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Biomedical subjects

L M Baddour

Publications and source records attributed to L M Baddour.

At least 73 records · Page 4Linked to original sources
PubMed1987

Phenotypic variation of Staphylococcus epidermidis slime production in vitro and in vivo.

Clinical studies performed by us and others have found an association between slime production and strains of coagulase-negative staphylococci that infect indwelling medical devices. By serial low-speed centrifugation of broth cultures we have isolated a stable, weakly adherent strain (RP62A-NA) from a strongly adherent, slime-producing, pathogenic strain of Staphylococcus epidermidis sensu stricto (RP62A, ATCC 35984). We obtained a second strain from RP62A-NA (RP62A-NAR) by serial subculture of glass-adherent cells of RP62A-NA. All three strains had the same pattern of biochemical reactions, antimicrobial susceptibilities, and plasmid analysis. Transmission electron micrograph sections stained with the mucopolysaccharide-specific stain alcian blue demonstrated that the adherent strains RP62A and RP62A-NAR were covered with an extracellular coat of polysaccharide-rich material. In contrast, the nonadherent RP62A-NA strain lacked this external coat. All three strains were used in a mouse model of foreign body infection and a rat model of catheter-induced infective endocarditis. The adherence characteristics of isolates of RP62A and RP62A-NA recovered from experimental animals were relatively stable, although we noted a slight but a significant increase in the adherence of RP62A-NA isolates recovered from the foreign body model. The adherence characteristics of RP62A-NAR isolates recovered from infected animals were variable; in general these isolates were less adherent than the laboratory strain of RP62A-NAR. In both models the 50% infective dose (calculated by the Reed and Muench method) was three times greater for the RP62A-NA strain than for the RP62A strain. The phenotypic expression of slime production is subject to both in vitro and in vivo variation and could play a role in the pathogenesis of foreign body infection.

Animals↗
PubMed1987

Bacterial concentration correlations in experimental endocarditis caused by Staphylococcus epidermidis.

Using 13 strains of Staphylococcus epidermidis to produce catheter-induced experimental endocarditis in rats, we found that bacterial concentrations in blood cultures obtained at the time of sacrifice correlated significantly with the number of organisms per gram of endocardial vegetation (P less than 0.001) and the total number of organisms per vegetation (P less than 0.001). Furthermore, blood culture concentrations correlated with vegetation weights (P less than 0.001) and sizes of infecting inocula (P less than 0.0001). Mean bacterial concentrations in vegetations more than doubled as bacterial concentrations in blood rose from less than 10 to greater than 100 CFU/ml. Mean values for vegetation weights, total organisms per vegetation, and sizes of infecting inocula were also reflected by the intensity of bacteremia. Moreover, intracardiac catheters were more likely colonized as bacterial concentrations in blood cultures increased, with all catheters culture positive in the 25 animals that exhibited high-grade bacteremia (greater than or equal to 100 CFU/ml). Slime production by the bacteria did not influence the above-mentioned correlations. These data indicate that the blood concentration of bacteria reflects the microbiologic status of infected vegetations in experimental infective endocarditis.

Animals↗
PubMed1986

Coagulase-negative staphylococcal endocarditis. Occurrence in patients with mitral valve prolapse.

Although coagulase-negative staphylococci (CoNS) are frequent etiologic agents in prosthetic valve endocarditis, they rarely infect native heart valves. We report three cases of CoNS endocarditis in patients with mitral valve prolapse (MVP). Review of other reports of MVP-associated endocarditis and of the limited experience with CoNS infection of native heart valves suggests that our experience is not unique. Coagulase-negative staphylococcal endocarditis superimposed on MVP may be difficult to recognize and to treat. The cardiac dysfunction can be quite subtle, the clinical course indolent, the blood culture results difficult to interpret, and the response to antimicrobial agents suboptimal.

Adolescent↗
PubMed1986

Comparison of microbiologic characteristics of pathogenic and saprophytic coagulase-negative staphylococci from patients on continuous ambulatory peritoneal dialysis.

