Artículos (Microbiología)

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Division macronucléaire du cilié laurentiella acuminata
(Editions du C.N.R.S., 1982) Torres Rueda, Antonio Ildefonso; Calvo Ruiz, Purificación; Muñoz, J. J.; Pérez Silva, Julio; Universidad de Sevilla. Departamento de Microbiología
The distribution of DNA in the macronuclear division of the Hypotrich ciliate Laurentiella acuminata has been studied by cytophotometric techniques. The mean degree of inequality found in the distribution of DNA between sister cells is 10.05 %. Differences in DNA contents in randomly-paired cells is greater than in sister cells, this result could be due to accumulation of small differences over many divisions.
Genetic and biochemical study of threonine-overproducing mutants of Saccharomyces cerevisiae
(1982) Delgado, Marco A.; Guerrero, Josefa; Conde, Jaime; Universidad de Sevilla. Departamento de Microbiología
Three threonine-overproducing mutants were obtained as prototrophic revertants of a hom3 mutant strain of Saccharomyces cerevisiae. The gene HOM3 codes for aspartokinase (aspartate kinase; EC 2.7.2.4), the first enzyme of the threonine-methionine biosynthetic route, which is subjected to feedback inhibition by threonine. Enzymatic studies indicated that aspartokinase from the revertants has lost the feedback inhibition, resulting in overproduction of threonine. These revertants also bore one or two additional mutations, named texl-J and tex2-1, which alone or jointly made possible the excretion of the threonine accumulated. The effect of these two genes on excretion is potentiated by excess inositol in the medium.
Complex Carbohydrates in the Cyst Wall of Histriculus similis
(Society for Genral Microbiology, 1983) Calvo Ruiz, Purificación; Torres Rueda, Antonio Ildefonso; Navas, P.; Pérez Silva, Julio; Universidad de Sevilla. Departamento de Microbiología
The ultrastructure of the cyst wall has been studied in severa! hypotrichous ciliates. In Oxytrichafallax (Grimes, 1973),Pleurotricha sp. (Matsusaka, 1976), Stylonychia mytilus (Walker et al., 1975), Gastrostyla steinii (Walker et al., 1980) and Laurentiella acuminata (Gutierrez et al., l 980), the cyst wall is composed of four layers called, from outside to inside :the ectocyst, meso cyst, endocyst and granular layers. In these ciliates a resorption of cilia and kinetosomes occurs during encystment, and the mature cyst is termed kinetosome resorbing. Diophrys scutum (Walker & Maugel , 1980) has a three layered cyst wall and the mature cyst is non kinetosome resorbing. In the present work a structural and cytochemical study of the cyst wall in Histriculus similis was carried out by means of light microscopy and transmission electron microscopy .
Étude ultrastructurale de la morphogenese corticale. De régénération chez le cilié hypotriche histriculus similis
(Éditions du Centre national de la recherche scientifique, 1984) Calvo Ruiz, Purificación; Fedriani Iriso, Concepción; Nieto Gutiérrez, Joaquín José; Torres Rueda, Antonio Ildefonso; Universidad de Sevilla. Departamento de Microbiología
La régénération chez Histriculus similis a été étudiée en microscopie électronique. Les premiers signes du procesus de régénération s'observenl une heure apres le traitement par l'urée. Pendant la morphogenese corticale de régénération tanl du primordium oral que des primordiums de la ciliature parorale et des cirres, les états premiers sont constitués par des couples de cinétosomes, qui portent des microtubules postciliaires dans le cinétosome postérieur et des microtubules transverses a l'antérieur. L'orientation de ces couples dépend du primordium qu'ils vonl produire. Une fois que les couples de cinétosomes sont alignés, a Iieu une prolifération de nouveaux cinélosomes proches de ces couples. Plus tard il y a une fragmentation transversale de ces primordiums , a l'exception du primordium paroral qui se divise longitudinalement.
