Group B streptococcal infection of a pacemaker wire following sigmoidoscopy.
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Female↗
Biomedical subjects
L M Baddour
Publications and source records attributed to L M Baddour.
Staphylococcus aureus microcapsule expression attenuates bacterial virulence in a rat model of experimental endocarditis.
The virulence of the Staphylococcus aureus strains that differed only in capsule expression was compared in a rat model of catheter-induced experimental endocarditis. The ID50 of all the strains was low (less than 3 x 10(3) cfu of S. aureus), suggesting that this model may be more sensitive than other animal models to differences in bacterial virulence. Compared with the wild-type strains that expressed type 5 or type 8 capsular polysaccharides, mutant strains devoid of capsule had significantly lower ID50 values. In contrast, a mutant that produced scant amounts of the type 5 polysaccharide had an ID50 similar to that of the parental type 5 isolate. As the bacterial inoculum was increased, each of the S. aureus strains reached final concentrations of 10(10)-10(11) cfu/g of vegetation; however, the nonencapsulated mutants colonized the left-sided vegetations at lower inocula than did the wild-type strains. This study indicates that microcapsule expression attenuates bacterial virulence in a rat model of catheter-induced endocarditis.
Animals↗
Right middle lobe syndrome caused by Mycobacterium fortuitum in a patient with human immunodeficiency virus infection.
We have reported a previously undescribed syndrome of Mycobacterium fortuitum infection manifested as localized pulmonary disease that required lung resection and prolonged combined chemotherapy for clinical response in a patient with HIV infection. M fortuitum infections must be considered in HIV-infected patients with possible infectious pulmonary complications.
Adult↗
Colonial morphology of staphylococci on Memphis agar: phase variation of slime production, resistance to beta-lactam antibiotics, and virulence.
The growth of Staphylococcus epidermidis sensu stricto and Staphylococcus saprophyticus on Memphis agar yielded up to 6 morphotypes with each strain. With S. epidermidis, one morphotype produced slime (rho) but became non-slime-producing (epsilon) at a high frequency. The slime-producing rho variants were methicillin-resistant and more virulent than methicillin-susceptible epsilon variants in an endocarditis model. With S. saprophyticus, phase variation was of higher frequency. Nitrosoguanidine mutagenesis produced a stable blue epsilon form that was more virulent than the parent in a mouse model of urinary tract infection. Mutants with the blue epsilon phenotype differed from gold epsilon parents in a variety of phenotypic properties, including increased resistance to oxacillin. These staphylococcal species have a high frequency of phase variation: Phase variants differ in antibiotic resistance and virulence, which is only partially correlated with suggested virulence factors such as slime production.
Animals↗
Identification of an antigenic marker of slime production for Staphylococcus epidermidis.
The pathogenic Staphylococcus epidermidis strain RP62A (ATCC 35984) adheres to smooth surfaces by forming a tenacious bacterial film known as slime. The mechanism of slime production is not known; however, workers in the laboratory of G. Pier (Harvard Medical School, Boston, Mass.) have isolated from RP62A a galactose-rich capsular polysaccharide adhesin (CPA) which mediates the attachment of the organism to smooth surfaces. We have obtained two daughter strains from RP62A that no longer produce slime. One daughter strain, H4A, was obtained by selection for a spontaneous variant; the other strain, HAM892, was obtained by treating growing cultures of RP62A with acriflavin. Using an antiserum generated against whole cells of RP62A, we have examined lysozyme-lysostaphin digests of RP62A, H4A, and HAM892 by double immunodiffusion. The two strains that no longer produced slime no longer produced a particular antigen, which we refer to as the slime-associated antigen (SAA). SAA was also produced by unrelated strains of slime-producing S. epidermidis. SAA was heat and protease stable, had a molecular weight of greater than 50,000, and could be partially purified by chromatographing trypsin-digested material over a Sephadex G-200 column. Chemical analysis of partially purified SAA by gas-liquid chromatography found SAA to be glucose rich (59%) and galactose poor (1.4%). This analysis chemically distinguished SAA from CPA. When tested together by double immunodiffusion with anti-RP62A and anti-CPA antisera, partially purified SAA did not cross-react with CPA. Kinetic studies suggested that SAA is a marker for surface accumulation whereas CPA mediates initial adherence.
Adhesins, Bacterial↗
Phenotypic variation of Staphylococcus epidermidis in infection of transvenous endocardial pacemaker electrodes.
