Antimicrobial efficacy in orthopedic device infections is diminished because of bacterial biofilms which express tolerance to antibiotics. Recently, the use of high doses of levofloxacin with rifampin has been recommended for staphylococcal infections. In the present study, we evaluated the efficacy of levofloxacin at doses of 50 mg/kg/day and 100 mg/kg/day (mimicking the usual and high human doses of 500 mg/day and 750 to 1,000 mg/day, respectively) and compared it to that of to linezolid, cloxacillin, vancomycin, and rifampin in a rat tissue cage model of experimental foreign-body infection by Staphylococcus aureus. The antimicrobial efficacy in vitro (by MIC, minimum bactericidal concentration, and kill curves) for logarithmic-and stationary-phase bacteria was compared with the in vivo efficacy. In vitro bactericidal activity at clinically relevant concentrations was reached by all drugs except rifampin and linezolid in the log-phase studies but only by levofloxacin in the stationary-phase studies. The bacterial count decreases from in vivo tissue cage fluids (means) for levofloxacin at 50 and 100 mg/kg/day, rifampin, cloxacillin, vancomycin, linezolid, and controls, respectively, were: ؊1.24, ؊2.26, ؊2.1, ؊1.56, ؊1.47, ؊1.15, and 0.33 (all groups versus controls, P < 0.05). Levofloxacin at 100 mg/kg/day (area under the concentration-time curve/MIC ratio, 234) was the most active therapy (P ‫؍‬ 0.03 versus linezolid). Overall, in vivo efficacy was better predicted by stationary-phase studies, in which it reached a high correlation coefficient even if the rifampin group was excluded (r ‫؍‬ 0.96; P < 0.05). Our results, including in vitro studies with nongrowing bacteria, pharmacodynamic parameters, and antimicrobial efficacy in experimental infection, provide good evidence to support the use of levofloxacin at high doses (750 to 1,000 mg/day), as recently recommended for treating patients with orthopedic prosthesis infections.Patients suffering from orthopedic device infections will have usually undergone surgical interventions and received antibiotic therapies over a long period of time, these being major clinical issues. It is very difficult to eradicate such infections using antibiotics because of the formation of biofilm, a protein matrix including bacteria with reduced metabolism and with tolerance to antimicrobials (2,9,11,38).These infections are frequently caused by Staphylococcus aureus, and rifampin has been shown to be the most effective antimicrobial agent in such cases, in in vitro and experimental studies (26, 48) and in clinical practice (14,15,46). Since this drug should not be given alone due to the development of early bacterial resistance, antibiotic combinations are required. The combination of rifampin and fluoroquinolones has been found to be particularly efficacious and is thus usually recommended (10,14,44).In recent years, the experimental foreign-body infection model developed by Lucet et al. (26) has provided relevant data regarding the antimicrobial efficacy of several antibiotics ...

Pseudomonas savastanoi pv. savastanoi causes olive knot disease, which is present in most countries where olive trees are grown. Although the use of cultivars with low susceptibility may be one of the most appropriate methods of disease control, little information is available from inoculation assays, and cultivar susceptibility assessments have been limited to few cultivars. We have evaluated the effects of pathogen virulence, plant age, the dose/response relationship, and the induction of secondary tumors in olive inoculation assays. Most P. savastanoi pv. savastanoi strains evaluated were highly virulent to olive plants, but interactions between cultivars and strains were found. The severity of the disease in a given cultivar was strongly dependent of the pathogen dose applied at the wound sites. Secondary tumors developed in noninoculated wounds following inoculation at another position on the stem, suggesting the migration of the pathogen within olive plants. Proportion and weight of primary knots and the presence of secondary knots were evaluated in 29 olive cultivars inoculated with two pathogen strains at two inoculum doses, allowing us to rate most of the cultivars as having either high, medium, or low susceptibility to olive knot disease. None of the cultivars were immune to the disease.

