RESUMO
BACKGROUND: We investigated the role of infectious disease consultation (IDC) on therapeutic appropriateness in Gram-negative bloodstream infections (GNBSIs) in a setting with a high proportion of antibiotic resistance. Secondary outcomes were in-hospital mortality and the impact of rapid diagnostic tests (RDTs). METHODS: Retrospective study on hospitalised patients with GNBSIs. Therapy was deemed appropriate if it had the narrowest spectrum considering infection and patients' characteristics. Interventional-IDC (I-IDC) group included patients with IDC-advised first appropriate or last non-appropriate therapy. Time to first appropriate therapy and survival were evaluated by Kaplan-Meier curves. Factors associated with therapy appropriateness were assessed by multivariate Cox proportional-hazard models. RESULTS: 471 patients were included. High antibiotic resistance rates were detected: quinolones 45.5%, third-generation cephalosporins 37.4%, carbapenems 7.9%. I-IDC was performed in 31.6% of patients (149/471), RDTs in 70.7% (333/471). The 7-day probability of appropriate treatment was 91.9% (95% confidence interval [95%CI]: 86.4-95.8%) vs. 75.8% (95%CI: 70.9-80.4%) with and without I-IDC, respectively (p-value = 0.0495); 85.5% (95%CI: 81.3-89.1%) vs. 69.4% (95%CI: 61.3-77.2%) with and without RDTs, respectively (p-value = 0.0023). Compared to RDTs alone, the combination with I-IDC was associated with a higher proportion of appropriate therapies at day 7: 81.9% (95%CI: 76.4-86.7%) vs. 92.6% (95%CI: 86.3-96.7%). At multivariate analysis, I-IDC and RDTs were associated with time to first appropriate therapy [adjusted hazard-ratio 1.292 (95%CI: 1.014-1.647) and 1.383 (95%CI: 1.080-1.771), respectively], with no impact on mortality. CONCLUSIONS: In a setting with a high proportion of antibiotic resistance, IDC and RDTs were associated with earlier prescription of appropriate therapy in GNBSIs, without impact on mortality.
Assuntos
Bacteriemia , Doenças Transmissíveis , Infecções por Bactérias Gram-Negativas , Sepse , Humanos , Antibacterianos/uso terapêutico , Estudos Retrospectivos , Bacteriemia/diagnóstico , Encaminhamento e Consulta , Sepse/tratamento farmacológico , Doenças Transmissíveis/tratamento farmacológicoRESUMO
OBJECTIVES: Using a hybrid long-read sequencing approach, we aimed to fully characterise four extensively-drug resistant (XDR) hypervirulent Klebsiella pneumoniae isolates, one of which represented the first strain isolated in Italy co-expressing NDM-1/5 and OXA-48 carbapenemases. METHODS: Whole-genome sequencing was performed using Illumina and Oxford Nanopore Technology platforms. An assembly pipeline was used to recover the structures both of the chromosome and plasmids. RESULTS: Multilocus sequence typing (MLST) showed that these strains belonged to high-risk sequence types (STs) not commonly circulating in Italy (ST383, ST147 and ST15). The hybrid sequencing approach allowed to characterise three multidrug resistance plasmids, which demonstrated high homology with previously sequenced plasmids, that were simultaneously detected in one ST383 strain carrying, respectively, blaNDM-1, blaNDM-5 and blaOXA-48. CONCLUSION: This is the first report in Italy of new hypervirulent XDR K. pneumoniae clones characterised by co-production of OXA-48, NDM-1 and NDM-5. The discovery of new high-risk clones harbouring multiple mobile elements is a growing problem that poses a great challenge for public health.
Assuntos
Infecções por Klebsiella , Klebsiella pneumoniae , Humanos , Klebsiella pneumoniae/genética , Testes de Sensibilidade Microbiana , Tipagem de Sequências Multilocus , beta-LactamasesRESUMO
In this work we compared the most frequently used Klebsiella pneumoniae typing methods: PFGE, cgMLST and coreSNP. We evaluated the discriminatory power of the three methods to confirm or exclude nosocomial transmission on K. pneumoniae strains isolated from January to December 2017, in the framework of the routine surveillance for multidrug-resistant organisms at the San Raffaele Hospital, in Milan. We compared the results of the different methods to the results of epidemiological investigation. Our results showed that cgMLST and coreSNP are more discriminant than PFGE, and that both approaches are suitable for transmission analyses. cgMLST appeared to be inferior to coreSNP in the K. pneumoniae CG258 phylogenetic reconstruction. Indeed, we found that the phylogenetic reconstruction based on cgMLST genes wrongly clustered ST258 clade1 and clade2 strains, conversely properly assigned by coreSNP approach. In conclusion, this study provides evidences supporting the reliability of both cgMLST and coreSNP for hospital surveillance programs and highlights the limits of cgMLST scheme genes for phylogenetic reconstructions.
