Zygospores: the last word in identification of rare or atypical zygomycetes isolated from clinical specimens.

Three zygomycetes (order Mucorales), isolated from clinical specimens, whose generic or species identification were uncertain, were definitively identified on the basis of the production of zygospores resulting from mating studies. These three isolates were identified as Mucor circinelloides f. circinelloides, Rhizomucor pusillus, and Absidia corymbifera. The production of true zygospores, the "last word" in zygomycete taxonomy, should be considered as a diagnostic tool for the definitive identification of rare, unusual, or atypical heterothallic zygomycetes. Practical considerations, however, limit this method to reference laboratories.

The recovery of Mycobacterium avium complex and Mycobacterium tuberculosis from blood specimens of AIDS patients using the nonradiometric BACTEC NR 660 medium.

The ability of the nonradiometric BACTEC NR 660 aerobic 6A blood culture medium to support mycobacterial growth was investigated. During a 19-month period blood cultures from 140 AIDS patients were sent to the microbiology laboratory. After the cultures were incubated for seven days, aliquots of medium from the vials were centrifuged, sediments examined microscopically for mycobacteria, and cultured to mycobacterial media. Seventy-one AIDS patients (51%) had at least one blood culture positive for mycobacteria. There was a significant difference in the percent of female AIDS patients positive for mycobacteria compared to male patients (72% vs. 44%, P less than 0.01). Forty-four percent of all subsequently positive cultures were detected by an acid fast stain of the specimen sediment. Subcultures from the BACTEC 6A suspensions were positive on mycobacterial media at one-seven weeks (mean three weeks) after planting. Sixty-nine of the isolates were Mycobacterium avium complex, while two were Mycobacterium tuberculosis. Some bacteremias with M. tuberculosis may have been undetected because growth experiments with a reference strain showed that, in contrast to M. avium complex, M. tuberculosis did not increase in concentration in 6A medium.

The use of 5-fluorocytosine and ketoconazole in the culture of the erythrocytic stages of Plasmodium falciparum and some tumor cell lines.

In vitro culture systems are often contaminated by bacteria and fungi. It is therefore often necessary to supplement culture media with agents such as penicillin/streptomycin, gentamycin or amphotericin B. The latter cannot be used in the in vitro culture of erythrocytic stages of P. falciparum, and thus anti-fungal agents have not been regularly used in this system. We describe the prophylactic use of 5-fluorocytosine (5-FC) and ketoconazole (KTZ) in tissue cultures at concentrations up to 300 and 10 micrograms/ml respectively which have no effect on the growth of P. falciparum (FCR-3 strain). A melanoma cell line (C32) and a line of uterine carcinoma (C41) were also unaffected by similar concentrations of 5-FC and KTZ. When dissolved in complete culture medium (RPMI 1640) with 10% human plasma, the minimum inhibitory concentration of 5-FC for a susceptible strain of Candida remained below 2 micrograms/ml. These experiments suggest that 5-FC (at 50 micrograms/ml) alone or in combination with KTZ (at 1 microgram/ml) is a useful addition to the armamentarium of antimicrobials available to the tissue culture biologist for a variety of cell culture systems.

Fusarium solani osteomyelitis with probable nosocomial spread.

A case of Fusarium solani osteomyelitis is reported in a previously healthy adult male who received multiple injuries during an automobile accident. Combined histologic and mycologic data proved it to be a case of hyalohyphomycosis resulting from Fusarium. To the best of the authors' knowledge, this is the first reported case of osteomyelitis resulting from F. solani. A concurrent case of saprophytic wound colonization by the same organism is reported in another patient in the same ward who had sustained similar injuries. Evidence suggests that this represents nosocomial spread from the first case.

Rapid detection of positive blood cultures with the BACTEC NR-660 does not require first-day subculturing.

An analysis of blood culture data was performed to determine whether subculturing within the first 24 h of incubation decreased the time to detection of positive blood cultures when compared with the routine use of the BACTEC NR-660 system (Johnston Laboratories, Inc., Towson, Md.). During a 9-month period (June 1985 to February 1986), 17,913 blood cultures were received in our laboratory, of which 1,463 (8.2%) became positive. Of the positive cultures, 97% were detected with equal or greater rapidity by the NR-660 system than by visual inspection and first-day blind subculturing. There were 37 delayed positive cultures from which only one isolate (0.07%) was not eventually detected by the NR-660 system. Coagulase-negative staphylococcus was the most frequent isolate among the delayed positive cultures, but only 3 of 15 isolates were known to be clinically significant isolates. The longest delay in detection by the NR-660 system was 6 days for one isolate of Cryptococcus neoformans and one isolate of Klebsiella pneumoniae. Although subculturing may decrease the time to detection of a few cultures, the majority of positive blood cultures were detected faster or with equal speed by the NR-660 system. When the data were evaluated, routine use of the NR-660 system was sufficient for the detection of positive blood cultures and was cost-effective.