The sequence of the gene iaaL of Pseudomonas savastanoi EW2009 was used to design primers for PCR amplification. The iaaL-derived primers directed the amplification of a 454-bp fragment from genomic DNA isolated from 70 strains of P. savastanoi, whereas genomic DNA from 93 non-P. savastanoi isolates did not yield this amplified product. A previous bacterial enrichment in the semiselective liquid medium PVF-1 improved the PCR sensitivity level, allowing detection of 10 to 100 CFU/ml of plant extract. P. savastanoi was detected by the developed enrichment-PCR method in knots from different varieties of inoculated and naturally infected olive trees. Moreover, P. savastanoi was detected in symptomless stem tissues from naturally infected olive plants. This enrichment-PCR method is more sensitive and less cumbersome than the conventional isolation methods for detection of P. savastanoi.Pseudomonas savastanoi and its pathovars savastanoi, fraxini, and nerii incite a disease of olive (Olea europaea L.), ash (Fraxinus excelsior L.), other Oleaceae plants and oleander (Nerium oleander L.) that is characterized by tumorous outgrowths (4,19). This development of knots is dependent on bacterial production of the phytohormone indoleacetic acid (IAA) and cytokinins (3,7,16,18). P. savastanoi can conjugate IAA with lysine to form 3-indoleacetyl-ε-L-lysine (IAA-lysine) (6). The two enzymes involved in IAA biosynthesis are tryptophan monooxygenase, which converts tryptophan to indoleacetamide, and indoleacetamide hydrolase, which catalyzes the conversion of indoleacetamide to IAA (12). The enzyme involved in the conversion of IAA to IAA-lysine is (indole-3-acetyl)-L-lysine synthethase (5). The genes for tryptophan monooxygenase (iaaM), indoleacetamide hydrolase (iaaH), and IAA-lysine synthethase (iaaL) reside on the 52-kb plasmid pIAA1 in the oleander P. savastanoi strain EW2009, and they have been sequenced (3,5,14,20). Sequence analysis revealed that iaaM and iaaH have significant similarity with homologous genes of other plant-associated bacteria (13,20). In contrast, to date, no nucleotide homologies have been found with the iaaL gene.Detection of P. savastanoi is currently based on bacterial isolation followed by pathogenicity tests and biochemical or serological techniques (2,8,17,21). These conventional methods are time-consuming and expensive, requiring bacterial isolation. We used the published sequence of iaaL (14) to design specific primers for amplification of this gene. We report here the development of a new sensitive and specific detection method for P. savastanoi based on amplification of iaaL after a bacterial enrichment. The developed enrichment-PCR assay can be applied to specifically detect low levels of P. savastanoi in inoculated and naturally infected plants.Specificity of the PCR assay. Seventy strains of P. savastanoi isolated from olive, oleander, ash, and jasmine (Jasminus officinalis L.) plants from different countries, 23 outgroup strains, and 70 saprophytic isolates from olive plants were used to te...

Registro de acceso restringido Este recurso no está disponible en acceso abierto por política de la editorial. No obstante, se puede acceder al texto completo desde la Universitat Jaume I o si el usuario cuenta con suscripción. Registre d'accés restringit Aquest recurs no està disponible en accés obert per política de l'editorial. No obstant això, es pot accedir al text complet des de la Universitat Jaume I o si l'usuari compta amb subscripció. Restricted access item This item isn't open access because of publisher's policy. The full--text version is only available from Jaume I University or if the user has a running suscription to the publisher's contents.

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ObjectiveThe aim of this study was to evaluate whether the establishment of a preoperative screening and decolonization protocol for Staphylococcus aureus carriers undergoing total knee arthroplasty (TKA) could decrease the incidence of periprosthetic joint infection (PJI) caused by this microorganism.MethodsWe conducted a retrospective study comparing a control group comprising 400 patients (134 men, and 266 women; mean age: 72.2 ± 6.8 years) who went through surgery between January 2009 and December 2013, with a second intervention group of 403 patients (125 men, and 278 women; mean age: 72.4 ± 6.9 years) in which the protocol of screening and decolonization of S. aureus nasal carriers was applied between January 2014 and December 2016. During this latter period patients were preoperatively screened and, if positive, treated with mupirocin nasal ointment and chlorhexidine soap, for 5 days prior to surgery.ResultsIn the control group, 17 of 400 patients (4.2%) had a SSI, 8 (2%) of them caused by S. aureus and 9 (2.2%) by other microorganisms. In the intervention group 20.6% of patients had a positive S. aureus nasal swab and were treated according to the protocol. 5 of 403 patients (1.2%) in this group had a SSI, 1 (0.2%) due to S. aureus and 4 (1%) to other microorganisms. When comparing surgical-site infection (SSI) rates between the two groups, we found a statistically significant reduction in both global SSI (p = 0.009) and specifically S. aureus SSI (p = 0.02), in the intervention group. No decolonized S. aureus nasal carrier presented a SSI.DiscussionIn patients undergoing TKA a preoperative screening and decolonization protocol for S. aureus nasal carriers, using mupirocin nasal ointment and chlorhexidine soap, is an effective measure to reduce the rate of SSI caused by this microorganism.Level of EvidenceLevel III; Therapeutic Study.

In a large number of cases, the etiology of community-acquired pneumonia (CAP) is not established. Some cases are probably caused byStreptococcus pneumoniae. Transthoracic needle aspiration (TNA) culture has a limited sensitivity which might be improved by antigen detection or gene amplification techniques. We evaluated the capacity of a PCR assay and a latex agglutination test to detectS. pneumoniae in samples obtained by TNA from 95 patients with moderate-to-severe CAP. Latex agglutination and PCR had sensitivities of 52.2 and 91.3%, specificities of 88.7 and 83.3%, positive predictive values of 62.3 and 65.6%, and negative predictive values of 83.3 and 96.5%, respectively, when culture techniques were used as the “gold standard.” When we considered expanded criteria for the diagnosis of pneumococcal pneumonia as a standard for our calculations, latex agglutination and PCR had sensitivities of 53.6 and 89.7%, specificities of 93.0 and 90.0%, positive predictive values of 78.9 and 81.3%, and negative predictive values of 80.3 and 94.7%, respectively. The additional diagnosis provided by the PCR assay compared to latex agglutination was 12.2% (95% confidence interval of the difference from 0.4 to 20.1%). PCR was more sensitive than TNA culture, particularly in patients who had received prior antibiotic therapy (83.3 versus 33.3%). Although PCR is a very sensitive and specific technique, it has not proved to be cost-effective in clinical practice. Conversely, latex agglutination is a fast and simple method whose results might have significant implications for initial antibiotic therapy.