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Biomedical subjects

S M Opal

Publications and source records attributed to S M Opal.

At least 91 records · Page 5Linked to original sources
PubMed1990

Travel to developing countries: pre-departure medical advice.

Travelers to developing countries are at risk of contracting tropical infectious diseases that they or their physicians may be unfamiliar with. Proper pre-travel counsel should be given concerning general health risks that may be encountered abroad, immunizations, malaria prophylaxis and prevention and treatment of traveler's diarrhea. In Rhode Island, expert advice may be obtained at the Traveler's Clinics at the Miriam Hospital in Providence (401-274-3700 or 331-8500, ext. 4075) and the Memorial Hospital in Pawtucket (401-722-6000, ext. 2545). The Miriam Traveler's Clinic is open Wednesday (9-1) and all day Friday while the Memorial Traveler's Clinic is open Tuesday afternoon. These Traveler's Clinics are headed by Drs G.R. Olds and S.M. Opal, respectively.

Altitude Sickness↗
PubMed1990

Traveler's diarrhea: methods of prevention and treatment.

Traveler's diarrhea can often be avoided by following safe food and water practices while traveling in developing countries. Prophylactic agents are generally not indicated in the prevention of traveler's diarrhea. Should traveler's diarrhea develop, fluid replacement is the principal therapeutic modality. Other useful treatments include bismuth subsalicylate or anti-motility agents such as loperamide or diphenoxylate. Early empiric use of antimicrobial agents including trimethoprim-sulfamethoxazole or quinolone agents offers an excellent means of treating traveler's diarrhea and preventing its potential complications. Travelers who develop dysentery, high fever, or prolonged diarrhea lasting more than 10-14 days should seek medical attention for specific diagnosis and appropriate antimicrobial therapy.

Diarrhea↗
PubMed1989

Investigation of a food-borne outbreak of salmonellosis among hospital employees.

An explosive outbreak of Salmonella enterocolitis developed in 27 hospital employees in an acute-care community hospital in Rhode Island in 1987. Salmonella typhimurium was isolated from the stools of 19 employees during the outbreak. In each patient the implicated organism had an identical antibiotic susceptibility pattern, biotype, plasmid profile, and restriction endonuclease digestion pattern. The outbreak was limited to health care workers and other hospital employees; there were no cases in hospitalized patients. Of the afflicted employees 96% ate in the hospital cafeteria on July 11 or 12, 1987. Food-specific attack rates, based on the dietary histories of ill employees and 50 healthy employees who ate in the cafeteria that weekend, indicated an association between the ingestion of salads and illness (p less than 0.01). One food service employee, in whom symptoms of abdominal cramping and diarrhea had developed 6 days earlier, had prepared the implicated foods. S. typhimurium with the identical characteristics of the outbreak strain was isolated from the stools of this food service employee. Environmental cultures and cultures of meat, poultry, and dairy sources for the cafeteria all showed negative results. Food service employees need to be counseled against working during any symptomatic enteric illness and require thorough instruction on hygienic food handling.

Adult↗
PubMed1989

Oral ciprofloxacin and a monoclonal antibody to lipopolysaccharide protect leukopenic rats from lethal infection with Pseudomonas aeruginosa.

To study the treatment of infection with Pseudomonas aeruginosa, a leukopenic rat model was developed that closely mimics the pathogenesis of Pseudomonas infection in man. This model achieved approximately 90% mortality within 10 d of infection. Pseudomonas organisms were inconsistently shed from the feces despite gastrointestinal colonization (9 fecal v. 23 cecal cultures positive for challenge strain in 28 rats). Treatment of rats with oral ciprofloxacin at 40 mg/kg afforded complete protection. A suboptimal dose of ciprofloxacin (20 mg/kg), achieving peak levels of 0.31 micrograms/mL in serum and 26.3 micrograms/mL in stool, resulted in survival of 8 (40%) of 20 rats. Intraperitoneal administration of a monoclonal antibody directed at the lipopolysaccharide of the challenge strain of Pseudomonas resulted in survival of 5 rats (26%). The combination of the two increased the survival to 75% (15 of 20, P less than 0.05 compared to either treatment alone). Thus, the combination of suboptimal doses of ciprofloxacin and a monoclonal antibody appears to protect leukopenic rats from lethal infection better than either treatment alone.

Administration, Oral↗
PubMed1989

Modification of homogeneous resistance in a methicillin-resistant strain of Staphylococcus aureus by acquisition of a beta-lactamase encoding plasmid.

