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Conventional diagnostic methods for bacterial meningitis are frequently not rapid or sensitive enough to guide initial antimicrobial therapy. Streptococcus pneumoniae is the most frequent and severe cause of community-acquired bacterial meningitis and treatment is complicated by the increasing prevalence of antimicrobial resistance to third-generation cephalosporins. We used a new rapid antigen test in the cerebrospinal fluid and urine of patients with suspected bacterial meningitis, and found it to be highly sensitive and specific for the detection of pneumococci. This test might help guide initial therapy for bacterial meningitis according to the local rates of pneumococcal antimicrobial resistance. [ABSTRACT FROM AUTHOR]

Most attention is given to seasonal influenza and respiratory syncytial virus outbreaks, but the cumulative burden caused by other respiratory viruses (RV) is not widely considered. The aim of the present study is to describe the circulation of RV in the general population during six consecutive seasons from 2006 to 2012 in Catalonia, Spain. Cell culture, immunofluorescence and PCR-based assays were used for the RV laboratory-confirmation and influenza subtyping. Phylogenetic and molecular characterizations of viral haemagglutinin, partial neuraminidase and matrix 2 proteins were performed from a representative sampling of influenza viruses. A total of 6315 nasopharyngeal samples were collected, of which 64% were laboratory-confirmed, mainly as influenza A viruses and rhinoviruses. Results show the significant burden of viral aetiological agents in acute respiratory infection, particularly in the youngest cases. The study of influenza strains reveals their continuous evolution through either progressive mutations or by segment reassortments. Moreover, the predominant influenza B lineage was different from that included in the recommended vaccine in half of the studied seasons, supporting the formulation and use of a quadrivalent influenza vaccine. Regarding neuraminidase inhibitors resistance, with the exception of the 2007/08 H275Y seasonal A(H1N1) strains, no other circulating influenza strains carrying known resistance genetic markers were found. Moreover, all circulating A(H1N1)pdm09 and A(H3N2) strains finally became genetically resistant to adamantanes. A wide knowledge of the seasonality patterns of the RV in the general population is well-appreciated, but it is a challenge due to the unpredictable circulation of RV, highlighting the value of local and global RV surveillance., (Copyright © 2016 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.)

Objectives: To investigate the potential relationship between quinolone resistance and biofilm production in a collection of Salmonella enterica clinical isolates and in S. enterica serovar Typhimurium serial mutants with increasing resistance to ciprofloxacin., Methods: Nalidixic acid susceptibility and biofilm formation were assessed in a collection of 122 S. enterica clinical isolates. An in vitro quinolone-resistant mutant, 59-64, was obtained from a biofilm-producing and quinolone-susceptible clinical isolate, 59-wt, in a multistep selection process after increasing ciprofloxacin concentrations. The quinolone resistance mechanisms [target gene and multidrug resistance (MDR) regulatory mutations, MICs of several antibiotics, cell envelope protein analysis, real-time PCR and ciprofloxacin accumulation] were characterized for mutant strains. In addition, analysis of fitness, biofilm formation, rdar morphotype and expression of biofilm-related genes by real-time PCR were also determined., Results: Nalidixic acid-susceptible S. enterica strains were more prevalent in producing biofilm than the resistant counterparts. Strain 59-64 acquired five target gene mutations and showed an MDR phenotype. AcrAB and acrF overexpression were ruled out, whereas TolC did show increased expression in 59-64, which, in addition, accumulated less ciprofloxacin. Consistently, increased ramA expression was seen in 59-64 and attributed to a mutation within its promoter. Reduced biofilm production related to diminished csgB expression as well as reduced fitness was seen for 59-64, which was unable to form the rdar morphotype., Conclusions: Quinolone resistance acquisition may be associated with decreased production of biofilm due to lower csgB expression. Efflux, biofilm production and fitness seem to be interrelated., (© The Author 2014. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)

The objective of this study was to determine whether the prevalence of Pneumocystis jirovecii dihydropteroate synthase (DHPS) gene mutations has changed since the introduction of combined antiretroviral therapy (cART) and whether the mutations are associated with poor outcome in Spanish HIV-1-infected patients with Pneumocystis pneumonia (PcP). We studied 167 PcP episodes in HIV-1-infected patients diagnosed during the pre-cART (1989-1995) and cART (2001-2004) periods. Molecular genotyping of DHPS was successfully performed in 98 patients (43 pre-cART and 55 cART). Seventeen patients (17/98, 17%; 95% confidence interval [CI], 10-25%) had mutations in the DHPS gene: 14 patients (14/43, 33%; 95% CI, 19-49%) from the pre-cART period and 3 patients (3/55, 5.5%; 95% CI, 1.3-16%) from the cART period (P < 0.01). In the multivariate analysis, the pre-cART period, previous PcP prophylaxis with sulfa drugs, and homosexuality as an HIV risk factor were found to be associated with a higher risk of presenting DHPS mutations. Overall, 95% of patients were treated with trimethoprim and sulfamethoxazole (TMP-SMX). In-hospital mortality was similar in patients with (out) mutations (6% versus 11%, P = 0.84). DHPS gene mutations were more common during the pre-cART period and were associated with previous sulfa exposure and homosexuality. However, their presence did not worsen prognosis of PcP. The response to TMP-SMX with therapeutic doses was successful in most cases.

This study evaluated the daptomycin activity against two methicillin-resistant Staphylococcus epidermidis (MRSE) clinical isolates with different vancomycin susceptibilities: MRSE-375, with a vancomycin MIC of 2 microg/ml, and NRS6, a glycopeptide-intermediate S. epidermidis (GISE) strain with a vancomycin MIC of 8 microg/ml. The in vivo activity of daptomycin at two different doses (standard dose [SD-daptomycin], 6 mg/kg of body weight/day intravenously [i.v.]; high dose [HD-daptomycin], 10 mg/kg/day i.v.) was evaluated in a rabbit model of infective endocarditis and compared with that of a standard dose of vancomycin (SD-vancomycin; 1 g i.v. every 12 h) for 2 days. For the MRSE-375 strain, high-dose vancomycin (HD-vancomycin; 1 g i.v. every 6 h) was also studied. For MRSE-375, SD- and HD-daptomycin therapy sterilized significantly more vegetations than SD-vancomycin therapy (9/15 [60%] and 11/15 [73%] vegetations, respectively, versus 3/16 [19%] vegetations; P = 0.02 and P = 0.002, respectively). HD-daptomycin sterilized more vegetations than HD-vancomycin (11/15 [73%] versus 5/15 [33%] vegetations; P = 0.03) and was more effective than SD- and HD-vancomycin in reducing the density of bacteria in valve vegetations (0 log(10) CFU/g vegetation [interquartile range {IQR}, 0 to 1 log(10) CFU/g vegetation] versus 2 log(10) CFU/g vegetation [IQR, 2 to 2 log(10) CFU/g vegetation] and 2 log(10) CFU/g vegetation [IQR, 0 to 2.8 log(10) CFU/g vegetation]; P = 0.002 and P = 0.01, respectively). For the NRS6 strain, SD- and HD-daptomycin were significantly more effective than vancomycin in reducing the density of bacteria in valve vegetations (3.7 log(10) CFU/g vegetation [IQR, 2 to 6 log(10) CFU/g vegetation] versus 7.1 log(10) CFU/g vegetation [IQR, 5.2 to 8.5 log(10) CFU/g vegetation]; P = 0.02). In all treatment arms, isolates recovered from vegetations remained susceptible to daptomycin and vancomycin and had the same MICs. In conclusion, daptomycin at doses of 6 mg/kg/day or 10 mg/kg/day is more effective than vancomycin for the treatment of experimental endocarditis due to MRSE and GISE.

