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1.
Int J Mol Sci ; 22(2)2021 Jan 08.
Artículo en Inglés | MEDLINE | ID: mdl-33430070

RESUMEN

The nosocomial opportunistic Gram-negative bacterial pathogen Acinetobacter baumannii is resistant to multiple antimicrobial agents and an emerging global health problem. The polymyxin antibiotic colistin, targeting the negatively charged lipid A component of the lipopolysaccharide on the bacterial cell surface, is often considered as the last-resort treatment, but resistance to colistin is unfortunately increasing worldwide. Notably, colistin-susceptible A. baumannii can also develop a colistin dependence after exposure to this drug in vitro. Colistin dependence might represent a stepping stone to resistance also in vivo. However, the mechanisms are far from clear. To address this issue, we combined proteogenomics, high-resolution microscopy, and lipid profiling to characterize and compare A. baumannii colistin-susceptible clinical isolate (Ab-S) of to its colistin-dependent subpopulation (Ab-D) obtained after subsequent passages in moderate colistin concentrations. Incidentally, in the colistin-dependent subpopulation the lpxA gene was disrupted by insertion of ISAjo2, the lipid A biosynthesis terminated, and Ab-D cells displayed a lipooligosaccharide (LOS)-deficient phenotype. Moreover, both mlaD and pldA genes were perturbed by insertions of ISAjo2 and ISAba13, and LOS-deficient bacteria displayed a capsule with decreased thickness as well as other surface imperfections. The major changes in relative protein abundance levels were detected in type 6 secretion system (T6SS) components, the resistance-nodulation-division (RND)-type efflux pumps, and in proteins involved in maintenance of outer membrane asymmetry. These findings suggest that colistin dependence in A. baumannii involves an ensemble of mechanisms seen in resistance development and accompanied by complex cellular events related to insertional sequences (ISs)-triggered LOS-deficiency. To our knowledge, this is the first study demonstrating the involvement of ISAjo2 and ISAba13 IS elements in the modulation of the lipid A biosynthesis and associated development of dependence on colistin.

2.
Eur J Clin Microbiol Infect Dis ; 38(9): 1765-1771, 2019 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-31214796

RESUMEN

Recent studies show that rectal colonization with low-level ciprofloxacin-resistant Escherichia coli (ciprofloxacin minimal inhibitory concentration (MIC) above the epidemiological cutoff point, but below the clinical breakpoint for resistance), i.e., in the range > 0.06-0.5 mg/L is an independent risk factor for febrile urinary tract infection after transrectal ultrasound-guided biopsy (TRUS-B) of the prostate, adding to the other risk posed by established ciprofloxacin resistance in E. coli (MIC > 0.5 mg/L) as currently defined. We aimed to identify the quinolone that by disk diffusion best discriminates phenotypic wild-type isolates (ciprofloxacin MIC ≤ 0.06 mg/L) of E. coli from isolates with acquired resistance, and to determine the resistance genotype of each isolate. The susceptibility of 108 E. coli isolates was evaluated by ciprofloxacin, levofloxacin, moxifloxacin, nalidixic acid, and pefloxacin disk diffusion and correlated to ciprofloxacin MIC (broth microdilution) using EUCAST methodology. Genotypic resistance was identified by PCR and DNA sequencing. The specificity was 100% for all quinolone disks. Sensitivity varied substantially, as follows: ciprofloxacin 59%, levofloxacin 46%, moxifloxacin 59%, nalidixic acid 97%, and pefloxacin 97%. We suggest that in situations where low-level quinolone resistance might be of importance, such as when screening for quinolone resistance in fecal samples pre-TRUS-B, a pefloxacin (S ≥ 24 mm) or nalidixic acid (S ≥ 19 mm) disk, or a combination of the two, should be used. In a setting where plasmid-mediated resistance is prevalent, pefloxacin might perform better than nalidixic acid.


