RESUMEN

OBJECTIVES: To report an outbreak due to an unusual strain of Enterococcus faecium containing both the vanA and vanB genes, in France, where the rate of glycopeptide-resistant enterococci (GRE) is below 1%. METHODS: Cases were patients infected or colonized with GRE on the haematology ward. Contact patients were screened by real-time PCR performed on rectal swabs. Clinical features were compared for GRE-positive and GRE-negative patients. GRE isolates were characterized by phenotypic and molecular methods including PFGE. Conjugation experiments were performed to identify van genetic support. RESULTS: After the index patient presented a bacteraemia with vanA/vanB E. faecium, 56 contact patients were screened, 7 of whom were found to be GRE positive: 6 additional cases with vanA/vanB E. faecium and 1 with GRE carrying vanA only. PFGE confirmed the clonal relationship of the seven vanA/vanB E. faecium strains, whereas the vanA isolate was distinct. Only the vanA gene could be transferred to enterococcal recipients by conjugation, and it was probably localized on a mobile genetic element. All isolates were resistant to vancomycin (MIC > 256 mg/L) and teicoplanin (MIC = 24-32 mg/L), but were susceptible to tigecycline (MIC = 0.09 mg/L), linezolid (MIC = 0.75 mg/L) and daptomycin (MIC = 1-2 mg/L). Significant differences (P < 0.001) between carriers and non-carriers of GRE were observed for the median duration of hospitalization (57 days versus 16.5 days) and of neutropenia (40 days versus 6 days), the median number of antibiotics used (5 versus 1.5) and the duration of glycopeptide treatment (14.5 days versus 0 days). CONCLUSIONS: vanA/vanB E. faecium strains, although rare, can emerge in the absence of previous outbreaks of vanA-GRE or vanB-GRE.

Asunto(s)

Proteínas Bacterianas/genética , Ligasas de Carbono-Oxígeno/genética , Enterococcus faecium/genética , Glicopéptidos/farmacología , Enfermedades Hematológicas/genética , Resistencia a la Vancomicina/genética , Brotes de Enfermedades , Enterococcus faecium/metabolismo , Francia/epidemiología , Glicopéptidos/uso terapéutico , Enfermedades Hematológicas/tratamiento farmacológico , Enfermedades Hematológicas/epidemiología , Unidades Hospitalarias , Humanos , Resistencia a la Vancomicina/efectos de los fármacos

RESUMEN

STUDY: A comparative study which compared PPD skin testing inserted according to the French Society of Pneumology's recommendations and interferon gamma release assay (IGRA) (QuantiFERON((R)) TB Gold In-tube, QF-TB-IT, Cellestis, Carnegie, Australia) was performed during a tuberculosis contact investigation in our hospital. PATIENTS: Nineteen French health-care workers (HCWs) volunteered to participate. All of the HCW enrolled were BCG vaccinated and had a normal chest X-ray at entry. RESULTS: Among the HCW, 68.4% were TST positive. By comparison, only 31.6% had a positive QF-TB-IT result. We took advantage of the negative tube and the corresponding plasma for antibody detection by ELISA. None were ELISA positive. Fourteen HCWs were followed up. None of the HCWs accepted a course of antiTB chemoprophylaxis. Despite the difficulty in establishing a trend in kinetics, we saw the complexity of interpretation of a dynamic T-cell response after contact with an index case. CONCLUSION: This initial and first French picture provides us with the observation that only 44% of TST-positive HCW were IGRA positive, and the IGRA test allowed the detection of LTBI in two TST negative HCWs.