Assuntos
Infecção Hospitalar/transmissão , Eletroforese em Gel de Campo Pulsado/métodos , Infecções por Klebsiella/transmissão , Klebsiella pneumoniae/classificação , Tipagem de Sequências Multilocus/métodos , Técnicas de Tipagem Bacteriana , Surtos de Doenças , Farmacorresistência Bacteriana Múltipla , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Klebsiella pneumoniae/genética , Klebsiella pneumoniae/isolamento & purificação , Filogenia , Polimorfismo de Nucleotídeo Único , Vigilância da População , Sensibilidade e Especificidade , Sequenciamento Completo do GenomaRESUMO
Clostridium difficile infection (CDI) became a public health problem for the global spreading of the so-called hypervirulent PCR ribotypes (RTs) 027 and 078, associated with increases in the transmission and severity of the disease. However, especially in Europe, several RTs are prevalent, and the concept of hypervirulence is currently debated. We investigated the toxin and resistance profiles and the genetic relatedness of 312 C. difficile strains isolated in a large Italian teaching hospital during a 5-year period. We evaluated the role of CDI-related antibiotic consumption and infection control practices on the RT predominance in association with their molecular features and transmission capacity. Excluding secondary cases due to nosocomial transmission, RT018 was the predominant genotype (42.4%) followed by RT078 (13.6%), while RT027 accounted for 0.8% of the strains. RT078 was most frequently isolated from patients in intensive care units. Its prevalence significantly increased over time, but its transmission capacity was very low. In contrast, RT018 was highly transmissible and accounted for 95.7% of the secondary cases. Patients with the RT018 genotype were significantly older than those with RT078 and other RTs, indicating an association between epidemic RT and age. We provide here the first epidemiological evidence to consider RT018 as a successful epidemic genotype that deserves more attention in clinical practice.
Assuntos
Clostridioides difficile/classificação , Clostridioides difficile/genética , Infecções por Clostridium/epidemiologia , Infecções por Clostridium/microbiologia , Colite/epidemiologia , Colite/microbiologia , Ribotipagem , Idoso , Idoso de 80 Anos ou mais , Clostridioides difficile/isolamento & purificação , Epidemias , Feminino , Hospitais de Ensino , Humanos , Itália , Masculino , Pessoa de Meia-Idade , Epidemiologia Molecular , Reação em Cadeia da Polimerase , PrevalênciaRESUMO
Microbial identification from blood cultures is essential to institute optimal antibiotic therapy and improve survival possibilities. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has been successfully applied to identify bacteria and yeasts from positive blood cultures broths. The aim of this multicentre study was to evaluate the reliability of the lysis-filtration technique associated with MALDI-TOF MS to directly identify microorganisms from 765 positive blood cultures collected in six Italian hospitals. Overall, 675/765 (78.1%) blood isolates were correctly identified at the species level, with significant differences between Gram-negative and Gram-positive bacteria (92.6%, and 69.8%, respectively). Some difficulties arise in identifying Streptococcus pneumoniae, Staphylococcus aureus, yeasts and anaerobes. The lysis-filtration protocol is a suitable procedure in terms of performance in identifying microorganisms, but it is quite expensive and technically time-consuming since the time of filtration is not regular for all the samples. The application of the MALDI-TOF MS technique to the direct microbial identification from positive blood cultures is a very promising approach, even if more experience must be gained to minimize errors and costs.
Assuntos
Bactérias/isolamento & purificação , Infecções Bacterianas/microbiologia , Técnicas de Tipagem Bacteriana/métodos , Sangue/microbiologia , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Bactérias/química , Bactérias/classificação , Infecções Bacterianas/sangue , HumanosRESUMO
Clostridium difficile infection (CDI), one of the most common hospital-acquired infections, is increasing in incidence and severity with the emergence and diffusion of hypervirulent strains. CDI is precipitated by antibiotic treatment that destroys the equilibrium of the gut microbiota. Human α-defensin 5 (HD5), the most abundant enteric antimicrobial peptide, is a key regulator of gut microbiota homeostasis, yet it is still unknown if C. difficile, which successfully evades killing by other host microbicidal peptides, is susceptible to HD5. We evaluated, by means of viability assay, fluorescence-activated cell sorter (FACS) analysis, and electron microscopy, the antimicrobial activities of α-defensins 1 and 5 against a panel of C. difficile strains encompassing the most prevalent epidemic and hypervirulent PCR ribotypes in Europe (012, 014/020, 106, 018, 027, and 078). Here we show that (i) concentrations of HD5 within the intestinal physiological range produced massive C. difficile cell killing; (ii) HD5 bactericidal activity was mediated by membrane depolarization and bacterial fragmentation with a pattern of damage peculiar to C. difficile bacilli, compared to commensals like Escherichia coli and Enterococcus faecalis; and (iii) unexpectedly, hypervirulent ribotypes were among the most susceptible to both defensins. These results support the notion that HD5, naturally present at very high concentrations in the mucosa of the small intestine, could indeed control the very early steps of CDI by killing C. difficile bacilli at their germination site. As a consequence, HD5 can be regarded as a good candidate for the containment of hypervirulent C. difficile strains, and it could be exploited in the therapy of CDI and relapsing C. difficile-associated disease.