The cyst of urostyla grandis (hypotrichida : Urostylidae) : ultrastructure and evolutionary implications
(Éditions du Centre national de la recherche scientifique, 1985) Ríos Sánchez, Rosa María; Torres Rueda, Antonio Ildefonso; Calvo Ruiz, Purificación; Fedriani Iriso, Concepción; Universidad de Sevilla. Departamento de Microbiología
L'examen , en microscopie électronique, du kyste d'Uros1y la grandis a révélé que sa paroi se compose de trois couches : un exokyste fibrillaire, un endokyste a structure homogéne et une couche granulaire avec une structure granulaire ou fibrillaire. Le maintien de quelques cinétosomes, microtubules subpellicula ires et d'autres particularités permettent de distinguer ces kystes des kystes KR et NKR. On propose d'ajouter un nouveau groupe a la classification de WALKER et MAUG EL. On commente quelques relations phylogéniques reposan! sur des caractéristiques comparatives.
Accumulation of Poly(beta-Hydroxybutyrate) by Halobacteria
(American Society for Microbiology, 1986) Fernández Castillo, Rosario; Rodríguez Valera, Francisco; González Ramos, J.; Ruiz Berraquero, Francisco; Universidad de Sevilla. Departamento de Microbiología; Comisión Asesora de Investigación Científica y Técnica (CAICYT). España
Some species of extremely halophilic archaebacteria, Halobacteriaceae, have been shown to accumulate large amounts of poly(P-hydroxybutyrate) under conditions of nitrogen limitation and abundant carbon source. The production of poly(P3-hydroxybutyrate), at least in large quantities, was restricted to two carbohydrate-utilizing species, Halobacterium mediterranei and H. volcanii. In addition to the nutrients in the media, the salt concentration also influenced poly(P-hydroxybutyrate) accumulation, which was greater at lower salt concentrations. The possible application of these microorganisms for the production of biodegradable plastics is discussed.
Uptake and intracellular activity of an optically active ofloxacin isomer in human neutrophils and tissue culture cells
(American Society for Microbiology, 1990-01-01) Pascual Hernández, Álvaro; García Luque, Isabel; Perea Pérez, Evelio José; Universidad de Sevilla. Departamento de Microbiología
The penetration of an optically active ofloxacin isomer [(-)-ofloxacin] into human neutrophils and different tissue culture cells (HEp-2, McCoy, MDCK, and Vero) was studied and compared with that of ofloxacin by a fluorometric assay. The cellular-to-extracellular-concentration ratios (C/E) of (-)-ofloxacin were always higher than 6, significantly greater than those of ofloxacin at extracellular concentrations of 5 and 10 mg/liter. The penetration of (-)-ofloxacin and ofloxacin was doubled when neutrophils were stimulated by phorbol myristate acetate but not affected after ingestion of opsonized Staphylococcus aureus. The C/E ratios of (-)-ofloxacin and ofloxacin for different tissue culture epithelial cells and fibroblasts were lower than those of neutrophils but still higher than 2. Both compounds produced a significant reduction in viable intraphagocytic S. aureus during 3 h of exposure to antimicrobial agents. We conclude that (-)-ofloxacin appears to reach higher intracellular concentrations than ofloxacin, remaining active inside the neutrophils.