Asunto(s)

Anticuerpos/sangre , Trazado de Contacto/métodos , Interferón gamma/inmunología , Mycobacterium tuberculosis/inmunología , Enfermeras y Enfermeros , Tuberculosis/inmunología , Adulto , Formación de Anticuerpos , Vacuna BCG/administración & dosificación , Ensayo de Inmunoadsorción Enzimática , Femenino , Francia , Humanos , Masculino , Persona de Mediana Edad , Radiografía Torácica , Factores de Riesgo , Sensibilidad y Especificidad , Prueba de Tuberculina , Tuberculosis/diagnóstico , Tuberculosis/epidemiología , Adulto Joven

RESUMEN

OBJECTIVES: In a bid to combat methicillin-resistant Staphylococcus aureus (MRSA) more efficiently in our department, we performed a study to 1) clarify the MRSA carriage rate in patients hospitalized in the department; 2) evaluate the rate of MRSA acquisition during hospitalization; 3) describe the MRSA carrier profile; 4) study the morbidity and mortality associated with MRSA. PATIENTS AND METHODS: We conducted a three-month prospective study in all patients hospitalized for more than 24hours in the dermatology department of the Saint-Louis Hospital. Nasal swab cultures were performed on the day of admission, once a week thereafter and on the day of discharge. Clinical and epidemiological data were individually reviewed by means of a standardized questionnaire. RESULTS: In 310 patients, the prevalence of nasal MRSA carriage at admission was 6.5%. During hospitalization, 1.9% of our patients became colonized with MRSA. MRSA carriers were significantly older than non-carriers and had been hospitalized more frequently over the previous 12 months, principally in intensive care or in intermediate or long-term care facilities, and erosive and/or ulcerated dermatitis was more common in this population. Of the 27 patients colonized with MRSA, only three had MRSA infections, and these were successfully treated with antibiotics. DISCUSSION: The observed rate of MRSA carriage was close to that seen in intensive care units (7%). While systematic screening for MRSA in patients with erosive and/or ulcerated dermatitis would allow detection of twice as many cases of MRSA than the usual screening recommendations, this would be associated with little tangible benefit and high costs, and we therefore decided not to change the usual MRSA screening politic in our dermatology department.

Asunto(s)

Infección Hospitalaria/prevención & control , Tamizaje Masivo , Staphylococcus aureus Resistente a Meticilina/aislamiento & purificación , Cavidad Nasal/microbiología , Infecciones Estafilocócicas/prevención & control , Administración Oral , Adulto , Anciano , Anciano de 80 o más Años , Antibacterianos/administración & dosificación , Antibacterianos/uso terapéutico , Portador Sano/diagnóstico , Interpretación Estadística de Datos , Dermatología , Femenino , Departamentos de Hospitales , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Infecciones Estafilocócicas/diagnóstico , Infecciones Estafilocócicas/tratamiento farmacológico , Encuestas y Cuestionarios

RESUMEN

Fifty-two strains of Klebsiella pneumoniae producing an AmpC-type plasmid-mediated beta-lactamase were isolated from 13 patients in the same intensive care unit between March 1998 and February 1999. These strains were resistant to ceftazidime, cefotaxime and ceftriaxone, but susceptible to cefoxitin, cefepime and aztreonam. Plasmid content and genomic DNA restriction pattern analysis suggested dissemination of a single clone. Two beta-lactamases were identified, TEM-1 and ACC-1. We used internal bla(ACC-1) primers, to sequence PCR products obtained from two unrelated strains of Hafnia alvei. Our results show that the ACC-1 beta-lactamase was derived from the chromosome-encoded AmpC-type enzyme of H. alvei.

Asunto(s)

Proteínas Bacterianas , Infección Hospitalaria/microbiología , Hafnia/metabolismo , Infecciones por Klebsiella/microbiología , Klebsiella pneumoniae/metabolismo , beta-Lactamasas/metabolismo , Secuencia de Aminoácidos , Aztreonam/farmacología , Secuencia de Bases , Cefepima , Cefotaxima/farmacología , Cefoxitina/farmacología , Ceftazidima/farmacología , Ceftriaxona/farmacología , Cefalosporinas/farmacología , Cefamicinas/farmacología , Clonación Molecular , Infección Hospitalaria/epidemiología , Brotes de Enfermedades , Farmacorresistencia Microbiana , Electroforesis en Gel de Campo Pulsado , Francia/epidemiología , Hafnia/genética , Humanos , Infecciones por Klebsiella/epidemiología , Klebsiella pneumoniae/aislamiento & purificación , Pruebas de Sensibilidad Microbiana , Datos de Secuencia Molecular , Monobactamas/farmacología , Plásmidos/análisis , Reacción en Cadena de la Polimerasa , beta-Lactamasas/genética

