Mixed infection involving Actinomyces, Aggregatibacter, and Fusobacterium species presenting as perispinal tumor.

A representative case in which a polymicrobial infection involving Fusobacterium nucleatum, Actinomyces israelii and Aggregatibacter (formerly Actinobacillus) actinomycetemcomitans was initially diagnosed as malignancy in an edentulous patient. Additional history obtained after the nature of the syndrome was elucidated revealed that he had had his two remaining teeth extracted four months prior to this episode.

Trends in invasive disease due to Candida species following heart and lung transplantation.

Although invasive candidiasis (IC) causes significant morbidity and mortality in patients who undergo heart, lung, or heart-lung transplantation, a systematic study in a large cohort of thoracic organ transplant recipients has not been reported to date. Clinical and microbiological data were reviewed for 1305 patients who underwent thoracic organ transplantation at Stanford University Medical Center between 1980 and 2004. We identified and analyzed 76 episodes of IC in 68 patients (overall incidence 5.2% per patient).The incidence of IC was higher in lung (LTx) and heart-lung transplant (HLTx) recipients as compared with heart transplant (HTx) recipients (risk ratio [RR] 1.7, 95% confidence interval [CI] 1.1-2.7).The incidence of IC decreased over time in all thoracic organ transplant recipients, decreasing from 6.1% in the 1980-1986 time period to 2.1% in the 2001-2004 era in the HTx recipients, and from 20% in the 1980-1986 period to 1.8% in the 2001-2004 period in the LTx and HLTx recipients.The most common site of infection differed between the HTx and LTx cohorts, with bloodstream or disseminated disease in the former and tracheobronchitis in the latter. IC in the first year after transplant was significantly associated with death in both HTx (RR 2.9, 95% CI 1.8-4.6, P=0.001) and LTx and HLTx patients (RR 3.0, 95% CI 1.9-4.6, P<0.001). The attributable mortality from IC decreased during the 25-year period of observation, from 36% to 20% in the HTx recipients and from 39% to 15% in the LTx and HLTx recipients. There were a significant number of cases caused by non-albicans Candida species in all patients, with a trend toward higher mortality in the HTx group. In conclusion, the incidence and attributable mortality of IC in thoracic organ transplant recipients has significantly declined over the past 25 years.The use of newer antifungal agents for prophylaxis and treatment, the decrease in the incidence of cytomegalovirus disease, and the use of more selective immunosuppression, among other factors, may have been responsible for this change.

Elicitation of peritoneal polymorphonuclear neutrophils from mice.

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.

Actinomycotic pulmonary abscess in an immunosuppressed patient.

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.

Quality perceptions of microbiology services. A survey of infectious diseases specialists.

Opinions about the quality of their primary microbiology laboratory were received from more than 500 practicing infectious diseases specialists by a nationally distributed questionnaire. Approximately 92% of the respondents' primary laboratories were hospital-based. These sophisticated users rated the quality of their microbiology laboratories to be generally high, with bacteriology receiving highest scores and parasitology the lowest scores. Fortunately, the serious problems, such as failing to call a critical result and culture mishandled in the laboratory, were experienced rarely. Laboratories directed by pathologists with specialty microbiology training, PHD microbiologists, and infectious diseases specialists were judged to be of highest quality. American Board of Medical Microbiology certification of the laboratory director was related to higher overall quality perceptions. Whereas physician-customer opinions may not directly measure a laboratory's analytic quality, they are an important performance measure on which laboratories can base quality improvement activities in both service and analytical aspects of performance.

Methicillin-resistant Staphylococcus aureus outbreak: a consensus panel's definition and management guidelines.

OBJECTIVE: To provide medical personnel with a definition of an outbreak of methicillin-resistant Staphylococcus aureus (MRSA) and guidelines for managing potential outbreaks. PARTICIPANTS: Eighteen panel members were chosen from different specialties, types of institutions, and geographic regions. Representatives from the American Society of Consultant Pharmacists, the American Society of Health-Systems Pharmacists, the Society for Healthcare Epidemiology of America, and the National Association of Directors of Nursing Administration participated. CONSENSUS PROCESS: In preparation for the conference, panel members reviewed the literature and wrote abstracts outlining their personal opinions on the core issues, which were circulated to all participants. During a weekend conference, the panel summarized the reviewed literature, defined an MRSA outbreak, and developed management guidelines. EVIDENCE: Published literature, clinical experience, and expert opinion concerning the emergence and subsequent management of MRSA cases in health care institutions. RESULTS: An outbreak of MRSA was defined as either an increase in the rate of MRSA cases or a clustering of new cases due to the transmission of a single microbial strain in the health care institution. An increased rate of cases can be defined statistically or experientially and includes both infected and colonized patients. A potential outbreak should trigger stepwise, multidisciplinary actions consisting of basic epidemiologic procedures (phase I) to form an initial epidemiologic hypothesis of an outbreak (phase II) followed by a standard epidemiologic workup (phase III) and microbiologic studies (phase IV) to confirm the hypothesis. Mupirocin calcium treatments should be considered to decolonize health care workers during the fourth phase, even before typing is completed. CONCLUSIONS: Until studies can be conducted to delineate the effectiveness of different recommendations, the proposed guidelines may provide a useful starting point that can be adapted to meet an individual institution's specific needs.

Quality management and the clinical microbiology laboratory.

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.

Amikacin, ethambutol, and rifampin for treatment of disseminated Mycobacterium avium-intracellulare infections in patients with acquired immune deficiency syndrome.

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.

