Efficacy of microbial identification system for epidemiologic typing of coagulase-negative staphylococci

The lack of an adequate typing system hampers our understanding of the epidemiology of infections caused by coagulase-negative staphylococci (CoNS). CoNS have become recognized as important nosocomial pathogens and the principal cause of infections associated with invasive devices. Sensitive, specific, and convenient methods are needed to evaluate whether implementing infection control guidelines reduces the risk of nosocomial infections from CoNS and other pathogens. The Microbial Identification System (MIDI) (Microbial ID Inc., Newark, Del.), a semiautomated system for fatty acid methyl ester analysis, shows considerable promise for clinical and epidemiologic applications. Its predictive accuracy and reliability were tested by using epidemiologically related and replicated CoNS isolates as well as CoNS from epidemiologically unrelated clinical infections, which were obtained from five established hospital culture collections in diverse geographic locations. Two hundred isolates were fully characterized in 5 days by one person using MIDI, and the results were similar to those produced by more expensive and time-consuming conventional typing methods. MIDI appears to be a useful screening tool that could be used before more expensive and labor-intensive molecular methods. It offers important advantages to hospital epidemiologists and clinical microbiologists who must identify and type CoNS isolates.

Resistance of Candida albicans to fluconazole during treatment of oropharyngeal candidiasis in a patient with AIDS: documentation by in vitro susceptibility testing and DNA subtype analysis

We describe a patient with recurrent episodes of oropharyngeal candidiasis who required progressively higher doses of fluconazole to control and infection. The patient was treated for 14 infections over a 2-year period with doses of fluconazole that ranged from 100 to 800 mg per day. Clinical response, two methods of in vitro susceptibility testing, and molecular epidemiologic techniques were evaluated for 12 of the 14 episodes. Ultimately, the patient became unresponsive clinically to a dose of 800 mg of fluconazole per day. In vitro susceptibility testing of isolates obtained during these successive episodes of infection revealed the development of resistance to fluconazole, and molecular epidemiologic techniques confirmed the persistence of the same Candida albicans strain throughout all 12 episodes.

Evaluation of two commercial systems for identification of coagulase-negative staphylococci to species level

Bloodstream (224) and urine (nine) isolates of coagulase-negative staphylococci (CNS) were evaluated using MicroScan Pos ID and Rapid Pos ID panels. A modification of the conventional method of Kloos and Schleifer served as the reference method. The isolates were selected to include a broad range of CNS species, including 44 S. epidermidis, 50 S. hominis, 39 S. warneri, 33 S. capitis, 21 S. haemolyticus, 12 S. simulans, 11 S. saprophyticus, six S. cohnii, five S. lugdunensis, three S. xylosus, four S. auricularis, two S. schleiferi, two S. intermedius, and one S. sciuri. The Pos ID panel had an overall rate of agreement (correct plus probably correct) with the reference method of 79%, including 95% for S. epidermidis, 95% for S. haemolyticus, 64% for S. hominis, 67% for S. simulans, 79% for S. warneri, and 100% for S. saprophyticus. The Rapid Pos ID panel had an overall rate of agreement (correct plus probably correct) of 76%, including 91% for S. epidermidis, 90% for S. haemolyticus, 64% for S. hominis, 58% for S. simulans, 77% for S. warneri, and 100% for S. saprophyticus. Both systems are acceptable for the identification of the clinically significant species S. haemolyticus, S. saprophyticus, and S. epidermidis, but are less reliable for the infrequently isolated species of CNS.

Postoperative pneumonia: a prospective study of risk factors and morbidity

BACKGROUND

Postoperative pneumonia (PP) is a major complication that has been linked to microaspiration of pathogens originating in the gastrointestinal tract. This prospective study was performed to define the role of gastric bacterial aspiration in the development of PP.

METHODS

Informed consent was obtained before operations from 140 veterans scheduled for major elective procedures requiring nasogastric tubes, and cultures were obtained of the gastric contents and sputum twice daily after operation.

RESULTS

PP developed in 26 (18.6%) of 140 patients. The patients who had PP did not differ from those with no pneumonia after operation except for a history of chronic obstructive pulmonary disease, which was found in 38.5% of those with PP compared with 20% of patients with no pneumonia (p < 0.05). Morbidity was increased in association with PP, because length of stay in the surgical intensive care unit (6.2 vs 2.6 days), days intubated (2.7 vs 0.6), total postoperative days (15.3 vs 8.4), and mortality rates (19.2% vs 1.7%) were greater than in patients with no pneumonia. Gastric pathogens were present on entry in 38% of patients, and 32% of these had PP compared with 13% whose initial gastric cultures were sterile (p = 0.01). Colonization of sputum for greater than 24 hours with gastric pathogens occurred in 28% of patients. These patients had a 40% incidence of PP compared with 12% in patients without such evidence of microaspiration (p < 0.01).