RESUMEN

The accumulation of infected clots under the silicone septum of the reservoir of venous access ports (VAPs) has been reported. We analyzed the relationship between these deposits and the occurrence of VAP-related bloodstream infections (VAP-BSIs) by (1) evaluating the accuracy of paired quantitative blood cultures for diagnosing VAP-BSI before the removal of the device and (2) assessing the accuracy of cultures of the tip and septum (i.e., the internal lumen of the VAP) for diagnosing VAP-BSI after removal of the device. Over a 16-month period, all VAPs removed were prospectively investigated. Before VAP removal, paired quantitative blood cultures were 77% sensitive and 100% specific and had a positive predictive value of 100% and a negative predictive value of 98% for diagnosing VAP-BSI. After VAP removal, tip culture was only 46% sensitive, whereas septum culture was 93.3% sensitive for confirming the diagnosis of VAP-BSI. Thus infected deposits that accumulate under the VAP septum are the source of VAP-BSI.

Asunto(s)

Bacteriemia/diagnóstico , Catéteres de Permanencia/efectos adversos , Adolescente , Adulto , Anciano , Humanos , Persona de Mediana Edad , Estudios Prospectivos

RESUMEN

Cerebral tuberculosis (TB) was diagnosed in 6 (4%) of 156 HIV-infected patients with TB seen at our institution over 6 years. We describe here the clinical and radiologic features of these cases and of 15 others reported in the literature. Of the 21 patients, 59% were intravenous drug users. Presenting symptoms were fever (76%), confusion (52%), seizures (38%), and headache (38%). Fourteen patients (66%) had previous or active extracerebral TB at presentation. Cranial CT scan showed ring-(62%) or nodular-(24%) enhancing lesions or mixed forms (14%). Among the 12 patients who underwent a brain biopsy, bacteriologic evidence of TB was found in 9. Four patients (19%) died during hospitalization. Among the 17 others who received antituberculous therapy, only 1 developed neurologic sequelae. Five patients also received steroid therapy to control cerebral edema or paradoxical growth of the cerebral mass lesions. TB should be considered as a cause of cerebral mass lesions in HIV-infected patients, especially if tuberculous infection is suspected at other sites.

Asunto(s)

Síndrome de Inmunodeficiencia Adquirida/complicaciones , Encefalopatías/microbiología , Tuberculosis/complicaciones , Adulto , Antituberculosos/uso terapéutico , Encefalopatías/diagnóstico , Encefalopatías/tratamiento farmacológico , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Mycobacterium tuberculosis/aislamiento & purificación , Fotomicrografía , Estudios Retrospectivos , Tomografía Computarizada por Rayos X , Tuberculosis/diagnóstico , Tuberculosis/tratamiento farmacológico , Tuberculosis/microbiología

RESUMEN

Colonization of the digestive tract has been supposed to be the source of many hospital-acquired infections, especially nosocomial pneumonia. To assess the relationship between oropharyngeal and gastric colonization and subsequent occurrence of nosocomial pneumonia, we prospectively studied 86 ventilated, intensive care unit (ICU) patients. Oropharyngeal or gastric colonizations were detected and quantified on admission and twice weekly during ICU stay. When nosocomial pneumonia was suspected on clinical grounds (new chest X-ray infiltrate and purulent tracheal secretions), diagnosis was assessed on fiberoptic bronchoscopy with quantitative cultures of a protected specimen brush sampling and/or a plugged telescoping catheter sampling yielding > or = 10(3) cfu/ml of at least one microorganism. Bacterial strains responsible for colonization and infection (Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacteriaceae, and Staphylococcus aureus) were compared using pulsed-field electrophoresis. A total of 31 cases (36%) of pneumonia were diagnosed. Oropharyngeal colonization, detected either on admission or from subsequent samples, was a predominant factor of nosocomial pneumonia as compared with gastric colonization. For instance, oropharyngeal colonization with A. baumannii yielded a 7.45-fold estimated increased risk of pneumonia as compared with patients not yet or not identically colonized (p = 0.0004). DNA genomic analysis demonstrated that an identical strain was isolated from oropharyngeal or gastric samples and bronchial samples in all but three cases of pneumonia, due to S. aureus. These findings provide better knowledge of the pathophysiology of nosocomial pneumonia in mechanically ventilated patients.

