Carbapenem-Resistant Acinetobacter baumannii Infection in Children From a Third-Level Hospital in Mexico: Clinical Characteristics and Molecular Epidemiology.

BACKGROUND: Acinetobacter baumannii has emerged as a threat to public health due to the high prevalence of multidrug-resistant isolates. Information regarding the clinical and molecular characterization of carbapenem-resistant A. baumannii (CRAB) infections in children is scarce. Our study aimed to describe the clinical and molecular characteristics of CRAB infections in children from a third-level center in Mexico. METHODS: Consecutive cases of CRAB infections were documented during 2017-2022. Clinical and demographic data were collected from clinical records. Mass spectrometry was used for the identification of the isolates. The identification of A. baumannii strains was confirmed by conducting a polymerase chain reaction (PCR) assay targeting the gyrB sequence. In addition, the carbapenemase-encoding resistance genes were detected by PCR. RESULTS: Twenty-one cases of CRAB infections were documented: 76% female and 62% were neonates. The median hospital length of stay at the time of positive culture was 37 days (interquartile range, 13-54). Sixty-four percent of the isolates were recovered from bronchial secretions. A co-resistance rate greater than 60% was observed for most groups of antibiotics. All carbapenem-resistant isolates carried blaOXA-24 genes. BlaIMP genes were detected in half of the cases, with all strains co-harboring blaOXA-24 genes. CONCLUSIONS: The present study demonstrated a high proportion of CRAB infections in the neonatal population, a high prevalence of co-resistance to antibiotics, and a high rate of isolates carrying blaOXA-24 and blaIMP genes. CRAB is a significant concern due to the mortality rate and the lack of therapeutic alternatives; implementing infection prevention and control programs is urgent to stop the spread of carbapenem-resistant A. baumannii.

Caracterización fenotípica y molecular de cepas de Klebsiella pneumoniae productores de carbapenemasas tipo OXA-48 circulantes en Chile / Phenotypic and molecular characterization of OXA-48 like producing Klebsiella pneumoniae isolates in Chile

INTRODUCCIÓN: La aparición y diseminación de Enterobacterales resistentes a carbapenémicos ha generado un gran impacto en las infecciones asociadas a la atención de salud en el mundo. Recientemente, en Chile se detectó un brote por Klebsiella pneumoniae productora de carbapenemasas tipo oxacilinasas (OXA) de la subfamilia tipo OXA-48, reportándose los primeros casos en pacientes hospitalizados mayoritariamente en la zona norte del país. OBJETIVO: Determinar los perfiles fenotípicos, genotípicos y de susceptibilidad antimicrobiana de 16 cepas referidas durante mayo del año 2021 desde las regiones de Antofagasta y Metropolitana al Laboratorio de Referencia del Instituto de Salud Pública. METODOLOGÍA: Las cepas provenientes de muestras clínicas fueron analizadas mediante técnicas tradicionales (Kirby-Bauer y epsilometría) y automatizadas, además de técnicas colorimétricas, inmunocromatográficas y moleculares (RPC y PFGE). Resultados: Se detectó la presencia de los genes blaoxa-48 y blaoxa-232 con una resistencia inusual, tanto a carbapenémicos (ertapenem, imipenem y meropenem) como a cefalosporinas (cefepime, cefotaxima y ceftazidima), además de piperacilina/tazobactam y temocilina. Se detectaron dos subtipos por PFGE, siendo predominante el clon CL-Kpn-Spe-329 (93,8%) con dos mecanismos de resistencia identificados: carbapenemasa y β-lactamasa de espectro extendido (BLEE). CONCLUSIÓN: Ante esta alerta epidemiológica es necesario unificar criterios existentes en la red asistencial nacional para la oportuna detección, vigilancia y control de posibles brotes de cepas productores de oxacilinasa tipo OXA-48.

BACKGROUND: The appearance and spread of carbapenems-resistant Enterobacterales have generated a major impact on health care-associated infections worldwide. Recently, a Klebsiella pneumoniae outbreak expressing OXA-48 like-carbapenemases was detected in Chile, the first reported cases corresponded to hospitalized patients mainly from northern Chile. AIM: To characterize the phenotypic and genotypic profiles of antimicrobial susceptibility of 16 clinical isolates referred during May 2021 from Antofagasta and Metropolitan regions to the Reference Laboratory of Instituto de Salud Publica. METHODS: Antimicrobial susceptibility of all strains was analyzed using traditional (Kirby-Bauer and epsilometry) and automated methods, and complemented with colorimetric, immunochromatographic and molecular (PCR and PFGE) techniques. RESULTS: As a result of the genetic characterization, blaoxa-48 and blaoxa-232 genes were detected, showing the isolates an unusual resistance profile to both carbapenems (ertapenem, imipenem, and meropenem) and cephalosporins (cefepime, cefotaxime, and ceftazidine), as well as piperacillin/ tazobactam and temocillin. Two subtypes were detected by PFGE, with a predominant clone CL-Kpn-Spe-329 (93.8%), with two resistance mechanisms identified: carbapenemase and extended-spectrum β-lactamase (ESBL). CONCLUSION: Due to this epidemiological alert, it is essential the establishment of national guidelines for early detection, surveillance, and control of future outbreaks of OXA-48 like carbapenemases isolates.