Coagulase-negative staphylococci isolated from a patient with a pacemaker electrode infection were extensively evaluated by phenotypic and genotypic characterization. Findings from this evaluation were striking because different colony morphologic subtypes were recovered from blood and resected pacemaker electrodes. Staphylococci from each colony subtype (LBL, LBV, LBP, LBS) were identified as slime-producing strains of Staphylococcus epidermidis sensu stricto. Direct plating of isolates from a restricted electrode revealed a mixture of colony phenotypes when examined on a high-salt, low-glucose medium, Memphis agar. Bacteriophage typing employing 17 different phages and plasmid profile analysis were largely unsuccessful in further characterizing bacterial cells of each of the four colony morphotypes. On the other hand, restriction endonuclease analysis by EcoRI digestion of the chromosomal DNA demonstrated the probable common clonal origin of the four colony phenotypes.
Aged↗
The role of fibronectin binding in the rat model of experimental endocarditis caused by Streptococcus sanguis.
Inactivation of fibronectin (Fn) binding by insertional mutagenesis of Streptococcus sanguis with Tn916 reduces virulence of this bacterium in the rat model of infective endocarditis (IE). Transconjugants were screened for Fn adherence using an ELISA adherence test. One transconjugant had a decreased adherence to immobilized Fn. Southern hybridization demonstrated that the insertion occurred only once in this mutant. The parent strain and mutant strain JL113 were used as challenge strains in a rat endocarditis model. These experiments demonstrated that the mutant had a reduced ability (P less than 0.05) to produce IE. Spontaneous excision of Tn916 from JL113 produced strains identical to both the parental and mutant phenotypes. One strain (JLR-19) that retained the mutant phenotype and one (JLR-15) that regained the parental phenotype for Fn binding were tested for their ability to produce IE. These strains demonstrated that the ability to bind Fn and to produce IE were correlated after Tn916 excision. The reduced virulence of the mutant suggested that adherence of S. sanguis to immobilized Fn plays an important role in the production of IE.
Animals↗
Serious infections caused by coagulase-negative staphylococci in intravenous drug users.
While Staphylococcus aureus has been a well-recognized pathogen in patients who use illicit intravenous drugs, coagulase-negative staphylococci are not generally appreciated as causes of infectious complications in intravenous drug users. The authors present data suggesting the coagulase-negative staphylococci are potential pathogens in these high risk patients.
Adult↗
Molecular epidemiology of nosocomial, multiply aminoglycoside resistant Enterococcus faecalis.
The prevalence of high-level aminoglycoside resistance among Enterococcus faecalis at the Memphis VA Medical Center was 23.6% (59 of 250 isolates) from October to December 1986. Hybridization to a probe cloned from Ent. faecalis pIP1800 for 6' acetyltransferase-2" phosphotransferase (AAC6'-APH2") was observed in 55 (93.2%) of the resistant isolates and was associated with gentamicin resistance. Hybridization to a probe cloned from Ent. faecalis pJH1 for 3', 5" phosphotransferase type III (APH3', 5" III) was observed in 28 (47.4%) and was associated with streptomycin resistance. Twenty-five of the 32 isolates which were resistant to both gentamicin and streptomycin hybridized to both probes. Cell mating in conjunction with hybridization indicated that the AAC6'-APH2" gene is transferred separately from that for APH3', 5" (III), and the streptomycin resistant gene is cotransferred with the latter. The gentamicin-streptomycin resistant isolates therefore contain genes from two Ent. faecalis plasmids, and resistance to these two antibiotics appears to transfer separately. The genetic homogeneity of these isolates suggests nosocomial transmission of enterococci.
Aminoglycosides↗
The effect of slime production on vancomycin efficacy in the treatment of experimental endocarditis due to Staphylococcus epidermidis.
We compared the efficacy of vancomycin in the treatment of experimental endocarditis caused by either a parent strain of Staphylococcus epidermidis that produced slime or a daughter strain that produced less slime. After subcutaneously administered vancomycin, we noted similar cure rates and similar microbiological characteristics of endocardial infections in rats challenged with these strains, regardless of slime produced.
Adhesiveness↗
Invasive meningococcal disease: secondary spread in a day-care center.
We have reported the epidemiologic investigation and subsequent control measures precipitated by the occurrence of two temporally related cases of invasive meningococcal disease in a single day-care center classroom. A review of the literature indicates that day-care center contacts of patients with invasive meningococcal disease are at increased risk for secondary spread of infection. Our experience emphasizes the importance of reporting cases to the local health department, implementing rifampin prophylaxis for appropriate contacts, and considering immunization in select circumstances. Rifampin is indicated for all cases of meningococcal disease as well.
Bacterial Vaccines↗
Clinical comparison of single-oral-dose cefuroxime axetil and amoxicillin with probenecid for uncomplicated gonococcal infections in women.
