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Biomedical subjects

R B Roberts

Publications and source records attributed to R B Roberts.

At least 91 records · Page 5Linked to original sources
PubMed1978

Campylobacteriosis in man: pathogenic mechanisms and review of 91 bloodstream infections.

Five patients with Campylobacter fetus(previously called "Vibrio fetus") bacteremia are presented with enteric symptoms in four patients, a self-limited course in three, and with possible nosocomial infection in one patient who had disseminated malignancy. The clinical syndromes of 91 bacteremic patients with campylobacteriosis and C. fetus taxonomy and pathogenicity are reviewed. Studies of potential pathogenic mechanisms in enteric infections failed to reveal the production of either heat-stable or heat-labile, cholera-like enterotoxin, cytotoxicity or invasiveness. In comparison with different species of vibrio infections, C. fetus appears to produce disease by a different mechanism, one which involves a bloodstream infection, perhaps following penetration through the intestinal mucosa as has been demonstrated experimentally with salmonellae and yersinia. Such a pattern is consistent with the clinical pattern of C. fetus infections and the experimental studies reported herein.

Adult↗
PubMed1978

Nafcillin therapy for Staphylococcus aureus endocarditis.

Semisynthetic penicillinase-resistant penicillins are recommended for therapy of Staphylococcus aureus endocarditis, but evaluation of the efficacy and safety of individual agents has received little attention. At The New York Hospital, 11 heroin addicts and 5 nonaddicts were treated with nafcillin. The 11 addicts did well clinically, but four of the five nonaddicts had severe complications, and three of them died. Important adverse reactions to nafcillin occurred in two patients: one developed leukopenia, and one developed an extensive rash. Methicillin was employed to treat two heroin addicts and four nonaddicts. Five of the six patients were cured bacteriologically, but three patients developed nephritis and one patient developed an extensive rash. Nafcillin appears to be highly efficacious for the treatment of S. aureus endocarditis, yielding results at least equal to those obtained with other drugs. Because adverse reactions appear to occur more frequently with methicillin than with nafcillin, we regard nafcillin as the preferable penicillinase-resistant penicillin for the treatment of S. aureus endocarditis.

Endocarditis, Bacterial↗
PubMed1978

Attachment of virulent Treponema pallidum to human mononuclear phagocytes.

The predominant phagocyte in established human syphilitic lesions is the mononuclear phagocyte. As these leucocytes may be important in immunity to Treponema pallidum, the initial interaction between human phagocytes and pathogenic T. pallidum (Nichols strain) was studied in vitro. Motile, virulent T. pallidum attach to the surface membrane of phagocytes but are not ingested by these cells. Heated, non-motile treponemes are not cell-associated but are observed free in the extracellular medium. Attachment is polar, at one or both terminal portions of the treponeme, and is neither serum- nor complement-dependent. Ingestion of virulent treponemes was not observed by phase-contrast or by electron microscopy in the presence of normal human or rabbit serum and complement. Techniques were chosen to preserve both the fragile surface constituents of the treponeme and the phagocytic function of mononuclear cells. Unfixed preparations were observed by phase-contrast microscopical examination during incubation to differentiate motile from non-motile organisms and fixed preparations were used for quantitation of attachment. This model should be useful for studying humoral and cell-mediated immunity in syphilis.

Cell Adhesion↗
PubMed1978

The species of viridans streptococci associated with microbial endocarditis: incidence and antimicrobial susceptibility.

Streptococcal endocarditis has been well recognized for decades and over the years investigators at The New York Hospital have defined many of the diagnostic and therapeutic modalities currently employed in patients with this disease. In this study, speciation of the viridans streptococci has provided new insights into the relative frequency and antimicrobial susceptibility patterns of these organisms. Indeed, recent studies also suggest that S. milleri endocarditis is associated with a high incidence of suppurative complications and that patients with S. bovis endocarditis may have a significant incidence of underlying but asymptomatic lower gastrointestinal malignancies. Further studies correlating viridans streptococcal species with other clinical and laboratory parameters of endocarditis should provide additional insights into this disease.

Culture Media↗
PubMed1978

Streptococcus bovis bacteremia and underlying gastrointestinal disease.

Twenty-six adults with Streptococcus bovis endocarditis and ten with bacteremia alone were studied to determine possible portals of entry. Of 36 patients (17 with endocarditis, eight with bacteremia alone), 25 had gastrointestinal lesions or manipulation. In 22, the gastrointestinal tract appeared to be the source of S bovis bacteremia. Four patients had either carcinoma of the colon (two) or potentially malignant villous adenomas (two) when first seen because of S bovis bacteremia. None of these, nor two other patients with benign colonic polyps, had bowel-related symptoms or signs prior to admission. Since S bovis is a normal intestinal tract inhabitant, bacteremia may frequently be associated with bowel lesions. Streptococcus bovis bacteremia may provide an early clue to the presence of serious and clinically unexpected gastrointestinal disease. Gastrointestinal tract evaluation should be part of S bovis bacteremia patient management, with or without endocarditis.

Adult↗
PubMed1977

Antimicrobial therapy of vitamin B6-dependent streptococcal endocarditis.