From 27 April to 16 December 2009, we analyzed the hemagglutinin gene sequence of 2009 pandemic influenza A (H1N1) virus in 189 respiratory specimens. We only found the D225G mutation in 3 severe cases. However, it was not found in samples from other cases with or without clinical criteria of severity. The biologic significance of this mutation remains still unclear., (Copyright 2010 Elsevier Inc. All rights reserved.)

Background: Nalidixic acid resistance among Salmonella Typhimurium clinical isolates has steadily increased, whereas the level of ciprofloxacin resistance remains low. The main objective of this study was to characterize the fluoroquinolone resistance mechanisms acquired in a S. Typhimurium mutant selected with ciprofloxacin from a susceptible isolate and to investigate its invasion ability., Methodology/principal Findings: Three different amino acid substitutions were detected in the quinolone target proteins of the resistant mutant (MIC of ciprofloxacin, 64 microg/ml): D87G and G81C in GyrA, and a novel mutation, E470K, in ParE. A protein analysis revealed an increased expression of AcrAB/TolC and decreased expression of OmpC. Sequencing of the marRAB, soxRS, ramR and acrR operons did not show any mutation and neither did their expression levels in a microarray analysis. A decreased percentage of invasion ability was detected when compared with the susceptible clinical isolate in a gentamicin protection assay. The microarray results revealed a decreased expression of genes which play a role during the invasion process, such as hilA, invF and the flhDC operon. Of note was the impaired growth detected in the resistant strain. A strain with a reverted phenotype (mainly concerning the resistance phenotype) was obtained from the resistant mutant., Conclusions/significance: In conclusion, a possible link between fluoroquinolone resistance and decreased cell invasion ability may exist explaining the low prevalence of fluoroquinolone-resistant S. Typhimurium clinical isolates. The impaired growth may appear as a consequence of fluoroquinolone resistance acquisition and down-regulate the expression of the invasion genes.

This study evaluated the activity of daptomycin combined with either gentamicin or rifampin against three methicillin-resistant Staphylococcus aureus (MRSA) clinical isolates in vitro and one isolate in vivo against a representative strain (MRSA-572). Time-kill experiments showed that daptomycin was bactericidal against these strains at concentrations over the MIC. Daptomycin at sub-MIC concentrations plus gentamicin at 1x and 2x the MIC yielded synergy, while the addition of rifampin at 2 to 4 microg/ml resulted in indifference (two strains) or antagonism (one strain). The in vivo activity of daptomycin (6 mg/kg of body weight once a day) was evaluated +/- gentamicin (1 mg/kg intravenously [i.v.] every 8 h [q8h]) or rifampin (300 mg i.v. q8h) in a rabbit model of infective endocarditis by simulating human pharmacokinetics. Daptomycin plus gentamicin (median, 0 [interquartile range, 0 to 2] log10 CFU/g vegetation) was as effective as daptomycin alone (0 [0 to 2] log10 CFU/g vegetation) in reducing the density of bacteria in valve vegetations (P = 0.83), and both were more effective than daptomycin plus rifampin (3 [2 to 3.5] log10 CFU/g vegetation; P < 0.05) for the strain studied. In addition, daptomycin sterilized a ratio of vegetations that was similar to that of daptomycin plus gentamicin (10/15 [67%] versus 9/15 [60%]; P = 0.7), and both regimens did so more than daptomycin plus rifampin (3/15 [20%]; P = 0.01 and P = 0.02, respectively). No statistical difference was noted between daptomycin plus gentamicin and daptomycin alone for MRSA treatment. In the combination arm, all isolates from vegetations remained susceptible to daptomycin, gentamicin, and rifampin. Sixty-one percent of the isolates (8/13) acquired resistance to rifampin during monotherapy. In the daptomycin arm, resistance was detected in only one case, in which the daptomycin MIC rose to 2 microg/ml among the recovered bacteria. In conclusion, the addition of gentamicin or rifampin does not enhance the effectiveness of daptomycin in the treatment of experimental endocarditis due to MRSA.

Introduction: The objective of this investigation was to identify the mechanism of decreased susceptibility to gentamicin in a Salmonella clinical isolate, leading to the detection of a aminoglycoside acetyltransferase gene found in a class 1 integron., Methods: A multidrug-resistant Salmonella strain was recovered from feces of a traveler to Egypt. The antimicrobial susceptibility test to 12 antimicrobial agents was performed with the Kirby-Bauer method. The presence of class 1 integron was determined by PCR. The amplified product was recovered and sequenced in order to establish the genes carried. In addition, susceptibility to gentamicin C1a, gentamicin C1, sisomicin, neomycin, dibekacin, kanamycin, tobramycin, amikacin, netilmicin, apramycin, dactimicin, spectinomycin, streptomycin, lividomycin and butirosin, was established. The Champion pET101 Directional TOPO Expression Kit was used to clone and express the aac(3)-I gene., Results: The isolate was identified as Salmonella enterica serovar Haifa, showing resistance to nalidixic acid, tetracycline and decreased susceptibility to gentamicin. One integron with a size circa 1,500 bp, encoding an aac(3)-Id plus aadA7 genes was observed. The analysis of the susceptibility to different aminoglycosides in the E. coli TOP10F' transformed with the vector carrying aac(3)-Id gene showed resistance to gentamicin C1a, gentamicin C1, and dactimicin, in accordance with the presence of this enzyme but, was susceptible to sisomicin. The homology of the amino acid and nucleotide sequences with the AAC(3)-Id enzyme was of 100%., Conclusion: The presence of the AAC(3)-Id enzyme was described for the first time in a S. Haifa.