Four hundred sixty-six female patients were enrolled in a randomized study that compared the clinical efficacies of single oral doses of cefuroxime axetil and amoxicillin with probenecid in the treatment of uncomplicated gonorrhea. Two hundred ninety-five patients had culture-positive gonococcal infections and completed the investigation. Cure rates for the patients treated with cefuroxime axetil and those treated with amoxicillin with probenecid were high (greater than 95%) for genitorectal infections. Pharyngeal infections, however, were not uniformly eradicated by either cefuroxime axetil (60%) or amoxicillin with probenecid (64%). Approximately 13% of each patient group suffered adverse events, which were gastrointestinal in the majority and were transient. Compared with amoxicillin plus probenecid, cefuroxime axetil in a single oral dose was an equally safe and effective drug for the treatment of uncomplicated gonorrhea in women caused by penicillin-susceptible strains.
Adolescent↗
CDC group HB-5 as a cause of genitourinary infections in adults.
Isolates from five patients with genitourinary infections diagnosed over a 7-week period were identified as CDC group HB-5. The organisms caused clinical presentations of pelvic inflammatory disease in three women and urethritis in the only male in the series. The remaining patient received surgical treatment for a Bartholin gland abscess. Since the clinical and temporal presentations were remarkable and the questions of sexual mode of transmission and strain relatedness were of concern, the five strains were examined further by multilocus enzyme electrophoresis and ribosomal DNA typing. Overall, the five clinical isolates were more closely related to each other than to the control strains. This is the first report describing genitourinary infections caused by group HB-5. While the pathophysiology of group HB-5 infections remains to be fully elucidated, the possibility that this organism may be sexually transmitted deserves further study.
Abscess↗
Infections in open heart surgery.
More than 250,000 open heart surgical procedures are performed annually in the United States. The majority of these procedures are coronary artery bypass grafts (CABG) and valve replacements. In this forum our authors discuss the kinds of infections that occur in patients following open heart surgery, as well as the documented risk factors and microbiology of these infections. We also asked each author to outline the criteria used to diagnose post open heart surgery infections, and to address associated consequences and complications. Finally, we were interested in each author's definition of the infection control practitioner's role in the prevention of this particular subset of nosocomial infections.
Cardiac Surgical Procedures↗
Phenotypic selection of small-colony variant forms of Staphylococcus epidermidis in the rat model of endocarditis.
Four pathogenic strains of Staphylococcus epidermidis (sensu strictu)-EC, RP62A, LW, and HBSN--exhibited a mixed population of colony phenotypes when plated onto a high-salt, low-glucose agar ("Memphis agar"). When compared with challenge inocula, significant shifts in colony populations to the small-colony variant forms occurred for all four strains for isolates recovered from infected vegetations of rats with catheter-induced endocarditis. Various colony phenotypes of the HBSN strain were compared in virulence studies by using the rat model of endocarditis. The infectivity rate of the small-colony variant forms was significantly less than that of either the normal parent form (P less than .05) or the mixed phenotypic inoculum (P less than .05). These data indicate that the small-colony variant forms may be selected for, once endocardial infections are established, and that the small-colony variant forms alone are much less able to initiate and/or sustain intracardiac infections in experimental endocarditis.
Animals↗
Pneumonia due to Aeromonas hydrophila-complex: epidemiologic, clinical, and microbiologic features.
Review of published data examining the various types of infections produced by strains of the Aeromonas hydrophila-complex demonstrates a paucity of information on lower respiratory tract infections due to this organism. Although it is rarely cited as a cause of pneumonitis, we have been able to collect epidemiologic, clinical, and microbiologic data on eight patients who have had evidence of Aeromonas pneumonia. Interestingly, seven of the eight patients were male, and the average age for the group was 54.3 years. In contrast to reports showing a prevalence of other types of A hydrophila infections during the summer months, five of the pneumonitis cases occurred during late fall and early winter. Infections were both community-acquired and nosocomial. A proven or suspected history of aspiration was present in six patients. Preexisting medical conditions were noted in all patients, the majority having multiple predisposing factors, which included alcohol abuse and alcoholic liver disease, cardiovascular and cerebrovascular disease, and chronic lung disease. Three patients died of their acute pulmonary infection. Based on in vitro antimicrobial susceptibility testing, aminoglycoside therapy would seem appropriate in the treatment of these infections.
Adult↗
Proposed virulence factors among coagulase-negative staphylococci isolated from two healthy populations.
Proposed virulence factors, including multiple antibiotic resistance and slime-mediated adherence, among coagulase-negative staphylococci colonizing healthy individuals from two different study populations were examined. Resistance to methicillin was more commonly seen than initially anticipated. In addition, adherence characteristics, as quantitated by a microtiter plate method, were very similar to those of strains of coagulase-negative staphylococci causing nosocomial infections.
Bacterial Adhesion↗
Liver abscess: a harbinger of Crohn's disease.
A 24-yr-old man with no previous history of Crohn's disease presented with a 5-wk history of fever and malaise. Computed tomographic scan of the abdomen revealed a liver abscess. Upon intraoperative examination, the terminal ileum was noted to have changes characteristic of Crohn's disease. This case report represents the first documented occurrence of liver abscess as the initial manifestation of Crohn's disease.
Adult↗