Biomedical subjects
Publications and source records attributed to A Ferroni.
Explore the source record for details and available documents.
Food-borne pathogens can multiply if food is not maintained at an appropriate temperature and if there are delays between food preparation and distribution. The aim of this study was to evaluate the quality of meals during transport from the kitchens to the patients in three departments of a university hospital. Meals were transported inside insulated, cooled food carts. We analysed the delays at each step of the transport process, and measured the temperature inside the food cart and inside the meals. The total duration of the transport (mean=85.3 min; range 44-123 min) conformed to the official recommendations (<2 h at a temperature <10 degrees C before consumption). The internal temperature of 73.6% of the 30 food carts followed was below 10 degrees C. The internal temperature of the meals was below 10 degrees C in 91.7% of cases when the food cart was first opened, but in only 12% of cases by the time the last patient was served. No pathogens were isolated from any of the samples. However, 10% of meals, all of which were salads, had total viable counts of bacteria above the recommended limits. This study confirms that it is essential to control time and temperature to ensure food quality and safety in hospitals.
Tension-free vaginal tape (TVT) is considered as the treatment of choice for female stress urinary incontinence. Bowel erosion is a rare complication of TVT that generally occurs a few days after surgery with a clinical picture of peritonitis and/or intestinal obstruction. Herein is reported a case of a bowel erosion with a late clinical manifestation 3 months after hysterectomy and TVT placement for genital prolapse and urinary incontinence. Bowel erosion may complicate TVT operation several months after surgery and should be considered as differential diagnosis in patients presenting with a clinical picture of peritonitis and/or intestinal obstruction.
AIM: To study the bacterial aetiology of acute osteoarticular infections in children and to analyse the efficiency of culture methods. METHODS: Bacteriological data of 407 cases of clinically suspected osteoarticular infections affecting 406 children hospitalized in an orthopaedic surgery department between 1999 and 2002 were retrospectively reviewed. RESULTS: Bacterial cultures from clinical specimens were positive in 74 cases (18%): 38 cases of septic arthritis and 36 cases of bone infections (osteitis, osteomyelitis or osteoarthritis). The use of liquid medium bottles to grow bacteria from articular fluids increased the rate of positive cultures compared to the use of standard solid media (p = 0.0001). The most commonly recovered pathogen was Staphylococcus aureus (44%) followed by Kingella kingae (14%), Streptococcus pyogenes (10%) and Streptococcus pneumoniae (10%). K. kingae was most frequently isolated among children under 36 mo of age (p = 0.0003), whereas S. aureus was most frequently isolated among children over 36 mo (p = 0.0015). CONCLUSION: By improving our culture method, we observed a recrudescence of isolation of K. kingae, but S. aureus remains the main pathogen isolated from osteoarticular infections in children. This finding is useful for the adaptation of a probabilistic antibiotic treatment of these infections.
The aim of this study was to analyse the diagnostic, empirical and therapeutic strategies adopted when a blood culture from a hospitalized child with a central venous catheter is 'positive', and to assess whether practices complied with the consensus adopted in our hospital, inspired by published recommendations. One hundred and ten cases of bacteraemia were studied prospectively. Investigations to determine whether the catheter was the cause of infection were carried out in 45% of cases, and the catheter was removed as recommended in 39% of cases. Of the patients that received empirical treatment, 56% received broad-spectrum antibiotics with no apparent clinical justification. Following susceptibility testing on the isolated strain, the antibiotic treatment was considered to be appropriate in 58% of cases. Overall, compliance with the consensus recommendations was poor. This was partly due to the high turnover rate of antibiotic prescribers.
We describe a 7-month outbreak of nosocomial Burkholderia cepacia bacteremia involving eight children in a pediatric hospital and the results of epidemiological investigations. A B. cepacia strain genotypically identical to the blood isolates was recovered from the upper surface of capped rubber stoppers of bottles of a commercial lipid emulsion used for parenteral nutrition.