Assuntos
Antibacterianos/farmacologia , Clostridioides difficile/efeitos dos fármacos , alfa-Defensinas/farmacologia , Membrana Celular/efeitos dos fármacos , Clostridioides difficile/genética , Clostridioides difficile/isolamento & purificação , Clostridioides difficile/ultraestrutura , Enterococcus faecalis/efeitos dos fármacos , Enterococcus faecalis/ultraestrutura , Enterocolite Pseudomembranosa/microbiologia , Escherichia coli/efeitos dos fármacos , Escherichia coli/ultraestrutura , Humanos , Potenciais da Membrana/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Viabilidade Microbiana/efeitos dos fármacos , RibotipagemRESUMO
BACKGROUND: ST22-IV is a successful hospital-associated MRSA clone. Due to its known ability to replace other MRSA clones in hospitals, it became a dominant clone in Europe and beyond. So far, there are no studies investigating the relationship between the epidemiological success of MRSA clones and their capacity to withstand commonly encountered stresses. METHODS: We investigated the fitness of ST22-IV in comparison with the replaced clone ST228-I, evaluating its resistance to oxidative stress, autolytic activity, growth at high osmolarity and in acid and alkaline environments and survival under desiccation and heat shock. We also compared their phenotypic characteristics and examined the impact of antibiotic consumption on epidemiological success. RESULTS: Here we demonstrate that the dominance of ST22-IV is linked neither to changes in antibiotic consumption nor to acquisition of additional resistances over time. Strong α-haemolysin activity, the production of ß-haemolysin and the presence of an active agr could partly explain the virulence of ST22-IV previously observed in a murine model of pneumonia. Most importantly, we show that ST22-IV compared with ST228-I, besides retaining susceptibility to most antibiotics over time, has a superior capacity to survive under all stress conditions tested, which bacteria commonly face during their life cycle. CONCLUSIONS: Our results support our hypothesis that ST22-IV has a fitness advantage over ST228-I. This fitness advantage could have allowed ST22-IV to displace ST228-I without acquiring additional resistances and could help explain its epidemic success in hospital settings and its spread in Europe and beyond.
Assuntos
Staphylococcus aureus Resistente à Meticilina/fisiologia , Estresse Fisiológico , Ácidos/toxicidade , Álcalis/toxicidade , Bacteriólise , Europa (Continente)/epidemiologia , Genótipo , Humanos , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Staphylococcus aureus Resistente à Meticilina/genética , Staphylococcus aureus Resistente à Meticilina/crescimento & desenvolvimento , Pressão Osmótica , Estresse Oxidativo , Infecções Estafilocócicas/epidemiologia , Infecções Estafilocócicas/microbiologia , Fatores de Virulência/genéticaRESUMO
The mechanisms governing the epidemiology dynamics and success determinants of a specific healthcare-associated methicillin-resistant S. aureus (HA-MRSA) clone in hospital settings are still unclear. Important epidemiological changes have occurred in Europe since 2000 that have been related to the appearance of the ST22-IV clone. Between 2006 and 2010, we observed the establishment of the ST22-IV clone displacing the predominant Italian clone, ST228-I, in a large Italian university hospital. To investigate the factors associated with a successful spread of epidemic MRSA clones we studied the biofilm production, the competitive behavior in co-culture, the capacity of invasion of the A549 cells, and the susceptibility to infection in a murine model of acute pneumonia of the two major HA-MRSA clones, ST22-IV and ST228-I. We showed that persistence of ST22-IV is associated with its increased biofilm production and capacity to inhibit the growth of ST228-I in co-culture. Compared to ST228-I, ST22-IV had a significantly higher capacity to invade the A549 cells and a higher virulence in a murine model of acute lung infection causing severe inflammation and determining death in all the mice within 60 hours. On the contrary, ST228-I was associated with mice survival and clearance of the infection. ST22-IV, compared with ST228-I, caused a higher number of persistent, long lasting bacteremia. These data suggest that ST22-IV could have exploited its capacity to i) increase its biofilm production over time, ii) maintain its growth kinetics in the presence of a competitor and iii) be particularly invasive and virulent both in vitro and in vivo, to replace other well-established MRSA clones, becoming the predominant European clone.