Vitamin B6-dependent viridans streptococci were isolated from two patients with microbial endocarditis. Because of their unique requirement for pyridoxal hydrochloride, these organisms did not grow normally in the media usually used in diagnostic laboratories. When tested in supplemented media, both strains were resistant to penicillin G and relatively sensitive to streptomycin. Penicillin-streptomycin synergy was demonstrated in vitro as well as in experimental endocarditis. These laboratory findings confirmed the clinical observations in these two patients that penicillin-streptomycin therapy should be used in vitamin B6-dependent streptococcal endocarditis. Nutritionally varient streptococci may be important pathogens in microbial endocarditis and must be considered in patients with suggestive clinical findings but negative blood cultures.

Adult↗
PubMed1976

The obstetrician's role in reducing the risk of aspiration pneumonitis. With particular reference to the use of oral antacids.

Aspiration of gastric contents is the commonest cause of maternal anesthetic death. If the pH of the contents is below 2.5, morbidity and mortality rates are likely to be higher than if the pH is above 2.5. A study of 146 patients in labor shows that one in four patients is "at risk" to acid aspiration. No time interval between last mean and either onset of labor or delivery can guarantee an empty stomach. The use of oral antacids during labor reduces the number at risk to 1 in 35. Other methods by which the obstetrician may contribute to reducing the risk are discussed.

Anesthesia, Obstetrical↗
PubMed1976

Candida arthritis. A manifestation of disseminated candidiasis.

Fungal infections infrequently involve the joints. Review of the literature reveals that Candida arthritis is rare, that it is usually a complication of disseminated candidiasis and that it occurs as a primary joint infection without spread from adjacent osteomyelitis. In the patient we describe Candida arthritis and bursitis of separate joints developed as a late manifestation of disseminated infection following "transient" C. tropicalis fungemia. Treatment consisting of aspiration and parenteral amphotericin B eradicated the joint infection without the need for surgery. Bursectomy, however, was required to eradicate the bursal infection. Awareness of this as well as other late complications of candidemia which signify disseminated infection is important. Optimal therapy will be determined only by further clinical experience with this unusual manifestation of Candida infection.

Aged↗
PubMed1976

Relative efficacy of clindamycin, erythromycin, and penicillin in treatment of Treponema pallidum in skin syphilomas of rabbits.

The currently recommended antibiotic for treatment of fetal syphilis in pregnant women who are allergic to penicillin is erythromycin. However, clindamycin crosses the placenta more effectively than erythromycin. Therefore, an in vivo rabbit model of intradermal syphilomas was used to determine the effect of clindamycin compared with the effects of erythromycin and penicillin on the growth of virulent Treponema pallidum. The average number of motile treponemes in two, paired, mature lesions was determined before and after therapy in groups of four rabbits per dosage. Single intramuscular doses of clindamycin (15 and 40 mg/kg) and erythromycin (12 and 40 mg/kg) did not decrease treponeme counts significantly. Single injections of penicillin (10,000 units/kg) reduced treponemal counts by more than 250-fold. Multiple intramuscular injections of clindamycin reduced counts by five- to sevenfold, whereas multiple doses of erythromycin and penicillin decreased treponeme counts by greater than 300-fold. These studies indicate that clindamycin is far less active than erythromycin or penicillin in treatment of established syphilitic lesions in rabbits.

Animals↗
PubMed1975

The interaction in vitro between human polymorphonuclear leukocytes and Neisseria gonorrhoeae cultivated in the chick embryo.

Cultivation of Neisseria gonorrhoeae in the allantoic cavity of 10-day chick embryos ensured the following necessary properties for subsequent quantitive in vitro phagocytosis studies of viable gonococci: log phase of growth, resistance to the cidal effect of fresh human serum, maintenance of colonial type, and absence of clumping. Employing a modification of the Maaloe technique, phagocytosis of log-phase type 1 and 2 gonococci by human PMN leukocytes did not occur in the presence or absence of serum. These findings indicate that log-phase type 1 and 2 gonococci possess antiphagocytic surface factors Stationary-phase organisms of the same colonial type were ingested and rapidly killed by human PMN leukocytes under similar experimental conditions, thus emphasizing the necessity to employ log-phase gonococci in the study of phagocytosis and antiphagocytic surface factors. Log-phase type 4 gonococci were ingested and rapidly killed by human PMN leukocytes in the presence of fresh human serum but not heat-inactivated serum or in the absence of serum. Morphologic studies demonstrated that log-phase viable gonococci attach to the surface membrane of human PMN leukocytes. Interiorization of avirulent but not virulent organisms was observed in the presence of fresh human serum. Gonococci-human PMN leukocyte interactions thus provide a model for the investigation of the nonimmunologic and immunologic parameters associated with the attachment and ingestion stages of phagocytosis.

Animals↗
PubMed1975

The protean manifestations of Mycoplasma pneumoniae infection in adults.

Mycoplasma pneumoniae is a well recognized respiratory pathogen in children and young adults. In addition, M. pneumoniae infections may also involve other organ systems. Reviewed here are the various clinical syndromes in adults caused by this infectious agent, with emphasis on those which have recently been seen at The New York Hospital. Two previously unreported manifestations of M. pneumoniae infection, cranial nerve mononeuropathy and hepatitis, are described, and the laboratory methods for diagnosis are discussed.

Adolescent↗