Biomedical subjects
Publications and source records attributed to E J Baron.
Erythromycin ophthalmic ointment (E. Fougera & Co., Melville, N.Y.) and erythromycin gluceptate standards prepared in ointment base were stored at room temperature and heated at temperatures up to 45 degrees C for as long as 6 h before being assayed for bioactivity. We were unable to detect any significant loss of antibiotic bioactivity.
Synergistic combinations of achievable serum levels of amikacin, rifampin, and ethambutol were tested for their ability to inhibit growth of Mycobacterium avium-intracellulare strains isolated from seven patients with acquired immune deficiency syndrome. Even when the isolates were very resistant to the individual antimicrobial agents in vitro, growth was completely inhibited by all combinations of the three agents tested. Four of the patients treated with a combined regimen of amikacin, rifampin, and ethambutol showed clinical improvement. Synergistic antimicrobial susceptibility tests seem to more accurately represent the efficacy of combined regimens used to treat these extremely resistant mycobacteria than do conventional susceptibility determinations with individual antimicrobial agents.
Infections caused by species within the viridans streptococci have been associated with different clinical characteristics. We studied 36 patients with viridans streptococcal endocarditis. Complications were seen in 10 (32%) of 31 patients with native valve endocarditis and four (80%) of five with prosthetic valve endocarditis and included death in two, valve replacement in six, persistent infection in three, emboli in two, and congestive heart failure in nine. Two-dimensional echocardiograms demonstrated vegetations in 26 (72%) of 36, flail mitral valves in seven, disruption of aortic valve prosthesis in one, and perivalvular abscesses in three (two Streptococcus sanguis I and one Streptococcus intermedius I). All twelve patients with native valve endocarditis who suffered complications had vegetations detected by two-dimensional echocardiography, whereas seven patients with native valve endocarditis without vegetations, as detected by two-dimensional echocardiography, had no complications (P = .03). We found no significant correlation between streptococcal species and clinical outcome. To confirm our identifications, we sent 16 identical viridans streptococcal endocarditis isolates to five institutions; only three of 16 were identified as the same species by all five institutions. We conclude that viridans streptococcal endocarditis can be associated with a virulent clinical course and that there is marked variability in species designations of individual strains by different laboratories.
A total of 26 Mobiluncus strains (17 M. curtisii and 9 M. mulieris strains) were compared serologically by double immunodiffusion and immunoblotting against antisera prepared against representative isolates of each species. All strains from the same species were strongly reactive with homologous antisera but generally weakly reactive with antisera to the heterologous Mobiluncus spp. The antisera did not react with strains of the unrelated genera Campylobacter, Succinivibrio, Wolinella, Actinomyces, Anaerobiospirillum, and Anaerovibrio.
The bioactivity of imipenem at 20 micrograms/ml in various agar and broth media which are commonly used in susceptibility test assays was measured at different storage temperatures over time. Imipenem was found to be more stable at 4 degrees C than at -20 degrees C and least stable in all media at 35 degrees C.
The bactericidal capability of murine peritoneal polymorphonuclear neutrophils against virulent and nonvirulent Salmonella typhimurium was examined in an in vitro system. Although preincubation of the bacteria in specific murine antiserum elicited greater chemiluminescence from phagocytizing neutrophils than did incubation in normal murine serum, antiserum did not enhance ingestion, as less than 5% of the challenge was taken up by neutrophils under any of the conditions studied. Nonvirulent salmonellae showed a transient decrease in viable numbers early during in vitro incubation with or without intact neutrophils. Virulent salmonellae, however, were able to multiply without a lag period except when these bacteria were pretreated with antiserum and incubated in association with intact murine neutrophils. Results of these in vitro studies suggest that the murine polymorphonuclear neutrophil and antisalmonella antibody must act together to effect neutrophil-associated bactericidal activity against virulent salmonellae, and thus, that the neutrophil alone does not play a major role in the protection of unvaccinated, sensitive mice from disease caused by S. typhimurium.
