NDM-5-producing Klebsiella pneumoniae ST258 in a university hospital in Argentina.

Background: A drastic increase in carbapenem resistance among Klebsiella pneumoniae isolates occurred during the period 2019-22. Three epidemiological changes could be evidenced: (i) NDM became the predominant carbapenemase; (ii) NDM-5 replaced NDM-1; and (iii) the emergence of NDM-producing K. pneumoniae ST258 (NDM-KpST258).

MALDI-TOF MS-Based KPC Direct Detection from Patients' Positive Blood Culture Bottles, Short-Term Cultures, and Colonies at the Hospital.

Carbapenemase resistance in is a global public health problem and rapid and effective methods for detecting these resistance mechanisms are needed urgently. Our aim was to evaluate the performance of a MALDI-TOF MS-based " carbapenemase" (KPC) detection protocol from patients' positive blood cultures, short-term cultures, and colonies in healthcare settings. Bacterial identification and KPC detection were achieved after protein extraction with organic solvents and target spot loading with suitable organic matrices.

First nosocomial outbreak of SME-4-producing Serratia marcescens in South America.

Carbapenemase-producing-Serratia marcescens isolates, although infrequent, are considered important nosocomial pathogens due to their intrinsic resistance to polymyxins, which limits therapeutic options. We describe a nosocomial outbreak of SME-4-producing S. marcescens in Buenos Aires city which, in our knowledge, represents the first one in South America.

Molecular and Phenotypic Characterization of a Multidrug-Resistant Coproducing OXA-232 and MCR1.1 in Argentina.

The spread of arbapenem-resistant Enterobacterales has raised concern in clinical settings due to the limited therapeutic options available. OXA-48-like enzymes are still sporadic in South America. The aim of this study was to characterize a multidrug-resistant isolate from a hospitalized patient in Buenos Aires city.

synergistic activity of aztreonam (AZT) plus novel and old β-lactamase inhibitor combinations against metallo-β-lactamase-producing AZT-resistant .

The emergence of metallo-β-lactamase (MBL)-producing , mainly New Delhi metallo-β-lactamase (NDM), represents a clinical threat due to the limited therapeutic alternatives. Aztreonam (AZT) is stable to MBLs, but most MBL-producing isolates usually co-harbour other β-lactamases that confer resistance to AZT and, consequently, its use is restricted in these isolates. We compared the ability of sulbactam (SUL), tazobactam (TAZ), clavulanic acid (CLA) and avibactam (AVI) to restore the AZT activity in MBL-producing AZT-resistant isolates.

Activity of Minocycline Against Multidrug-Resistant Isolates-Evaluation of Clinical Breakpoints and Review of Literature.

Therapeutic options for the treatment of infections by multidrug-resistant strains are often limited. Minocycline (MIN) is an old antibiotic, with excellent activity against isolates, which can be administered orally. Currently, there is no single criterion regarding the breakpoints for MIN and The activity of MIN was examined against a collection of isolates recovered from 15 hospitals of 6 countries of South America.

In-house rapid colorimetric method for detection of ceftazidime/avibactam resistance in carbapenem resistant Enterobacterales.

A rapid colorimetric method, the Andrade screening antimicrobial test, was compared with the E-test method to detect ceftazidime/avibactam (CZA) resistance in carbapenem resistant Enterobacterales clinical isolates. A 106 non-duplicated isolates (86 susceptible and 20 resistant to CZA) were chosen for validation. The sensitivity and specificity were 100%.

synergistic activity of the sulbactam/avibactam combination against extensively drug-resistant .

The therapeutic options to treat infections are very limited. Our aim was to evaluate the activity of sulbactam combined directly with avibactam or the ampicillin-sulbactam/ceftazidime-avibactam combination against extensively drug-resistant isolates. Extensively drug-resistant isolates (=127) collected at several South American hospitals were studied.

LMB-1 producing Citrobacter freundii from Argentina, a novel player in the field of MBLs.

Carbapenemase-producing Enterobacterales expressing OXA-48, KPC, NDM, VIM or IMP enzymes are increasingly reported worldwide. We have characterized LMB-1, a novel metallo-β-lactamase (MBL) of Ambler class B3 from Citrobacter freundii 164 (Cf164) clinical isolate from Buenos Aires, Argentina. Cf164 displayed reduced susceptibility to carbapenems but gave inconsistent results with carbapenemase confirmatory tests, indicating the presence of a weak carbapenemase.

Discrepancies in susceptibility testing to colistin in Acinetobacter baumannii: The influence of slow growth and heteroresistance.