Asunto(s)
Antibacterianos/farmacología , Farmacorresistencia Bacteriana , Escherichia coli/efectos de los fármacos , Quinolonas/farmacología , Escherichia coli/genética , Humanos , Pruebas de Sensibilidad Microbiana , Fenotipo , Sensibilidad y Especificidad , Infecciones Urinarias/microbiología
3.
PLoS One ; 11(11): e0166527, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27835663

RESUMEN

OBJECTIVES: we assessed the incidence, risk factors and outcome of BSI over a 14-year period (2000-2013) in a Swedish county. METHODS: retrospective cohort study on culture confirmed BSI among patients in the county of Östergötland, Sweden, with approximately 440,000 inhabitants. A BSI was defined as either community-onset BSI (CO-BSI) or hospital-acquired BSI (HA-BSI). RESULTS: of a total of 11,480 BSIs, 67% were CO-BSI and 33% HA-BSI. The incidence of BSI increased by 64% from 945 to 1,546 per 100,000 hospital admissions per year during the study period. The most prominent increase, 83% was observed within the CO-BSI cohort whilst HA-BSI increased by 32%. Prescriptions of antibiotics in outpatient care decreased with 24% from 422 to 322 prescriptions dispensed/1,000 inhabitants/year, whereas antibiotics prescribed in hospital increased by 67% (from 424 to 709 DDD per 1,000 days of care). The overall 30-day mortality for HA-BSIs was 17.2%, compared to 10.6% for CO-BSIs, with an average yearly increase per 100,000 hospital admissions of 2 and 5% respectively. The proportion of patients with one or more comorbidities, increased from 20.8 to 55.3%. In multivariate analyses, risk factors for mortality within 30 days were: HA-BSI (2.22); two or more comorbidities (1.89); single comorbidity (1.56); CO-BSI (1.21); male (1.05); and high age (1.04). CONCLUSION: this survey revealed an alarming increase in the incidence of BSI over the 14-year study period. Interventions to decrease BSI in general should be considered together with robust antibiotic stewardship programmes to avoid both over- and underuse of antibiotics.


Asunto(s)
Bacteriemia/epidemiología , Candidiasis/epidemiología , Infección Hospitalaria/epidemiología , Fungemia/epidemiología , Infecciones por Bacterias Gramnegativas/epidemiología , Infecciones por Bacterias Grampositivas/epidemiología , Anciano , Antibacterianos/uso terapéutico , Bacteriemia/tratamiento farmacológico , Bacteriemia/microbiología , Bacteriemia/mortalidad , Candidiasis/tratamiento farmacológico , Candidiasis/microbiología , Candidiasis/mortalidad , Infecciones Comunitarias Adquiridas , Comorbilidad , Infección Hospitalaria/microbiología , Femenino , Fungemia/tratamiento farmacológico , Fungemia/microbiología , Fungemia/mortalidad , Infecciones por Bacterias Gramnegativas/tratamiento farmacológico , Infecciones por Bacterias Gramnegativas/microbiología , Infecciones por Bacterias Gramnegativas/mortalidad , Infecciones por Bacterias Grampositivas/tratamiento farmacológico , Infecciones por Bacterias Grampositivas/microbiología , Infecciones por Bacterias Grampositivas/mortalidad , Encuestas Epidemiológicas , Humanos , Masculino , Persona de Mediana Edad , Análisis Multivariante , Estudios Retrospectivos , Factores de Riesgo , Análisis de Supervivencia , Suecia/epidemiología
5.
Scand J Infect Dis ; 41(3): 171-81, 2009.
Artículo en Inglés | MEDLINE | ID: mdl-19173129