Morphologic, biochemical, and sodium-dodecyl sulfate polyacrylamide gel electrophoresis characteristics of twenty-six anaerobic curved rods isolated from vaginal discharge or transcervical uterine cultures were compared with each other and with those of five known control strains of anaerobic bacilli. The curved rods could be divided into two distinct groups, based on shared morphological characteristics and similar patterns of major cell protein bands. The protein band pattern exhibited by Group I organisms, which were short, Gram-variable, comma-shaped bacilli, did not resemble the protein band pattern of Group II organisms, which were seen as long, thin, Gram-negative curved rods. Polyacrylamide gel electrophoretic analysis of protein band patterns of these curved rods failed to show any strong similarities to the patterns of the five known bacterial strains that were tested. Although the role of these organisms in the etiology of bacterial vaginosis is not known at present, characterization studies such as this should facilitate the further recognition and identification of these bacilli as a prerequisite to determining their significance in human infection.
Although the mouse has been used extensively as a model for the study of host-parasite relationships, murine neutrophils have not been used nearly as often as PMNs from other species for in vitro functional assays due to lack of a commonly used procedure for murine neutrophil collection. These studies compared two eliciting agents and characterized the phagocytic and bactericidal activity of murine polymorphonuclear neutrophils elicited from the peritoneal cavity. We examined the effects of mouse strain (BALB/c, C57BL/6 and DBA/2) and sex, eliciting agent (0.2% glycogen vs. 3% fluid thioglycolate medium) and donor sacrifice method (ether vs. cervical dislocation) on the number of neutrophils recovered in peritoneal exudate. The greatest number of neutrophils was harvested when mice were sacrificed 5 h after intraperitoneal injection of 2.5 ml of 3% thioglycolate medium. This method as described allows reproducible collection of adequate numbers of neutrophils for use in in vitro assays of neutrophils phagocytic and bactericidal function.
The clinical history of a patient with rheumatoid arthritis and bacteriologic findings from a pulmonary abscess occurring during prednisone therapy are presented. Direct transthoracic aspiration of the lesion yielded a pure culture of Actinomyces odontolyticus. This is believed to be the first case of a deep visceral infection with this organism, an inhabitant of the normal mouth and gums. Immunosuppression of the host probably played a role in establishment of the infection.
A two-disk system is described which allows primary plate identification of group A beta-hemolytic streptococci. Group A beta-hemolytic streptococci could be visualized on primary throat culture plates by using trimethoprim-sulfamethoxazole to inhibit normal flora. In the heavily inoculated area of Trypticase soy agar plates containing 5% sheep blood, a 25-microgram/ml trimethoprim-sulfamethoxazole disk was placed contiguous to a 0.04-U bacitracin disk. A total of 259 throat specimens were examined with this two-disk system. The swabs from these throat specimens were incubated in Todd-Hewitt broth. The bacterial pellet from the broths was stained by fluorescent antibody as a control. Of the cultures that were determined to be positive on the plates, 75% could be read unequivocally after overnight incubation, whereas the remaining 25% required subculture. The plates recovered 91% of the cultures which were considered as true positives by the broth-fluorescent-antibody technique. This method provided a significant savings in time compared with standard plate methods and in cost of materials compared with broth-fluorescent-antibody methods. This technique is particularly valuable for producing rapid results in laboratories where fluorescence microscopy would not be cost-effective.
