Patients with MVAP identified during the studied period showed similar frequency to those reported in medical literature. Thus, this study corroborated that this is still a relevant medical problem in this hospital. Acinetobacter baumannii and Pseudomonas aeruginosa were the most frequently isolated microorganisms from patients with MVAP. Antimicrobial treatment, empirical or not, are still the main risk factors for the development of multidrug-resistant strains of bacteria. The rate of resistance to antibiotics of Acinetobacter baumannii and Pseudomonas aeruginosa strains isolated from patients with MVAP was higher than those isolated from infected patients without MAVP. Tigecycline and colistin were the only antibiotics fully effective against Acinetobacter baumannii strains isolated in 2011 from patients with MVAP; against Pseudomonas aeruginosa strains, only colistin was fully effective.
As a first national surveillance of Acinetobacter in Cuba, a total of 500 Acinetobacter spp. isolates recovered from 30 hospitals between 2010 and 2012 were studied. Acinetobacter baumannii–calcoaceticus complex accounted for 96.4% of all the Acinetobacter isolates, while other species were detected at low frequency (A. junii 1.6%, A. lwoffii 1%, A. haemolyticus 0.8%, A. soli 0.2%). Resistance rates of isolates were 34–61% to third-generation cephalosporins, 49–50% to β-lactams/inhibitor combinations, 42–47% to aminoglycosides, 42–44% to carbapenems and 55% to ciprofloxacin. However, resistance rates to colistin, doxycycline, tetracycline and rifampin were less than 5%. Among carbapenem-resistant isolates, 75% harboured different blaOXA genes (OXA-23, 73%; OXA-24, 18%; OXA-58, 3%). The blaNDM-1 gene was identified in an A. soli strain, of which the species was confirmed by sequence analysis of 16S rRNA gene, rpoB, rpoB–rpoC and rpoL–rpoB intergenic spacer regions and gyrB. The sequences of blaNDM-1 and its surrounding genes were identical to those reported for plasmids of A. baumannii and A. lwoffi strains. This is the first report of blaNDM-1 in A. soli, together with a high prevalence of OXA-23 carbapenemase for carbapenem resistance in Acinetobacter spp. in Cuba.
The emergence of Klebsiella pneumoniae producing carbapenemase (KPC) has now become a global concern. As a part of a nationwide multicentre surveillance study in Cuba, three K. pneumoniae clinical isolates resistant to carbapenems were detected for a 1-month period (September to October 2011). PCR and sequence analysis revealed that the three strains harboured blaKPC-2. They showed resistance or intermediate susceptibility to expanded-spectrum cephalosporins, other β-lactams, a β-lactam/β-lactamase inhibitor combination, and gentamicin. Two strains were susceptible only to colistin, whereas the other strain showing colistin resistance was susceptible to fluoroquinolones. These blaKPC-2-positive K. pneumoniae strains were classified into ST1271 (CC29), a novel clone harbouring blaKPC-2, and were revealed to be genetically identical by PCR-based DNA fingerprinting. The three patients infected with the KPC-producing K. pneumoniae had common risk factors, and had no overseas travel experience outside Cuba, suggesting local acquisition of the resistant pathogen. This is the first report of a KPC-producing K. pneumoniae in Cuba. Although detection of KPC in Enterobacteriaceae is still rare in Cuba, our finding indicated that KPC-producing bacteria are a global concern and highlighted the need to identify these microorganisms in clinical laboratories.
INTRODUCTION Nosocomial pneumonia associated with use of mechanical ventilators is one of the greatest challenges confronted by intensivists worldwide. The literature associates several bacteria with this type of infection; most common in intensive care units are Acinetobacter baumannii, Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus and some of the Enterobacteriaceae family.OBJECTIVES To identify the causal agents of nosocomial ventilatorassociated pneumonia in patients receiving mechanical ventilation in the intensive care units of Havana's Hermanos Ameijeiras Clinical-Surgical Teaching Hospital in 2011, and to characterize their antibiotic resistance. METHODS A cross-sectional descriptive study was conducted using hospital administrative data of quantitative cultures from positive tracheal aspirates for January through December, 2011. Records were analyzed from 77 intensive care unit patients who developed nosocomial ventilator-associated pneumonia. Variables examined were age and sex, and pathogens identifi ed from culture of tracheal aspirate and related antibiotic susceptibility.RESULTS Species most frequently isolated were: Acinetobacter baumannii in 53 patients (68.8%), Pseudomonas aeruginosa in 34 patients (44.2%), other species of Pseudomonas in 15 patients (19.5%), and Serratia marcescens, Klebsiella pneumoniae, and Escherichia coli in 12 patients each (15.6%). Some patients presented more than one pathogen in concurrent or successive infections. Antimicrobial susceptibility testing found high percentages of resistance to antibiotics in all these pathogens. Least resistance was found to colistin. CONCLUSIONSThe prevalence of antibiotic resistance in bacteria causing nosocomial ventilator-associated pneumonia is of concern. Colistin is the drug of choice among the antibiotics reviewed, but sensitivity to other antibiotics should be assessed to search for more appropriate broad-spectrum antibiotics for treating nosocomial ventilator-associated pneumonia. Our results also suggest the need to strengthen infection control efforts, particularly in intensive care units, and to reassess compliance with quality control procedures. Multidisciplinary research involving microbiologists, epidemiologists, internists and intensivists is needed to fully understand the etiological and resistance patterns observed.
Contribución de los autores:Manuel Medell: caracterización de cepas y redacción del documento. Marcia Hart y María Luisa Batista: recolección de cepas y revisión del manuscrito. ARTÍCULO ORIGINAL Biomédica 2014;34(Supl.
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