The incidence of Pneumocystis jirovecii pneumonia (PCP) in HIV-infected patients has decreased thanks to sulfa prophylaxis and combined antiretroviral therapy. The influence of P. jirovecii dihydropteroate synthase (DHPS) gene mutations on survival is controversial and has not been reported in Spain. This prospective multicenter study enrolled 207 HIV-infected patients with PCP from 2000 to 2004. Molecular genotyping was performed on stored specimens. Risk factors for intensive care unit (ICU) admission and mortality were identified using a logistic regression model. Seven patients (3.7%; 95% confidence interval [CI], 1.5-7.5%) had DHPS mutations. Overall mortality was 15% (95% CI, 10-21%), rising to 80% (95% CI, 61-92%) in patients requiring mechanical ventilation. None of the patients with DHPS mutants died, nor did they need ICU admission or mechanical ventilation. PaO(2) <60 mm Hg at admission was a predictor of ICU admission (P = 0.01), and previous antiretroviral therapy predicted non-ICU admission (P = 0.009). PaO(2) <60 mm Hg at admission and ICU admission during the 1st week were predictors of mortality (P = 0.03 and P < 0.001, respectively). The prevalence of DHPS mutants in Spain is low and is not associated with a worse outcome. Severe respiratory failure at admission is the strongest predictor of PCP outcome.

Daptomycin is a lipopeptide antibiotic with potent in vitro activity against gram-positive cocci, including Staphylococcus aureus. This study evaluated the in vitro and in vivo efficacies of daptomycin against two clinical isolates: methicillin-resistant S. aureus (MRSA) 277 (vancomycin MIC, 2 microg/ml) and glycopeptide-intermediate S. aureus (GISA) ATCC 700788 (vancomycin MIC, 8 microg/ml). Time-kill experiments demonstrated that daptomycin was bactericidal in vitro against these two strains. The in vivo activity of daptomycin (6 mg/kg of body weight every 24 h) was evaluated by using a rabbit model of infective endocarditis and was compared with the activities of a high-dose (HD) vancomycin regimen (1 g intravenously every 6 h), the recommended dose (RD) of vancomycin regimen (1 g intravenously every 12 h) for 48 h, and no treatment (as a control). Daptomycin was significantly more effective than the vancomycin RD in reducing the density of bacteria in the vegetations for the MRSA strains (0 [interquartile range, 0 to 1.5] versus 2 [interquartile range, 0 to 5.6] log CFU/g vegetation; P = 0.02) and GISA strains (2 [interquartile range, 0 to 2] versus 6.6 [interquartile range, 2.0 to 6.9] log CFU/g vegetation; P < 0.01) studied. In addition, daptomycin sterilized more MRSA vegetations than the vancomycin RD (13/18 [72%] versus 7/20 [35%]; P = 0.02) and sterilized more GISA vegetations than either vancomycin regimen (12/19 [63%] versus 4/20 [20%]; P < 0.01). No statistically significant difference between the vancomycin HD and the vancomycin RD for MRSA treatment was noted. These results support the use of daptomycin for the treatment of aortic valve endocarditis caused by GISA and MRSA.

Fifty million people are estimated to travel from industrial countries to the tropics annually. In spite of exhaustive studies and widely different diagnosis among returned patients, some cases of febrile illnesses remain without an etiological diagnosis, suggesting that these cases could be due to viral respiratory tract infections. From August 2005 to October 2006, 118 febrile patients without a specific diagnosis in their first visit at the Center for International Health of the Hospital Clínic of Barcelona were included. In all of them, in order to study respiratory viruses, a nasopharyngeal swab was collected. Clinical and radiological features and epidemiological data, as well as other samples for microbiologic studies, were also collected during consultation. Based on the physician's judgment at the time of consultation, patients were classified into four groups: respiratory symptoms (62%), febrile syndrome with nonspecific symptoms (24%), digestive symptoms (10%), and patients presenting both respiratory and digestive symptoms (4%). A pathogen microorganism was detected in 61 patients (52%). Respiratory viruses were detected in 44 out of 118 (37%) travelers included in the study, representing 56% of the patients with respiratory symptoms. The most frequently viruses detected were influenza virus (38%), rhinovirus (23%), adenovirus (9%), and respiratory syncytial virus (9%). Respiratory viruses have been shown to play an important role in imported fever. In light of the fact that international tourism is an increasing phenomenon, new strategies to prevent the spread of respiratory viruses should be considered, specially for influenza when a vaccine is available.

Community-acquired pneumonia (CAP) is a serious lower respiratory tract infection associated with significant morbidity and mortality in immunocompromised patients. The present study evaluated the clinical spectrum of CAP in immunocompromised hosts and the role of respiratory viruses, as well as the yield of viral diagnostic methods. Conventional microbiological tests were routinely performed in immunocompromised patients with CAP. Nasopharyngeal swabs were processed for respiratory viruses by indirect immunofluorescence assay, cell culture and PCR. Four groups were defined according to aetiology of CAP, as follows: group 1 (nonviral), group 2 (mixed, nonviral and viral), group 3 (only viral) and group 4 (unknown aetiology). Over a 1-yr period, 92 patients were included. An aetiological diagnosis was achieved in 61 (66%) patients: 38 (41%), group 1; 12 (13%), group 2; and 11 (12%), group 3. The most frequent pathogen detected was Streptococcus pneumoniae (n = 29, 48%), followed by rhinovirus (n = 11, 18%). PCR identified 95% of respiratory viruses. Clinical characteristics could not reliably distinguish among the different aetiological groups. Respiratory viruses represent a substantial part of the aetiologies of community-acquired pneumonia in immunocompromised patients and its routine assessment through PCR in nasopharyngeal swabs should be considered in the clinical care of these patients.

The aims of the study were to evaluate the incidence and the clinical implications of human herpesvirus (HHV)-7 primary infection in patients undergoing kidney transplantation and the probable interactions between the three beta-herpesviruses (cytomegalovirus [CMV], HHV-6, and HHV-7). Sixty kidney transplant recipients had sequential plasma and whole blood samples collected prior to transplantation and at 7, 14, 21, 28, 45, 60, 75, 90, and 180 days posttransplantation. We used indirect immunofluorescence assays to detect HHV-7 immunoglobulin (Ig) G antibodies in plasma and quantitative real-time polymerase chain reaction to assess CMV, HHV-6 and HHV-7 viral loads. Sixteen out of 60 patients (27%) did not show HHV-7 IgG antibodies prior to transplantation and they were selected for this study. Whereas 3 (18.75%) out of the 16 HHV-7 seronegative patients seroconverted after transplantation, only one patient (6%) had a high HHV-7 viral load from the seventh day posttransplantation in consecutive blood samples during follow-up without clinical manifestations. In our study, the incidence of posttransplant HHV-7 primary infection was low and asymptomatic.