RESUMEN

The activities of tigecycline and comparative agents on staphylococci and enterococci isolated from patients at general hospital wards (GHWs) and intensive care units (ICUs) at 3 university hospitals in Sweden were investigated. Oxacillin disc diffusion and minimal inhibitory concentration with E-test were used. The presence of mecA, vanA or vanB genes was determined with PCR. Statistically significant higher incidence of clindamycin, fusidic acid, rifampicin and multidrug-resistant CoNS was found at ICUs compared to GHWs. Resistance rates were low among S. aureus. Tigecycline, linezolid and vancomycin were the only agents with high activity against methicillin-resistant S. aureus and multidrug-resistant CoNS. Resistance rates were low among E. faecalis, except for high-level gentamicin-resistant (HLGR) E. faecalis. E. faecium showed high resistance rates to ampicillin, piperacillin/tazobactam and imipenem. The HLGR rates among E. faecium were lower than the rates for E. faecalis. Tigecycline and linezolid were the only drugs with high activity against all enterococci including vancomycin-resistant enterococci. No statistically significant differences in susceptibility rates were found between the ward levels for S. aureus and enterococcal isolates and no statistically significant differences were found between the hospitals.


Asunto(s)
Antibacterianos/farmacología , Enterococcus/efectos de los fármacos , Minociclina/análogos & derivados , Staphylococcus/efectos de los fármacos , Proteínas Bacterianas/genética , Ligasas de Carbono-Oxígeno/genética , Enterococcus/genética , Enterococcus/aislamiento & purificación , Hospitales Universitarios , Humanos , Unidades de Cuidados Intensivos , Resistencia a la Meticilina/genética , Pruebas de Sensibilidad Microbiana , Minociclina/farmacología , Habitaciones de Pacientes , Reacción en Cadena de la Polimerasa , Staphylococcus/genética , Staphylococcus/aislamiento & purificación , Estadísticas no Paramétricas , Suecia , Tigeciclina , Resistencia a la Vancomicina/genética
6.
Int J Med Microbiol ; 299(5): 323-32, 2009 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-19042153

RESUMEN

It has been hypothesized that nosocomial enterococci might have virulence factors that enhance their ability to colonise hospitalised patients. The objectives of this study were to investigate the prevalence of genes encoding 3 virulence factors: aggregation substance (asa1), enterococcal surface protein (esp), and 5 genes within the cytolysin operon (cylA, cylB, cylM, cylL(L), cylL(S)) and cytolysin production in 115 enterococcal clinical isolates (21 Enterococcus faecium and 94 E. faecalis). Adhesion to siliconized latex urinary catheters in relation to presence of esp was analysed in a subset of isolates. The isolates were previously characterised by pulsed-field gel electrophoresis (PFGE). esp was the only virulence gene found in E. faecium. It was found in 71% of the 21 E. faecium isolates. asa1, esp, and the cyl operon were found in 79%, 73% and 13% respectively, of the 94 E. faecalis isolates. There was a complete agreement between presence of the cyl operon and phenotypic cytolysin production. Isolates belonging to a cluster of genetically related isolates carried esp and asa1 more often when compared to unique isolates. No difference was found with respect to cyl genes. E. faecalis isolates adhered with higher bacterial densities than E. faecium. E. faecalis isolates within the same PFGE cluster adhered with similar bacterial densities, but there was no association between adhesion and the presence of esp when isolates within the same cluster were compared. In conclusion, E. faecalis isolates with high-level gentamicin resistance (HLGR) belonging to clusters of genetically related isolates widely distributed in Swedish hospitals, were likely to carry both esp and asa1. Adhesion was not affected by esp.