Cefoperazone plus tobramycin versus ticarcillin plus tobramycin in febrile granulocytopenic cancer patients.

Cefoperazone plus tobramycin was compared in a prospective, randomized trial with our standard regimen of ticarcillin plus tobramycin as empiric therapy of fever in granulocytopenic patients with cancer. Patients who received cefoperazone were also given vitamin K (5 mg orally twice a week). Of 39 microbiologically and clinically documented infections treated with ticarcillin plus tobramycin, 28 (72 percent) showed improvement. Of 27 microbiologically and clinically documented infections treated with cefoperazone plus tobramycin, 21 (78 percent) showed improvement. The overall response rates were similar (40 of 53, or 74 percent, for ticarcillin plus tobramycin versus 38 of 48, or 79 percent for cefoperazone plus tobramycin). There was no difference in response between groups according to site of infection. Serious side effects were minimal with both regimens. There were no enterococcal superinfections in patients receiving cefoperazone. These results suggest that the overall efficacy and toxicity of study regimens are similar.

Cytologic manifestation of an unusual bacterial form, Simonsiella species.

Puzzling rodlike structures overlying benign squamous cells in exfoliative cytologic specimens from the upper gastrointestinal and respiratory tracts were initially considered to be fungi, protozoa, bronchodilator crystals, hemoglobin tactoids or plastic fragments. Their morphologic similarity to Simonsiella, a gram-negative bacteria frequently found in the oral cavity, was ultimately recognized. Further studies of smears and cultures obtained from the oral cavities of the authors and from the American Type Culture Collection confirmed the nature of the original findings. These giant bacterial forms were usually found in caterpillarlike side-by-side arrangements of 10 to 12 organisms. Cytologists should be aware of their appearance to avoid possible confusion with pathogenic organisms.

A comparative trial of moxalactam plus ticarcillin and clavulanic acid or piperacillin as empiric antibiotic therapy for febrile cancer patients.

Resistance of bacteria to beta-lactam antibiotics remains a difficult clinical problem that can be compounded in infected patients with serious underlying illness, especially those who are immunocompromised. In a prospective randomized safety and efficacy trial, febrile cancer patients received either ticarcillin disodium combined with the beta-lactamase inhibitor clavulante potassium (Timentin, Beecham Laboratories, Bristol, TN) plus moxalactam (T+M), or piperacillin plus moxalactam (P+M) as initial empiric antimicrobial therapy. Sixty-six febrile episodes in 53 patients were studied. In the T+M group, 14 (78%) of 18 clinically evaluable infections in patients with profound granulocytopenia improved as did all 14 (100%) such infections in the P+M group. In the T+M group 17 of 21 (81%) similarly evaluable infections improved irrespective of granulocyte count, as did 14 (88%) of 16 of such infections in the P+M group. These results are not statistically significantly different. Serious side effects were infrequent and comparable with both regimens. There was one antibiotic related hemorrhage in the P+M group and a serious episode of nephrotoxicity in a patient who died without recovering renal function in the T+M group. These results suggest that the overall safety and efficacy of Timentin plus moxalactam, and piperacillin plus moxalactam are comparable and similar to previous empiric antibiotic trials.

Hymenolepis diminuta: one of three enteric pathogens isolated from a child.

This article describes a case of enteritis in a 3.5-yr-old child with persistent diarrhea and the isolation of three gastrointestinal pathogens, including a rare human pathogen Hymenolepis diminuta (rat tapeworm). This is the first reported case in the northeastern United States in 20 yr and demonstrates that persons living in homes infested with rodents and arthropods are at risk of acquiring this infection.

Association of Blastocystis hominis with signs and symptoms of human disease.

Purged stools from 389 patients were evaluated microscopically for the presence of Blastocystis hominis. A total of five or more B. hominis cells per 40X field were observed in 43 patients (11%), and B. hominis was the only intestinal parasite present in 23 (6%) of these patients. Of the 23 patients, 19 had symptoms which included abdominal discomfort (15 patients), anorexia (10 patients), diarrhea (9 patients), and flatus (9 patients). The remaining four patients were asymptomatic. The proportion of eosinophils in the peripheral blood ranged from 4 to 12% in 11 (58%) of the symptomatic patients. Absolute eosinophil counts were greater than 250/microliter in 8 patients and greater than 400/microliter in 5 patients. Eosinophilia was not observed in the remaining symptomatic or asymptomatic patients. This study supports the emerging concept of the role of B. hominis as an intestinal parasite causative of human disease.