A broad molecular phylogeny of ciliates: Identification of major evolutionary trends and radiations within the phylum
(National Academy of Sciences, 1992) Baroin-Tourancheau, Anne; Delgado, Pilar; Perasso, Roland; Adoutte, André; Universidad de Sevilla. Departamento de Microbiología
The cellular architecture of ciliates is one of the most complex known within eukaryotes. Detailed systematic schemes have thus been constructed through extensive comparative morphological and ultrastructural analysis of the ciliature and of its internal cytoskeletal derivatives (the infraciliature), as well as of the architecture of the oral apparatus. In recent years, a consensus was reached in which the phylum was divided in eight classes as defined by Lynn and Corliss [Lynn, D. H. and Corliss, J. O. (1991) in Microscopic Anatomy of Invertebrates: Protozoa (Wiley-Liss, New York), Vol. 1, pp. 333-467]. By comparing partial sequences of the large subunit rRNA molecule, and by using both distance-matrix and maximum- parsimony-tree construction methods (checked by bootstrapping), we examine the phylogenetic relationships of 22 species belonging to seven of these eight classes. At low taxonomic levels, the traditional grouping of the species is generally confirmed. At higher taxonomic levels, the branching pattern of these seven classes is resolved in several deeply separated major branches. Surprisingly, the first emerging one contains the heterotrichs and is strongly associated with a karyorelictid but deeply separated from hypotrichs. The litostomes, the oligohymenophorans, and the hypotrichs separate later in a bush-like topology hindering the resolution of their order of diversification. These results show a much more ancient origin of heterotrichs than was classically assumed, indicating that asymmetric, abundantly ciliated oral apparatuses do not correspond to 'highly evolved' traits as previously thought. They also suggest the occurrence of a major radiative explosion in the evolutionary history of the ciliates, yielding five of the eight classes of the phylum. These classes appear to differ essentially according to the cytoskeletal architecture used to shape and sustain the cellular cortex (a process of essential adaptative and morphogenetic importance in ciliates).
Uptake and intracellular activity of sparfloxacin in human polymorphonuclear leukocytes and tissue culture cells
(American Society for Microbiology, 1992-01-01) García Luque, Isabel; Pascual Hernández, Álvaro; Guzman Morgaz, Carmen; Perea Pérez, Evelio José; Universidad de Sevilla. Departamento de Microbiología
The penetration of sparfloxacin into human neutrophils (PMN) and different tissue culture cells (HEp-2 and McCoy) was evaluated. The cellular to extracellular concentration ratios (C/E) of sparfloxacin were always higher than 4 at extracellular concentrations ranging from 0.5 to 25 mg/liter. The uptake of sparfloxacin by PMN was rapid, nonsaturable, reversible, not energy dependent, and significantly reduced at pH 8. The penetration of this agent into PMN was similar when viable and Formalin-killed cells were used and was not affected by environmental temperature. Ingestion of opsonized zymosan significantly increased the amount of PMN-associated sparfloxacin. Sparfloxacin at a concentration of 0.5 mg induced a significant reduction in the survival of intracellular Staphylococcus aureus. It is concluded that sparfloxacin reaches intracellular concentrations within leukocytic cells much higher than extracellular concentrations, while remaining active intracellularly.
Índices clínicos y microbiología de la enfermedad periodontal: su valor pronóstico
(Ergon, 1993) Ríos-Santos, J.V.; Bullon, Pedro; Borobio Enciso, María Victoria; Fernández Palacín, Ana; Martínez-Sahuquillo Márquez, Ángel; Machuca-Portillo, Guillermo; Universidad de Sevilla. Departamento de Estomatología
Uptake and intracellular activity of fluconazole in human polymorphonuclear leukocytes
(American Society for Microbiology, 1993-01-01) Pascual Hernández, Álvaro; García Luque, Isabel; Conejo Gonzalo, Mª Carmen; Perea Pérez, Evelio José; Universidad de Sevilla. Departamento de Microbiología
The penetration of fluconazole into human polymorphonuclear leukocytes (PMNs) and tissue culture epithelial cells (McCoy) was evaluated. At different extracellular concentrations (0.5 to 10 mg/liter), fluconazole reached cell-associated concentrations greater than the extracellular ones in either human PMNs (intracellular concentration to extracellular concentration ratio, ≥2.2) or McCoy cells (intracellular concentration to extracellular concentration ratio, ≥1.3). The uptake of fluconazole by PMNs was rapid and reversible but was not energy dependent. The intracellular penetration of fluconazole was not affected by environmental pH or temperature. Ingestion of opsonized zymosan and opsonized Candida albicans did not significantly increase the amount of PMN-associated fluconazole. At therapeutic extracellular concentrations, the intracellular activity of fluconazole against C. albicans in PMNs was significantly lower than that of amphotericin B. It was concluded that fluconazole reaches high intracellular concentrations within PMNs but shows moderate activity against intracellular C. albicans in vitro.
