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Biomedical subjects

M T LaRocco

Publications and source records attributed to M T LaRocco.

At least 19 recordsLinked to original sources
PubMed2006

Comparison of risk factors for candidemia versus bacteremia in hospitalized patients.

BACKGROUND: Classic risk factors for candidemia include use of total parenteral nutrition (TPN), hospital location, use of central venous catheter, and others. Unfortunately, most of these variables are now also risk factors for antibiotic-resistant bacteria. Thus, use of these risk factors to identify patients at high risk for candidemia is difficult. The purpose of this study was to compare these classic risk factors for candidemia in patients with bloodstream infections to determine the relative strength of these predictors in differentiating patients with candidemia and bacteremia. METHODS: Clinical data were collected from the medical charts of patients who had been hospitalized between 2002 and 2004. Patients with their first episode of candidemia or bacteremia during their hospital stays were included. Risk factors were assessed using a multivariate logistic regression model and internally validated using a bootstrap analysis. A p-value < 0.05 was considered significant. RESULTS: A total of 164 patients (82 with candidemia) were evaluated. According to the logistic analysis, patients who had stayed in the intensive care unit (ICU) (OR = 6.24; 95% CI: 2.58-15.09) or had been using TPN (OR = 4.69; 95% CI: 1.76-12.48) were more likely to have candidemia than bacteremia. While patients with pulmonary (OR = 0.15; 95% CI: 0.055-0.39) or cardiac disease (OR = 0.21; 95% CI: 0.086-0.51) had a greater chance to have bacteremia than candidemia (p < 0.01 for all variables). These results were further validated using bootstrap analysis. CONCLUSION: Among classic risk factors for candidemia, the ICU location at the time of culture and TPN use were most predictive of candidemia while certain medical disorders predicted patients at the highest risk for bacteremia. These results can be used to help identify patients most likely to benefit from empiric antifungal therapy.

Adult↗
PubMed2000

Evaluation of an enzyme-linked viral inducible system for the rapid detection of Herpes simplex virus.

A commercial enzyme-linked viral inducible system (ELVIS HSV; BioWhittaker, USA) was evaluated in comparison with the spin-amplified tube cell culture (SATCC) method for the rapid detection of herpes simplex virus in 1007 clinical specimens. A total of 91 (9%) specimens were positive by SATCC. The sensitivity, specificity, positive predictive value, and negative predictive value of ELVIS was 88%, >99%, 99%, and 99%, respectively. Herpes simplex virus was detected sooner by ELVIS than by SATCC in 34 of 80 (42%) specimens. Preincubated ELVIS shell vials held at room temperature for 24 h prior to reincubation and inoculation produced results similar to those of freshly preincubated shell vials, with no reduction in either the number or the staining intensity of the infected cells. The results of this study indicate that ELVIS HSV is an accurate method for the rapid detection of herpes simplex virus in a wide variety of clinical specimens.

Cell Line↗
PubMed1999

Destructive native valve endocarditis caused by Staphylococcus lugdunensis.

Coagulase-negative staphylococci are uncommon causes of native valve endocarditis, and the clinical course after valvular infection with these organisms is variable. In clinical practice, species identification is frequently not done, and possible differences in the pathogenicity of various species may be unrecognized. We report a case of Staphylococcus lugdunensis native valve endocarditis associated with valve leaflet perforation and cerebral embolization. This recently described species appears to be more virulent when infecting native cardiac valves than other species of coagulase-negative staphylococci. We review S lugdunensis native valve endocarditis.

Adult↗
PubMed1997

Infection in the bone marrow transplant recipient and role of the microbiology laboratory in clinical transplantation.

Over the past quarter century, tremendous technological advances have been made in bone marrow and solid organ transplantation. Despite these advances, an enduring problem for the transplant recipient is infection. As immunosuppressive regimens have become more systematic, it is apparent that different pathogens affect the transplant recipient at different time points in the posttransplantation course, since they are influenced by multiple intrinsic and extrinsic factors. An understanding of this evolving risk for infection is essential to the management of the patient following transplantation and is a key to the early diagnosis and treatment of infection. Likewise, diagnosis of infection is dependent upon the quality of laboratory support, and services provided by the clinical microbiology laboratory play an important role in all phases of clinical transplantation. These include the prescreening of donors and recipients for evidence of active or latent infection, the timely and accurate microbiologic evaluation of the transplant patient with suspected infection, and the surveillance of asymptomatic allograft recipients for infection. Expert services in bacteriology, mycology, parasitology, virology, and serology are needed and communication between the laboratory and the transplantation team is paramount for providing clinically relevant, cost-effective diagnostic testing.

