Strains Of Clinical Isolates Research Articles

Investigations on the role of flagella in the colonization of infant mice with Campylobacter jejuni and attachment of Campylobacter jejuni to human epithelial cell lines.

The biochemical and biological properties of the flagella of Campylobacter jejuni have been investigated using two variants selected from a flagellate, motile clinical isolate (strain 81116): a flagellate, non-motile variant (SF-1) and an aflagellate variant (SF-2). Phenotypic and biochemical analysis of the strains and amino acid analysis of the isolated flagella suggest that the variants differed from the wild-type strain only in the absence of flagella and/or motility. The aflagellate variant poorly colonized the gastrointestinal tract of infant mice but the flagellate, non-motile variant colonized the mice as successfully as the wild-type strain. 35S-labelled organisms were used to investigate the attachment of the variants to human epithelial cell monolayers in vitro. The flagellate, non-motile strain attached more efficiently to the cells than the wild-type strain or the aflagellate strain. Differences in attachment suggest that an adhesin is intimately associated with flagella of C. jejuni and that active flagella mediate only a tenuous association with host cells. This adhesin attached most efficiently to cells of intestinal epithelial origin and was not specifically inhibited by various sugars.

The Type b Capsular Polysaccharide as a Virulence Determinant of Haemophilus influenzae: Studies Using Clinical Isolates and Laboratory Transformants

Haemophilus influenzae organisms elaborating one of six capsular polysaccharides (types a-f) colonize the respiratory tract of humans, but only type b strains commonly cause systemic infections. To investigate the role of capsular polysaccharides as virulence determinants, rats were inoculated with capsulated (types a-f) or noncapsulated clinical isolates or with laboratory-derived type b and type d transformants of a noncapsulated strain. After intraperitoneal inoculation, all capsulated strains possessed the potential for systemic infection, but type b strains were more virulent; noncapsulated strains were noninvasive. After intranasal inoculation, only type b strains were invasive. There was no difference in efficiency of nasopharyngeal colonization between type b and type d transformants. After intravenous inoculation, only type b strains resulted in persistent bacteremia. Thus, type b strains--clinical isolates or transformants--display unique virulence characteristics. These data suggest that elaboration of type b capsule is necessary and sufficient for this virulence of H. influenzae type b in the rat.

A possible role of R plasmids in bacterial permeability for beta-lactam antibiotics.

Four strains of clinical isolates of Serratia marcescens (13039, 13090, 13093, 14093) harboring R plasmids were highly resistant to ampicillin (ABPC) and cephaloridine (CER). With elimination of R plasmids from these strains by acriflavine treatment, ABPC-resistance levels of these strains were markedly reduced. Reduction of CER-resistance levels was also demonstrated in strains 13039 and 13093, but not in strains 13090 and 14093. The permeability of the former strains for CER was also decreased, but not in the latter strains. At the same time, beta-lactamase activity of these strains also almost completely disappeared when the R plasmids were eliminated. By broth matings with these strains. The recipient strains of S. marcescens 13031 (rif), Escherichia coli K-12 (rif), and E coli 15046 (rif) all acquired a high permeability barrier against CER with inheritance of the R plasmids from strains 13039 and 13093, but not from strains 13090 and 14093. The transconjugant of strain 13031 that inherited R plasmid 13093 was resistant not only to CER but also to cefazolin, cephalothin, and cephalexin. Its permeability to these antibiotics was significantly lower than that of the original strain. This fact suggest the possibility that the R plasmid from strain 13093 may be involved not only in production of beta-lactamases, but also in regulation of bacterial permeability for cephalosporins.

In vitro sensitivity of Trichomonas vaginalis and Candida albicans to chemotherapeutic agents.

Strains of fresh clinical isolates of Trichomonas vaginalis and Candida albicans have been tested in vitro for their sensitivity to eight drugs used in the therapy of monilial and trichomonal vaginitis. Three of the chemotherapeutic agents, chlorchinaldol, clotrimazole and broxyquinoline were effective against both organisms. Tinidazole and metronidazole were active against T. vaginalis. The strains of C. albicans were also sensitive to trichomycin, natamycin and nystatin. Tinidazole was the most effective trichomonacide, clotrimazole and chlorchinaldol were most effective against C. albicans, while chlorchinaldol had the best in vitro effect against both organisms. The ranges of the MICs are compared to values previously reported.

Esculin hydrolysis reaction by Escherichia coli

The literature contains variable reports concerning the hydrolysis of esculin by members of the family Enterobacteriaceae and particularly Escherichia coli. We examined 113 strains of fresh clinical isolates of E. coli and assessed the ability of colonies in a population to hydrolyze esculin with and without preincubation in inducible substrates at 24, 48, and 72 h. The number of strains capable of fermenting salicin, a sugar with a beta-glucoside linkage like esculin, was studied under the same conditions. A strip test that measured the presence of the constitutive glucosidase was also performed with and without preincubation in inducible substrates. No E. coli strain was able to produce constitutive enzyme; preincubation in esculin and salicin resulted in an induction of the beta-glucosidase. The number of colonies able to hydrolyze esculin increased with time. Only those strains preincubated in esculin or salicin were able to produce a positive constitutive strip test. Because the beta-glucosidase of E. coli is inducible, one should employe, when using growth media, a light inoculum obtained by touching the top of a colony with a bacteriological wire and read the reaction between 18 and 24 h, or perform a rapid strip or spot test.

Absence of 3',5'-Cyclic Adenosine Monophosphate and Related Enzymes in Neisseria gonorrhoeae

SummarycAMP, adenyl cyclase, and cAMP phosphodiesterase were not detected in spent culture media or cell extracts of a recent clinical isolate and laboratory strains of N. gonorrhoeae. cAMP and related enzymes were not detected in either T-1 or T-4 colonial types of N. gonorrhoeae or in other Neisseria spp.

Genetic analysis on the incompatibility system ofAjellomyces dermatitidis

Analysis of mating types of numerous single ascospore isolates obtained from crosses between various strains of Arthroderma dermatitidis showed a 1:1 ratio of +vs - type. From this and the similar results from mating type tests, using 22 fresh clinical isolates, it was concluded that mating in A. dermatitidis is controlled by a bipolar incompatibility.Fruiting competence of the perfect state is found to be directly related to the formation of buff to yellowish-brown pigment in each strain and is independent of the mating factors. All the yellowish brown strains of single-ascospore isolates or fresh clinical isolates produced cleistothecia in single cultures that were devoid of ascospores (pseudocleistothecia). The majority of deep buff strains also produced such structures when paired with the same mating type, but fertile cleistothecia with the opposite mating type. White strains never produced pseudocleistothecia in single cultures and were sterile or poorly fertile when paired with the opposite mating ...