The efficacy of telavancin, a novel lipoglycopeptide, was evaluated in experimental endocarditis in rabbits using two clinical isolates of glycopeptide-intermediate Staphylococcus aureus: ATCC 700788 and HIP 5836. Infected rabbits were treated for 2 days with telavancin (10 mg/kg of body weight once daily intravenously) or vancomycin (1 g twice daily intravenously), administered with a computer-controlled infusion pump system simulating human serum kinetics. Vegetations were harvested at 16 h postinoculation in the control group and at the end of treatment in the drug-treated group. For ATCC 700788, MICs and minimal bactericidal concentrations (MBCs), respectively, were 1 mg/liter and 4 mg/liter for telavancin and 8 mg/liter and 128 mg/liter for vancomycin. For HIP 5836, MICs and MBCs, respectively, were 4 mg/liter and 8 mg/liter for telavancin and 8 mg/liter and 128 mg/liter for vancomycin. Peak and trough levels were 90 microg/ml and 6 microg/ml, respectively, for telavancin and 46 microg/ml and 6 microg/ml, respectively, for vancomycin. In glycopeptide-intermediate S. aureus ATCC 700788, telavancin sterilized 6 of 16 vegetations (37%), whereas vancomycin sterilized 4 of 20 (20%) (P = 0.29) compared with 0 of 17 in the control group. In HIP 5836 experiments, telavancin and vancomycin sterilized 5 of 16 (31%) and 1 of 15 (7%) vegetations (P = 0.17), respectively, compared with none in the control group. Telavancin reduced vegetation titers by 2.0 and 2.3 logs greater than vancomycin for the ATCC 700788 (4.6 [2.0 to 5.8] versus 6.6 [2.0 to 6.9] log CFU/g vegetation; P = 0.05) and HIP 5836 (4.4 [2.0 to 7.4] versus 6.7 [4.5 to 8.7] log CFU/g vegetation; P = 0.09) strains, respectively; these differences did not reach statistical significance. All isolates from vegetations remained susceptible to telavancin after therapy. The results suggest that telavancin may be an effective treatment for endocarditis caused by glycopeptide-intermediate S. aureus.

Background: The role of viruses in community-acquired pneumonia may have been previously underestimated. We aimed to study the incidence and clinical characteristics of community-acquired pneumonia (CAP) due to respiratory viruses in adults adding PCR to routine conventional laboratory tests., Methods: Consecutive adult patients diagnosed of CAP from January 2003 to March 2004 were included. Conventional tests including cultures of blood, sputum, urine antigen detection of Streptococcus pneumoniae and Legionella pneumophila, and paired serologies were routinely performed. Nasopharyngeal swabs were processed for study of respiratory viruses through antigen detection by indirect immunofluorescence assay, isolation of viruses in cell culture and detection of nucleic acids by two independent multiplex RT-PCR assays. According to the aetiology, patients were categorized in 4 groups: group 1, only virus detected; group 2, only bacteria detected; group 3, viral and bacterial; and group 4, unkown aetiology., Results: Of 340 patients diagnosed with CAP, 198 had nasopharyngeal swabs available and were included in this study. Aetiology was established in 112 (57%) patients: group 1, n=26 (13%); group 2, n=66 (33%); group 3, n=20 (10%). The most common aetiological agent was S. neumoniae (58 patients, 29%), followed by respiratory viruses (46 patients, 23%). Forty-eight respiratory viruses were identified: influenza virus A (n=16), respiratory syncytial virus A (n=5), adenovirus (n=8), parainfluenza viruses (n=5), enteroviruses (n=1), rhinoviruses (n=8) and coronavirus (n=5). There were two patients coinfected by two respiratory viruses. Serology detected 6 viruses, immunofluorescence 8, viral culture 12, and PCR 45. For the viruses that could be diagnosed with conventional methods, the sensitivity and specificity of RT-PCR was 85% and 92%, respectively. The only clinical characteristic that significantly distinguished viral from bacterial aetiology was a lower number of leukocytes (P=0.004)., Conclusion: PCR revealed that viruses represent a common aetiology of CAP. There is an urgent need to reconsider routine laboratory tests for an adequate diagnosis of respiratory viruses, as clinical characteristics are unable to reliably distinguish viral from bacterial aetiology.

The prevalence of 31 virulence factors was analyzed among nalidixic acid-susceptible and -resistant Escherichia coli strains from phylogenetic group B2. Hemolysin, cytotoxic necrotizing factor 1, and S and F1C fimbriae genes were less prevalent among nalidixic acid-resistant E. coli strains. Quinolone resistance may be associated with a decrease in the presence of some virulence factors.

Amikacin-resistant Escherichia coli strains are isolated rarely from clinical samples. In the present study, investigation of an amikacin-resistant clinical isolate of E. coli demonstrated the presence of two class 1 integrons carrying the aacA4 gene plus the aacA7 gene, and the dfrA17 gene plus the aadA5 gene, respectively. Resistance to amikacin in this E. coli isolate was related to the presence of both aacA4 and aacA7.

Setting: Bata and Malabo districts, Equatorial Guinea, 1 March 1999 to 28 February 2001., Objective: To study the molecular epidemiology of tuberculosis (TB)., Results: During the study period, 429 patients were diagnosed with TB in the Bata and Malabo districts. A positive culture was obtained in 206 (48%) TB patients, with RFLP analysis being performed in 185 (89.8%). Ninety-two different patterns were identified. Single patterns were found in 71 strains (38.3%) and the remaining 114 strains (61.6%) were classified into 21 clusters (of 2 to 25 patients). In addition, 37 of the typing strains were resistant to one or more anti-tuberculosis drugs, and 30 were included in clusters (81%), with 21 low level isoniazid (MIC < or = 1 microg/ml) resistance strains in the same cluster. Statistical analysis showed that resistance to anti-tuberculosis drugs (OR 3.1; 95% CI 1.2-7.6; P = 0.014), and positive smear results (4+ grade smear) (OR 4.3; 95% CI 1.5-12; P = 0.005), were significantly more frequent among patients with clustered strains. No epidemiological links were related to clustering., Conclusions: The level of clustering (61.6%) observed suggests a high degree of recent transmission and a predominance of determined patterns of Mycobacterium tuberculosis strains among the population of Equatorial Guinea.