Bacterial Infections↗
PubMed1994

Fluconazole susceptibilities of Candida species and distribution of species recovered from blood cultures over a 5-year period.

The distribution and fluconazole susceptibilities of Candida species isolated over a 5-year period were investigated. Susceptibilities were determined by using a new microtiter procedure and the National Committee for Clinical Laboratory Standards (NCCLS) proposed standard. The new method correlated well with the NCCLS proposed standard and gave very clear end points. Results indicate that there are species-related differences in MICs as reflected in the MICs for 90% of species tested. Candida albicans is most susceptible to fluconazole, while Candida glabrata is among the least susceptible. These findings coincided with the observation of a shift in distribution of yeast species recovered from blood cultures from 1987 to 1992. C. albicans was the predominant species (87%) in the pre- or early fluconazole years but decreased to only 31% of the isolates in 1992. Thus, Candida species for which MICs of fluconazole were higher have become more prominent in recent years. Significantly, throughout this period, MICs for each species did not change appreciably.

Candida↗
PubMed1994

Comparison of E test with standard broth microdilution for determining antibiotic susceptibilities of penicillin-resistant strains of Streptococcus pneumoniae.

We compared the E test (AB Biodisk North America, Inc., Culver City, Calif.) with the National Committee for Clinical Laboratory Standards broth microdilution method for the determination of MICs of penicillin and cefotaxime for 108 isolates of Streptococcus pneumoniae. The E test was performed following manufacturer's recommendations with Mueller-Hinton blood agar, and the broth microdilution procedure was performed with lysed horse blood-supplemented Mueller-Hinton broth. The microdilution method classified 26 isolates as highly penicillin resistant (MIC, > or = 2 micrograms/ml), 33 as intermediately resistant to penicillin (MIC, > or = 0.1 < 2.0 micrograms/ml), and 49 as susceptible to penicillin (MIC, < 0.1 micrograms/ml). Discordant results obtained with the E test for penicillin susceptibility testing compared with broth microdilution occurred for 19 of the 108 isolates tested. Cefotaxime MICs for 90% of isolates found highly resistant, intermediately resistant, and susceptible to penicillin by broth microdilution were 2.0, 0.5, and 0.06 micrograms/ml, respectively. There were 16 susceptibility category changes when the E test was used to determine cefotaxime MICs. All of the discrepancies in the penicillin and cefotaxime MICs determined by the E test occurred at the susceptibility category breakpoints, and all represented differences of only one twofold dilution factor. Properly performed and controlled, the E test should be a reliable quantitative procedure for more accurately predicting the susceptibility of S. pneumoniae to several antibiotics.

Cefotaxime↗
PubMed1993

Reevaluation of the linkage between acute hemorrhagic shock and bacterial translocation in the rat.

The present study was undertaken to determine the conditions under which acute periods of hemorrhagic shock induce bacterial translocation. Rats (at least six per group) were anesthetized intraperitoneally with the barbiturate, pentobarbital (50 or 65 mg/kg), or the inhalation anesthetic methoxyflurane. Following anesthesia, the femoral artery was catheterized, from which blood was withdrawn to maintain a mean arterial blood pressure of 30 mmHg for 30, 60, or 90 min, followed by reinfusion of shed blood. Instrumented, but nonshocked animals served as controls. Rats were sacrificed at 0, 2, or 24 hr postshock, and quantitative bacterial cultures of the mesenteric lymph node complex (MLN), liver, and spleen were made. Within groups, the effects of heparinization were also determined. In pentobarbital-treated animals, regardless of the extent of heparinization, consistent translocation to both MLN and distant organs occurred when shock was prolonged for 90 min, and assessment of translocation was made 24 hr after reinfusion of shed blood. Furthermore, a mortality rate of approximately 30% was found in rats subjected to this protocol. The magnitude of translocation was less consistent, and did not differ from that in sham shock controls, under other conditions of shock and evaluation. In rats anesthetized with methoxyflurane, no mortality occurred, and no statistical significance between the incidence or degree of translocation in shocked animals vs. sham shock controls could be demonstrated, regardless of the shock protocol. In additional studies, effects of these anesthetics on intestinal morphology and superior mesenteric arterial (SMA) flow in the context of hemorrhagic shock were assessed.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia↗
PubMed1992