Asunto(s)

Infección Hospitalaria/microbiología , ADN Bacteriano/análisis , Orofaringe/microbiología , Neumonía Bacteriana/microbiología , Estómago/microbiología , Adulto , Anciano , Anciano de 80 o más Años , Bacterias/aislamiento & purificación , Dermatoglifia del ADN , Electroforesis en Gel de Campo Pulsado , Femenino , Humanos , Unidades de Cuidados Intensivos , Masculino , Persona de Mediana Edad , Neumonía Bacteriana/etiología , Estudios Prospectivos , Respiración Artificial

RESUMEN

SHV-6 was previously identified by its susceptibility pattern and biochemical criteria in a clinical isolate of Klebsiella pneumoniae which was resistant to ceftazidime. It contains only a single point difference with the beta laSHV-1 gene as determined by PCR amplification and nucleotide sequencing. This is the result of a single amino acid substitution, Ala for Asp, at position 179. Directed mutagenesis experiments have shown this substitution to confer selective resistance to ceftazidime in the TEM family.

Asunto(s)

Klebsiella pneumoniae/enzimología , beta-Lactamasas/química , Secuencia de Aminoácidos , Secuencia de Bases , Ceftazidima/farmacología , Pruebas de Sensibilidad Microbiana , Datos de Secuencia Molecular , Relación Estructura-Actividad , beta-Lactamasas/genética , beta-Lactamasas/fisiología

RESUMEN

A one year prospective, observational survey was performed to evaluate the abnormal carriage of multi-resistant Klebsiella pneumoniae and/ or Acinetobacter baumannii, to determine associated risk factors for carriage, and to correlate the abnormal carriage with infectious morbidity and mortality in the intensive care unit (ICU) of a University Hospital. Two hundred and ninety-eight patients who stayed in the ICU > 48h, and were not neutropenic, were studied. Salivary and rectal samples were obtained on admission and weekly until discharge. Out of 265 evaluable patients, 88 (33%) developed oropharyngeal and/or rectal carriage within a median of nine days. Three factors were significantly associated with abnormal carriage: higher 'severity of illness' score on admission, a threefold increase in ICU stay, and the need for mechanical ventilation. K. pneumoniae or A. baumannii accounted for 57/158 (36%) of all ICU-acquired infections (in 46 patients). They were considered as secondary endogenous infections (SEI) in 42 patients who were previously colonized with the same strains, and developed infection within a median of three days (range 0-68 days). Prolonged stay in ICU was the only factor associated with SEI in the carrier population. Mortality was significantly greater in the carrier group (43 vs 25%, P = 0.0006). Post hoc stratification suggested that abnormal carriage only influenced mortality in patients showing a low severity of illness score on admission to ICU. Abnormal carriage was found in the most severely ill patients, predisposed to secondary nosocomial infections, and could influence mortality in the less severely ill.

Asunto(s)

Acinetobacter/efectos de los fármacos , Portador Sano/microbiología , Infección Hospitalaria/microbiología , Resistencia a Múltiples Medicamentos , Unidades de Cuidados Intensivos , Klebsiella pneumoniae/efectos de los fármacos , Acinetobacter/clasificación , Infecciones por Acinetobacter/microbiología , Infecciones por Acinetobacter/mortalidad , Adulto , Anciano , Infección Hospitalaria/mortalidad , Infección Hospitalaria/prevención & control , Mortalidad Hospitalaria , Hospitales Universitarios , Humanos , Infecciones por Klebsiella/microbiología , Infecciones por Klebsiella/mortalidad , Persona de Mediana Edad , Orofaringe/microbiología , Paris , Estudios Prospectivos , Recto/microbiología , Factores de Riesgo