The aim of this work was to determine whether diazepam could induce the multiple antibiotic resistance (Mar) phenotype in Klebsiella pneumoniae and Escherichia coli strains. The Mar phenotype is characterized by decreased susceptibility to multiple antibiotics due to the loss of porins and/or increased expression of active efflux systems. The effect of subinhibitory concentrations of diazepam on the susceptibility of different antimicrobial agents, outer-membrane protein expression and norfloxacin intracellular accumulation was studied. The results revealed that diazepam concentrations equal or twice adult dosage induced the same Mar phenotype as two well known E. coli marRAB inducers, sodium salicylate and sodium benzoate. Susceptibility to norfloxacin in a K. pneumoniae clinical isolate and E. coli strain Ag100 decreased due to enhanced active efflux and loss of porin expression. A decreased susceptibility to chloramphenicol, tetracycline, nalidixic acid and beta-lactam antibiotics was also observed. In conclusion, like sodium salicylate or sodium benzoate, diazepam may induce the Mar phenotype.

Conventional antifungal therapy for fungal endocarditis has been associated with a poor cure rate. Therefore, combined medical and surgical therapy has been recommended. However, new potent antifungal agents, such as echinocandins, could increase the medical options and, in some cases, avoid the need for surgery. We report a case of Candida endocarditis treated successfully without valve replacement with intravenous liposomal amphotericin B (total dose, 4 g) and intravenous caspofungin (a 100-mg loading dose followed by 50 mg per day for 8 weeks) as induction therapy and intravenous caspofungin (100 mg 3 times per week for 12 weeks) as maintenance therapy.

The evolution of antimicrobial resistance in Salmonella isolates causing traveler's diarrhea (TD) and their mechanisms of resistance to several antimicrobial agents were analyzed. From 1995 to 2002, a total of 62 Salmonella strains were isolated from stools of patients with TD. The antimicrobial susceptibility to 12 antibiotics was determined, and the molecular mechanisms of resistance to several of them were detected as well. The highest levels of resistance were found against tetracycline and ampicillin (21 and 19%, respectively), followed by resistance to nalidixic acid (16%), which was mainly detected from 2000 onward. Molecular mechanisms of resistance were analyzed in 16 isolates. In these isolates, which were resistant to ampicillin, two genes encoding beta-lactamases were detected: oxa-1 (one isolate) and tem-like (seven isolates [in one strain concomitantly with a carb-2]). Resistance to tetracycline was mainly related to tetA (five cases) and to tetB and tetG (one case each). Resistance to chloramphenicol was related to the presence of the floR and cmlA genes and to chloramphenicol acetyltransferase activity in one case each. Different genes encoding dihydrofolate-reductases (dfrA1, dfrA12, dfrA14, and dfrA17) were detected in trimethoprim-resistant isolates. Resistance to nalidixic acid was related to the presence of mutations in the amino acid codons 83 or 87 of the gyrA gene. Further surveillance of the Salmonella spp. causing TD is needed to detect trends in their resistance to antimicrobial agents, as we have shown in our study with nalidixic acid. Moreover, such studies will lead to better treatment and strategies to prevent and limit their spread.

The effect of salicylate, a marRAB inducer, on the resistance to beta-lactams was characterized in an AmpC beta-lactamase hyperproducer Morganella morganii clinical isolate (the M1 strain). Results were compared with those of the effect of salicylate in a wild-type M. morganii strain. Salicylate induced a decreased susceptibility to nalidixic acid, norfloxacin and tetracycline and simultaneously increased the susceptibility to beta-lactams apparently due to the repression of AmpC beta-lactamase synthesis in the M1 strain. Likewise, salicylate only repressed 46 kDa outer membrane protein expression in the wild-type strain, since the clinical isolate M1 did not express it.

Objectives: The aim of this study was to determine the roles of mutations in the gyrA and parC genes and the overexpression of efflux pump(s) as mechanisms of resistance to quinolones. Forty-five Yersinia enterocolitica O:3 clinical isolates (41 nalidixic acid-resistant, three nalidixic acid-susceptible and one nalidixic acid-resistant strain obtained in vitro) were analysed., Results: All the nalidixic acid-resistant strains showed mutations in the gyrA gene and none in the parC gene. The presence of the inhibitor produced decreases in the MIC values of nalidixic acid by two to six serial dilution steps in 37 of the 41 nalidixic acid-resistant strains. Meanwhile, the MIC value of ciprofloxacin was affected in two strains whose values diminished three serial dilution steps. The nalidixic acid-resistant mutant obtained in vitro was also affected by the inhibitor decreasing the MIC value of nalidixic acid three serial dilutions steps whereas the MICs for the nalidixic acid-susceptible strains were not affected., Conclusions: Our results show that the high level of resistance to nalidixic acid is likely due to an overexpression of an efflux pump plus a mutation in the gyrA gene, whereas decreased susceptibility to ciprofloxacin is only associated with the presence of a mutation in the gyrA gene.

The Phoenix system (BD Diagnostic Systems), a rapid ID/AST system, was compared with the MicroScan WalkAway-40 system for accuracy of identification and antimicrobial susceptibility test results. The 327 bacterial isolates, were comprised of 191 Gram-negative bacilli (187 Enterobacteriaceae and 4 Aeromonas spp.) and 136 Gram-positive cocci (27 Staphylococcus aureus, 53 coagulase-negative staphylococci, 45 enterococci and 11 beta haemolytic streptococci). The overall rate of agreement between the two systems for species level identification was 95.8% and 96.3% for Gram-negative bacilli and Gram-positive cocci, respectively. Enterococcus and Streptococcus species both achieved a 100% rate of species level agreement. The genus level agreement was >99% overall. Arbitration of the 8 Gram-negative bacilli disagreements resolved with 7 in agreement with the Phoenix identification. For the 5 Gram-positive cocci disagreements, 3 resolved in agreement with Phoenix. Overall, 3688 antimicrobial/organism combinations were evaluated in both systems. For Gram-negative isolates, the rate of essential agreement for the MICs was 98.5%, while the categorical agreement rate was 95.9%. Arbitration of 13 Gram-negative disagreements resolved with 11 in agreement with the Phoenix system. For Staphylococcus spp. and Enterococcus spp. isolates, the essential agreement rates were 96.4% and 99% respectively. Categorical agreement rates for both genera were 94.7% and 96.1%, respectively. Arbitration of 5 staphylococci disagreements resolved with 2 in agreement with Phoenix system. Our results show that the Phoenix system is a rapid and reliable system for both identification and antimicrobial susceptibility testing of common clinical isolates.