Cortical development associated with conjugation of Paramecium
(Company of Biologists Ltd, 1993-03) Romero, Maria Rosario; Torres Rueda, Antonio Ildefonso; Universidad de Sevilla. Departamento de Microbiología; Junta de Andalucía
The cortical cytoskeleton of Paramecium is characterized by a complex, polarized and asymmetrical organization. In order to analyse the cortical development of Paramecium tetraurelia during the sexual process of conjugation, different antibodies have been used to follow the development of five cortical components: basal bodies, ciliary rootlets, outer lattice, epiplasm and cytospindle. This study demonstrates that the cortex of Paramecium undergoes an elaborate development process following conjugation. Some of the cortical structures that are not renewed at any other moment of the cell cycle, are resorbed after conjugation and replaced by other newly formed ones. The reorganization of the cortical components occurs according to different morphogenetic waves that spread over the cell surface. The oral system and the preoral suture line act as morphogenetic epicentres.
A peripheral protein associated with the cis-Golgi network redistributes in the intermediate compartment upon brefeldin A treatment
(Rockefeller University Press, 1994) Ríos Sánchez, Rosa María; Tassin, Anne-Marie; Celati, Claude; Antony, Claude; Boissier, Marie-Christophe; Homberg, Jean-Claude; Bornens, Michel; Universidad de Sevilla. Departamento de Microbiología; Ministerio de Sanidad y Consumo. España
Human autoantibodies offer unique tools for the study of cellular constituents since they usually recognize highly conserved components, the most difficult to detect due to their low immunogenicity. The serum from a patient with Sjogren's syndrome (RM serum) showing a very high reactivity to the Golgi complex has been shown to immunoprecipitate and to immunodetect by Western blotting experiments a protein of mol wt 210,000 (p210) that was shown to be peripheral and cytoplasmically disposed. A close examination of the p210 labeling revealed some differences with Golgi markers: RM serum staining was slightly more extensive than several Golgi markers and showed a discontinuous or granular appearance. Nocodazole induced a specific and early segregation of many p210-associated vesicles or tubules from Golgi apparatus. Upon brefeldin A treatment, p210 did not redistribute in the ER as did other Golgi proteins. In contrast, it exhibited a vesicular pattern reminiscent to that displayed by proteins residing in the intermediate compartment. Double staining immunofluorescence using the RM serum and the marker of the intermediate compartment, p58, revealed segregation of both proteins in control conditions but colocalization in BFA-treated cells. We have further demonstrated by combining different drug treatments that p210-containing elements in brefeldin A-treated cells belong indeed to the intermediate compartment. Experiments on brefeldin A recovery suggested that these p210 elements might play a role in reformation and repositioning of the Golgi apparatus. Ultrastructural localization performed by immunoperoxidase staining allowed us to establish that p210 interacted with the external side of an abundant tubulo-vesicular system on the cis side of the Golgi complex which extended to connecting structures and vesicles between saccules or stacks of cisternae. p210 appears to be a novel protein residing in the cis- Golgi network that may cycle between the Golgi apparatus and the intermediate compartment.
