Recurrent invasive pneumococcal disease in children: Underlying clinical conditions, and immunological and microbiological characteristics.

Purpose Clinical, immunological and microbiological characteristics of recurrent invasive pneumo-coccal disease (IPD) in children were evaluated, differentiating relapse from reinfection, in order to identify specific risk factors for both conditions. Methods All patients<18 years-old with recurrent IPD admitted to a tertiary-care pediatric center from January 2004 to December 2011 were evaluated. An episode of IPD was defined as the presence of clinical findings of infection together with isolation and/or pneumococcal DNA detection by Real-Time PCR in any sterile body fluid. Recurrent IPD was defined as 2 or more episodes in the same individual at least 1 month apart. Among recurrent IPD, we differentiated relapse (same pneumococcal isolate) from reinfection. Results 593 patients were diagnosed with IPD and 10 patients died. Among survivors, 23 episodes of recurrent IPD were identified in 10 patients (1.7%). Meningitis was the most frequent form of recurrent IPD (10 episodes/4 children) followed by recurrent empyema (8 episodes/4 children). Three patients with recurrent empyema caused by the same pneumococcal clone ST306 were considered relapses and showed high bacterial load in their first episode. In contrast, all other episodes of recurrent IPD were considered reinfections. Overall, the rate of relapse of IPD was 0.5% and the rate of reinfection 1.2%. Five out of 7 patients with rein- fection had an underlying risk factor: cerebrospinal fluid leak (n = 3), chemotherapy treatment (n = 1) and a homozygous mutation in MyD88 gene (n = 1). No predisposing risk factors were found in the remainder. Conclusions recurrent IPD in children is a rare condition associated with an identifiable risk factor in case of reinfection in almost 80% of cases. In contrast, recurrent IPD with pleuropneumonia is usually a relapse of infection

Detection of Streptococcus pneumoniae and Haemophilus influenzae type B by real-time PCR from dried blood spot samples among children with pneumonia: a useful approach for developing countries

Correction https://doi.org/10.1371/journal.pone.0147678Background: Dried blood spot (DBS) is a reliable blood collection method for storing samples at room temperature and easily transporting them. We have previously validated a Real-Time PCR for detection of Streptococcus pneumoniae in DBS. The objective of this study was to apply this methodology for the diagnosis of S. pneumoniae and Haemophilus influenzae b (Hib) in DBS samples of children with pneumonia admitted to two hospitals in Mozambique and Morocco. Methods: Ply and wzg genes of S. pneumoniae and bexA gene of Hib, were used as targets of Real-Time PCR. 329 DBS samples of children hospitalized with clinical diagnosis of pneumonia were tested. Results: Real-Time PCR in DBS allowed for a significant increase in microbiological diagnosis of S. pneumoniae and Hib. When performing blood bacterial culture, only ten isolates of S. pneumoniae and none of Hib were detected (3·0% positivity rate, IC95% 1·4-5·5%). Real-Time PCR from DBS samples increased the detection yield by 4x fold, as 30 S. pneumoniae and 11 Hib cases were detected (12·4% positivity rate, IC95% 9·0-16·5%; P<0·001). Conclusion: Real-Time PCR applied in DBS may be a valuable tool for improving diagnosis and surveillance of pneumonia caused by S. pneumoniae or Hib in developing countries

Biophysical mechanisms of endotoxin neutralization by cationic amphiphilic peptides

Bacterial endotoxins (lipopolysaccharides (LPS)) are strong elicitors of the human immune system by interacting with serum and membrane proteins such as lipopolysaccharide-binding protein (LBP) and CD14 with high specificity. At LPS concentrations as low as 0.3 ng/ml, such interactions may lead to severe pathophysiological effects, including sepsis and septic shock. One approach to inhibit an uncontrolled inflammatory reaction is the use of appropriate polycationic and amphiphilic antimicrobial peptides, here called synthetic anti-LPS peptides (SALPs). We designed various SALP structures and investigated their ability to inhibit LPS-induced cytokine secretion in vitro, their protective effect in a mouse model of sepsis, and their cytotoxicity in physiological human cells. Using a variety of biophysical techniques, we investigated selected SALPs with considerable differences in their biological responses to characterize and understand the mechanism of LPS inactivation by SALPs. Our investigations show that neutralization of LPS by peptides is associated with a fluidization of the LPS acyl chains, a strong exothermic Coulomb interaction between the two compounds, and a drastic change of the LPS aggregate type from cubic into multilamellar, with an increase in the aggregate sizes, inhibiting the binding of LBP and other mammalian proteins to the endotoxin. At the same time, peptide binding to phospholipids of human origin (e.g., phosphatidylcholine) does not cause essential structural changes, such as changes in membrane fluidity and bilayer structure. The absence of cytotoxicity is explained by the high specificity of the interaction of the peptides with LPS