Molecular Detection of Drug-Resistance Genes of blaOXA-23-blaOXA-51 and mcr-1 in Clinical Isolates of Pseudomonas aeruginosa.

Pseudomonas aeruginosa has caused high rates of mortality due to the appearance of strains with multidrug resistance (MDR) profiles. This study aimed to characterize the molecular profile of virulence and resistance genes in 99 isolates of P. aeruginosa recovered from different clinical specimens. The isolates were identified by the automated method Vitek2, and the antibiotic susceptibility profile was determined using different classes of antimicrobials. The genomic DNA was extracted and amplified by multiplex polymerase chain reaction (mPCR) to detect different virulence and antimicrobial resistance genes. Molecular typing was performed using the enterobacterial repetitive intergenic consensus (ERIC-PCR) technique to determine the clonal relationship among P. aeruginosa isolates. The drug susceptibility profiles of P. aeruginosa for all strains showed high levels of drug resistance, particularly, 27 (27.3%) isolates that exhibited extensively drug-resistant (XDR) profiles, and the other isolates showed MDR profiles. We detected the polymyxin E (mcr-1) gene in one strain that showed resistance against colistin. The genes that confer resistance to oxacillin (blaOXA-23 and blaOXA-51) were present in three isolates. One of these isolates carried both genes. As far as we know from the literature, this is the first report of the presence of blaOXA-23 and blaOXA-51 genes in P. aeruginosa.

High Frequency of OXA-253-Producing Acinetobacter baumannii in Different Hospitals in Recife, Brazil.

Here, we report the isolation of 31 Acinetobacter baumannii strains producing OXA-253 in a single large Brazilian city. These strains belonged to five different sequence types (STs), including 4 STs not previously associated with blaOXA-253 In all strains, the blaOXA-253 gene was located in a plasmid within a genetic environment similar to what was found previously in Brazil and Italy. The reported data emphasize the successful transmission of the blaOXA-253 gene through a large area and the tendency for this resistance determinant to remain in the A. baumannii population.

Early dissemination of OXA-72-producing Acinetobacter baumannii strain in Colombia: a case report

Nosocomial infections caused by carbapenem-resistant Acinetobacter baumannii isolates have reached epidemic levels in past decades. Currently this microorganism is responsible for outbreaks of difficult eradication and with high mortality rates worldwide. We herein report a rare case of an OXA-72-producing A. baumannii isolate colonizing a 47-year-old male patient with peritonitis due to abdominal stab wound, four years earlier than the first report of this carbapenemase in Acinetobacter pittii in Colombia. Although OXA-72 presents a low prevalence compared with OXA-23, our study demonstrated that A. baumannii isolates carrying the blaOXA-72 gene were present in the hospital environment in Colombia and could act as a reservoir for further spread to other Acinetobacter species, like A. pittii, causing carbapenem-resistance.

Early dissemination of OXA-72-producing Acinetobacter baumannii strain in Colombia: a case report.

Nosocomial infections caused by carbapenem-resistant Acinetobacter baumannii isolates have reached epidemic levels in past decades. Currently this microorganism is responsible for outbreaks of difficult eradication and with high mortality rates worldwide. We herein report a rare case of an OXA-72-producing A. baumannii isolate colonizing a 47-year-old male patient with peritonitis due to abdominal stab wound, four years earlier than the first report of this carbapenemase in Acinetobacter pittii in Colombia. Although OXA-72 presents a low prevalence compared with OXA-23, our study demonstrated that A. baumannii isolates carrying the blaOXA-72 gene were present in the hospital environment in Colombia and could act as a reservoir for further spread to other Acinetobacter species, like A. pittii, causing carbapenem-resistance.

Influence of whole-body washing of critically ill patients with chlorhexidine on Acinetobacter baumannii isolates.

BACKGROUND: Acinetobacter baumannii is 1 of the most important nosocomial pathogens and the causative agent of numerous types of infections, especially in intensive care units (ICUs). Our aim was to evaluate the effect of 2% chlorhexidine gluconate (CHG) whole-body washing of ICU patients on A baumannii in a tertiary care hospital. METHODS: During the 6-month intervention period, 327 patients were subjected to whole-body bath with 2% CHG-impregnated wipes. blaIMP (active on imipenem), blaVIM (Verona integron-encoded metallo-ß-lactamase), and blaoxacillinase (OXA) of A baumannii were typed. Isolates were genotyped by pulsed-field gel electrophoresis. Minimum inhibitory concentrations (MIC) to CHG were determined by the agar dilution method and drug susceptibility determined using the broth microdilution method. Biofilm formation was determined by crystal violet staining. RESULTS: We analyzed 80 isolates during the baseline period and 69 isolates during the intervention period. There was a decrease in the MIC50 and MIC90 values for CHG for isolates (8 mg/L and 16 mg/L, respectively). All isolates typed positive for OXA51-like and 86% typed positive for OXA24-like pulsed-field gel electrophoresis identified 2 main clone types. During the intervention period the frequency of clone A decreased and that of clone B increased. Both clones were OXA24-like positive. CONCLUSIONS: The A baumannii isolates recovered from patients who received body washing with 2% CHG presented with a significant decrease in CHG MIC values associated with a change in clonality correlating with increased biofilm production.