Asunto(s)
Adhesión Bacteriana , Proteínas Bacterianas/genética , Cateterismo , Enterococcus faecalis/fisiología , Enterococcus faecium/fisiología , Microbiología Ambiental , Factores de Virulencia/genética , Análisis por Conglomerados , Dermatoglifia del ADN , Electroforesis en Gel de Campo Pulsado , Enterococcus faecalis/clasificación , Enterococcus faecalis/genética , Enterococcus faecalis/aislamiento & purificación , Enterococcus faecium/clasificación , Enterococcus faecium/genética , Enterococcus faecium/aislamiento & purificación , Genotipo , Hospitales , Humanos , Suecia
7.
Scand J Infect Dis ; 39(11-12): 1002-12, 2007.
Artículo en Inglés | MEDLINE | ID: mdl-17852944

RESUMEN

A multicentre susceptibility study was performed on staphylococci and enterococci isolated from patients at 3 different ward levels: primary care centres (PCCs), general hospital wards (GHWs) and intensive care units (ICUs), in Denmark, Finland, Norway and Sweden. There was a markedly higher incidence of resistance among CoNS in ICUs compared to GHWs and PCCs. Resistance rates were low among S. aureus isolates and no differences were found between the ward levels. Oxacillin resistance was found among 1.6% of S. aureus and 47% of CoNS isolates. 14% of CoNS and 0.9% of S. aureus isolates were glycopeptide intermediate. The prevalence of E. faecium isolates in this study differed significantly between the ward levels with the lowest prevalence found at PCCs. High level gentamicin resistant (HLGR) enterococci occurred in 11-25% of E. faecium and 6-20% of E. faecalis isolates. The HLGR rate was significantly higher among E. faecalis from hospitalized patients (GHWs and ICUs) compared to patients at PCCs. For enterococcal isolates, no other significant differences in antimicrobial resistance were found between the ward levels. All enterococci were teicoplanin susceptible, but decreased susceptibility to vancomycin was found among 2.0% and 0.6% of the E. faecium and E. faecalis isolates, respectively.


Asunto(s)
Antibacterianos/farmacología , Farmacorresistencia Bacteriana Múltiple , Enterococcus/efectos de los fármacos , Staphylococcus/efectos de los fármacos , Enterococcus/aislamiento & purificación , Europa (Continente) , Unidades Hospitalarias , Hospitales , Humanos , Pruebas de Sensibilidad Microbiana , Staphylococcus/aislamiento & purificación
8.
APMIS ; 113(5): 361-73, 2005 May.
Artículo en Inglés | MEDLINE | ID: mdl-16011663

RESUMEN

Staphylococcus epidermidis often causes foreign-body infections such as those associated with hip prostheses, but the underlying pathogenic mechanisms are not fully understood. We performed spectrophotometry to study the ability of S. epidermidis to bind to immobilised fibrinogen, fibronectin, vitronectin, and collagen. The strains were isolated from infected hip prostheses or from normal flora and the well-known protein-binding strain Staphylococcus aureus Cowan was used as positive control. We also analysed the interaction between neutrophils and a fibrinogen-bound prosthesis-derived strain of S. epidermidisby measuring chemiluminescence to determine the neutrophil oxidative response and binding of annexin V to indicate neutrophil apoptosis. We found that binding of S. epidermidis to extracellular matrix proteins varied under different growth conditions, and that prosthesis isolates adhered better to vitronectin than did strains from normal flora. The oxidative response caused by fibrinogen-bound S. epidermidis was not above the background level, which was in marked contrast to the distinct response induced by fibrinogen-associated S. aureus Cowan. Furthermore, fibrinogen-adhering S. epidermidis retarded neutrophil apoptosis. We conclude that surface-bound S. epidermidis induces only a weak inflammatory response, which in combination with the ability of the adherent bacteria to retard neutrophil apoptosis may contribute to low-grade inflammation and loosening of prostheses.


Asunto(s)
Adhesión Bacteriana , Proteínas de la Matriz Extracelular/metabolismo , Neutrófilos/enzimología , Oxidorreductasas/metabolismo , Infecciones Estafilocócicas/microbiología , Staphylococcus epidermidis/patogenicidad , Apoptosis , Bioensayo , Proteínas de la Matriz Extracelular/química , Fibrinógeno/química , Fibrinógeno/farmacología , Neutrófilos/citología , Neutrófilos/efectos de los fármacos , Staphylococcus epidermidis/química , Virulencia
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