-risk clones and horizontal gene transfer. A trade-off between carrying more antibiotic resistance and less virulence-related genes could partially account for the evolutionary advantages featured by successful clones.