RESUMEN

Severe disseminated infection due to Mycobacterium avium intracellulare, with unusual cutaneous features, is reported in a patient with acquired immunodeficiency syndrome (AIDS). The eruption appeared as disseminated pustular lesions which showed necrotic features and which led to varioliform scarring. Bacterial culture from the skin, blood, and bone marrow, and ultimately from the bronchoalveolar fluid and sputum, was positive for M. avium intracellulare. The patient was successfully treated using a multiple agent anti-mycobacterial regimen including clarithromycin, which appeared to be the most effective drug. This resulted in resolution of the cutaneous and general symptoms. Our patient illustrates the wide spectrum of skin presentations that may be seen with mycobacterial infections in subjects infected with the human immunodeficiency virus (HIV). Clarithromycin is an important agent for the treatment of these severe infections.

Asunto(s)

Infecciones Oportunistas Relacionadas con el SIDA/complicaciones , Síndrome de Inmunodeficiencia Adquirida/complicaciones , Infección por Mycobacterium avium-intracellulare/complicaciones , Enfermedades Cutáneas Bacterianas/complicaciones , Infecciones Oportunistas Relacionadas con el SIDA/tratamiento farmacológico , Infecciones Oportunistas Relacionadas con el SIDA/patología , Adulto , Antibacterianos/uso terapéutico , Claritromicina/uso terapéutico , Humanos , Masculino , Infección por Mycobacterium avium-intracellulare/tratamiento farmacológico , Infección por Mycobacterium avium-intracellulare/patología , Enfermedades Cutáneas Bacterianas/tratamiento farmacológico , Enfermedades Cutáneas Bacterianas/patología

RESUMEN

Preliminary results suggested that the diffusion in France of the SHV-4 extended-spectrum beta-lactamase was probably due to the spread of one single epidemic strain of Klebsiella pneumoniae. In this study, we tested various phenotypic and genotypic markers to compare K. pneumoniae strains producing this enzyme isolated in 14 French hospitals between 1987 and 1989. All of the strains were of the same capsule serotype, K25. Twelve of them were of the same biotype: weak urease activity and no sucrose fermentation. Among the six plasmid profiles observed, one accounted for eight strains. Large plasmids of 170 kb encoding SHV-4 beta-lactamase were present in all strains of K. pneumoniae and could be transferred by conjugation with high frequency to Escherichia coli J53-2 or HB101 from all except one strain. Plasmid EcoRI restriction patterns suggested that these plasmids were closely related and similar to pUD18 encoding SHV-3 beta-lactamase, originally described in France and differing from SHV-4 by one amino acid substitution. Ribotyping with EcoRI and HindIII and genomic fingerprinting with XbaI by pulsed-field gel electrophoresis were concordant and suggested that 12 of the isolates recovered from the 14 hospitals were probably the same strain. Dissemination in France of the SHV-4 extended-spectrum beta-lactamase was thus essentially due to the diffusion of a single K. pneumoniae clone.

Asunto(s)

Klebsiella pneumoniae/genética , beta-Lactamasas/biosíntesis , Conjugación Genética , Dermatoglifia del ADN , Electroforesis en Gel de Campo Pulsado , Francia , Hospitales , Humanos , Focalización Isoeléctrica , Klebsiella pneumoniae/efectos de los fármacos , Klebsiella pneumoniae/enzimología , Pruebas de Sensibilidad Microbiana , Fenotipo , Plásmidos , ARN Ribosómico/genética

