Frequency Of Resistant Bacteria Research Articles

Device-Associated Infections in COVID-19 Patients: Frequency of Resistant Bacteria, Predictors and Mortality in Medellín, Colombia.

Increased antimicrobial use during the COVID-19 pandemic has raised concerns about the spread of resistant bacteria. This study analyzed the frequency of device-associated infections (DAI) caused by resistant bacteria, the predictors of these infections, and 30-day all-cause mortality in patients with and without COVID-19. A retrospective cohort study was conducted on DAI patients admitted to the ICU (intensive care unit) in 20 hospitals in Medellin, Colombia (2020-2021). The exposure assessed was the COVID-19 diagnosis, and outcomes analyzed were resistant bacterial infections and 30-day mortality. Clinical and microbiological information was collected from surveillance databases. Statistical analysis included generalized linear mixed-effects models. Of the 1521 patients included, 1033 (67.9%) were COVID-19-positive and 1665 DAI were presented. Carbapenem-resistant Enterobacteriaceae (CRE) infections predominated during the study (n = 98; 9.9%). The patients with COVID-19 had a higher frequency of metallo-beta-lactamase-producing CRE infections (n = 15; 33.3%) compared to patients without the disease (n = 3; 13.0%). Long-stay in the ICU (RR: 2.09; 95% CI: 1.39-3.16), diabetes (RR: 1.73; 95% CI: 1.21-2.49), and mechanical ventilation (RR: 2.13; 95% CI: 1.01-4.51) were CRE infection predictors in COVID-19 patients, with a mortality rate of 60.3%. CRE infections were predominant in COVID-19 patients. In pandemic situations, the strategies to control DAI should be maintained to avoid infections caused by resistant bacteria, such as length of stay in the ICU and duration of mechanical ventilation.

Etiology and Factors Affecting Severe Complications and Mortality of Febrile Neutropenia in Children with Acute Leukemia

Febrile neutropenia (FN) is an important complication that causes high rates of morbidity and mortality in patients with malignancies. We aimed to investigate the etiology, epidemiological distribution and its change over the years, clinical courses, and outcomes of FN in children with acute leukemia. We retrospectively analyzed the demographic data, clinical characteristics, laboratory results, severe complications, and mortality rates of pediatric patients with FN between January 2010 and December 2020. In 153 patients, a total of 450 FN episodes (FNEs) occurred. Eighty-four (54.9%) of these patients were male, the median age of the patients was 6.5 (range: 3-12.2) years, and 127 patients (83%) were diagnosed with acute lymphoblastic leukemia. Fever with a focus was found in approximately half of the patients, and an etiology was identified for 38.7% of the patients. The most common fever focus was bloodstream infection (n=74, 16.5%). Etiologically, a bacterial infection was identified in 22.7% (n=102), a viral infection in 13.3% (n=60), and a fungal infection in 5.8% (n=26) of the episodes. Twenty-six (23.2%) of a total of 112 bacteria were multidrug resistant (MDR) The rate of severe complications was 7.8% (n=35) and the mortality rate was 2% (n=9). In logistic regression analysis, refractory/relapsed malignancies and high C-reactive protein (CRP) at first admission were found to be the most important independent risk factors for mortality. Prolonged neutropenia after chemotherapy, diagnosis of acute myeloid leukemia, identification of fever focus or etiological agents, invasive fungal infections, polymicrobial infections, and need for intravenous immunoglobulin treatment increased the frequency of severe complications. We found that there was no significant change in the epidemiological distribution or frequency of resistant bacteria in our center in the last 10 years compared to previous years. Prolonged duration of fever, relapsed/refractory malignancies, presence of fever focus, and high CRP level were significant risk factors for poor clinical course and outcome.

Pseudolysogeny and sequential mutations build multiresistance to virulent bacteriophages in Pseudomonas aeruginosa.

Coevolution between bacteriophages (phages) and their prey is the result of mutualistic interactions. Here, we show that pseudolysogeny is a frequent outcome of infection by virulent phages of Pseudomonas aeruginosa and that selection of resistant bacterial mutants is favoured by continuous production of phages. We investigated the frequency and characteristics of P. aeruginosa strain PAO1 variants resisting infection by different combinations of virulent phages belonging to four genera. The frequency of resistant bacteria was 10- 5 for single phage infection and 10- 6 for infections with combinations of two or four phages. The genome of 27 variants was sequenced and the comparison with the genome of the parental PAO1 strain allowed the identification of point mutations or small indels. Four additional variants were characterized by a candidate gene approach. In total, 27 independent mutations were observed affecting 14 genes and a regulatory region. The mutations affected genes involved in biosynthesis of type IV pilus, alginate, LPS and O-antigen. Half of the variants possessed changes in homopolymer tracts responsible for frameshift mutations and these phase variation mutants were shown to be unstable. Eleven double mutants were detected. The presence of free phage DNA was observed in association with exclusion of superinfection in half of the variants and no chromosomal mutation could be found in three of them. Upon further growth of these pseudolysogens, some variants with new chromosomal mutations were recovered, presumably due to continuous evolutionary pressure.

Bacteriological analysis in the management of conjunctivitis. Comparison of antibiotic resistance between 1982 and 2008

ObjectiveTo demonstrate the need for bacteriological analysis for the rational treatment of infections of the corneal surface, including conjunctivitis. MethodsThe results of 1970 consecutive bacteriological analyses obtained from 2001 to 2008 in patients with ocular hyperemia and discharge were analyzed and compared with a similar study done in 1982 in the same geographical area. ResultsBacterial growth was obtained in 1044 cases (53%). The most frequent bacteria were Staphylococci spp. (56.6%), followed by Streptococci spp. (21.4%), Haemophili spp. (12.1%), and other Gram-negative bacteria (9.9%). No antibiotic was effective against all the bacteria isolated. The frequency of resistant bacteria against neomycin, tobramycin, erythromycin and gentamicin was significantly increased with respect to the study of 1982. ConclusionsBacteriological analysis of conjunctival specimens is necessary to ensure the choice of an effective antibiotic against bacteria of the ocular surface when the initial treatment fails.