The increasing use of polymyxins as last-resort drugs for managing infections by Acinetobacter baumannii has led to the emergence of resistance. This study aimed to determine the resistance mechanisms in Acinetobacter baumannii isolates with colistin MIC ≥ 4 mg/L and to relate the mechanisms of resistance with the difficulties in detecting them. Absolute agreement among the different methodologies (Phoenix automatized system, broth and agar dilution, and a rapid colorimetric test) in the 140 colistin-susceptible isolates was observed; whereas in the 25 resistant isolates, the performance varied according to the colistin MIC value.

In-house rapid colorimetric method for detection of colistin resistance in : A significant impact on resistance rates.

A rapid colorimetric method, the Andrade Screening Antimicrobial Test (ASAT) was evaluated to detect colistin resistance in clinical isolates. The sensitivity and specificity were 90.7% and 100%, respectively.

SME-4-producing Serratia marcescens from Argentina belonging to clade 2 of the S. marcescens phylogeny.

Background: SME carbapenemases are increasingly reported, especially from North and South America. Here, we describe an SME-4-producing Serratia marcescens (SME-Sm) clinical isolate from Argentina and compare its genome with other SME-Sm and Sm isolates recovered from public databases.

Methods: Sm isolates were characterized by WGS using Illumina technology, susceptibility testing and MIC determination.

[Molecular epidemiology of carbapenem-resistant isolates of Acinetobacter baumannii in Argentina].

One hundred sequential, epidemiologically unrelated carbapenem-resistant- Acinetobacter baumannii isolates from 11 hospitals in 10 Argentine provinces were collected between January and August 2016. Genes coding for Ambler class D and B carbapenemases were investigated by PCR using specific primers. All isolates were typed using the 3-locus sequence typing and blalike sequence-based typing techniques.

Current scenario of plasmid-mediated colistin resistance in Latin America.

Colistin resistance can occur by chromosomal mutations and by acquisition of plasmid-carrying determinants, mainly mcr-1. In the recent years, we have observed the outburst of this resistance gene in our region. Due to the risk of the rapid dissemination of mcr-1, this finding has worried and alerted different actors from the health field and has become one of the most prolific topics.

Carbapenemases in Acinetobacter baumannii. Review of their dissemination in Latin America.

Carbapenem resistance in gram-negative bacteria by production of carbapenemases is one of the most challenging issues regarding healthcare worldwide. We review the epidemiology and prevalence of carbapenemases in carbapenem-resistant Acinetobacter baumannii isolates from Latin American countries. High resistance rates to antimicrobial agents, particularly to carbapenems, are observed in this region.

First case of bacteraemia due to harbouring in an immunocompromised patient.

Clinically significant NDM-1-producing has not yet been described in the literature. We report the first case of bacteraemia due to an strain harbouring recovered from an immunocompromised patient. Our report reinforces the fact that NDM-1 can easily be acquired by species.

Molecular epidemiology of carbapenem-resistant Acinetobacter baumannii in South America.

One hundred and twenty-six epidemiologically sequential, unrelated, carbapenem-resistant Acinetobacter baumannii isolates from nine hospitals in six countries of South America were collected between July 2013 and June 2014. Genes coding for Ambler class D and B carbapenemases were sought by PCR. All isolates were typed using the 3-locus sequence typing and blaOXA-51-like sequence-based typing techniques.

Rapid Blue-Carba test: reduction in the detection time of carbapenemases performed from a 4-hour bacterial lawn.

The increase in carbapenem-resistant gram-negative bacteria is a matter of concern due to the limited therapeutic options available. In severe infections caused by these isolates, the rapid detection of the mechanisms of resistance is vital. We described a slightly modified version of the Blue-Carba test, rapid Blue-Carba test, which allows the detection of carbapenemases at 4 h of incubation from a haze of bacterial growth obtained from a positive blood culture.

Outbreak of bla-producing Acinetobacter baumannii in South America.

Thirty-five Acinetobacter baumannii isolates were recovered from two medical centres in Guayaquil City, Ecuador, from November 2012 to October 2013. Isolates were identified using MALDI-TOF and confirmed by rpoB. PCR methods were employed for epidemiological analysis.

[In vitro activity of ampicillin-ceftriaxone against Enterococcus faecalis isolates recovered from invasive infections].

In vitro activity of the combination of ampicillin- ceftriaxone against 30 Enterococcus faecalis isolates recovered from invasive infections in patients admitted to Hospital de Clínicas José de San Martin in the city of Buenos Aires was assessed. Ampicillin- ceftriaxone synergies were determined by microdilution in Müeller-Hinton (MH) broth with and without subinhibitory concentrations of ceftriaxone. Synergy was detected in 22/30 isolates.