CONCLUSIONS

PP is a morbid postoperative complication associated with not only chronic obstructive pulmonary disease but also the presence of gastric bacteria during operation and transmission of gastric bacteria to the pulmonary tree after operation.

Ampicillin-sulbactam susceptibility testing criteria

In vitro studies in five different medical centers documented the susceptibility of 2,440 consecutive isolates of the Enterobacteriaceae against ampicillin-sulbactam disks of different potencies. For determination of MICs, both 2:1 or 1:1 ratios were used as long as the concentrations of sulbactam at the breakpoints remained the same, i.e. MIC < or = 16/8.0 micrograms/ml or < or = 8.0/8.0 micrograms/ml for the susceptible category. Disks containing 10 micrograms of ampicillin and 10 micrograms of sulbactam are still to be preferred with interpretive criteria of > or = 15 mm for susceptible and < or = 11 mm for resistant (MIC > or = 64/32 micrograms/ml or > or = 32/32 micrograms/ml). The reliability of the disk test actually diminished when the amount of sulbactam in the disk was increased.

Relative efficacy of tazobactam, sulbactam and clavulanic acid in enhancing the potency of ampicillin against clinical isolates of Enterobacteriaceae

Three beta-lactamase inhibitors were combined with ampicillin in a fixed 2:1 ratio. The activity of ampicillin was enhanced by tazobactam and by clavulanic acid, and to a lesser extent by sulbactam when tested against fresh clinical isolates of Enterobacteriaceae. At a concentration of 8 micrograms/ml, ampicillin alone inhibited 49.6% of 2,434 consecutive isolates of enteric bacilli compared to 81% inhibited by ampicillin combined with tazobactam or clavulanic acid and 69.3% inhibited by the sulbactam/ampicillin combination. A four-fold or greater reduction in ampicillin MICs was observed in comparable numbers of isolates with all three combinations, but the most marked effects were seen with strains that were highly resistant to ampicillin.

Impact of the changing epidemiology of fungal infections in the 1990s

The increase in fungal infections over the past decade is striking. This is particularly true for hospitalized patients where the rate of candidal bloodstream infection has increased by as much as 487% over the decade of the 1980s. This increase in fungal infections is accompanied by a significant excess mortality and excess length of stay in hospital. The emergence of "new" fungal pathogens such as Candida krusei, Torulopsis glabrata, Fusarium and Trichosporon beigelii is now recognized as a significant problem in many patient populations. The documentation of nosocomial transmission of fungal pathogens and the recognition of resistance to both new and established anti-fungal agents poses a significant problem entering the 1990s. Continued effort is needed to develop new and better therapeutic agents and more effective strategies for prophylaxis of endogenous infections and prevention of transmission within the hospital setting.

Methods for estimating days of hospitalization due to nosocomial infections

While there is little agreement at the individual patient level of analysis, estimates of mean NI-attributed days of stay for the two methods were essentially the same. The lack of agreement at the individual patient level may reflect fundamental differences in the methods used to derive these estimates: incorporation of noninfected patient data versus exclusive reliance on data from infected patients; and, focus on length of stay rather than the actual care being received. The potential advantages of the AEP-based method include the following: 1) all patients with NI can be included in developing estimates; 2) estimates are based on the care provided rather than simple length of stay differences; 3) data on which to form the NI-day estimates are readily available in the medical record; 4) the AEP is a validated and commonly used utilization review instrument; 5) the AEP-based method has acceptable reliability; 6) this method is designed to provide individual and group estimates of NI-attributed days; 7) because every day of stay is reviewed, additional information is available, which results in greater precision of study of the development, diagnosis, and treatment of the NI relative to the other care that originally brought the patient into the hospital. The AEP-based method for estimating NI-days is a promising alternative to the historical cohort approach. Additional applications of this approach are encouraged to further assess its reliability,validity, and additional information yield.