Intracellular penetration and activity of BAY Y 3118 in human polymorphonuclear leukocytes
(American Society for Microbiology, 1994-01-01) García Luque, Isabel; Pascual Hernández, Álvaro; Perea Pérez, Evelio José; Universidad de Sevilla. Departamento de Microbiología
The penetration of a new quinolone (BAY Y 3118) into human polymorphonuclear leukocytes (PMNs) was evaluated by a fluorometric assay. The cellular concentration-to-extracellular concentration (C/E) ratio was higher than 6.3 at extracellular concentrations ranging from 2 to 100 mg/liter. The uptake of BAY Y 3118 was rapid, reversible and nonsaturable. The intracellular penetration of BAY Y 3118 was significantly affected by environmental temperature (C/E ratio at 4°C, 5.4 ± 0.5; control, 7.5 ± 0.9; P < 0.05) and cell viability (C/E ratio in dead PMNs, 5.5 ± 0.8; control, 7.5 ± 0.9; P < 0.05), but it was not affected by metabolic inhibitors. The ingestion of opsonized zymosan or opsonized Staphylococcus aureus significantly decreased the levels of PMN-associated BAY Y 3118. Cell stimulation by a membrane activator, however, significantly increased the intracellular concentration of this quinolone. At therapeutic extracellular concentrations (0.5, 2, and 5 mg/liter), BAY Y 3118 showed intracellular activity greater than that of ciprofloxacin against S. aureus in human PMNs. It was concluded that BAY Y 3118 reaches high intracellular concentrations within human PMNs and remains active intracellularly.
Estudio longitudinal (2 años) de la periodontitis crónica del adulto: respuesta clínica y microbiológica
(Ergon, 1995) Ríos-Santos, J.V.; Borobio Enciso, María Victoria; Velasco-Ortega, Eugenio; Martínez-Sahuquillo Márquez, Ángel; Machuca-Portillo, Guillermo; Bullon, Pedro; Universidad de Sevilla. Departamento de Estomatología
Se realiza un seguimiento clínico y microbiológico durante dos años de 20 pacientes (2228 zonas) con periodontitis crónica del adulto evaluando la respuesta al raspado y alisado radicular. Se observa una recuperación de inserción al finalizar el raspado, que se pierde en parte a los dos años. Un análisis discriminante demostró que el sangrado es un buen factor de agrupación de las bolsas, encontrándose correlacionado con placa y nivel de inserción. Un análisis de regresión múltiple estimó que cuando la bolsa sangraba al comienzo del estudio, la respuesta clínica satisfactoria se reducía al 50%. Se observó una reducción de la flora patógena a los seis meses del raspado con reinstalación de los periodontopatógenos a los dos años. Además, los pacientes con evolución clínica desfavorable tenían mayor concentración al comienzo del estudio de bacilos gram negativos anaerobios y facultativos que los pacientes con evolución favorable.
Comparison of E-test with broth microdilution and disk diffusion for susceptibility testing of coryneform bacteria
(American Society for Microbiology, 1995) Martínez Martínez, Luis; Universidad de Sevilla. Departamento de Microbiología
The susceptibilities of 135 coryneform bacteria isolated from clinical samples to ampicillin (AMP), cephalothin (CR), cefoxitin (FOX), cefotaxime (CTX), erythromycin (E), ciprofioxacin (CIP), tetracycline (TE), amikacin (AK), vancomycin (VA), and rifampin (R) were determined by disk diffusion, broth microdilution, and the E-test. The following species (number of isolates in parentheses) were included: Corynebacterium urealyticum (30), Corynebacterium minutissimum (20), coryneform CDC group ANF-1 (20), Corynebacterium striatum (20), Corynebacterium jeikeium (15), coryneform CDC group 12 (8), Listeria monocytogenes (7), Corynebacterium xerosis (5), and other coryneform bacteria (10). Agreement within one twofold dilution between the E-test and broth microdilution was 31% (VA), 64% (AK), 71% (CTX), 77% (FOX and CIP), 79% (TE), 84% (AMP), 87% (E), and 88% (CR and R). For the 1,350 combinations of microorganisms and antimicrobial agents, 85 (6.3%) discrepancies in interpretive category were found (4.2% minor, 1.2% major, and 0.9% very major). Seventy (5.1%) disagreements in interpretive category were found between disk diffusion and the E-test (3.8% minor, 0.4% major, and 0.9% very major), and 85 (6.3%) disagreements were found between microdilution (reference method) and disk diffusion (4.2% minor, 0.5% major, and 1.5% very major). MICs obtained with the E-test were highly reproducible. No category discrepancy was observed for VA, despite quantitative results. Considering interpretive categories, there is a good overall agreement between the three methods studied here, but further evaluation of current methodologies for susceptibility testing is required when considering coryneform bacteria and determination of quantitative activity of antimicrobial agents.