We used partial 16S rRNA gene (16S DNA) sequencing for the prospective identification of nonfermenting Gram-negative bacilli recovered from patients attending our cystic fibrosis center (hôpital Necker-Enfants malades), which gave problematic results with conventional phenotypic tests. During 1999, we recovered 1093 isolates of nonfermenting Gram-negative bacilli from 702 sputum sampled from 148 patients. Forty-six of these isolates (27 patients) were not identified satisfactorily in routine laboratory tests. These isolates were identified by 16S DNA sequencing as Pseudomonas aeruginosa (19 isolates, 12 patients), Achromobacter xylosoxidans (10 isolates, 8 patients), Stenotrophomonas maltophilia (9 isolates, 9 patients), Burkholderia cepacia genomovar I/III (3 isolates, 3 patients), Burkholderia vietnamiensis (1 isolate), Burkholderia gladioli (1 isolate) and Ralstonia mannitolilytica (3 isolates, 2 patients). Fifteen isolates (33%) were resistant to all antibiotics in routine testing. Sixteen isolates (39%) resistant to colistin were recovered on B. cepacia-selective medium: 2 P. aeruginosa, 3 A. xylosoxidans, 3 S. maltophilia and the 8 Burkholderia--Ralstonia isolates. The API 20NE system gave no identification for 35 isolates and misidentified 11 isolates (2 P. aeruginosa, 2 A. xylosoxidans and 1 S. maltophilia classified as B. cepacia ). Control measures and/or treatment were clearly improved as a result of 16S DNA sequencing in three of these cases. This study confirms the weakness of phenotypic methods for identification of atypical nonfermenting Gram-negative bacilli recovered from cystic fibrosis patients. The genotypic methods, such as 16S DNA sequencing which allows identification of strains in routine practice, appears to have a small, but significant impact on the clinical management of CF patients.
Despite growing concern about electromagnetic radiation, the interaction between 50- to 60-Hz fields and biological structures remains obscure. Epidemiological studies have failed to prove a significantly correlation between exposure to radiation fields and particular pathologies. We demonstrate that a 50- to 60-Hz magnetic field interacts with cell differentiation through two opposing mechanisms: it antagonizes the shift in cell membrane surface charges that occur during the early phases of differentiation and it modulates hyperpolarizing K channels by increasing intracellular Ca. The simultaneous onset of both mechanisms prevents alterations in cell differentiation. We propose that cells are normally protected against electromagnetic insult. Pathologies may arise, however, if intracellular Ca regulation or K channel activation malfunctions.
The laboratory plays a significant role in the epidemiologic investigations by the comparative analysis of the bacterial strains involved in the outbreaks. Recently, the use of molecular analysis methods provided better performance than traditional phenotypic methods which are still used as preliminary tests because of their relatively low cost and technical simplicity. These analyses deal with either the whole chromosome of the bacterium, plasmids or particular genes. The classification of these methods runs up against the lack of consensus concerning their nomenclature. A clearer denomination based upon the technique responsible for revealing the polymorphisms of these various targets, makes it possible to divide these methods in two principal groups: methods of RFLP (based on the fragments resulting from digestion with restriction enzymes) and methods of AFLP (based on the products of amplification by PCR). The knowledge of the typability of the strains and the qualities of these various methods, particularly their discriminatory power, is essential to the accuracy of the laboratory analysis in the investigations of outbreaks.
Antibiotherapy is one of the main treatments of cystic fibrosis, contributing to a better nutritional and respiratory status and a prolonged survival. The choice of antibiotics depends on quantitative and qualitative analysis of sputum, bacteria resistance phenotypes and severity of infection. Haemophilus influenzae infection can be treated orally with the association of amoxicillin-clavulanic acid or a cephalosporin. Staphylococcus aureus generally remains sensitive to usual antibiotics; in case of a methicillin-resistant strain, an oral bitherapy or a parenteral cure can be proposed. Treatment of Pseudomonas aeruginosa is different in case of first colonization or chronic infection: in first colonization, parenteral antibiotherapy (beta-lactams-aminoglycosids) followed by inhaled antibiotherapy may eradicate the bacteria; in chronic infections, exacerbations require parenteral bi-antibiotherapy (beta-lactams or quinolons and aminoglycosids) for 15 to 21 days, inhaled antibiotics between the cures being useful to decrease the number of exacerbation. A careful monitoring of antibiotherapy is necessary because of possible induction of bacterial resistance, nephrotoxicity and ototoxicity of aminosids and allergy to beta-lactams.
Antibiotherapy is one of the main treatment in cystic fibrosis. Antibiotic administration schedules are different from normal patients because of pharmacokinetic and pharmacodynamic particularities. In moderate disease, the digestive resorption of antibiotics is delayed and their half-life is reduced due to an increase in total clearance. In severe disease, the volume of distribution of antibiotics is increased due to the higher proportion of lean mass in these malnourished patients. Other particularities limit the action of antibiotics such as thick sputum, which limits drug penetration; the property of Pseudomonas aeruginosa to be surrounded by a biofilm; alteration of local antibacterial defense; and inhibition of antibiotics by local factors. Systematic prescription of a biotherapy beta-lactam-aminoglycoside and obtaining high antibiotic concentration in situ might limit this antagonism. In spite of particular therapeutic schedules such as single daily dose for aminoglycoside and continuous infusion for beta-lactams, the intervals between administrations must be narrowed for time-dependent antibiotics, and the total daily dose increased by 20 to 30% for concentration-dependent antibiotics.