Effects of fluconazole on the sterol and carbohydrate composition of four species of Candida

The effects of fluconazole, a bis-triazole antifungal agent, on the sterol and carbohydrate composition of Candida albicans, Candida tropicalis, Candida krusei and Candida parapsilosis were investigated. Exposure of Candida species to fluconazole resulted in a profound depletion of ergosterol with a corresponding increase in lanosterol content versus control cells. Carbohydrate analysis revealed a significant increase in chitin and either a decrease (Candida albicans, Candida tropicalis and Candida parapsilosis) or an increase (Candida krusei) in glucan content in fluconazole-treated cells. The decreased ergosterol and increased lanosterol content is consistent with 14-alpha-demethylase inhibition by fluconazole. The increase in cell wall chitin is most likely due to deregulation of chitin synthesis secondary to ergosterol depletion in the cell membrane. Because chitin, glucan and ergosterol are critical components of the fungal cell, perturbation of the production and localization of these components by fluconazole is likely to contribute to the selective toxicity of this compound to Candida species and other fungi.

In vitro selection of resistance to vancomycin in bloodstream isolates of Staphylococcus haemolyticus and Staphylococcus epidermidis

The purpose of the study was to determine whether vancomycin-resistant strains of Staphylococcus haemolyticus could be selected regardless of the initial MIC of vancomycin. Twenty-one bloodstream isolates of Staphylococcus haemolyticus were studied by broth and agar selection methods. The broth method selected strains for which MICs of vancomycin ranged from 4 to 32 micrograms/ml and MBCs from 16 to greater than 128 micrograms/ml. The agar method selected strains for which MICs ranged from 8 to 32 micrograms/ml and MBCs from 8 to greater than 128 micrograms/ml. For comparison, seven strains of Staphylococcus epidermidis were evaluated by the agar selection method. Final MICs of vancomycin ranged from 8 to 16 micrograms/ml; MBCs ranged from 16 to 64 micrograms/ml. Clearly, in vitro exposure to vancomycin can select strains of Staphylococcus haemolyticus and Staphylococcus epidermidis for which MIC values are beyond the susceptible breakpoint.

Assigning responsibility: using feedback to achieve sustained control of methicillin-resistant Staphylococcus aureus

Sustained control of endemic methicillin-resistant Staphylococcus aureus (MRSA) originating from multiple sources has not been reported. We describe a simple, inexpensive program based on feedback to physicians that resulted in significant reduction of nosocomial MRSA. When nosocomial cases were identified, the epidemiologist contacted the team resident to encourage increased emphasis on hand washing. Handouts, periodic hand cultures of house staff, and monthly presentations at morning report were also employed. In the first 15 months, nosocomial MRSA decreased from 1.025 to 0.508 cases per 1,000 patient days (p less than 0.01). Monthly rates were significantly decreased for 9 months of 1989 and the first 2 months of 1990. Feedback and assignment of responsibility resulted in a 50% reduction in nosocomial MRSA that has been sustained for 15 months.

Application of DNA probes to antimicrobial susceptibility testing of Legionella pneumophila

The commercial availability of a DNA probe assay for the detection of Legionella (Gen-Probe Incorporated, San Diego, CA) provides a unique opportunity to investigate the application of this technology to antibiotic susceptibility testing of L. pneumophila. We examined the ability of erythromycin, rifampin, and ciprofloxacin to kill L. pneumophila in buffered ACES-yeast extract broth (YEB). The test organism was incubated for a total of 96 hr in the presence of 10 micrograms/ml erythromycin, 1 micrograms/ml rifampin, or 1 micrograms/ml ciprofloxacin. Growth was monitored at 24-hr intervals by quantitative plating and the DNA probe assay. The correlation between organism concentration [colony-forming units (CFU) per ml] and DNA probe activity (counts per min) was excellent (r = 0.97). The percent decrease in CFU/ml at 96 hr relative to control counts was greater than 99% for erythromycin, rifampin, and ciprofloxacin. The percent decrease in CPM at 96 hr versus control was 87% for erythromycin, 89% for rifampin, and 93% for ciprofloxacin. This data documents a novel application of DNA probe technology, which may be useful in future studies of in vitro susceptibility of Legionella to various agents.