Caracterización de los mecanismos de resistencia de aislamientos clínicos de Pseudomonas aeruginosa no sensibles a carbapenems y factores de riesgo asociados a su adquisición

The epidemiology-related features of antibiotic resistant Pseudomonas aeruginosa strains (Pa) isolated in the University Hospital of Navarra from January 2002 to February 2009 were analyzed. An increase of Pa isolates not susceptible to carbapenems (Pa-nsc) was detected and the profile of antibiotic resistance of these organisms was markedly different from that of carbapenem susceptible Pa (Pasc). Both Pa-nsc and the overall Pa isolates increased their resistance to several antibiotic classes, whereas Pa-sc maintained their level of susceptibility. Phenotypic methods most commonly used for detection of metallo-beta-lactamase producing strains (MBL) including E-test MBL, simple microdilution test, double disk synergy test and disks combined test were compared and found to render 100% sensitivity. The combined disk test using imipenem and EDTA provided the greatest specificity. The susceptibility to doripenem in Pa isolates not susceptible to imipenem and meropenem was analyzed. Depending on the cut-off points established by CLSI, EUCAST and FDA, it was found that 28.6% to 11.9% of the strains not susceptible to imipenem were susceptible to doripenem, while 26.2% to 10.7% of strains not susceptible to meropenem were susceptible to doripenem. The mechanisms of resistance to carbapenems in clinical isolates of Pa-nsc were characterized. The altered expression of the porin OprD was the most common resistance mechanism (87.5%), followed by the overproduction of AmpC (33.3%). Four MBL-producing strains of the VIM-2 family were detected including the first MBL-producing strain sensitive to doripenem (MIC 1 ì/ml). The use of urinary catheter and the consumption of broad-spectrum antibiotics (piperacillin-tazobactam, carbapenems, fluoroquinolones and aminoglycosides) were established as risk factors for the acquisition of Pa-nsc. Exposure to hospital environment and the use of mechanical ventilation were identified as risk factors when the groups under comparison were Pa-nsc isolates versus isolates different from Pa. Finally, a prolonged hospital admission, the isolation of multiresistant Pa, the administration of chemotherapy and the use of immunosuppressive drugs were predictors of mortality attributable to Pa-nsc

Treatment of infections caused by carbapenemase-producing Enterobacterales

Antibiotic resistance is one of the main menaces to public and individual health worldwide. In the last two decades, an increase in the detection of carbapenem-resistant Enterobacterales has been reported. The treatment of infections caused by these strains is a therapeutic challenge. The use of carbapenems may be beneficial depending on MIC value and source of infection. New drugs, with different activity against the different classes of carbapenemases, are developed showing significant benefits

Free thiol group of MD-2 as the target for inhibition of the lipopolysaccharide-induced cell activation

MD-2 is a part of the Toll-like 4 signaling complex with an indispensable role in activation of the lipopolysaccharide (LPS) signaling pathway and thus a suitable target for the therapeutic inhibition of TLR4 signaling. Elucidation of MD-2 structure provides a foundation for rational design of inhibitors that bind to MD-2 and inhibit LPS signaling. Since the hydrophobic binding pocket of MD-2 provides little specificity for inhibitors, we have investigated targeting the solvent-accessible cysteine residue within the hydrophobic binding pocket of MD-2. Compounds with affinity for the hydrophobic pocket that contain a thiol-reactive group, which mediates covalent bond formation with the free cysteine residue of MD-2, were tested. Fluorescent compounds 2-(4'-(iodoacetamido)anilino)naphthalene-6-sulfonic acid and N-pyrene maleimide formed a covalent bond with MD-2 through Cys(133) and inhibited LPS signaling. Cell activation was also inhibited by thiol-reactive compounds JTT-705 originally targeted against cholesterol ester transfer protein and antirheumatic compound auranofin. Oral intake of JTT-705 significantly inhibited endotoxin-triggered tumor necrosis factor alpha production in mice. The thiol group of MD-2 also represents the target of environmental or endogenous thiol-reactive compounds that are produced in inflammation

