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1.
J Clin Microbiol ; 38(2): 656-61, 2000 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-10655363

RESUMEN

A multicenter study was conducted to assess the inter- and intralaboratory reproducibility of the Etest for susceptibility testing of the rapidly growing mycobacteria. The accuracy also was evaluated by comparing Etest results to those obtained by broth microdilution. Ten isolates (four of the Mycobacterium fortuitum group, three of Mycobacterium abscessus, and three of Mycobacterium chelonae) were tested against amikacin, cefoxitin, ciprofloxacin, clarithromycin, doxycycline, imipenem, and trimethoprim-sulfamethoxazole in each of four laboratories. At each site, isolates were tested three times on each of three separate days (nine testing events per isolate) using common lots of media and Etest strips. Interlaboratory agreement among MICs (i.e., mode +/- 1 twofold dilution) varied for the different drug-isolate combinations and overall was best for trimethoprim-sulfamethoxazole (75% for one isolate and 100% for all others), followed by doxycycline and ciprofloxacin. Interlaboratory agreement based on interpretive category also varied and overall was best for doxycycline (100% for all isolates), followed by trimethoprim-sulfamethoxazole and ciprofloxacin. Interlaboratory reproducibility among MICs was most variable for imipenem, and agreement by interpretive category was lowest for imipenem and amikacin. Modal Etest MICs agreed with those by broth microdilution only for doxycycline and the sulfonamides. For all other drugs, the modal MICs by the two methods differed by more than +/- 1 twofold dilution for one or more isolates. In all cases, the Etest MIC was higher and would have caused reports of false resistance. In summary, the Etest in this evaluation did not perform as well as broth microdilution for susceptibility testing of the rapidly growing mycobacteria. It was problematic for most species and drugs, primarily because of a trailing endpoint and/or high MICs compared to broth. Its use will necessitate further investigation, including determination of the optimal medium and incubation conditions and clarification of endpoint interpretation.


Asunto(s)
Antibacterianos/farmacología , Mycobacterium chelonae/efectos de los fármacos , Mycobacterium fortuitum/efectos de los fármacos , Micobacterias no Tuberculosas/efectos de los fármacos , Humanos , Laboratorios/normas , Pruebas de Sensibilidad Microbiana/métodos , Infecciones por Mycobacterium no Tuberculosas/microbiología , Tiras Reactivas , Reproducibilidad de los Resultados
2.
J Clin Microbiol ; 37(6): 1676-82, 1999 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-10325306

RESUMEN

A multicenter study was conducted to assess the interlaboratory reproducibility of broth microdilution testing of the more common rapidly growing pathogenic mycobacteria. Ten isolates (four Mycobacterium fortuitum group, three Mycobacterium abscessus, and three Mycobacterium chelonae isolates) were tested against amikacin, cefoxitin, ciprofloxacin, clarithromycin, doxycycline, imipenem, sulfamethoxazole, and tobramycin (M. chelonae only) in four laboratories. At each site, isolates were tested three times on each of three separate days (nine testing events per isolate) with a common lot of microdilution trays. Agreement among MICs (i.e., mode +/- 1 twofold dilution) varied considerably for the different drug-isolate combinations and overall was best for cefoxitin (91.7 and 97.2% for one isolate each and 100% for all others), followed by doxycycline, amikacin, and ciprofloxacin. Agreement based on the interpretive category, using currently suggested breakpoints, also varied and overall was best for doxycycline (97.2% for one isolate and 100% for the rest), followed by ciprofloxacin and clarithromycin. Reproducibility among MICs and agreement by interpretive category was most variable for imipenem. Based on results reported from the individual sites, it appears that inexperience contributed significantly to the wide range of MICs of several drugs, especially clarithromycin, ciprofloxacin, and sulfamethoxazole. New interpretive guidelines are presented for the testing of M. fortuitum against clarithromycin; M. abscessus and M. chelonae against the aminoglycosides; and all three species against cefoxitin, doxycycline, and imipenem.


Asunto(s)
Antibacterianos/farmacología , Pruebas de Sensibilidad Microbiana/métodos , Mycobacterium chelonae/efectos de los fármacos , Mycobacterium fortuitum/efectos de los fármacos , Micobacterias no Tuberculosas/efectos de los fármacos , Amicacina/farmacología , Cefoxitina/farmacología , Ciprofloxacina/farmacología , Claritromicina/farmacología , Medios de Cultivo , Doxiciclina/farmacología , Humanos , Imipenem/farmacología , Infecciones por Mycobacterium no Tuberculosas/microbiología , Mycobacterium chelonae/aislamiento & purificación , Mycobacterium fortuitum/aislamiento & purificación , Micobacterias no Tuberculosas/aislamiento & purificación , Sulfametoxazol/farmacología , Tobramicina/farmacología
3.
J Clin Microbiol ; 35(1): 121-4, 1997 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-8968892