Background and Objective: The use of risk indexes, originally developed in the US for the assessment of SSI risk, is an useful instrument that must be analyzed according to each specific procedure. The addition of other possible SSI risk factors, like the use of perioperative antibiotic prophylaxis, could improve the predictive value of these indexes. The aim of this study was to determine the SSI incidence rate for craniotomy in patients admitted to the Neurosurgical Unit of the Hospital Clinic of Barcelona (Spain), to assess the use of standard NNIS and SENIC indexes, and to assess the possible effect of the addition of a new risk factor (adequate or inadequate use of perioperative antibiotic prophylaxis) to these indexes., Patients and Method: Risk factors for SSI were assessed following common standard definitions and procedures (CDC-NNIS) over a three-year period (1999-2001). NNIS and SENIC risk indexes were calculated. The effect of the addition of a new variable, namely perioperative antibiotic prophylaxis adequate (0 points) or inappropriate/no prophylaxis (1 point) on these indexes (modified indexes NNISa and SENICa) was also assessed. Statistical analysis included both parametric and non-parametric standard tests., Results: The study included a total of 203 patients undergoing a craniotomy procedure (40% of all neurosurgical procedures). The overall SSI incidence rate was 6.8% (14 patients developed SSI). The cut-off point (75 percentile) for the duration of the procedure was 180 minutes instead of the commonly US reported 240 minutes. Patients who develop SSI had a trend towards having shorter operation times. For those patients in the lower risk groups, the SSI incidence rate was: NNIS (0, 1): 6.9%; SENIC (0, 1): 6.2%. If the modified indexes were used, the SSI incidence rate was: NNISa (0, 1): 4.2%; SENICa (0, 1): 4.9%. When NNIS and SENIC indexes, both standard and modified (NNISa and SENICa), were compared, no statistically significant differences between infected and non-infected patients were observed., Conclusions: When applied to a health system other than the US, SENIC and NNIS indexes could be useful if adapted to each specific situation and procedure. The added value of a new risk factor (perioperative antibiotic prophylaxis) on standard NNIS and SENIC indexes shows a slight improvement in their prediction rate for SSI in patients undergoing craniotomy, mainly in those patients at lower risk for developing superficial SSI.

Setting: Five districts in Equatorial Guinea, March 1999 to February 2001., Objectives: To determine tuberculosis drug resistance among new and previously treated cases, the risk factors associated with resistance, and the mutations associated with isoniazid and rifampicin (katG, inhA and rpoB genes) resistance, and to genotype resistant strains., Results: A positive culture identified as Mycobacterium tuberculosis complex was obtained in 240/499 patients. Susceptibility testing was performed in 236 strains. The overall resistance rate in new cases was 16.9% compared to 41.6% in previously treated cases. Isoniazid resistance was the most frequent (respectively 12.5% and 16.6%) in the two groups, while multidrug resistance was observed in 1.7% and 25% of new and previously treated cases, respectively. Female sex was statistically associated with resistance in new cases. Of 41 isoniazid-resistant strains, 33 (80.5%) had mutations in the inhA gene; none had mutations in the katG gene and eight had no mutations in either gene. All strains had low-level isoniazid resistance. Of eight strains resistant to rifampicin, six had mutations in the rpoB gene. Genotyping defined seven clusters., Conclusions: Moderate resistance was found in new cases. Low-level isoniazid resistance predominated among mutations in the inhA gene, with a high percentage of clustering in resistant strains.

Objective: To determine whether non-epidemiologically related, antibiotic-resistant isolates of Acinetobacter baumannii from different geographical origins possess common type 1 integrons., Methods: The epidemiologic relationships between seven A. baumannii strains recovered from different Spanish hospitals were established by pulsed-field gel electrophoresis, the presence of integrons being determined by PCR and DNA sequencing., Results: Integron analysis showed the presence of four different integrons, containing six different known genes (aacC1, aacA4, aadA1, aadB, oxa21 and oxa37) plus an ORF. It was found that the same integron was present in different unrelated strains and that related strains could have different integrons., Conclusion: These results show the potential risk of integron dissemination among different strains of A. baumannii.

The frequency of isolation and antifungal susceptibility patterns to established and two new antifungal agents were determined for 218 Candida spp isolates causing bloodstream infection from 1996 to 2001. Overall, 41.7% of the candidemias were due to C. albicans, followed by C. parapsilosis (22%), C. tropicalis (16.1%), C. glabrata (11.9%), C. krusei (6%) and miscellaneous Candida spp (2.3%). Isolates of C. albicans C. parapsilosis and C. tropicalis (80% of isolates) were highly susceptible to fluconazole (94 to 100% at /= 32 microg/ml).

The MIC of gemifloxacin and five other quinolones was tested against 31 clinical isolates of Neisseria gonorrhoeae; strains were analyzed for the presence of mutations in both the gyrA and parC genes. Only seven strains were resistant to nalidixic acid due to a mutation in the gyrA gene but not in the parC gene, with six and two considered intermediate to ciprofloxacin and levofloxacin, respectively. The activity of gemifloxacin was similar to that of trovafloxacin and moxifloxacin, but was more active than nalidixic acid, ciprofloxacin or levofloxacin against the gyrA mutant strains. Gemifloxacin is a valid therapeutic alternative to treat infections with N. gonorrhoeae, retaining its activity against strains already presenting a mutation in gyrA.

The objective of this study was to describe a nosocomial outbreak of influenza during a period without influenza epidemic activity in the community. Outbreak investigation was carried out in an infectious diseases ward of a tertiary hospital. Presence of two or more of the following symptoms were used to define influenza: cough, sore throat, myalgia and fever. Epidemiological survey, direct immunofluorescence, viral culture, polymerase chain reaction, haemagglutination-inhibition test in throat swabs and serology for respiratory viruses were performed. Twenty-nine of 57 healthcare workers (HCW) (51%) and eight of 23 hospitalised patients (34%) fulfilled the case definition. Sixteen HCW (55%) and three inpatients (37%) had a definitive diagnosis of influenza A virus infection (subtype H1N1). Among the symptomatic HCW, 93% had not been vaccinated against influenza that season. Affected inpatients were isolated and admissions in the ward were cancelled for 2 weeks. Symptomatic HCW were sent home for 1 week. On the seventeenth day of the outbreak the last case was declared. The incidence of cases in this outbreak of influenza, which occurred during a period without influenza epidemic activity in the community, was notably high. Epidemiological data suggest transmission from healthcare workers to inpatients. Most healthcare workers were not vaccinated against influenza. Vaccination programmes should be reinforced among healthcare workers.