Staphylococcus aureus colonization and infection in patients on continuous ambulatory peritoneal dialysis

Staphylococcus aureus is the most common cause of peritonitis in patients undergoing peritoneal dialysis in Brazil. Using restriction endonuclease analysis of plasmid DNA, we investigated the importance of chronic carriage of S. aureus in the development of peritonitis in patients on continuous ambulatory peritoneal dialysis at the Division of Nephrology, Escola Paulista de Medicina, Sao Paulo, Brazil. A total of 117 isolates (30 patients) of S. aureus were available for typing, including 51 isolates (22 patients) from the nares, 58 isolates (27 patients) from pericatheter skin, and 8 isolates (6 patients) from peritoneal fluid, from patients with peritonitis. Restriction endonuclease subtyping showed that although most patients harbored more than one subtype of S. aureus, in the majority of patients nasal and/or pericatheter skin isolates with identical restriction endonuclease digest patterns were recovered on more than one occasion. Furthermore, 95% of patients with both nasal and pericatheter colonization were colonized with the same subtypes at both sites. All of the patients with peritonitis were infected with a subtype which colonized the nares, pericatheter skin, or both. These results demonstrate the importance of an endogenous source of S. aureus in the development of continuous ambulatory peritoneal dialysis-associated peritonitis.

Effects of cilofungin (LY121019) on carbohydrate and sterol composition of Candida albicans

Cilofungin (LY 121019) is a novel analogue of echinocandin B with potent activity against Candida albicans. The effects of cilofungin on the sterol and cell wall carbohydrate composition of Candida albicans were investigated. Exposure of Candida albicans to cilofungin resulted in a 55-60% decrease in ergosterol and a 4-13% decrease in lanosterol content relative to controls. Carbohydrate analysis revealed a 72-79% decrease in glucan content and no significant decrease in mannan or chitin content relative to controls. These studies suggest that cilofungin specifically inhibits glucan synthesis in Candida albicans and thus may be less toxic to mammalian cells. The effects of cilofungin on sterol composition may be non-specific and will require additional investigation.

Value of the Cand-Tec Candida antigen assay in the diagnosis and therapy of systemic candidiasis in high-risk patients

A total of 911 sera from 171 patients at risk for systemic candidiasis and 24 sera from 24 non-hospitalized control subjects were analyzed for the presence of candida antigen using a commercially available latex agglutination test (Cand-Tec). Thirty-seven (22%) patients had systemic candidiasis documented by positive blood cultures, deep biopsy culture and histopathology or autopsy. Six patients had transient candidemia, 20 patients had candiduria, 53 patients had mucous membrane colonization, 21 patients were not colonized but received empiric amphotericin B, and 34 patients were not colonized and not treated with amphotericin B. The intraobserver reproducibility was 90% for the exact titer and 100% for a deviation of one dilution. The sensitivity and specificity of the candida antigen test in detection of systemic candidiasis was 95% and 50% (greater than or equal to 1:2), 73% and 72% (greater than or equal to 1:4), and 46% and 80% (greater than or equal to 1:8) respectively. Despite the poor specificity, serial antigen determinations in patients with documented systemic candidiasis demonstrated both an early diagnostic and prognostic role for the candida antigen test. Seventy-one percent of patients whose antigen titer increased during the course of amphotericin B therapy of documented infection died versus only 13% of those whose titer decreased while on therapy (p = 0.01). The candida antigen test has a limited yet potentially useful role in the diagnosis and management of systemic candidiasis in high-risk patients.

In vitro comparison of cefpirome and four other beta-lactam antibiotics alone and in combination with tobramycin against clinical isolates of Pseudomonas aeruginosa

In vitro susceptibility studies of cefpirome versus cefotaxime, ceftazidime, imipenem, and piperacillin alone and in combination with tobramycin were performed against 153 clinical isolates of Pseudomonas aeruginosa from four medical centers. The minimal inhibitory concentration (MIC) for each antibiotic alone was determined by a standardized dilution method. Antibiotic combination studies were performed using a modified checkerboard technique. Cefpirome alone was more active (MIC90 64 micrograms/ml) than piperacillin (MIC90 128 micrograms/ml) or cefotaxime (MIC90 256 micrograms/ml) but less active than imipenem (MIC90 2 micrograms/ml) or ceftazidime (MIC90 32 micrograms/ml). The addition of tobramycin reduced the MICs of all of the beta-lactam antibiotics except for imipenem. The MIC90 for cefpirome when combined with tobramycin was 8 micrograms/ml compared to 16 micrograms/ml for cefotaxime and piperacillin, 8 micrograms/ml for ceftazidime, and 4 micrograms/ml for imipenem. The combination of tobramycin and cefpirome proved to be additive or synergistic for 82% of the isolates (highest rate) compared to 31% with imipenem (lowest rate). The potent in vitro antipseudomonal activity of cefpirome alone and in combination with an aminoglycoside (tobramycin) suggests that this agent may play a useful role in the therapy of infections due to P. aeruginosa.