RESUMEN

The reliability of the ESP Culture System II (ESP II; Difco Laboratories, Detroit, Mich.), a continuously monitoring mycobacterial culture system, was evaluated by comparing its performance with the BACTEC TB 460 (BACTEC TB) and Middlebrook 7H11/7H11 selective agar systems. A total of 2,283 specimens of all types (70.7% were respiratory specimens) were cultured; 149 (6.5%) yielded mycobacteria. The most common species recovered were Mycobacterium avium complex (MAC, 73 isolates) and Mycobacterium tuberculosis complex (MTBC, 53 isolates). The recovery rates by individual system were 87, 81, and 65% for ESP II, BACTEC TB, and Middlebrook agar, respectively, for all mycobacteria; the recovery rates were 89, 92, and 89%, respectively, for MTBC. For liquid plus solid medium system combinations, recovery rates for all mycobacteria and for MTBC, respectively, were 91 and 94% for ESP II plus Middlebrook agar and 85 and 96% for BACTEC TB plus Middlebrook agar. The difference between the recovery rates of all mycobacteria by ESP II and by BACTEC TB was not significant, whereas for the individual species, the only significant difference was recovery of more isolates of MAC by ESP II. For those isolates recovered in the individual systems, mean times to detection of all mycobacteria, MTBC, and MAC, respectively, were 13.1, 15.5, and 10.9 days for ESP II; 14.4, 16.6, and 12.1 days for BACTEC TB; and 17.8, 18.3, and 18.8 days for Middlebrook agar. ESP II is a reliable, nonradiometric, less labor-intensive alternative to BACTEC TB for growth and detection of mycobacteria, but as with other liquid culture methods, ESP II should be used in combination with a solid medium, not as a stand-alone system.


Asunto(s)
Técnicas de Cultivo de Célula/métodos , Mycobacterium/clasificación , Técnicas de Tipificación Bacteriana , Medios de Cultivo , Estudios de Evaluación como Asunto , Humanos , Mycobacterium/aislamiento & purificación
4.
Infect Immun ; 60(4): 1363-7, 1992 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-1548062

RESUMEN

An experimental animal model was used to assess the slime layer of Staphylococcus epidermidis as a pathogenic factor in tunnel tract infections. Mice were inoculated with high-slime-producing or non-slime-producing strains of S. epidermidis, either along the length of a subcutaneous catheter or in the area where a catheter had been placed and immediately removed (controls). Among the catheter-bearing mice, the phenotypically distinct staphylococci produced similar, high frequencies of abscess formation (72% [44 of 61] versus 81% [31 of 38]; P = 0.29). In controls, the non-slime-producing organisms were significantly more pathogenic (87% [40 of 46] versus 57% [25 of 44] abscess formation; P = 0.001). No consistent difference was detected between blood isolates obtained from patients with central venous catheter bacteremia and those from neonates with bacteremia in the absence of a prosthetic medical device. Quantitative culture of removed catheters showed greater adherence by the slime-producing isolates (P = 0.014). In this mouse model, slime production by S. epidermidis did not increase the risk of catheter tunnel tract infection, despite the greater catheter adherence of the slime-producing organisms. These findings suggest that traumatized tissue may be a sufficient condition for the development of S. epidermidis catheter-associated infections.


Asunto(s)
Absceso/etiología , Infecciones Estafilocócicas , Staphylococcus epidermidis/patogenicidad , Infección de la Herida Quirúrgica , Animales , Cateterismo Venoso Central/efectos adversos , Modelos Animales de Enfermedad , Ratones
5.
Infect Immun ; 59(8): 2853-5, 1991 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-1856001

RESUMEN

The gene encoding the major outer membrane protein (MOMP) of the psittacine Chlamydia psittaci strain 6BC was cloned and sequenced. N-terminal protein sequencing of the mature MOMP indicated that it is posttranslationally processed at a site identical to the site previously identified in the MOMP of Chlamydia trachomatis L2. The nucleotide sequence of the C. psittaci 6BC MOMP gene was found to be 67 to 68% identical to those of human C. trachomatis strains, 73% identical to that of Chlamydia pneumoniae IOL-207, 79% identical to that of the C. psittaci guinea pig inclusion conjunctivitis strain, GPIC, and 83% identical to that of the C. psittaci ovine abortion strain S26/3. In contrast, the 6BC sequence was found to be greater than 99% identical to the sequences reported for two strains of C. psittaci, A22/M and Cal-10 meningopneumonitis, believed to be of nonpsittacine avian origin. Monoclonal antibody analysis confirmed the nonpsittacine avian origin of A22/M but identified the Cal-10 strain from which the MOMP gene was previously sequenced as a psittacine strain. These results confirm that psittacine and nonpsittacine avian strains of C. psittaci are closely related and distinct from the mammalian guinea pig inclusion conjunctivitis and ovine abortion strains of C. psittaci.