Influence of shock on development of infection during acute pancreatitis in the rat.

This study tested the hypothesis that hypovolemic shock elicits or promotes the development of infection during acute pancreatitis. Pancreatitis was induced in rats by ligation of the common biliopancreatic duct; nonlaparotomized animals served as controls. After 24 hr, the animals were subjected to either sham-shock (instrumented only) or to shock by withdrawal of blood through a femoral artery line by maintaining the mean arterial blood pressure at 30 mm Hg for 1 or 2 hr. After completion of the shock period, the shed blood was returned to the animal. All animals were sacrificed 24 hr later and specimens obtained from portal and systemic blood, liver, spleen, pancreas, and mesenteric lymph nodes for bacteriologic culture using standard techniques. The pancreas was also analyzed by morphometric techniques. The histologic changes of pancreatitis induced by biliopancreatic obstruction were characterized by marked edema with accompanying mild inflammation, hemorrhage, and necrosis. Concomitant with these morphologic findings was an associated translocation of enteric organisms to the mesenteric lymph nodes without spread to distant organs. Shock by itself induced only a mild edema in the pancreas and did not cause bacterial translocation. Furthermore, shock failed to aggravate the morphologic alterations of acute pancreatitis and did not promote bacterial spread to mesenteric nodes over that observed with pancreatitis alone. Thus, we conclude that periods of severe shock lasting up to 2 hr do not play a major role in the pathogenesis of infection in our model of pancreatitis.

Acute Disease↗
PubMed1992

Latex agglutination-negative methicillin-resistant Staphylococcus aureus recovered from neonates: epidemiologic features and comparison of typing methods.

An unusual strain of methicillin-resistant Staphylococcus aureus (MRSA) was repeatedly isolated from infants in a newborn special care unit (NBSC) and a newborn intensive care unit. Between January 1989 and March 1990, approximately 100 isolates from infected or colonized infants were recovered. Surveillance cultures taken during this time revealed a 20% colonization rate, which was defined as recovery of MRSA from the nares, umbilicus, or groin. Isolates were identified as S. aureus by tube coagulase reactivity and heat-stable nuclease production but were unreactive in a latex agglutination assay. Representative isolates that were collected during the outbreak and that were found to share the latex agglutination assay-negative phenotype were compared by antibiogram (12 isolates), bacteriophage typing (20 isolates), capsular polysaccharide typing (30 isolates), and plasmid as well as chromosomal DNA analyses (20 isolates). All isolates known to be associated with the outbreak had nearly identical antibiograms and were notably susceptible to clindamycin. Staphylococcal bacteriophage typing was not useful in determining the relatedness of the isolates, since the majority were nontypeable. Plasmid pattern analysis revealed one large plasmid (approximately 100 kb) of equivalent size among the isolates. Capsular polysaccharide typing revealed that 14 of 30 isolates tested were type 5. Isolates identified in children at two other hospitals in the city which were also unreactive by the latex agglutination assay and clindamycin susceptible had plasmid and antibiogram patterns identical to those of isolates from the NBSC. Pulsed-field gel electrophoresis of restriction enzyme-digested genomic DNAs from the outbreak isolates demonstrated identical patterns which could be clearly differentiated from those of other unrelated MRSA. The strain from the NBSC is, therefore, unique and underscores the need for caution in interpreting the latex agglutination reactivities of MRSA isolates.

Bacterial Typing Techniques↗
PubMed1991

Latex agglutination for rapid identification of methicillin-resistant Staphylococcus aureus recovered from selective media.