National survey of the in vitro spectrum of piperacillin-tazobactam tested against more than 40,000 aerobic clinical isolates from 236 medical centers.

Hospital microbiology laboratories from 41 states participated in a bacterial antimicrobial susceptibility study comparing in vitro results generated by the standardized disk diffusion method. Over 41,000 freshly isolated aerobic and facultative strains, representing all specimen types (except stools and urines), were tested for their susceptibility to piperacillin-tazobactam and 21 other antimicrobial agents. Enterococcus spp. was the second or third most common isolate from intraabdominal, gynecologic, and cutaneous infections, confirming its growing importance as a nosocomial pathogen. Escherichia coli was the most frequent isolate overall, despite the exclusion of urinary tract specimens from the study. Pseudomonas aeruginosa was the second most prevalent species, ranking first in frequency of recovery from lower-respiratory-tract specimens. Piperacillin-tazobactam was the most active beta-lactamase inhibitor combination tested against Gram-negative bacteria. Its activity against Gram-positive bacteria and Haemophilus influenzae was similar to that of ampicillin-sulbactam (95-97% susceptible). Imipenem and piperacillin-tazobactam displayed similar spectrums of activity against Gram-positive organisms and Haemophilus influenzae. Against Enterobacteriaceae, piperacillin-tazobactam and ceftazidime exhibited similarly wide spectrums of activity, but with some gaps, particularly among Enterobacter spp. and Citrobacter freundii. In this large-scale in vitro study, piperacillin-tazobactam and imipenem displayed the widest antimicrobial spectrums, inhibiting > 90% of all isolates tested.

Impact of CLIA 88 on the clinical microbiology laboratory.

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.

Gangrenous and perforated appendicitis with peritonitis: treatment and bacteriology.

A comparison of single-agent antimicrobial therapy in the treatment of patients with perforated or gangrenous appendicitis and peritonitis was performed in a double-blind, randomized, prospective trial. Pathologic documentation of advanced appendicitis and positive intraoperative specimen cultures were required for inclusion in the study. Ceftizoxime (2 gm every 12 hours) and cefoxitin (2 gm every six hours) were compared. There were no significant differences between the treatment groups. Ninety-seven percent of patients treated with ceftizoxime and 89% of those treated with cefoxitin were cured or improved; there was no mortality in either group. By the use of optimal sampling, transport, and culture techniques, the number and diversity of bacteria recovered from these patients with advanced appendicitis were found to be much larger than previously suspected. Peritoneal fluid, abscess contents (if present), and appendiceal tissue (obtained so as to exclude the lumen) were cultured from all patients. An average number of 3.1 aerobic or facultative bacteria species and 8.5 anaerobic species were isolated from each specimen. Twenty-eight different genera and more than 55 species were encountered, including a previously undescribed fastidious gram-negative anaerobic bacillus. Bacteroides fragilis group and Escherichia coli were isolated from almost all specimens, and within the B fragilis group, eight species were represented. The recovery of such an unexpectedly large and diverse flora may be the reason for the therapeutic failures in these patients. We conclude that single-agent antimicrobial therapy in patients with advanced appendicitis and peritonitis is both safe and effective, and, with ceftizoxime, can be accomplished by a twice-daily dosing regimen.

Genetic aspects of methicillin resistance in Staphylococcus aureus and methods used for its detection in clinical laboratories in the United States.

The mecA gene in methicillin-resistant Staphylococcus aureus (MRSA) directs production of a novel penicillin-binding protein (PBP 2A), an enzyme active in cell wall synthesis. MecA, alone, however, does not determine the degree of resistance expressed by strains of MRSA. Differential resistance or variations in other genes that participate in cell wall synthesis, such as laboratory mutant fem genes, may account, in part, for the heterogeneity of methicillin resistance expression in MRSA. The exact mechanisms of methicillin resistance expression in clinical isolates remain to be elucidated. Laboratories use selective agars containing oxacillin and turbidity pattern recognition programs in automated instruments to identify MRSA, although not all mecA-containing strains are detected. Until a rapid and inexpensive DNA probe assay is widely available, newer test methods such as the E test (AB Biodisk), oxidation-reduction indicators in MIC trays (Alamar), and the rapid fluorescent BBl. Crystal system seem promising.

Biochemical and polyacrylamide gel electrophoretic analyses of vaginosis-associated anaerobic curved rods.

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.

Bilophila wadsworthia: a unique Gram-negative anaerobic rod.

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.

Rapid identification of bacteria and yeast: summary of a National Committee for Clinical Laboratory Standards proposed guideline.

Using colony morphology on selected agars, Gram-stain morphology, and a number of 1-step biochemical or enzymatic tests, skilled microbiologists can identify the species of the majority of isolates seen routinely in a clinical laboratory. These results are often available more quickly than and are as accurate as those derived from conventional methods. The National Committee for Clinical Laboratory Standards has produced a guideline that describes tests that can be used to identify a number of aerobic gram-negative rods and gram-positive cocci, a number of commonly isolated anaerobes, and 3 species of yeast. An overview of the organisms included in the guideline, the tests that identify them, and the situations in which rapid testing is appropriate is presented here.

Inefficient in vitro killing of virulent or nonvirulent Salmonella typhimurium by murine polymorphonuclear neutrophils.

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.

Primary plate identification of group A beta-hemolytic streptococci utilizing a two-disk technique.

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.

Comparison of susceptibilities of anaerobic bacteria determined by agar dilution and by a microbroth method.

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.

Bioactivity of imipenem as a function of medium, time, and temperature.

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.