The application of molecular and immunologic techniques to study the epidemiology of Legionella pneumophila serogroup 1

We applied monoclonal antibody typing and restriction endonuclease analysis of plasmid DNA to study 28 clinical and 35 environmental (potable water) isolates of Legionella pneumophila serogroup 1 from three hospitals in Iowa between 1981 and 1986. Monoclonal antibody typing employed a panel of seven antibodies and delineated eight different subtypes. Plasmids were present in 57% of the isolates including 12 of 28 (43%) clinical and 25 of 35 (69%) potable water isolates. The plasmids ranged in size from 28 to 98 kilobase pairs and comprised eight distinct subtypes by restriction endonuclease analysis with Eco RI. Combination of monoclonal antibody and restriction endonuclease subtyping (composite subtyping) revealed 19 different composite subtypes of Legionella pneumophila serogroup 1. The most common composite subtype, 09:04, comprised 29% (18 of 63) of the isolates and was only found in clinical and potable water samples from a single pavilion in hospital A during an outbreak of Legionella pneumophila serogroup 1 pneumonia. Aside from this cluster the diversity of composite subtypes of Legionella pneumophila serogroup 1 observed in clinical and potable water sources over the 5-year period was striking. The combination of monoclonal antibody and restriction endonuclease typing resulted in improved strain delineation and a more useful use of epidemiologic markers for Legionella pneumophila serogroup 1.

Fungicidal activity of cilofungin (LY121019) alone and in combination with anticapsin or other antifungal agents

Cilofungin (LY121019) was shown to have potent fungicidal activity against clinical isolates of Candida albicans and Candida tropicalis but not Candida parapsilosis. Fungicidal activity was evident against both replicating and non-replicating Candida albicans and was progressive over the first 12 h of incubation. The combination of cilofungin (LY121019) with anticapsin but not with amphotericin B, ketoconazole or 5-fluorocytosine resulted in synergistic fungicidal activity. This compound warrants further investigation of its safety and efficacy in the treatment of Candida infections.

Cost of nosocomial infection: relative contributions of laboratory, antibiotic, and per diem costs in serious Staphylococcus aureus infections

This study reports an analysis of the relative importance of laboratory antibiotic, and per diem costs of caring for 58 patients with serious Staphylococcus aureus nosocomial infections. Laboratory costs accounted for 2%, antibiotics for 21%, and per diem costs for 77% of total infection-related costs. Only 45% of patients were hospitalized for additional days specifically because of infection, but these patients stayed an average of 18 extra days. Nosocomial infections with S. aureus resistant to penicillinase-resistant penicillins (PRP) were more frequently associated with additional infection-related days of hospitalization than were PRP-susceptible infections. The cost of PRP-resistant infections was also significantly greater than PRP-susceptible infections, primarily because of the costs of additional days of hospitalization. Rational strategies to control costs of nosocomial infection should focus on two approaches: (1) prevention and (2) reduction of acute hospital days attributable to infections.

Multiple Candida strains in the course of a single systemic infection

Species and strain variabilities have been monitored during the history of a prolonged Candida infection in a single compromised bone marrow transplant patient by analyzing sugar assimilation patterns, high-frequency switching repertoires, and Southern blot hybridization patterns with two cloned mid-repeat sequences (Ca3 and Ca7) which are species specific for Candida albicans and one cloned mid-repeat sequence (Ct13-8) which is species specific for Candida tropicalis. Evidence is presented that during the course of this infection (i) two strains of C. albicans and three strains of C. tropicalis were distinguished by their switching repertoires, Southern blot hybridization patterns, and sugar assimilation patterns; (ii) the three C. tropicalis strains were in a high-frequency mode of switching; (iii) two C. tropicalis strains coexisted in the blood and three C. tropicalis strains coexisted in the throat at different times during the history of the infection; (iv) amphotericin B treatment selectively removed one of two C. tropicalis strains coexisting in the blood and this strain exhibited greater susceptibility to amphotericin B in vitro (the remaining strain was subsequently removed from the blood by flucytosine treatment); and (v) both the strain removed from the blood by amphotericin B and the strain removed from the blood by flucytosine reappeared several days later at another site of infection. It is demonstrated for the first time that C. tropicalis is capable of high-frequency switching of colony morphology just as C. albicans is, that there is more than one strain-specific switching repertoire in C. tropicalis, and that a C. tropicalis mid-repeat sequence can be used for discriminating species and assessing strain relatedness, as previously demonstrated for C. albicans mid-repeat sequences.

