Measurement of biofilm formation by clinical isolates of Escherichia coli is method-dependent.

AIMS: In this study, we have evaluated the impact of methodological approaches in the determination of biofilm formation by four clinical isolates of Escherichia coli in static assays. METHODS AND RESULTS: The assays were performed in microtitre plates with two minimal and two enriched broths, with one- or two-steps protocol, and using three different mathematical formulas to quantify adherent bacteria. Different biofilm formation patterns were found depending on the E. coli strain, culture medium and reading optical density on one- and two-steps protocol. Strong or moderate biofilm formation occurred mostly in minimal media. The mathematical formulas used to quantify biofilm formation also gave different results and bacterial growth rate should be taken into account to quantify biofilm. CONCLUSIONS: Escherichia coli forms biofilms on static assays in a method-dependent fashion, depending on strain, and it is strongly modulated by culture conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: As verified in the studied E. coli strains, biofilm formation by any organism should be cautiously interpreted, considering all variables in the experimental settings.

Prosthetic valve endocarditis caused by Brucella melitensis. A report of four cases successfully treated with tetracycline, streptomycin, and sulfamethoxazole and trimethoprim plus valve replacement.

Optimal treatment of prosthetic valve endocarditis due to Brucella melitensis is unknown. The presence of ring abscess makes extensive surgical débridement and valve replacement essential steps of management. Antimicrobial therapy with tetracycline hydrochloride plus streptomycin sulfate or sulfamethoxazole and trimethoprim can achieve the sterilization of infected cardiac tissue. Late bland periprosthetic leaks occur frequently. Reoperation can be safely performed after a period of antimicrobial therapy. Prolonged treatment with doxycycline hyclate seems advisable.

Reciprocal antimicrobial synergism between Escherichia coli and Bacteroides fragilis in the presence of metronidazole.

We have studied the antimicrobial action of metronidazole against Bacteroides fragilis and Escherichia coli both in pure cultures and in combination. Concentrations of metronidazole above the minimal inhibitory concentration (MIC) produced a marked bactericidal effect on B fragilis at six hours. E coli however showed only a slight and transitory decrease in population when exposed to concentrations of metronidazole close to its MIC. Kinetic studies of this drug's effect on mixed cultures of both organisms showed mutual bactericidal synergy between E coli and metronidazole against B fragilis and between B fragilis and metronidazole against E coli. These in vitro findings agree with the results obtained in vivo by other authors.

[Lemierre's syndrome (post-anginal sepsis): a forgotten infection]. / Síndrome de Lemierre (sepsis postangina): una infección olvidada.

Septic thrombophlebitis of the jugular vein (Lemierre's syndrome) is a severe complication of oropharyngeal infections. The extension of the infection to the cardiovascular system favors its dissemination to the lung and, eventually, to other points in the organism. We report two cases of Lemierre's syndrome seen in a 10-year period. The diagnostic and therapeutic aspects are particularly emphasized so as to stimulate the knowledge of this uncommon condition.

Effects of human serum albumin, ibuprofen and N-acetyl-L-cysteine against biofilm formation by pathogenic Escherichia coli strains.

The aim of this study was to evaluate the effects of human serum albumin (HSA), ibuprofen sodium (IBU) and N-acetyl-L-cysteine (NAC) against biofilm formation by seven biofilm-producing strains of Escherichia coli. Biofilm formation was studied using polystyrene microtitre plates in static conditions. The impact of the three compounds on bacterial growth and biofilm formation was tested by applying each compound in solution and as pre-treatment (coating) of polystyrene wells. When studied in solution, the minimum biofilm inhibitory concentrations of HSA, IBU and NAC were 8 mg/L (all strains), 2-125 mg/L (five strains) and 30-125 mg/L (five strains), respectively. Pre-treatment of polystyrene plates with HSA at 8 and 32,000 mg/L significantly reduced biofilm formation by all strains, whereas coating with 125 mg/L IBU and 1000 mg/L NAC did not. When HSA at 8 and 32,000 mg/L was combined with either 125 mg/L IBU or 1000 mg/L NAC in pre-treatment assays, more potent inhibition of biofilm was observed for some strains. Our results suggest that biofilm formation by E. coli may be prevented by coating medical devices with HSA alone or in combination with IBU or NAC. In addition, IBU and NAC could be useful in the treatment of urinary tract infections caused by E. coli due to their inhibitory effect on both bacterial growth and biofilm formation.

Comparative activities of aztreonam and cefotaxime against Escherichia coli and Bacteroides spp. in pure and mixed cultures.

The activities of aztreonam and cefotaxime against one Escherichia coli strain and three Bacteroides strains have been studied by using pure and mixed cultures of aerobic and anaerobic bacteria. A fixed concentration (8 micrograms/ml) of cefotaxime or aztreonam killed E. coli that was exposed in pure culture, but the pressure of Bacteroides spp. in the same system deteriorated cefotaxime, allowing the full growth of E. coli after 24 h. On the other hand, the presence of Bacteroides spp. produced less deterioration of aztreonam, which reduced the initial E. coli inoculum. This observation could be useful in clinical practice when treating mixed aerobic and anaerobic infections.

["Yersinia pseudotuberculosis" in a case of mesenteric lymphadenitis (author's transl)]. / A propósito de un caso de adenitis mesentérica por "Yersinia pseudotuberculosis".