Assuntos
Staphylococcus aureus Resistente à Meticilina/genética , Infecções Estafilocócicas/microbiologia , Idoso , Animais , Biofilmes , Linhagem Celular Tumoral , Técnicas de Cocultura , Infecção Hospitalar , Hospitais , Humanos , Cinética , Pulmão/microbiologia , Camundongos , Camundongos Endogâmicos C57BL , Pessoa de Meia-Idade , Infecções Estafilocócicas/genética , Fatores de VirulênciaRESUMO
We present three cases of pre-term low-weight infants with suspected necrotizing enterocolitis (NEC) [one eventually recognized as a connatal cytomegalovirus (CMV) infection], microbiologically monitored using a molecular assay detecting bacterial and fungal DNA in blood. The detection of DNA from enteric pathogens in blood was interpreted as a sign of ongoing perforation, and represented a useful complement in the management of the presented cases. Moreover, these cases suggest the opportunity for larger future studies to assess the possible role of a molecular approach in the close monitoring of infants with suspected NEC or with other conditions at-risk for intestinal perforation.
Assuntos
DNA Bacteriano/sangue , Enterobacter/isolamento & purificação , Infecções por Enterobacteriaceae/microbiologia , Enterocolite Necrosante/microbiologia , Doenças do Prematuro/microbiologia , Antibacterianos/uso terapêutico , Infecções por Citomegalovirus/diagnóstico , Infecções por Citomegalovirus/tratamento farmacológico , DNA Bacteriano/isolamento & purificação , Enterobacter/genética , Infecções por Enterobacteriaceae/tratamento farmacológico , Enterocolite Necrosante/tratamento farmacológico , Feminino , Humanos , Recém-Nascido de Baixo Peso , Recém-Nascido , Recém-Nascido Prematuro , Doenças do Prematuro/tratamento farmacológico , Perfuração Intestinal/diagnóstico , Perfuração Intestinal/cirurgia , Masculino , Prole de Múltiplos NascimentosRESUMO
Sepsis, a leading cause of morbidity and mortality throughout the world, is a clinical syndrome with signs and symptoms relating to an infectious event and the consequent important inflammatory response. From a clinical point of view, sepsis is a continuous process ranging from systemic inflammatory response syndrome (SIRS) to multiple-organ-dysfunction syndrome (MODS). Blood cultures are the current "gold standard" for diagnosis, and they are based on the detection of viable microorganisms present in blood. However, on some occasions, blood cultures have intrinsic limitations in terms of sensitivity and rapidity, and it is not expected that these drawbacks will be overcome by significant improvements in the near future. For these principal reasons, other approaches are therefore needed in association with blood culture to improve the overall diagnostic yield for septic patients. These considerations have represented the rationale for the development of highly sensitive and fast laboratory methods. This review addresses non-culture-based techniques for the diagnosis of sepsis, including molecular and other non-culture-based methods. In particular, the potential clinical role for the sensitive and rapid detection of bacterial and fungal DNA in the development of new diagnostic algorithms is discussed.
Assuntos
Infecções Bacterianas/diagnóstico , Sangue/microbiologia , Técnicas de Laboratório Clínico/métodos , Técnicas de Diagnóstico Molecular/métodos , Micoses/diagnóstico , Sepse/diagnóstico , Sepse/microbiologia , Humanos , Sensibilidade e Especificidade , Fatores de TempoRESUMO
Sensitive and specific techniques to detect and identify Mycobacterium tuberculosis directly in clinical specimens are important for the diagnosis and management of patients with tuberculosis (TB). We developed two real-time PCR assays, based on the IS6110 multicopy element and on the senX3-regX3 intergenic region, which provide a rapid method for the diagnosis of mycobacterial infections. The sensitivity and specificity of both assays were established by using purified DNA from 71 clinical isolates and 121 clinical samples collected from 83 patients, 20 of whom were affected by TB. Both assays are accurate, sensitive, and specific, showing a complementary pattern of Mycobacterium recognition: broader for the IS6110-based assay and restricted to the M. tuberculosis complex for the senX3-regX3-based assay. Moreover, the addition of a synthetic DNA calibrator prior to DNA extraction allowed us to measure the efficiency of DNA recovery and to control for the presence of PCR inhibitors. The mycobacterial burden of the clinical samples, as assessed by direct microscopy, correlates with the M. tuberculosis DNA load measured by the senX3-regX3-based assay. In addition, reduced levels of M. tuberculosis DNA load are present in those patients subjected to successful therapy, suggesting a potential use of this assay for monitoring treatment efficacy. Therefore, these assays represent a fully controlled high-throughput system for the evaluation of mycobacterial burden in clinical specimens.