Phenotypic characteristics of 31 strains of Corynebacterium striatum isolated from clinical samples
(American Society for Microbiology, 1995) Martínez Martínez, Luis; Suárez, Ana Isabel; Winstaley, Judith; Ortega, M. Carmen; Bernard, Kathryn; Universidad de Sevilla. Departamento de Microbiología
During a 34-month period (January 1991 to October 1993), 31 Corynebacterium striatum strains recovered from clinical samples from 24 patients were characterized. Twenty (64%) strains were isolated from wound exudates, 5 (16%) were isolated from bronchial aspirates, 2 (7%) were isolated from urine, 2 (7%) were isolated from endotracheal tubes, 1 (3%) was isolated from a catheter, and 1 (3%) was isolated from empyema. The organisms were identified by conventional culture and phenotypic characterization, the API CORYNE system, and cellular fatty acid composition analyses. The colonies of C. striatum could be confused with those of coagulase-negative staphylococci upon primary isolation from clinical material. A consistent phenotypic pattern was observed: all strains reduced nitrate, hydrolyzed tyrosine, and produced acid from glucose, fructose, and sucrose but not from maltose. API CORYNE profile numbers were 3100105 (28 strains) and 3000105 (3 strains). Susceptibility testing of C. striatum was performed by disk diffusion. All strains were susceptible to both imipenem and vancomycin and resistant to fosfomycin; most strains were susceptible to ampicillin and cephalosporins and resistant to clindamycin, erythromycin, and tetracycline. Performing a Gram stain of fosfomycin-resistant 'Staphylococcus-like' colonies was critical in order to identify C. striatum.
Comparison of broth microdilution and E-test for susceptibility testing of Neisseria meningitidis
(American Society for Microbiology, 1996) Pascual Hernández, Álvaro; Joyanes, Providencia; Martínez Martínez, Luis; Suárez, Ana Isabel; Perea Pérez, Evelio José; Universidad de Sevilla. Departamento de Microbiología
The susceptibilities of 54 clinical isolates of Neisseria meningitidis to penicillin, cefotaxime, ceftriaxone, cefepime, imipenem, ciprofloxacin, chloramphenicol, and rifampin were determined by the microdilution method in both cation-adjusted Mueller-Hinton broth (CAMHB) and Haemophilus test medium (HTM). Poor growth was observed in 16.6 and 9% of the strains in CAMHB and HTM, respectively. As a result, the growth of the 54 N. meningitidis strains was evaluated in three other commercially available hatches of CAMHB and in one in-house batch of HTM. Poor growth was observed for 9.3 to 16.6% of the strains in all four batches. More important, three of the CAMHB batches failed to support growth for 3.7 to 33.3% of the strains; 3.7% of the strains did not grow in the in-house-prepared HTM. Ten (18.7%) strains were relatively resistant to penicillin (RRP; MIC, >0.125 μg/ml) in CAMHB and 13 (24%) strains were RRP in HTM. The percentages of agreement obtained by using CAMHB as the reference ranged from 78% for cefepime to 100% for ceftriaxone. Seven minor errors were observed for penicillin; five of them were for strains susceptible to penicillin in CAMHB and RRP in HTM. All strains were susceptible to the other antimicrobial agents evaluated. The growth of N. meningitidis was also evaluated in four batches of Mueller-Hinton agar (MHA). In two of them, 3.7 and 44.4% of the strains did not grow, and considering all four batches, 5.5 to 11.1% grew poorly. All strains grew adequately in MHA supplemented with blood (MHA-b). The activities of penicillin and cefotaxime were also evaluated by the E-test in MHA and MHA-b. The proportion of RRP strains were 24% in MHA and 59% in MHA-b. For penicillin, the percentages of agreement of the E-test with the microdilution method in CAMHB (reference) were 64.8 and 70.3% in MHA and MHA-b, respectively. For cefotaxime, the agreement was 98.1%. Minor errors for the penicillin MIC were detected for 38% of the strains tested. Further studies are needed to define adequate culture media for reference methods to evaluate the susceptibility of N. meningitidis to antimicrobial agents.