Twenty-one microbiologically documented episodes of coagulase-negative staphylococcal peritonitis occurred in 21 continuous ambulatory peritoneal dialysis patients. All strains involved in these infections were tested for antimicrobial susceptibility and in vitro adherence assays. Twenty of the strains were species identified using two commercially available systems. For comparison, 20 saprophytic strains of coagulase-negative staphylococci obtained from the nares and axillae of 10 uninfected, peritoneal dialysis patients were included for in vitro characterization. Staphylococcus epidermidis was the species most often identified for both clinical and saprophytic strains. Eighteen of the 21 (86%) clinical strains were resistant to penicillin G. Methicillin resistance, which was present in five clinical strains, was not found in saprophytic strains. Adherence assay determinations showed marked differences between clinical versus colonization strains, with the clinical isolates significantly more adherent (p less than 0.025) than colonization strains. Electron microscopic examination of silastic catheter segments incubated with a strain of S. epidermidis in used and unused dialysis fluids demonstrated marked differences in attachment of bacteria to catheter material.

Bacterial Adhesion↗
PubMed1986

Hepatobiliary abnormalities associated with postanginal sepsis. Common manifestations of an uncommon disease.

We describe eight patients with postanginal sepsis, a rare, potentially life-threatening complication of oropharyngeal infection. Six of the patients manifested jaundice, hepatomegaly, and liver function abnormalities, and in several this led to an erroneous suspicion of primary hepatobiliary disease. All eight patients survived the infection, although many suffered local or disseminated septic complications and required prolonged hospitalization. The pathophysiologic mechanisms responsible for hepatotoxicity in patients with postanginal sepsis are not understood. Physicians must be cognizant, however, of the frequent occurrence of jaundice in septicemic anaerobic processes, and this finding should not obscure the existence of postanginal parapharyngeal and jugular venous infection.

Adolescent↗
PubMed1986

A hospital cafeteria-related food-borne outbreak due to Bacillus cereus: unique features.

Although Bacillus cereus is a well-known cause of food-borne illness, hospital-related outbreaks of food-borne disease due to B. cereus have rarely been documented. We report a hospital employee cafeteria outbreak due to foods contaminated with B. cereus in which an outside caterer was employed to prepare the suspect meals. Data were collected from 249 of 291 employees who had eaten either of the two meals. With a mean incubation period of 12.5 hours, 64% (160 of 249) of employees manifested illness. Symptoms, which averaged 24.3 hours in duration, included diarrhea (96.3%), abdominal cramps (90%), nausea (50.6%), weakness (24.7%), and vomiting (13.8%). Eighty-seven employees sought medical attention, 84 of whom were seen in an emergency room. Although a significant difference was not demonstrated in food-specific attack rates, B. cereus was cultured from both rice and chicken items that were served at both meals. Sixty-three employees submitted stools for culture that grew no enteric pathogens, but none were examined for B. cereus. This food-borne outbreak demonstrates: the need for hospital kitchen supervisors to ensure proper handling of food when outside caterers are employed; that significant differences in food-specific attack rates may not be demonstrated in outbreaks, which may be related to several factors; and the importance of notifying microbiology laboratory personnel when B. cereus is a suspect enteric pathogen, since many laboratories do not routinely attempt to identify this organism in stool specimens.

Animals↗
PubMed1986

Selective screening of hospitalized patients for the presence of asymptomatic hepatitis B virus carriage: predictability based on census tract data.

Review of all hepatitis B surface antigen-positive patients reported to the county health department over the past 3 years showed that 60% of patients had been diagnosed at our hospital, which serves an inner city, predominantly black, indigent population. Sera from 524 adult patients admitted to the hospital were prospectively collected and tested for hepatitis B surface antigen, eight (1.5%) of which were antigen-positive. Census tract data allowed us to perform selective screening of sera from 95 other patients who were subsequently hospitalized and deemed "high risk" for hepatitis B infection. Nine of 95 (9.5%) selectively screened samples were positive for hepatitis B surface antigen, which represented a significantly higher rate of antigen carriage (P less than 0.0001) in hospitalized patients from "high risk" areas than that found in the general population screen. The methodology presented herein may be useful in providing a means of identifying hepatitis B surface antigen-positive patients from adult, urban, indigent care populations.