RESUMEN

The accuracy of paired quantitative blood cultures (PQtBCs) collected in pediatric Isolator 1.5-ml tubes compared to central venous catheter (CVC) segment cultures (hub and tip) to diagnose catheter-related bacteremia (CRB) was evaluated in 58 bacteremic adult patients. The second aim of this study was to state precisely whether the tip or the hub (or both) of the infected device was the source of the bacteremia in case of significant results of PQtBC. Fifty-eight bacteremic patients with suspected CRB entered the study. In 52 patients, the diagnosis was obtained before CVC removal by PQtBC and was confirmed by CVC segment cultures: CRB in 30 patients, non-catheter-related bacteremia in 22 patients. Six patients had CRB not found by PQtBC. 1) PQtBC is 83% sensitive, 100% specific (negative predictive values 78%, positive predictive values 100%). 2) Sixteen bacteremic patients had authentic hub-related bacteremia (positive hub culture associated with negative tip cultures). When CRB is suspected in bacteremic patients, a negative tip culture cannot exclude the diagnosis of CRB. In all cases, CVC tip culture must be associated either with PQtBC or with hub cultures.

Asunto(s)

Bacteriemia/etiología , Cateterismo/efectos adversos , Cateterismo/instrumentación , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Sangre/microbiología , Humanos , Klebsiella pneumoniae/aislamiento & purificación , Persona de Mediana Edad , Complicaciones Posoperatorias , Estudios Prospectivos , Staphylococcus aureus/aislamiento & purificación , Staphylococcus epidermidis/aislamiento & purificación

Asunto(s)

Enfermedades de la Médula Ósea/microbiología , Difteria/microbiología , Choque Séptico/etiología , Enfermedades de la Médula Ósea/complicaciones , Enfermedades de la Médula Ósea/etiología , Enfermedades de la Médula Ósea/patología , Difteria/complicaciones , Difteria/patología , Humanos , Masculino

RESUMEN

A clinical isolate of Klebsiella pneumoniae was more resistant to aztreonam than to cefotaxime and ceftazidime. It produced a clavulanate-susceptible beta-lactamase with an isoelectric point of 6.3 which readily hydrolyzed penicillins, cefotaxime, and ceftazidime, but which hydrolyzed aztreonam poorly. The enzyme was encoded by a gene on a 15-kb plasmid; the gene hybridized with an intragenic DNA probe of blaTEM.

Asunto(s)

Aztreonam/farmacología , Cefalosporinas/farmacología , Klebsiella pneumoniae/efectos de los fármacos , beta-Lactamasas/metabolismo , Antibacterianos/farmacología , Sondas de ADN , ADN Bacteriano/biosíntesis , Humanos , Focalización Isoeléctrica , Cinética , Infecciones por Klebsiella/microbiología , Klebsiella pneumoniae/enzimología , Klebsiella pneumoniae/genética , Fenotipo , Plásmidos , Inhibidores de beta-Lactamasas , beta-Lactamasas/genética

RESUMEN

This retrospective study compared the epidemiological, clinical and bacteriological characteristics of tuberculosis in HIV-infected (HIV+) and seronegative (HIV-) patients in France. It included 67 cases of tuberculosis observed in the hospital setting between 1985 and 1990. The 35 HIV+ patients (52.2%) were more frequently of European origin, while those of African origin were HIV-. Disseminated tuberculosis predominated in HIV+ patients, as opposed to pulmonary tuberculosis in HIV- patients. The tuberculin test was more often positive in HIV- patients than in HIV+ ones (65.6 versus 17.1%; p < 0.001). Direct bacteriological examination of the sputum was positive more frequently in HIV- than HIV+ patients (56.2 versus 22.8%; p < 0.01). A high percentage of the Mycobacterium tuberculosis strains isolated from HIV+ patients (20%) was resistant to anti-tuberculous drugs, primarily isoniazid, while no resistance was found in HIV- patients. The initial response to treatment and the therapy-associated side effects did not differ between the two groups. Four relapses (11.4%) occurred in HIV+ patients, raising the question of the indication of drug prophylaxis following tuberculosis in HIV-infected patients.