Streptococcus pneumoniae is suspected to cause an important proportion of community-acquired pneumonia (CAP) whose aetiology cannot be detected with conventional tests. In this study, the authors evaluated the diagnostic yield of a new immunochromatographic membrane test (ICT) for the detection of the S. pneumoniae antigen in the urine of patients admitted with diagnosed CAP. ICT was performed in unconcentrated and concentrated urine from all the patients. ICT was repeated 1 month after discharge in a group initially testing positive. The authors also studied the ICT in clinically stable human immunodeficiency virus type 1 (HIV1)-infected patients. S. pneumoniae antigen was detected in all of the 68 (100%) patients tested with definitive pneumococcal pneumonia. In five of these cases ICT was only positive when it had been performed on the patients. The S. pneumoniae antigen was also detected in 36 (69.2%) of 52 patients with probable pneumococcal pneumonia and in 50 of 277 (18%) patients without pneumococcal pneumonia. ICT remained positive in 16 (69.5%) of 23 patients, 1 month after hospital discharge. Nasopharyngeal colonisation with S. pneumoniae was detected in 8 (12%) of 68 clinically stable HIV1 infected patients, but none tested ICT positive. The Binax NOW it immunochromatographic membrane test is a rapid, sensitive and specific test for detecting pneumococcal community-acquired pneumonia in adults. The test may remain positive for several weeks after pneumococcal pneumonia.

Objective: To study the activity of five different fluoroquinolones against 22 epidemiologically related and unrelated strains of Staphylococcus aureus (13 methicillin-resistant (MRSA) strains and nine methicillin-susceptible (MSSA) strains) in which the mechanisms of quinolone resistance are also investigated., Methods: The MICs of the different fluoroquinolones were determined by the microdilution method, in the presence and absence of reserpine. The quinolone resistance-determining regions of the gyrA, gyrB, grlA and grlB genes were amplified and sequenced to establish the presence of mutations. The molecular epidemiology of the 22 strains was performed by low-frequency restriction analysis of chromosomal DNA with SmaI., Results: MSSA strains showed lower homology than MRSA strains, in which only two clones were seen. Trovafloxacin showed the best activity against these clinical isolates of S. aureus, since strains carrying one amino acid change in both GyrA and GrlA subunits remained susceptible to this antimicrobial agent. Furthermore, trovafloxacin did not seem to be a substrate for NorA., Conclusion: Trovafloxacin was the most active quinolone tested against S. aureus strains, followed by levofloxacin and sparfloxacin, whereas ciprofloxacin and norfloxacin were the least active quinolones, in both the presence and absence of reserpine. Epidemiologically related S. aureus strains presented different mechanisms of quinolone resistance, suggesting a divergent evolution of the same clone. Finally, 16 S. aureus strains with a ciprofloxacin plus reserpine MIC > or = 1 mg/L already showed a mutation in the grlA gene. This MIC may be useful as a marker of mutation in this gene, contraindicating the use of this quinolone, since a second mutation may develop during treatment.

Early diagnosis of tuberculosis and screening of other mycobacteria is required for the appropriate management of patients. We have therefore developed a 5'-exonuclease fluorogenic PCR assay in a single-tube balanced heminested format that simultaneously detects Mycobacterium tuberculosis complex (MTC) and members of the Mycobacterium genus (MYC) using the 16S ribosomal DNA target directly on clinical samples. One hundred twenty-seven clinical samples (65 smear negative and 62 smear positive) with a positive culture result from 127 patients were tested, including 40 negative control specimens. The finding of both a positive MTC and probe value and a positive MYC probe value confirmed the presence of MTC or mycobacteria with a 100% positive predictive value. However, a negative value for MTC or MYC did not discount the presence of mycobacteria in the specimen. Interestingly, the addition of the MYC probe allowed the diagnosis of an additional 7% of patients with tuberculosis and rapid screening of nontuberculous mycobacteria (NTM). Thus, over 75% of the patients were diagnosed with mycobacterial disease by PCR. The sensitivity was much higher on smear-positive samples (90.3%) than smear-negative samples (49.2%) and was slightly higher for MTC than NTM samples. With regard to the origin of the sample, MTC pulmonary samples gave better results than others. In conclusion, we believe this test may be useful for the rapid detection of mycobacteria in clinical samples and may be a valuable tool when used together with conventional methods and the clinical data available.

A total of 33 Stenotrophomonas maltophilia clinical isolates were tested for their susceptibility to clinafloxacin in comparison with ciprofloxacin, levofloxacin, moxifloxacin, nalidixic acid, norfloxacin, sparfloxacin and trovafloxacin. The MIC(50) and MIC(90) were as follows: ciprofloxacin 4 and 64 microg/mL; clinafoxacin 0.5 and 4 microg/mL; levofloxacin 2 and 32 microg/mL; moxifloxacin 1 and 8 microg/mL; nalidixic acid 8 and 128 microg/mL; norfloxacin 64 and 256 microg/mL; sparfloxacin 1 and 16 microg/mL; and trovafloxacin 1 and 8 microg/mL. Clinafloxacin was the most active quinolone, with only a 15.1% of strains showing resistance. When the MICs were determined in the presence of 25 microg/ml of reserpine, the MIC(90) of trovafloxacin and moxifloxacin did not change, whereas decreased 2-fold for clinafloxacin, levofloxacin, sparfloxacin and nalidixic acid, and 4- and 8-fold for ciprofloxacin and norfloxacin respectively. No clinafloxacin-resistant strains were observed when the MIC was performed in the presence of reserpine. Therefore, clinafloxacin shows the better "in vitro"activity against these 33 strains of S.maltophilia.

We studied the frequency of mutation of clinical isolates of Neisseria gonorrhoeae (two nalidixic acid susceptible and two nalidixic acid resistant), and the stability of the mutants obtained, in the presence of three different concentrations of five fluoroquinolones. The frequency of mutation was low for all the quinolones. Only one N. gonorrhoeae mutant, obtained with trovafloxacin at 4 x MIC presented a stable increase in the MIC of this quinolone, not attributable to novel mutation(s), both in the gyrA and parC genes, although not showing any increase in the MIC of the other quinolones tested. In summary, gemifloxacin was the only quinolone tested for which resistant mutants were not obtained.

The aim of this study was to use restriction fragment length polymorphism to detect unsuspected cases of nosocomial transmission of tuberculosis (TB) among patients who had been admitted to a university hospital. One hundred fifty-one samples of Mycobacterium tuberculosis isolated from patients with pulmonary TB were studied. The isolates from 37 patients (24.5%) defined 11 clusters. None of the patients infected with these cluster isolates had hospital stays that coincided with one another, and for 5.4% of the patients, the epidemiological link was clearly outside the hospital. Previous incarceration was associated with infection with cluster isolates. In addition, 109 patients without TB (41 of whom were infected with human immunodeficiency virus) who shared a room with patients who had TB were followed for 18-60 months. Among the patients who survived, secondary cases of TB due to nosocomial transmission were not detected.