NCC27 belongs to a family of small, highly conserved, organellar ion channel proteins. It is constitutively expressed by native CHO-K1 and dominantly localized to the nucleus and nuclear membrane. When CHO-K1 cells are transfected with NCC27-expressing constructs, synthesized proteins spill over into the cytoplasm and ion channel activity can then be detected on the plasma as well as nuclear membrane. This provided a unique opportunity to directly compare electrophysiological characteristics of the one cloned channel, both on the nuclear and cytoplasmic membranes. At the same time, as NCC27 is unusually small for an ion channel protein, we wished to directly determine whether it is a membrane-resident channel in its own right. In CHO-K1 cells transfected with epitope-tagged NCC27 constructs, we have demonstrated that the NCC27 conductance is chloride dependent and that the electrophysiological characteristics of the channels are essentially identical whether expressed on plasma or nuclear membranes. In addition, we show that a monoclonal antibody directed at an epitope tag added to NCC27 rapidly inhibits the ability of the expressed protein to conduct chloride, but only when the antibody has access to the tag epitope. By selectively tagging either the amino or carboxyl terminus of NCC27 and varying the side of the membrane from which we record channel activity, we have demonstrated conclusively that NCC27 is a transmembrane protein that directly forms part of the ion channel and, further, that the amino terminus projects outward and the carboxyl terminus inward. We conclude that despite its relatively small size, NCC27 must form an integral part of an ion channel complex.
Ras-GRF, a neuron-specific Ras exchange factor of the central nervous system, was transfected in the SK-N-BE neuroblastoma cell line and stable clones were obtained. When exposed to retinoic acid, these clones showed a remarkable enhancement of Ras-GRF expression with a concomitant high increase in the level of active (GTP-bound) Ras already after 24 h of treatment. In the presence of retinoic acid, the transfected cells stopped growing and acquired a differentiated neuronal-like phenotype more rapidly than the parental ones. Cells expressing Ras-GRF also exhibited a more hyperpolarized membrane potential. Moreover, treatment with retinoic acid led to the appearance of an inward rectifying potassium channel with electrophysiological properties similar to IRK1. This current was present in a large number of cells expressing Ras-GRF, while only a small percentage of parental cells exhibited this current. However, Northern analysis with a murine cDNA probe indicated that IRK1 mRNA was induced by retinoic acid at a similar level in both kinds of cells. Brief treatment with a specific inhibitor of the mitogen-activated protein kinase (MAPK) pathway reduced the number of transfected cells showing IRK1 activity. These findings suggest that activation of the Ras pathway accelerates neuronal differentiation of this cell line. In addition, our results suggest that Ras-GRF and/or Ras-pathway may have a modulatory effect on IRK1 channel activity.
We used capillary electrophoresis-single-strand conformation polymorphism (CE-SSCP) analysis of PCR-amplified 16S rRNA gene fragments for rapid identification of Pseudomonas aeruginosa and other gram-negative nonfermenting bacilli isolated from patients with cystic fibrosis (CF). Target sequences were amplified by using forward and reverse primers labeled with various fluorescent dyes. The labeled PCR products were denatured by heating and separated by capillary gel electrophoresis with an automated DNA sequencer. Data were analyzed with GeneScan 672 software. This program made it possible to control lane-to-lane variability by standardizing the peak positions relative to internal DNA size markers. Thirty-four reference strains belonging to the genera Pseudomonas, Brevundimonas, Burkholderia, Comamonas, Ralstonia, Stenotrophomonas, and Alcaligenes were tested with primer sets spanning 16S rRNA gene regions with various degrees of polymorphism. The best results were obtained with the primer set P11P-P13P, which spans a moderately polymorphic region (Escherichia coli 16S rRNA positions 1173 to 1389 [M. N. Widjojoatmodjo, A. C. Fluit, and J. Verhoef, J. Clin. Microbiol. 32:3002-3007, 1994]). This primer set differentiated the main CF pathogens from closely related species but did not distinguish P. aeruginosa from Pseudomonas alcaligenes-Pseudomonas pseudoalcaligenes and Alcaligenes xylosoxidans from Alcaligenes denitrificans. Two hundred seven CF clinical isolates (153 of P. aeruginosa, 26 of Stenotrophomonas maltophilia, 15 of Burkholderia spp., and 13 of A. xylosoxidans) were tested with P11P-P13P. The CE-SSCP patterns obtained were identical to those for the corresponding reference strains. Fluorescence-based CE-SSCP analysis is simple to use, gives highly reproducible results, and makes it possible to analyze a large number of strains. This approach is suited for the rapid identification of the main gram-negative nonfermenting bacilli encountered in CF.