In vivo selection of porin-deficient mutants of Klebsiella pneumoniae with increased resistance to cefoxitin and expanded-spectrum cephalosporins
(American Society for Microbiology, 1996-02-01) Martínez Martínez, Luis; Hernández Allés, Santiago; Albertí, Sebastián; Tomás, Juan M.; Benedí, Vicente J.; Jacoby, George A.; Universidad de Sevilla. Departamento de Microbiología
Four Klebsiella pneumoniae isolates (LB1, LB2, LB3, and LB4) with increased antimicrobial resistance were obtained from the same patient. The four isolates were indistinguishable in biotype, plasmid content, lipopolysaccharide, and DNA analysis by pulse-field gel electrophoresis. Isolate LB1 made TEM-1 and SHV-1 β-lactamases. Isolates LB2, LB3, and LB4 produced SHV-5 in addition to TEM-1 and SHV-1. MICs of cefoxitin, ceftazidime, and cefotaxime against LB1 were 4, 1, and 0.06 μg/ml, respectively. MICs of ceftazidime against K. pneumoniae LB2, LB3, and LB4 were >256 μg/ml, and those of cefotaxime were 2, 4, and 64 μg/ml, respectively. MICs of cefoxitin against K. pneumoniae LB2 and LB3 were 4 μg/ml, but that against K. pneumoniae LB4 was 128 μg/ml. K. pneumoniae LB4 could transfer resistance to ceftazidime and cefotaxime, but not that to cefoxitin, to Escherichia coli. Isolate LB4 and cefoxitin-resistant laboratory mutants lacked an outer membrane protein of about 35 kDa whose molecular mass, mode of isolation, resistance to proteases, and reaction with a porin-specific antiserum suggested that it was a porin. MICs of cefoxitin and cefotaxime reverted to 4 and 2 μg/ml, respectively, when isolate LB4 was transformed with a gene coding for the K. pneumoniae porin OmpK36. We conclude that the increased resistance to cefoxitin and expanded-spectrum cephalosporins of isolate LB4 was due to loss of a porin channel for antibiotic uptake.
Antimicrobial susceptibility pattern of Corynebacterium striatum
(American Society for Microbiology, 1996-11-01) Martínez Martínez, Luis; Pascual Hernández, Álvaro; Bernard, Kathryn; Suárez, Ana Isabel; Universidad de Sevilla. Departamento de Microbiología
The in vitro activities of 16 antimicrobial agents against 86 strains of Corynebacterium striatum were evaluated by microdilution using cation- adjusted Mueller-Hinton broth. MICs at which 90% of strains were inhibited were 0.06 μg/ml for teicoplanin, 1 μg/ml for vancomycin, 0.03 to 8 μg/ml for β-lactams, 8 μg/ml for sparfloxacin, 16 μg/ml for ciprofloxacin, 16/304 μg/ml for co-trimoxazole (trimethoprim-sulfamethoxazole), 64 μg/ml for tetracycline, 128 μg/ml for gentamicin, and >128 μg/ml for amikacin, erythromycin, and rifampin.

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