Vinícius Victor Lorenzoni

Phenotypic methods for screening carbapenem-resistant Enterobacteriaceae and assessment of their antimicrobial susceptibility profile

INTRODUCTION: In this study, we used phenotypic methods to screen carbapenem-resistant Enterobacteriaceae (CREs) and evaluated their antimicrobial sensitivity profile. METHODS: One hundred and seventy-eight CREs were isolated at a university hospital in south Brazil in a one-year period. Samples were assessed using disk diffusion tests with inhibitors of β-lactamases such as phenylboronic acid (AFB), cloxacillin (CLOXA), and ethylenediaminetetraacetic acid (EDTA). Strains with differences in zone diameters ≥ 5mm for disks supplemented or not were considered producers of carbapenemases. RESULTS: Klebsiella pneumoniae was the most prevalent CRE, which appeared in 80.3% cases (n = 143). Among clinical materials, the rectal swab was responsible for 43.4% of the isolations (n = 62), followed by urine (18.9%; n = 27). Among the CREs identified in this study, the growth of 56.7% (n = 101) isolates, which were putative producers of Klebsiella pneumoniae carbapenemase (KPC), were inhibited by AFB, whereas 7.3% (n = 13) isolates were inhibited by both AFB and CLOXA and were considered as putative producers of plasmid-mediated AmpC; approximately 3.4% (n = 6) were inhibited by EDTA, which possibly produced metallo-β-lactamase. Lastly, 32.6% (n = 58) cases showed negative results for AFB, CLOXA, and EDTA sensitivity, and represented another class of β-lactamases and/or mechanism of resistance. CONCLUSIONS: Phenotypic screening of CREs is important for clinical laboratories that monitor outbreaks of resistant microbes. Phenotypic tests that use carbapenemase inhibitors and enhancers such as AFB, CLOXA, and EDTA are necessary since they are good screening methods for the detection of carbapenemases.

Increased antimicrobial resistance in Klebsiella pneumoniae from a University Hospital in Rio Grande do Sul, Brazil

INTRODUCTION The spread of multidrug-resistant Gram-negative bacilli is a health threat, limiting therapeutic options and increasing morbimortality rates. METHODS This study aimed to evaluate the antimicrobial susceptibility profile of 1805 Klebsiella pneumoniae isolates collected from Hospital Universitário de Santa Maria between January 2015 and December 2016. RESULTS Resistance to colistin (239.3%), meropenem (74.2%), ciprofloxacin (68%), gentamicin (35.1%), tigecycline (33.9%), imipenem (29.7%), ertapenem (26.8%), and amikacin (21.4%) was found increased. CONCLUSIONS Infection control measures in the hospitals are necessary for reducing the spread of multidrug-resistant microorganisms and preventing efficacy loss of these drugs.

RESISTÊNCIA À COLISTINA EM ISOLADOS DE HEMOCULTURAS DE RECÉM-NASCIDOS ADMITIDOS EM UM HOSPITAL ESCOLA

The objective of this study was to evaluate resistance against colistin in isolates of blood cultures from newborns (NB) admitted in a School Hospital in a 4-year period. The identification tests and antimicrobial susceptibility profiles were performed using automated systems. At the period of this study, 923 blood cultures were positive, 92.09% (850/923) were caused by Gram-positive microorganisms and 7.91% (73/923) by Gram-negative. Of these, two isolates were resistant to colistin: Acinetobacter baumannii and Sphingomonas paucimobilis; and a Pseudomonas aeruginosa isolate showed an intermediate profile to this antimicrobial, also presenting resistance to carbapenems. This profile is worrying since these antimicrobials are the last alternative for the treatment of infections caused by multiresistant Gram-negative bacilli. The results of this study indicate the follow-up of the monitoring of this resistance.

Evaluation of carbapenem-resistant Enterobacteriaceae in a tertiary-level reference hospital in Rio Grande do Sul, Brazil

INTRODUCTION The rapid global spread of carbapenem-resistant Enterobacteriaceae (CRE) is a threat to the health system. METHODS We evaluated the antimicrobial susceptibility profiles of 70 CRE isolated in a tertiary hospital in Brazil between August and December 2015, and determined their resistance mechanisms. RESULTS The most prevalent microorganism was Klebsiella pneumoniae (95.7%); it showed high-level resistance to carbapenems (>98%), with sensitivity to colistin (91.4%) and amikacin (98.6%). The bla KPC gene was detected in 80% of the CRE isolates. CONCLUSIONS Evaluation of bacterial resistance contributes to an appropriate treatment, and the reduction of morbimortality and dissemination of resistance.