Pneumococcal Serotypes Causing Acute Otitis Media Among Children in Barcelona (1992–2011): Emergence of the Multiresistant Clone ST320 of Serotype 19A

Background: There is scarce information about changes in serotypes and clonal types of Streptococcus pneumoniae causing acute otitis media (AOM) in recent years, particularly in European countries. Methods: Pneumococcal serotypes and clones from S. pneumoniae strains isolated from children with AOM who were attended at Hospital Sant Joan de Déu, Barcelona (1992 to 2011), were studied. Heptavalent pneumococ- cal conjugate vaccine (PCV7) was introduced in June 2001. We defined 3 periods: prevaccine period 1992 to 2001, early vaccine period 2002 to 2006 and late vaccine period 2007 to 2011. Results: There were 376 pneumococcal strains causing AOM, and 373 (99.2%) of them were serotyped. AOM caused by PCV7 serotypes declined significantly: 161 of 245 (65.7%) episodes in 1992 to 2001 versus 22 of 67 (32.8%) in 2002 to 2006 versus 8 of 61 (13.1%) in 2007 to 2011 P < 0.001. In the last period (2007 to 2011), the potential serotype coverage for the PCV10 was 16.4% and for the PCV13 was 68.9% (P < 0.001). Sero- type 19A increased from 5.7% in 1992 to 2001 to 42.6% in 2007 to 2011 (P < 0.001). Among strains with penicillin minimal inhibitory concentra- tion ≥0.12 μg/mL (n = 241), serotype 19A rose from 2.3% in the first period to 57.9 % in the last period (P < 0.001). The clonal-type ST320 was initially detected in 2005, and in the period 2007 to 2011, the ST320 was found in 72.7% of nonsusceptible serotype 19A isolates. Conclusions: Among children with AOM, a rapid expansion of the mul- tiresistant clone ST320 expressing serotype 19A has been observed in Bar- celona. The implementation of PCV13, which includes this serotype, may decrease the prevalence of AOM and reduce antimicrobial resistance

Direct Identification of Urinary Tract Pathogens from Urine Samples, Combining Urine Screening Methods and Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry

Early diagnosis of urinary tract infections (UTIs) is essential to avoid inadequate or unnecessary empirical antibiotic therapy. Microbiological confirmation takes 24 to 48 h. The use of screening methods, such as cytometry and automated microscopic analysis of urine sediment, allows the rapid prediction of negative samples. In addition, matrix-assisted laser desorption ioniza- tion–time of flight mass spectrometry (MALDI-TOF MS) is a widely established technique in clinical microbiology laboratories used to identify microorganisms. We evaluated the ability of MALDI-TOF MS to identify microorganisms from direct urine samples and the predictive value of automated analyzers for the identification of microorganisms in urine by MALDI-TOF MS. A total of 451 urine samples from patients with suspected UTIs were first analyzed using the Sysmex UF-1000i flow cytometer, an automatic sediment analyzer with microscopy (SediMax), culture, and then processed by MALDI-TOF MS with a simple triple- centrifuged procedure to obtain a pellet that was washed and centrifuged and finally applied directly to the MALDI-TOF MS plate. The organisms in 336 samples were correctly identified, mainly those with Gram-negative bacteria (86.10%). No microor- ganisms were misidentified, and no Candida spp. were correctly identified. Regarding the data from autoanalyzers, the best bac- teriuria cutoffs were 1,000 and 200 U/l for UF-1000i and SediMax, respectively. It was concluded that the combination of a urine screening method and MALDI-TOF MS provided a reliable identification from urine samples, especially in those contain- ing Gram-negative bacteria