Análisis bacteriológicos en el tratamiento de las conjuntivitis. Comparación de la resistencia a antibióticos entre 1982 y 2008

ObjectiveTo demonstrate the need for bacteriological analysis for the rational treatment of infections of the corneal surface, including conjunctivitis. MethodsThe results of 1,970 consecutive bacteriological analysis obtained from 2001 to 2008 in patients with ocular hyperemia and discharge were analysed and compared with a similar study done in 1982 in the same geographical area. ResultsBacterial growth was obtained in 1,044 cases (53%). The most frequent bacteria were Staphylococci spp. (56.6%), followed by Streptococci spp. (21.4%), Haemophili spp. (12.1%), and other gram-negative bacteria (9.9%). No antibiotic was effective against all the bacteria isolated. The frequency of resistant bacteria against neomycin, tobramycin, erythromycin and gentamicin was significantly increased with respect to the study of 1982. ConclusionsBacteriological analysis of conjunctival specimens are necessary to ensure the choice of an effective antibiotic against bacteria of the ocular surface when the initial treatment fails.

The cost of antibiotic resistance from a bacterial perspective

The emergence, spread and stability of antibiotic resistance in a bacterial population will be determined by several factors including (a) the volume of drug use, (b) the rate of formation of resistant mutants, (c) the biological cost of resistance and (d) the rate and extent of the genetic compensation of the costs. Generally, resistance is associated with a cost, suggesting that the frequency of resistant bacteria might decline when the use of antibiotics is decreased. However, evolution to reduce these costs, without a concomitant loss of resistance, can occur and result in a stabilization of the resistant bacteria in the population. The rate and trajectory of this compensatory evolution is dependent on the bacterial species, the specific resistance mutation and the environmental conditions under which evolution occurs. Copyright 2000 Harcourt Publishers Ltd.

Mercury concentration in the sediment at different gold prospecting sites along the Carmo stream, Minas Gerais, Brazil, and frequency of resistant bacteria in the respective aquatic communities

In Brazil mercury is used indiscriminately at prospecting sites for gold extraction, with a consequent enormous discharge of this metal into the aquatic ecosystem. Mercury concentration was investigated in 1995, 1996 and 1997 in the sediments of ten sites along the Carmo stream, MG, Brazil, almost all of them located in prospecting areas. Analysis of mercury in the sediments of all sampling sites showed that the levels were above the tolerable limit (0.1μg g−1), except for sites P4 (1997), P6 (1995) and P9 (1995 and 1997). The results showed wide mercury contamination in an environment not limited to the active or inactive prospecting areas, but also including sites outside these areas but downstream from them. There was a high incidence of bacteria resistant to mercury in the aquatic communities of the sites under study, ranging from 27.3 to 77.1%, except for P1 (an ecological station upstream from the sites under study) in which all bacteria isolated from water were sensitive. Furthermore, the fall in mercury concentration in the sediment at site P5 was not as marked as at other sites, with a frequency of resistant bacteria of only 27.3%, possibly indicating a slower detoxification. The statistical analysis (Pearson’s correlation = − 0,527) showed that the hypothesis about negative correlation between the incidence of bacterial resistance and the total mercury concentration in this environment is supported. Hence, all these data denote a moderate association between the distribution of resistant bacteria and the presence of mercury compounds.

The population genetics of antibiotic resistance.

Mathematical models are used to ascertain the relationship between the incidence of antibiotic treatment and the frequency of resistant bacteria in the commensal flora of human hosts, as well as the rates at which these frequencies would decline following a cessation of antibiotic use. Recent studies of the population biology of plasmid-encoded and chromosomal antibiotic resistance are reviewed for estimates of the parameters of these models and to evaluate other factors contributing to the fate of antibiotic-resistant bacteria in human hosts. The implications of these theoretical and empirical results to the future of antibacterial chemotherapy are discussed.

Salmon farming and the environment

. The growth of the aquaculture industry and the general awareness of the environment have increased the concern of’ the environmental impact from aquaculture. As fish farms are open systems, all material that is not harvested as fish is released to the environment. The most important effluents are solid particles like feed and faeces, dissolved substances like nutrients and excretion products, and antibacterial agents. The effect of these substances varies with their nature and quantity and with local conditions. Production and biomass of phytoplankton seem to be little influenced. The benthic community beneath and close to the cages is often altered. At poorly flushed sites the sea-bed may be anoxic and methane and hydrogensulphide are released from the sediments. Wild fauna, like fish, otters and birds are attracted to the farms. The respiration and excretion of the fish directly influence water quality. Usually the oxygen tension is somewhat reduced in the net cages, while the concentration of ammonia is elevated in the net. Such conditions are assumed to influence fish growth and health. Most of the antibiotic agents used in fish farming are persistent and may remain in high concentrations in the sediments up to one year after medication. The frequency of resistant bacteria in the sea-bed is normally increased, and there is a temporary drop in sediment metabolism after medication. Wild fish have been found to have high residues of antibiotic agents. The organic loading of the sea-bed, the evolution of resistant bacteria and residues in the wild flsh are considered to be the most severe environmental impact of aquaculture. These are all associated with effluent of large particles, and thus mainly restricted to the site area.