The impact of ageing on the incidence and mortality rate of bloodstream infection: A hospital-based case-cohort study in a tertiary public hospital of Brazil.

OBJECTIVE: Over the past few decades, life expectancy in Brazil has increased from 48 years in 1950s to 76 years in 2017. The aim of this study was to investigate the impact of ageing on: (1) the frequency of hospitalisations due to bloodstream infection (BSI); (2) the incidence of hospital-acquired BSI (H-BSI); (3) the incidence of BSI caused by multidrug-resistant (MDR) agents and (4) the mortality rate of BSI in a public hospital. METHODS: A hospital-based case-cohort study was conducted between 1 December 2013 and 31 December 2015. The data were analysed using multivariable logistic regression. RESULTS: A total of 500 BSI episodes were detected, among 11,102 hospitalizations. The incidence of hospitalisations resulting from BSI was significantly higher in older than younger patients (3.7/100 vs. 2.0/100, p < 0.01). Similarly, the incidence of hospital-acquired BSI was significantly higher in older patients (2.7/100 vs. 0.9/100, p < 0.01). Klebsiella pneumoniae (15.9%), Staphylococcus aureus (14.3%), Escherichia coli (13.1%) and Acinetobacter spp. (12.1%) were the most common agents isolated. MDR agents caused 37.6% of the BSI episodes; enteric Gram-negative bacilli resistant to third- or fourth-generation cephalosporins (9.7%) and carbapenem-resistant Acinetobacter spp. (9.2%) were the most common MDR agents. The following complications were independently associated with ageing: Charlson comorbidity index (OR = 1.16; 95% CI = 1.09-1.24); BSI secondary to urinary tract infection (OR = 2.14; 95% CI = 1.29-3.55); BSI secondary to pneumonia (OR = 1.77; 95% CI = 1.07-2.93) and 30-day mortality following BSI (OR = 2.19; 95% CI = 1.43-3.36). CONCLUSIONS: These data suggest ageing has a significant impact on hospitalisations due to BSI, H-BSI incidence and mortality from BSI in older patients attending a Brazilian public hospital. Age was not significantly associated with MDR-related BSI. These results indicate that age plays an important role in the increase in morbidities and mortality resulting from BSI in Brazil and that with the increased life expectancy observed over recent decades in Brazil, the burden of BSI will be expected to continue to increase. This dynamic needs to be better understood with additional studies.

Colistin resistance emerges in pandrug-resistant Klebsiella pneumoniae epidemic clones in Rio de Janeiro, Brazil.

Klebsiella pneumoniae is an important human pathogen, able to accumulate and disseminate a variety of antimicrobial resistance genes. Resistance to colistin, one of the last therapeutic options for multi-drug-resistant bacteria, has been reported increasingly. Colistin-resistant K. pneumoniae (ColRKp) emerged in two hospitals in Rio de Janeiro state, Brazil in 2016. The aim of this study was to investigate if these ColRKp isolates were clonally related when compared between hospitals, to identify the molecular mechanisms of colistin resistance, and to describe other antimicrobial resistance genes carried by isolates. Twenty-three isolates were successively recovered, and the whole-genome sequence was analysed for 10, each of a different pulsed-field gel electrophoresis (PFGE) type. Although some PFGE clusters were found, none of them included isolates from both hospitals. Half of the isolates were assigned to CC258, three to ST152 and two to ST15. One isolate was pandrug resistant, one was extensively drug resistant, and the others were multi-drug resistant. Colistin resistance was related to mutations in mgrB, pmrB, phoQ and crrB. Eleven new mutations were found in these genes, including two nucleotide deletions in mgrB. All isolates were carbapenem resistant, and seven were associated with carbapenemase carriage (blaKPC-2 in six isolates and blaOXA-370 in one isolate). All isolates had a blaCTX-M, and two had a 16S ribosomal RNA methyltransferase encoding gene (armA and rmtB). ColRKp were composed of epidemic clones, but cross-dissemination between hospitals was not detected. Colistin resistance emerged with several novel mutations amid highly resistant strains, further restricting the number of drugs available and leading to pandrug resistance.