Asunto(s)

Infecciones por VIH/inmunología , Seropositividad para VIH/complicaciones , Tuberculosis/etiología , Infecciones Oportunistas Relacionadas con el SIDA , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Estudios de Seguimiento , Infecciones por VIH/complicaciones , Infecciones por VIH/epidemiología , Seronegatividad para VIH , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Factores de Tiempo , Tuberculosis/epidemiología , Tuberculosis/microbiología , Tuberculosis Resistente a Múltiples Medicamentos/tratamiento farmacológico , Tuberculosis Pulmonar/epidemiología , Tuberculosis Pulmonar/etiología , Tuberculosis Pulmonar/microbiología

RESUMEN

A clinical isolate of Klebsiella pneumoniae sensu lato isolated from throat and a blood culture taken from a neutropenic patient treated for 2 weeks with ceftazidime and vancomycin was resistant to ceftazidime (MIC: 32 micrograms/ml) and moderately susceptible to aztreonam (MIC: 4 micrograms/ml). The isolate contained a plasmid of 180 kb which, when transferred to Escherichia coli by conjugation, conferred resistance to ceftazidime and tetracycline. The transconjugant had decreased susceptibility to ceftazidime (128-fold) and aztreonam (8-fold). Clavulanic acid and sulbactam each inhibited the resistance and clavulanic acid showed a synergistic effect when associated with ceftazidime and aztreonam. An extended-spectrum beta-lactamase with an isoelectric point of 7.6 was detected in the clinical isolates from blood and its transconjugant. This beta-lactamase showed similar substrate and inhibition profiles to SHV-1. In particular it did not hydrolyse ceftazidime. Hybridization with an intragenic probe for SHV-3 indicates that this beta-lactamase is an SHV-type enzyme. We propose that this novel CAZ-type extended-spectrum beta-lactamase be named SHV-6.

Asunto(s)

Ceftazidima/farmacología , Klebsiella pneumoniae/enzimología , beta-Lactamasas/análisis , Conjugación Genética , Farmacorresistencia Microbiana/genética , Klebsiella pneumoniae/efectos de los fármacos , Pruebas de Sensibilidad Microbiana , Hibridación de Ácido Nucleico , Plásmidos

RESUMEN

One hundred and fifty-four clinical isolates of Klebsiella pneumoniae resistant to broad-spectrum cephalosporins, aztreonam and amikacin were responsible for an outbreak of nosocomial infections lasting eight months in a university hospital in Paris. This outbreak occurred in the intensive care unit (39 patients), haematology units (8 patients) and surgical and medical units (11 patients). Antibiotic resistant strains were isolated from the urinary tract (48%), wound and drainage fluids (21%), respiratory tract (14%), blood (12%) and stools (5%). High resistance to oxyimino-beta-lactams was mediated by a plasmid-encoded beta-lactamase with an isoelectric point of 7.8 (SHV-4). This CAZ-type enzyme conferred a higher level of resistance to ceftazidime and aztreonam (geometric mean MIC 135 mg/l) than to cefotaxime (geometric mean MIC 14 mg/l). All isolates were of the same biotype (weakly urease positive and no sucrose fermentation). Eight Klebsiella pneumoniae strains isolated in different units and at different times of the outbreak were of the same serotype, had common plasmid patterns and harboured a large self-transferable plasmid of about 180 kilobases encoding resistance to penicillins, oxyimino-beta-lactams, aminoglycosides, tetracycline and trimethoprim. These eight large plasmids had indistinguishable EcoRI restriction patterns. These results suggest that a single strain of Klebsiella pneumoniae was responsible for this outbreak.

Asunto(s)

Infección Hospitalaria/microbiología , Brotes de Enfermedades , Infecciones por Klebsiella/microbiología , Klebsiella pneumoniae/enzimología , beta-Lactamasas/biosíntesis , Antibacterianos/farmacología , Técnicas de Tipificación Bacteriana , Infección Hospitalaria/epidemiología , Farmacorresistencia Microbiana/genética , Humanos , Unidades de Cuidados Intensivos , Focalización Isoeléctrica , Infecciones por Klebsiella/epidemiología , Klebsiella pneumoniae/efectos de los fármacos , Klebsiella pneumoniae/genética , Paris/epidemiología , Factores R , Sistema Respiratorio/microbiología , Factores de Riesgo , Sepsis/microbiología , Infección de la Herida Quirúrgica/microbiología , Sistema Urinario/microbiología , beta-Lactamasas/química , beta-Lactamas