Nearly all clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) are heterogeneously resistant and produce beta-lactamases which generally are plasmid mediated. In order to study the role of beta-lactamase plasmids in the expression of methicillin resistance, a beta-lactamase plasmid from Enterococcus faecalis HH22 (pBEM10) was transferred into a homogeneously resistant, beta-lactamase-negative strain of MRSA (MUSC284). By single disc diffusion testing at 42 degrees C, beta-lactamase producing transconjugants (SA-MM1) were found to be more susceptible than the parent strain to methicillin, imipenem, SCH 34343 and cloxacillin, but more resistant to piperacillin. The heterogeneity observed in transconjugants was not affected by the addition of clavulanic acid, indicating that beta-lactamase itself was not responsible for this effect. By population analysis over 50% of MUSC284 colonies and less than 1% of SA-MM1 colonies remained viable after incubation at 42 degrees C in agar plates containing 25 mg/l of cloxacillin. Cured derivatives of SA-MM1 reverted to homogeneous resistance to beta-lactam antibiotics as observed in the initial parenteral strain MUSC284. Thus, the introduction of a beta-lactamase coding plasmid into a homogeneously resistant MRSA yielded transconjugants which resembled heterogeneously resistant strains of MRSA. These results suggest that regulatory genes, capable of altering the expression of methicillin resistance, may be located on beta-lactamase plasmids commonly found in these organisms.

Chromosomes, Bacterial↗
PubMed1989

Relapse of Pneumocystis carinii pneumonia in the upper lobes during aerosol pentamidine prophylaxis.

Pneumocystis carinii pneumonia was diagnosed by bronchoalveolar lavage of the upper lobes in a patient with the acquired immunodeficiency syndrome (AIDS) receiving aerosol pentamidine prophylaxis. Serendipitous availability of a normal premorbid lung gallium scan indicated that pneumocystosis had developed during aerosol pentamidine prophylaxis; at the time of presentation a repeat gallium scan indicated disease limited to the upper lobes. The relation of this unusual form of isolated upper lobe Pneumocystis carinii pneumonia to aerosol pentamidine prophylaxis warrants further investigation.

Administration, Inhalation↗
PubMed1989

Unusual nosocomial pathogens.

Multiple factors, including the widespread use of antibiotics, the spread of bacterial resistance plasmids and transposons, and the increased use of invasive procedures in traumatized or immunocompromised patients, have abetted the emergence of constant changes in the nosocomial microflora with selection for highly resistant and virulent bacteria. The introduction of new technologies, including enhanced life support techniques ranging from blood products to parenteral nutrient supplementation, also afford opportunities for previously nonpathogenic organisms to take advantage of new niches. Changes in the inanimate environment, such as ventilatory systems, and changes in personnel and infection control protocols (for example, disinfectants) may also alter the resident nosocomial flora. The resultant challenges to clinicians are to be aware of changes in the prevalence of different organisms and susceptibility patterns in the local hospital and community, and to be knowledgeable about new anti-microbial agents that have activity against multiply resistant pathogens. Judicious antibiotic use and careful application of hospital infection control measures are likely to be effective in meeting these challenges. Ongoing clinical and molecular epidemiological studies are required to better anticipate the emergency and spread of new, distinctive nosocomial pathogens.

Cross Infection↗
PubMed1988

Survey of purported virulence factors of Escherichia coli isolated from blood, urine and stool.

One hundred randomly selected urinary and blood isolates and 50 stool isolates of Escherichia coli were analyzed for phenotypic characteristics which may contribute to their virulence potential. Bacteremic isolates were more likely to have K1 capsules and express mannose-sensitive hemagglutination compared to stool isolates. Blood-stream isolates more frequently contained complete 0 side-chains in their lipopolysaccharide layer and less frequently exhibited mannose-resistant hemagglutination when compared to urinary isolates. Total plasmid content, hemolysin, total colicin and colicin V production were not significantly increased in Escherichia coli from blood or urine when compared to those recovered from stool.

Antigens, Bacterial↗
PubMed1988

Staphylococcal scalded skin syndrome in two immunocompetent adults caused by exfoliatin B-producing Staphylococcus aureus.

An exfoliatin B-producing strain of Staphylococcus aureus was isolated from two adults with typical staphylococcal scalded skin syndrome (SSSS). One patient developed desquamation after a local staphylococcal infection of the hand, and the other developed exfoliation after nosocomially acquired staphylococcal endocarditis. Neither patient was immunocompromised, had evidence of renal insufficiency, or manifested other potential risk factors for SSSS. Purified toxin, isolated from the causative organisms, produced a Nikolsky sign in neonatal mice. The toxins were shown to be exfoliatin B by biochemical and immunologic methods and heretofore had been described only in children with SSSS. Analysis of plasmid DNAs from both strains revealed a 23-megadalton plasmid with identical restriction endonuclease digestion fragments. One isolate belonged to phage group II (3B/3C/6/7/47/54/55), whereas the other isolate belonged to phage groups I and III (7/29/52/52A/53/54/80). The observation that a non-phage group II exfoliatin-producing strain of S. aureus may produce SSSS in adults indicates the need to better define the diagnostic criteria for SSSS. Immunocompetent adults may remain susceptible to some strains of exfoliatin B-producing S. aureus.