Although comprising less than 0.01% of the normal human gastrointestinal microbiota, Bilophila wadsworthia is the third most common anaerobe recovered from clinical material obtained from patients with perforated and gangrenous appendicitis. Since its discovery in 1988, B. wadsworthia has been recovered from clinical specimens associated with a variety of infections, including sepsis, liver abscesses, cholecystitis, Fournier's gangrene, soft tissue abscesses, empyema, osteomyelitis, Bartholinitis, and hidradenitis suppurativa. In addition, it has been found in the saliva and vaginal fluids of asymptomatic adults and even in the periodontal pockets of dogs. The organism is a saccharolytic, fastidious, and is easily recognized by its strong catalase reaction with 15% H2O2, production of hydrogen sulfide, and growth stimulation by bile (oxgall) and pyruvate. Approximately 75% of strains are urease positive. When grown on pyruvate-containing media, > 85% of strains demonstrate beta-lactamase production. Ribosomal RNA-based phylogenetic studies show Bilophila to be a homogeneous species, most closely related to Desulfovibrio species. Both adherence to human cells and endotoxin have been observed, and preliminary work suggests that environmental iron has a role in expression of outer membrane proteins. Penicillin-binding proteins appear to mediate the organism's susceptibility to at least some beta-lactam agents, which induce spheroplast formation that results in a haze of growth on agar dilution susceptibility test plates which is difficult to interpret. Bilophilastrains are inhibited in vitro by most antibiotics.
Quality management in today's health care environment requires a fresh approach. Laboratories that have traditionally directed their efforts toward meeting the needs of physicians must now also satisfy the needs of society, the greater public health, and the agency's administrators. Technical advances must today be considered in the context of patient care cost-effectiveness or final outcomes. Examples of strategies for improving quality in the laboratory, such as seeking input from all individuals involved in interpreting or using laboratory test results, forming multidisciplinary committees for development of critical pathways, issuing surveys for assessing the level of satisfaction of the laboratory's customers, and providing visual feedback of the results of activities, are described.
The Clinical Laboratory Improvement Amendments (CLIA 88) to the Clinical Laboratory Improvement Act of 1967 continues to undergo transformation since its implementation more than 2 years ago. The law and its subsequent regulatory modifications were intended to promote high quality in and accurate results from laboratory testing procedures, regardless of the site at which testing occurred. A number of federal regulatory agencies and committees such as the Healthcare Financing Administration, the Clinical Improved Amendments Committee, and the Commission on Laboratory Accreditation, as well as numerous new or modified regulations and requirements have gained importance since CLIA 88 was enacted. In this discussion, components of CLIA 88 that have the greatest impact on clinical microbiology laboratories are presented. In addition, the potential future significance of CLIA 88 are outlined.
The minimal inhibitory concentrations (MICs) of 110 anaerobic bacteria (84% fresh clinical isolates) to nine antimicrobial agents were determined simultaneously by the tentative reference agar-dilution method of the National Committee for Clinical Laboratory Standards and a prototype commercial microbroth panel (Microscan). MICs (determined visually for either system) differed by greater than 1 log2 dilution in 17% of all tests. With the exceptions of the MICs of tetracycline and moxalactam, however, all compared antimicrobial MICs were within 1 log2 dilution for at least 82% of all tests. Twenty-three anaerobic bacterial strains (21%) failed to grow in the microdilution panel (Wilkins-Chalgren broth), and seven strains (6%) failed to grow on the reference Wilkins-Chalgren agar. However, for those bacterial strains that could be tested, the microbroth panel appeared to be less cumbersome than the agar-dilution procedure for susceptibility testing of anaerobic microorganisms.
A case of Lactobacillus casei endocarditis that occurred on a Carpentier-Edwards porcine valve is reported. A review of the literature, which yielded 23 other reports of endocarditis due to this organism, suggests that Lactobacillus is a rare cause of endocarditis. Typically, it occurs in a patient with preexisting structural heart disease (20 of 24 [83%]) and often with some form of recent dental infection or manipulation (18 of 24 [75%]). Six (25%) of 24 patients died of this infection; however, only one (5%) of 19 who were treated with adequate antimicrobial therapy died. The response to antimicrobial therapy was better in the more recent cases. Of those 18 patients who completed a full course of therapy, seven (39%) experienced a relapse; five of these were cured of their infection with a second course of antimicrobial therapy, which usually included higher doses of intravenous penicillin. Our case represents the second reported case that required surgical intervention for cure. Embolic phenomena occurred in 10 (42%) of 24 cases. Various combinations of antibiotics have been successful in achieving cure; however, at present, high-dose penicillin (greater than 25 million units/day) in combination with an aminoglycoside for a period of six weeks appears to be the optimum therapy.