Asunto(s)
Proteínas de la Membrana Bacteriana Externa/genética , Chlamydophila psittaci/genética , Secuencia de Aminoácidos , Animales , Anticuerpos Monoclonales/inmunología , Proteínas de la Membrana Bacteriana Externa/inmunología , Línea Celular , Clonación Molecular , Técnica del Anticuerpo Fluorescente , Genes Bacterianos , Ratones , Datos de Secuencia Molecular , Homología de Secuencia de Ácido Nucleico
6.
J Clin Microbiol ; 29(5): 857-61, 1991 May.
Artículo en Inglés | MEDLINE | ID: mdl-2056051

RESUMEN

The presumed host defense against coagulase-negative staphylococci (ConS), recognized pathogens in hosts with compromised immunity or indwelling medical devices, is opsonophagocytosis. Targets for opsonization remain unclear. Using radiolabeling techniques, we identified the surface-exposed proteins of ConS and determined the innate humoral immune responses to them among healthy adults. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of surface proteins extrinsically labeled with 125I demonstrated 20 to 30 proteins with molecular weights of 15,000 to greater than 130,000. Five to ten of these proteins were immunogenic and recognized by normal human sera, including predominant 18-, 41-, 48-, and 51-kDa proteins. We also evaluated the humoral response of cancer patients with ConS bacteremia. Patients' sera obtained before bacteremic episodes demonstrated a pattern of reactivity similar to that of normal human sera. When patients' sera obtained after bacteremic episodes were used to determine whether an expanded immune response followed infection, only one of seven showed reactivity with more proteins than seen with the innate response. Western blot (immunoblot) analysis and whole-cell enzyme-linked immunosorbent assays were also evaluated. This study identifies (i) the surface-exposed proteins available for host interaction, (ii) the innate human antibody response to these proteins, and (iii) the immune response of cancer patients with ConS bacteremia.


Asunto(s)
Anticuerpos Antibacterianos/biosíntesis , Proteínas Bacterianas/inmunología , Staphylococcus/inmunología , Adolescente , Adulto , Proteínas Bacterianas/química , Proteínas Bacterianas/aislamiento & purificación , Niño , Preescolar , Coagulasa/metabolismo , Humanos , Leucemia/complicaciones , Leucemia/inmunología , Proteínas de la Membrana/química , Proteínas de la Membrana/inmunología , Proteínas de la Membrana/aislamiento & purificación , Peso Molecular , Proteínas Opsoninas , Fagocitosis , Sepsis/complicaciones , Sepsis/inmunología , Staphylococcus/enzimología
7.
J Clin Microbiol ; 28(12): 2757-60, 1990 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-2280006

RESUMEN

Three Staphylococcus epidermidis isolates of differing bacteriophage types were studied to define proteins confined to the cell wall, which were surface exposed and thus available to interact with the host. Three major proteins of 37, 41, and 51 kDa were identified in all whole-cell lysates and cell wall extracts by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. Two additional proteins of 18 and 25 kDa became evident by using 125I labeling to delineate surface-exposed proteins. A classification scheme using P1 to P5 to delineate the 51-, 41-, 37-, 25- and 18-kDa proteins is proposed. Additionally, murine immune sera were used to identify two immunodominant proteins of 51 and 25 kDa (P1 and P4, respectively).


Asunto(s)
Proteínas Bacterianas/aislamiento & purificación , Staphylococcus epidermidis/análisis , Proteínas Bacterianas/clasificación , Proteínas Bacterianas/inmunología , Pared Celular/química , Inmunoquímica , Peso Molecular
8.
Infect Immun ; 56(12): 3021-5, 1988 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-3182069

RESUMEN

The incorporation of [35S]methionine into protein by intracellular and host-free Chlamydia psittaci 6BC was analyzed at intervals between 15 min and 28 h postinfection by autoradiography of sodium dodecyl sulfate-polyacrylamide gels. The profiles of proteins synthesized in the two systems were similar at all times, indicating that the host-free system can be used to monitor the temporal expression of genes in chlamydiae. The host-free system permitted detection of synthesis of chlamydial proteins as early as 15 min postinfection. Some of the proteins synthesized during the initial phases of reorganization of elementary bodies to reticulate bodies either were not synthesized or were synthesized in greatly reduced amounts during the other phases of the developmental cycle. The effects of rifampin and actinomycin D indicated that host-free protein synthesis was at least partially dependent on the initiation and continuation of RNA synthesis in the isolated organisms.


Asunto(s)
Proteínas Bacterianas/biosíntesis , Chlamydophila psittaci/metabolismo , Chlamydophila psittaci/citología , Dactinomicina/farmacología , Peso Molecular , Biosíntesis de Proteínas , Rifampin/farmacología , Factores de Tiempo , Transcripción Genética
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