Bacterial Toxins↗
PubMed1988

Plasmid, serotypic, and enterotoxin analysis of Bacillus cereus in an outbreak setting.

Bacillus cereus is a recognized agent of food-borne disease. In this report we describe an outbreak of B. cereus gastroenteritis associated with consumption of beef stew among patients and staff at a Rhode Island nursing home. The beef had been improperly stored after preparation. The predominant symptoms of the illness were cramps and diarrhea; it lasted an average of 16 h. No deaths occurred. The organism was recovered from 10 of 23 stools collected from ill patients and 1 of 21 stools collected from controls (P = 0.0044, Fisher's two-tailed exact test). All isolates had the same biotype and serotype, newly designated H.26; all elaborated the diarrheal B. cereus enterotoxin when tested in rabbits by the vascular permeability reaction; and all had identical plasmid profiles, which differed from those of B. cereus strains selected randomly from other outbreaks. Plasmid analysis may prove to be a useful new tool in investigating outbreaks of B. cereus food poisoning.

Adult↗
PubMed1988

Group B streptococcal sepsis in adults and infants. Contrasts and comparisons.

Group B streptococcal infection may result in significant morbidity and mortality in both infants and adults. The experience with group B streptococcal disease was analyzed at one medical center over a ten-year period from 1975 to 1984. Streptococcus agalactiae bacteremia was observed in 29 adults and 26 infants, with an attack rate of 0.2 cases per 1000 adult admissions and 3.2 cases per 1000 live births, respectively. The majority of adult infections apparently occurred as a result of nosocomial acquisition and was associated with a high mortality rate of 38%. Risk factors for group B streptococcal sepsis in adults include diabetes mellitus, malignancy, and hepatic failure. The majority (73%) of neonatal cases occurred within seven days of birth and occurred in a setting of maternal fever, prolonged rupture of membranes, or prematurity. The mortality rate in infants was remarkably low at only 15%. Fatalities occurred in both adults and infants, despite appropriate antimicrobial therapy. Infection control strategies against group B streptococcus must address potential nosocomial dissemination in adults as well as vertical transmission in infants.

Adult↗
PubMed1987

Antibacterial therapy in patients with malignancies.

Patients with malignant disease may be predisposed to bacterial infections because of neoplastic disruption of normal tissue barriers, exogenous immunosuppressive therapy (drugs with or without radiation), and intrinsic host immune deficits secondary to these diseases. Diminished polymorphonuclear leukocyte numbers or function and impaired humoral immunity are highly correlated with the development of serious bacterial infections. The usual signs and symptoms of infection may be absent or altered in a compromised host. Therapy must be instituted promptly upon clinical suspicion of bacterial infection, and empirical choices should usually include combinations that are synergistic for likely pathogens based on knowledge of the local predominant flora and susceptibility data. Synergism has most often been demonstrated in combinations that utilize a beta-lactam (semisynthetic penicillin or cephalosporin) and an aminoglycoside. Triple drug therapy has not been shown to be advantageous. Monotherapy with third generation cephalosporins, carbapenems, monobactams, or ureidopenicillins has not been proven to offer advantages over 2-drug regimens for these patients. Patients with blood deficient in granulocytes (granulocytopenic) who respond to 2-drug therapy but remain deficient in neutrophils (neutropenic) may need continued treatment until the neutropenia subsides. Those who do not respond and remain febrile with an unclear focus of infection may need to be started on antifungal therapy in addition to the antibacterial agent. The use of oral agents for the prophylaxis of neutropenic patients against bacteremia remains controversial. If drugs are used, co-trimoxazole and nystatin suspension may be preferable.

Anti-Bacterial Agents↗
PubMed1987

Polymicrobial bacteremic pneumonia: report of three cases caused by Staphylococcus aureus and Streptococcus pneumoniae.

Three patients are reported with simultaneous bacteremia caused by Staphylococcus aureus and Streptococcus pneumoniae complicating community-acquired pneumonia. Polymicrobial bacteremia caused by pyogenic organisms has rarely been reported. Two of the patients had severe underlying hepatic disease, and the third had suffered a recent myocardial infarction. The infection ultimately proved fatal in each patient. The pathophysiologic aspects and clinical consequences of polymicrobial bacteremia arising from respiratory as well as from other sources is briefly reviewed.

Adult↗