Evaluation of the AutoMicrobic system Gram-Negative General Susceptibility-Plus Card.

The MICs of 10 antimicrobial agents were determined for 1,000 clinical aerobic and facultatively anaerobic gram-negative bacilli by the 6-h AutoMicrobic system Gram-Negative General Susceptibility-Plus Card (GSC+) (Vitek Systems, Inc., Hazelwood, Mo.) and by an 18-h reference agar dilution method. Results obtained by both systems were evaluated for twofold dilution discrepancies and for interpretive category discrepancies. MICs that differed by more than one twofold dilution between the two test systems were considered to be discrepant. The overall twofold dilution agreement of the GSC+ MICs to agar dilution MICs was 94.0%. The agreement for each drug tested ranged from 91.7% (ampicillin and chloramphenicol) to 96.5% (carbenicillin). Interpretive categories were considered in agreement when the susceptibility interpretations obtained by the two systems were both very susceptible, moderately susceptible, or resistant. The overall interpretive category agreement was 80.5%. This agreement increased to 95.8% when all minor errors (moderately susceptible, one system; very susceptible, the other system) that would not affect therapy were omitted. The AutoMicrobic system GSC+ provides rapid and accurate susceptibility test results for clinical aerobic and facultatively anaerobic gram-negative bacilli.

Surface cultures and isolation procedures in infants born under unsterile conditions.

Umbilical and axillary skin cultures for bacteria and yeast were obtained within two hours of birth from 108 term infants born vaginally under sterile (52) and nonsterile (56) conditions. The skin of infants born under nonsterile conditions was more frequently colonized (91%) than that of infants born under sterile conditions (66%). The most common skin flora of both groups was Staphylococcus epidermidis, diphtheroids, and Escherichia coli. A significantly higher frequency of colonization with gram-positive cocci and diphtheroids was noted in infants born under nonsterile conditions. Cultures obtained on day 3 or 4 from infants born under sterile conditions revealed a higher frequency of colonization with E coli, enteric organisms, and potential pathogens than cultures obtained immediately after delivery. Cultures did not aid in clinical management, since in this sample no overt infection developed. Culture and isolation procedures in clinically well term infants born under nonsterile conditions are not warranted.

The oral flor as a source of septicemia in patients with acute leukemia.

This study was performed to determine the role of the oral cavity in causing septicemia in patients with acute leukemia. Thirty-three patients with acute nonlymphocytic leukemia were investigated prospectively via clinical, hematologic, and microbiologic techniques. The mouth was the most likely source of septicemia in seven of twelve cases. Necessary dental treatment prior to chemotherapy was accompanied by a significant reduction in the rate of septicemia. The authors conclude that oral sources of bacteremia should be eliminated prior to chemotherapy in patients with acute leukemia.

Regulation of phosphoglycerate dehydrogenase levels and effect on serine synthesis in Escherichia coli K-12.

The level of phosphoglycerate dehydrogenase, the first enzyme in the biosynthetic pathway to serine and glycine, has been studied in Escherichia coli grown under different conditions. The enzyme level was not reduced by growth in a medium which contained the end products of the pathway, nor was it elevated when the growth rates was limited by the supply of serine. Elevation of phosphoglycerate dehydrogenase did not occur when charging of tRNA ser was inhibited by serine hydroxamate. However, phosphoglycerate dehydrogenase levels were subject to regulation. Elevated levels of enzyme activity were observed in merodiploids containing multiple copies of the serA gene, and lowered enzyme levels were found in cells grown on carbon sources other than glucose or when certain amino acids were present in the growth medium. The combined effect of these nutritional changes (carbon source and amino acids) reduced the level of phosphoglycerate dehydrogenase to 10 to 12% of that found in wild-type cells and to about 5% of the level in the merodiploids. By using antibody prepared against purified phosphoglycerate dehydrogenase we established that the decrease in enzyme activity reflected decreased amounts of enzyme protein. Constant intracellular concentrations of 3-phosphoglycerate and serine were found in cells with marked differences in phosphoglycerate dehydrogenase activity, indicating that end product inhibition of phosphoglycerate dehydrogenase activity, rather than the amount of the biosynthetic enzymes, is the major factor in regulating the intracellular concentration of serine.