The aim of this study was to clinically validate a heminested polymerase chain reaction (PCR) method, based on the IS6110 insertion segment of Mycobacterium tuberculosis complex, for the diagnosis of tuberculosis. Samples of pulmonary, extrapulmonary and blood origin were collected prospectively from 331 patients. All samples were processed to detect acid-fast bacilli by direct stain, culture and PCR. The gold standard comparison was a clinically based final case definition of tuberculosis corresponding to group 3 of the American Thoracic Society's classification system. The sensitivities of stain, culture and PCR were 41%, 65% and 59%, respectively. Overall specificity exceeded 97% for all techniques. The combination of PCR and direct stain achieved a sensitivity similar to that of culture alone. The PCR method detected 74 of 95 (78%) culture-positive results. In a hospital setting, PCR could be a useful, reliable tool for diagnosis of tuberculosis and may be introduced as a complementary routine diagnostic laboratory method.

Unlabelled: To determine the need of prenatal screening for toxoplasmosis in our hospital from a seroepidemiological point of view., Patients and Methods: The prevalence of IgG anti-T. gondii was retrospectively analyzed in 7.090 women of childbearing age attended in the Hospital Clínic of Barcelona from February 1992 to April 1999. The association among the seroprevalence and the variables year, age, birthplace (province of Barcelona/other provinces) and place of residence (urban/rural) was analyzed. A decreasing trend was observed in the prevalence (p < 0.001), currently being < 40% in the average women between 15 and 45 years. Infection was also directly related to age of women (p < 0.001) and birthplace out of the province of Barcelona (p = 0.001). Habitat (rural or urban) was not associated with seroprevalence. Prenatal screening for toxoplasmosis is necessary due to the high rate of seronegative women exposed to infection and the evidence of a high number of primoinfections in the childbearing period.

Yersinia spp infection in human people are increasing attention last thirty years. We have reviewed the bacteremia in our hospital last five years. Three episodes were Yersinia spp bacteremia. Presence of disease or predisponent therapy were present in most of episodes. All patients were more than seventy years old. The septic metastasis were present in all the cases: one with meningitis, other with liver abscess and one with septic arthritis. We have documented a good clinical evolution, though the mortality in different reports is around 50%. The election therapy for all episodes were cephalosporins, and in two cases we added quinolones.

Background: To study the usefulness of IgG and IgM titration, and avidity of IgG to date IgM anti-Toxoplasma gondii., Methods: VIDAS Toxo IgG, VIDAS Toxo IgM and VIDAS Toxo IgG Avidity tests were used. 64 sera containing both IgM and IgG T. gondii antibodies were analyzed, 32 from 12 individuals infected 40 weeks previously (group I), and the remainder from 17 individuals with an infection of more than 40 weeks (group II)., Results: An IgM index < 1.05 was associated with an infection > 12 weeks. An avidity index > 0.164 excluded 100% infections of < or = 12 weeks. Avidity indexes > 0.26 and 0.45 excluded infections of < or = 20 and < or = 40 weeks, respectively., Conclusions: The serology methods used in this study can adequately identify residual IgM anti-T. gondii, often avoiding the need of a new blood extraction to analyze IgG kinetics in pregnant women.

In order to achieve more sensitive and specific results for the rapid diagnosis of tuberculosis, we have developed a new method, named balanced heminested PCR, which avoids the inconvenience of asymmetric amplification and has the advantages of single-tube heminested PCR. This was achieved by replacing the outer primer that participates in both rounds of amplification in the standard heminested technique by another primer containing the sequence of the inner primer attached at its 5' end. When both techniques were tested for the IS6110 target of Mycobacterium tuberculosis complex in 80 smear-negative culture-positive sputum samples and 60 control samples, the results showed 100% specificity for both techniques and sensitivities of 60 and 75% for heminested PCR and balanced heminested PCR, respectively (P = 0.02). In conclusion, the balanced heminested technique shows a higher sensitivity than that of the standard heminested, and it could be applied to any PCR by attaching the inner primer at the 5' end of the opposite outer primer. Thus, the balanced heminested technique provides a target for the inner primer in both strands, avoiding asymmetric amplification and thereby resulting in a more efficient amplification, and, in practice, a higher sensitivity without loss of specificity and with a minimum risk of cross-contamination.

Five quinolone-resistant strains were developed from a clinical Morganella morganii isolate (M1 strain) which was susceptible to nalidixic acid and fluoroquinolones. All five in vitro selected mutants showed diminished norfloxacin accumulation and two of them also decreased the expression of the AgO in the outer membrane lipopolysaccharide with respect to their parent strain and to the M. morganii NCTC-235 type strain. Likewise, the M1 strain did not express a 37-38 kDa protein and accumulated less norfloxacin than the M. morganii NCTC-235 strain. The decreased norfloxacin uptake in the five mutants compared with the M. morganii NCTC-235 strain was due to an enhanced proton-dependent active efflux plus a pre-existent decreased expression of a 37-38 kDa protein in the parent strain.

To assess whether methicillin resistance is a microbial characteristic associated with deleterious clinical outcome, we performed a cohort study on 908 consecutive episodes of Staphylococcus aureus bacteremia and a case-control study involving 163 pairs of patients matched for preexisting comorbidities, prognosis of the underlying disease, length of hospitalization, and age. Of 908 bacteremic episodes, 225 (24.8%) were due to methicillin-resistant S. aureus (MRSA). Multivariate analysis did not reveal that methicillin resistance was an independent predictor for mortality when shock, source of bacteremia, presence of an ultimately or rapidly fatal underlying disease, acquisition of the infection in an intensive care unit (ICU), inappropriate empirical therapy, female sex, and age were taken into account. Nonetheless, methicillin resistance was an independent predictor for shock. The case-control study could not confirm that shock was linked to MRSA when prior antimicrobial therapy, inappropriate treatment, ICU residence, and female sex were considered. Our data suggest that cohort studies tend to magnify the relationship of MRSA with clinical markers of microbial pathogenicity and that this effect is a shortcoming of these kind of studies that is caused by inadequate control for underlying diseases.

The use of 0.5% sodium dodecyl sulfate in polyacrylamide separation gels allowed the resolution in several bands of high-molecular-mass components in smooth lipopolysaccharide of bacterial outer membrane from Escherichia coli, Morganella morganii, Citrobacter freundii and Citrobacter diversus. With or without 0.1% SDS, however, such a result was not possible.