Development of the quantitative micro-test for slime production by coagulase-negative staphylococci

The macro-test for slime production by coagulase-negative staphylococci was adapted to a spectrophotometric micro-test assay to obtain more objective and quantitative information on slime production. A total of 135 isolates of coagulase-negative staphylococci (70 macro-test-positive and 65 macro-test-negative) were tested by both methods. The quantitative micro-test optical density readings were (mean +/- SD) 1.176 +/- 0.294 and 0.130 +/- 0.095 for the macro-test-positive and -negative groups, respectively. The micro-test was reproducible and demonstrated quantitative differences in slime production among the different species of coagulase-negative staphylococci. Aside from Staphylococcus epidermidis, the majority of the coagulase-negative staphylococci had very low optical density readings, indicating little or no slime production under the conditions employed in this assay. This test allows one to study the relative production of slime by different strains and species of coagulase-negative staphylococci, and may be useful in studying the effects of different conditions, such as antibiotic exposure, on slime production.

Antimicrobial activity of U-76,252 (CS-807), a new orally administered cephalosporin ester, including recommendations for MIC quality control

U-76,253A (R-3746), the active metabolite of the new cephalosporin ester, U-76,252 (CS-807), was tested against 4,742 fresh clinical isolates from four large medical centers. U-76,253A was very active against nearly all species of Enterobacteriaceae (87.7% inhibited at less than or equal to 4.0 micrograms/ml). Staphylococcus spp., and the streptococci. The U-76,253A spectrum was superior to the comparison orally administered cephalosporins (cephalexin, cephradine, cefaclor). Pseudomonas spp., Acinetobacter spp., and the enterococci were resistant to U-76,253A and the other tested drugs. Broth microdilution MIC quality control (QC) limits were established for U-76,253A in a multilaboratory investigation using a minimum of 125 MIC determinations per organism. The following MIC QC ranges were recommended; Escherichia coli (ATCC 25922) = 0.25-1.0 micrograms/ml, Staphylococcus aureus (ATCC 29213) = 2.0-4.0 micrograms/ml and Pseudomonas aeruginosa (ATCC 27853) = greater than 32 micrograms/ml.

Multicenter comparison of MicroScan and BACTEC blood culture systems

Recently, MicroScan (Baxter MicroScan Div., W. Sacramento, Calif.) introduced a radiolabeled-blood-culture system that is compatible with the BACTEC 460 (Johnston Laboratories, Inc., Towson, Md.). A multicenter blood culture study was initiated to evaluate this new system. Approximately 20 ml of blood was obtained from each patient and divided equally between BACTEC and MicroScan bottles which were incubated and processed identically. Aerobic bottles were examined twice on days 1 and 2 and once on days 3, 4, 5, 6, and 7. Anaerobic bottles were examined once a day for 7 days. There were 3,451 cultures evaluated, and 414 of these subsequently grew microorganisms. Of these positive cultures, 64 were judged to be contaminated. Of the remaining 350 positive cultures, 253 grew in both systems, 54 grew in BACTEC bottles only, and 43 grew in MicroScan bottles only. The average times to detect positive cultures were 1.8 and 2.1 days by the BACTEC and the MicroScan systems, respectively. No significant difference in the number or kind of organisms recovered or in the detection times for positive cultures was observed between the two blood-culturing systems.

Predictive value of surveillance cultures for systemic infection due to Candida species

Weekly fungal surveillance cultures (1,542 cultures) of urine (475), stool (520) and oropharyngeal (547) specimens from 111 patients on the bone marrow transplant and hematologic malignancy services were analyzed. Forty-three percent of the patients were colonized by Candida albicans and 10.8% by Candida tropicalis. There were 22 proven systemic fungal infections, ten due to Candida albicans, eight to Candida tropicalis, one each to Candida pseudotropicalis and Torulopsis glabrata, and two to Aspergillus species. Positive surveillance cultures for Candida tropicalis were highly predictive of systemic infection. The finding of two or more positive cultures yielded high positive predictive values (100%) as a function of body site. Positive surveillance cultures for Candida albicans were not predictive of disease but negative cultures for Candida albicans and Candida tropicalis had a high negative predictive value (95-99%). Surveillance culture data for specific Candida species may aid in diagnostic and therapeutic decision making.