Adult↗
PubMed1985

Non-group A beta-hemolytic streptococcal cellulitis. Association with venous and lymphatic compromise.

Cellulitis occurring in the limbs of patients who have previously undergone saphenous venectomy and coronary bypass surgery has been the subject of several recent reports. Although isolation of pathogenic microorganisms from these lesions has been uncommon, this report describes three patients who had undergone venectomy previously and in whom non-group A beta-hemolytic streptococci were recovered either during acute episodes of cellulitis or during quiescent intervals. There are to date only four other reported cases of post-venectomy cellulitis from which beta-hemolytic streptococci were isolated: one was non-group A and the others were not serologically characterized. Moreover, studies in patients without bypass who have experienced cellulitis in extremities with compromised venous and/or lymphatic circulation have also yielded a substantial number of non-group A streptococci. The data thus far implicate non-group A beta-hemolytic streptococci as a major cause of cellulitis, especially in the setting of circulatory compromise.

Adult↗
PubMed1985

Adherence of coagulase-negative staphylococci to plastic tissue culture plates: a quantitative model for the adherence of staphylococci to medical devices.

The adherence of coagulase-negative staphylococci to smooth surfaces was assayed by measuring the optical densities of stained bacterial films adherent to the floors of plastic tissue culture plates. The optical densities correlated with the weight of the adherent bacterial film (r = 0.906; P less than 0.01). The measurements also agreed with visual assessments of bacterial adherence to culture tubes, microtiter plates, and tissue culture plates. Selected clinical strains were passed through a mouse model for foreign body infections and a rat model for catheter-induced endocarditis. The adherence measurements of animal passed strains remained the same as those of the laboratory-maintained parent strain. Spectrophotometric classification of coagulase-negative staphylococci into nonadherent and adherent categories according to these measurements had a sensitivity, specificity, and accuracy of 90.6, 80.8, and 88.4%, respectively. We examined a previously described collection of 127 strains of coagulase-negative staphylococci isolated from an outbreak of intravascular catheter-associated sepsis; strains associated with sepsis were more adherent than blood culture contaminants and cutaneous strains (P less than 0.001). We also examined a collection of 84 strains isolated from pediatric patients with cerebrospinal fluid (CSF) shunts; once again, pathogenic strains were more adherent than were CSF contaminants (P less than 0.01). Finally, we measured the adherence of seven endocarditis strains. As opposed to strains associated with intravascular catheters and CSF shunts, endocarditis strains were less adherent than were saprophytic strains of coagulase-negative staphylococci. The optical densities of bacterial films adherent to plastic tissue culture plates serve as a quantitative model for the study of the adherence of coagulase-negative staphylococci to medical devices, a process which may be important in the pathogenesis of foreign body infections.

Animals↗
PubMed1984

Recurrent cellulitis after coronary bypass surgery. Association with superficial fungal infection in saphenous venectomy limbs.

Certain patients who have undergone coronary artery bypass grafts suffer from episodes of acute cellulitis, often repeatedly, in the saphenous vein donor extremity. We describe nine patients with this entity, five of whom suffered recurrent attacks (range, two to greater than 20). The mean interval between surgery and the initial bout of cellulitis was 15 months (range, two to 46 months). A characteristic clinical syndrome was present in the majority of patients that included the abrupt onset of chills, followed by fever (generally greater than 38.8 degrees C), prostration, and obvious cellulitis. Seven patients also suffered from tinea pedis; in two instances, measures to control the dermatophytosis were instituted and attacks ceased. The pathogenesis of the entity may involve complex interactions between fungal and bacterial agents. Factors such as direct bacterial infection, hypersensitivity to streptococcal exotoxins, and id reactions to dermatophytes are probably involved in varying combinations.

Acute Disease↗