Inward rectification, an important determinant of cell excitability, can result from channel blockade by intracellular cations, including Ca2+. However, mostly on the basis of indirect arguments, Ca2+-mediated rectification of inward rectifier K+ current (IK1) is claimed to play no role in the mammalian heart. The present study investigates Ca2+-mediated IK1 rectification during the mammalian ventricular action potential. Guinea pig ventricular myocytes were patch-clamped in the whole-cell configuration. The action potential waveform was recorded and then applied to reproduce normal excitation under voltage-clamp conditions. Subtraction currents obtained during blockade of K+ currents by either 1 mmol/L Ba2+ (IBa) or K+-free solution (I0K) were used to estimate IK1. Similar time courses were observed for IBa and I0K; both currents were strongly reduced during depolarization (inward rectification). Blockade of L-type Ca2+ current by dihydropyridines (DHPs) increased systolic IBa and I0K by 50.7% and 254.5%, respectively. beta-Adrenergic stimulation, when tested on I0K, had an opposite effect; ie, it reduced this current by 66.5%. Ryanodine, an inhibitor of sarcoplasmic Ca2+ release, increased systolic IBa by 47.7%, with effects similar to those of DHPs. Intracellular Ca2+ buffering (BAPTA-AM) increased systolic IBa by 87.7% and blunted the effect of DHPs. Thus, IK1 may be significantly reduced by physiological Ca2+ transients determined by both Ca2+ influx and release. Although Ca2+-induced effects may represent only a small fraction of total IK1 rectification, they are large enough to affect excitability and repolarization. They may also contribute to facilitation of early afterdepolarizations by conditions increasing Ca2+ influx.
An outbreak of 14 cases of urinary tract infections by Pseudomonas aeruginosa, including six symptomatic infections, occurred from September to November 1994 in a paediatric surgical unit. During the outbreak, urine samples from patients and multiple samples from the environment of patients were tested for the presence of P. aeruginosa. Bacterial isolates were studied by pulsed-field gel electrophoresis. Genotypic analysis showed that most of the isolates from children were different. Multiple P. aeruginosa isolates were also found in the tap water, as the only putative source of contamination. Two of these isolates were identified in two infected patients, indicating possible direct contamination of patients via tap water and this was related to the distal colonization of faucets. Bacteria were eradicated from tap water by replacement of taps. The cluster of cases of P. aeruginosa urinary infection was, therefore, related to multiple contaminations through tap water. These results illustrate an unexpected risk of nosocomial infection and emphasizes the importance of checking tap water to prevent bacterial contamination through handwashing in contaminated water.
OBSERVATION: We report the case of a 2.5-month-old infant with Bacillus cereus meningitis who was initially admitted for Reye syndrome. Gram positive bacteria was isolated in CSF and shown to be located inside the polymorphonuclears. This pathogen was further identified by sequencing of the 16S RNA. Early administration of imipenem in association with amikacin resulted in a rapid recovery. No obvious immune defect or invasive procedure could be assessed. CONCLUSION: Although Bacillus cereus is mainly associated with contamination, repeated isolations of this bacteria may be due to true infection.
An outbreak of nosocomial diarrhea that occurred in a pediatric orthopedic service between 1 December 1993 and 15 April 1994 is reported. A total of 37 patients (mean age, 9.6 years; range, 2 months-19.3 years) were involved in the outbreak, including six patients with bacteriologically documented Clostridium difficile infection. A multivariate analysis identified lincomycin treatment for at least three days as the only significant risk factor. Stool samples from four asymptomatic patients were also positive for Clostridium difficile and its cytotoxins. Isolates from all patients belonged to serogroup C, were highly resistant to lincomycin, and exhibited the same restriction pattern by pulsed-field gel electrophoresis. The outbreak ended after treatment with lincomycin was discontinued and hygiene control measures were implemented.