An eleven-year old girl's case of an inflammatory process of the right lower abdomen is described, with a positive agglutination reaction to "Y. pseudotuberculosis", serotype I-A. The surgical operation disclosed a normal coecal appendix as well as a mass of clustered ganglionar adenopathies, exclusively located in the ileo-coecal junction. Histologic findings were a pulpar and follicular hyperplasia with mastocytes accumulation and metachromatic staining of capsule and connective tissue. From homogenized ganglionar mass an agent was isolated, further identified as "Y. pseudotuberculosis" type I-A. A comment follows on the frequency of mesenteric lymphadenitis as cause of inflammatory processes of the lower right abdomen in children and the rarity of isolation of "Y. pseudotuberculosis" as etiological agent as compared with the more common "Y. enterocolitica".

[Bacteremia caused by Alcaligenes (Achromobacter) xylosoxidans. Description of 3 cases and review of the literature]. / Bacteriemia por Alcaligenes (Achromobacter) xylosoxidans. Descripción de 3 casos y revisión de la literatura.

BACKGROUND: Alcaligenes (Achromobacter) xylosoxidans occasionally cause infections, mainly in immunocompromised hosts. METHODS: Three cases of bacteremia due to A. xylosoxidans observed at the Fundación Jiménez Díaz between 1985-1994 were described. Moreover, 38 single cases of bacteremia due to A. xylosoxidans and 21 episodes associated with outbreak were reviewed by using computerized bibliography data base MEDLINE (1970-december 1994). RESULTS: From 41 patients with bacteremia (including our 3 cases) reviewed, 27 were immunosuppressed hosts (twenty had neoplasia disease). The most common clinical presentation was primary bacteremia (11 cases, 27%) and pneumonia (10, 24%), followed by catheter-associated bacteremia (8, 20%), meningitis (4), bacteremia from abdominal cavity (4), endocarditis (3) and pyelonephritis (1). The mortality rate was higher (39%), specially in patients whom were a intensive care unit acquisition (87%), and illness with endocarditis (100%). No patient with catheter-related bacteremia died. All of 21 outbreak episodes of bacteremia had a autolimited form and low mortality (4.8%). CONCLUSION: A. xylosoxidans is a microorganism with demonstrated capacity of cause bacteremia, mainly in immunocompromised hosts, with high mortality rates. Sometimes, it causes outbreaks of bacteremia with low mortality.

Synthesis of PAF-acether and blood volume changes in gram-negative sepsis.

Gram-negative sepsis was induced in rats by intraperitoneal injection of Escherichia coli. The development of bacterial peritonitis and septicemia was monitored by counting the number of peritoneal cells and by performing cultures of blood samples. Mortality reached a 50% rate when rats were injected with 2 X 10(8) colony-forming units. Rats injected with the doses of bacteria which induced mortality showed a time- and dose-dependent increase of vascular permeability as judged by the presence of abundant peritoneal exudate and by the depletion of the circulating volume. In order to know whether the generation of PAF-acether could be involved in the development of the permeability changes, the formation of this mediator was measured in the peritoneal cells and spleen of animals at different times and in response to different doses of E. coli. Significant amounts of PAF-acether could be obtained preceding the development of blood volume depletion in response to the injection of doses of E. coli which induced both mortality and the development of permeability. These data suggest that PAF-acether might be one of the inflammatory mediators involved in the pathogenesis of the hemodynamic changes observed in endotoxemia.

[Fasciola hepatica infestation. Biopathology and new diagnostic and therapeutic aspects]. / Infestación por Fasciola hepatica. Biopatología y nuevos aspectos diagnósticos y terapéuticos.

We present here 6 patients with Fasciola hepatica infection, all from rural origin, and with the risk factors of eating wild watercress. The more common symptoms were: fever (83%), abdominal pain (100%), weight loss (83%) and generalized myalgia and joint pain (67%). All patients presented with an absolute eosinophil count above 1,000 cell/mm3. The diagnosis was established in five cases by means of serologic techniques (haemagglutination) and with direct visualization of adult worms while surgery in one case. A CT abdominal scan was performed in five patients, revealing specific lesions of tissue infiltration in four of them. Praziquantel was used in four patients, achieving clinical cure in three cases. In two patients, bithionol was used, with clinical cure in both cases. We review also some newer diagnostic and therapeutic approaches to this parasitic disease.

[Open lung biopsy in immunocompromised patients with diffuse pulmonary infiltrates]. / La biopsia pulmonar abierta en pacientes inmunocomprometidos con infiltrados pulmonares difusos.

In order to evaluate the diagnostic usefulness of open lung biopsy and to determine how could it influence the treatment and the evolution of the disease, the clinical histories of 19 immunocompromised patients with diffuse lung infiltrates were reviewed. One or more specific diagnosis were obtained in 14 patients (73%) by open lung biopsy. However, the initial treatment was modified, in view of the results of the biopsy only in 3 cases (15%). Only 5 patients survived and were discharged. There were no differences in the survival rate of patients with a specific or a nonspecific diagnosis (11 out of 14 deaths and 3 out of 5 respectively). 5 patients suffered severe complications from the surgical procedure. Open lung biopsy should not be used routinarily in the study of diffuse lung infiltrates in immunocompromised patients.