The accuracy of combining latex agglutination with selective media for the identification of methicillin-resistant Staphylococcus aureus (MRSA) was determined. Test strains were identified by latex agglutination on blood agar, the heat-stable thermonuclease test and broth microdilution MICs of oxacillin and included 97 MRSA, 56 methicillin-susceptible Staphylococcus aureus, 52 methicillin resistant, and 49 methicillin-susceptible Staphylococcus species. Isolates were grown on trypticase-soy agar with 5% sheep red blood cells (TSAB), Mueller-Hinton agar (MHA), mannitol-salt agar (MSA), and four media designed for the selective growth of MRSA:TSAB with clindamycin and gentamicin, MHA with oxacillin, MSA with oxacillin, and lipovitellin-salt-mannitol agar (LVSM) with 1 microgram oxacillin disks applied. The mean sensitivity, specificity, and positive predictive value for the combination of latex agglutination with selective media for the identification of MRSA was 96%, 99% and 98% respectively.

Culture Media↗
PubMed1991

The role of the gut in the development of sepsis in acute pancreatitis.

The pathogenesis of sepsis in acute pancreatitis is unknown. Since the intestinal tract has recently been identified as a possible source for sepsis in other conditions, we explored whether the gut may serve as a reservoir for bacteria causing systemic and pancreatic infection in acute pancreatitis. Bacterial translocation, alterations of intestinal microflora, and intestinal motility, as reflected by gut propulsion, were studied in a rat pancreatitis model. Acute pancreatitis was induced by biliopancreatic obstruction (AP); sham manipulated animals served as controls (sham). Bacteriologic cultures were obtained from various segments of the intestinal tract and from blood, liver, spleen, pancreas, and mesenteric lymph nodes 48 and 96 hr after induction of AP or sham. Bacteria were recovered from mesenteric lymph nodes of all 12 animals with AP, but only from 3/14 sham animals (P less than 0.05). Spread to distant organ sites occurred in 4 of 12 animals with AP compared to none of the sham animals (P less than 0.05). A disruption of the intestinal microflora was found in the cecum, where the gram-negative bacterial count (log/g) was significantly higher during AP when compared with sham controls: 10.62 +/- 1.04 vs 8.05 +/- 1.45 at 48 hr and 7.92 +/- 0.62 vs 6.79 +/- 0.87 at 96 hr, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1991

Salmonella infection of the biliary and intestinal tract of wild opossums.

Bacteriologic cultures were taken from the mesenteric lymph nodes, biliary tract, blood, liver, spleen and pancreas of opossums (Didelphis virginiana) obtained directly from the wild for use as research animals. The overall incidence of salmonellosis outside the intestinal tract was 61% among 18 opossums. Salmonella was recovered from the gallbladder of six (33%) animals, indicating chronic biliary tract infection. Among these six animals, translocation of Salmonella to regional lymph nodes was observed in five animals, bacteremia in three animals, and spread to liver or spleen in five animals, respectively. The biliary tract was sterile in 12 opossums (67%). In these 12 animals, bacteria were isolated from the celiac and superior mesenteric lymph nodes of five animals, the blood of two animals, and the liver and spleen of one animal, respectively. Bacteriologic cultures were obtained from the intestinal tract and from extraintestinal sites in nine opossums. Salmonella were found in the small bowel of two animals, both of which had biliary salmonellosis. In addition, Salmonella was isolated from extraintestinal organs of three animals with negative cultures from the gut. All isolates identified were: S. enterica subsp houtenae. These data establish the biliary tract of wild opossums as a reservoir for Salmonella enterica subsp houtenae which may be particularly important when opossums are used in research laboratories.

Animals↗
PubMed1990

Cultivation of Nocardia spp. on chemically defined media for selective recovery of isolates from clinical specimens.

Isolation of Nocardia spp. from clinical specimens can be enhanced by the use of paraffin baiting, which relies on the selective ability of the organism to metabolize paraffin. We evaluated 44 Nocardia isolates, 18 group IV mycobacterial isolates, and 4 Streptomyces isolates for growth on blood agar (BA) and on carbon-free agar containing single or double substrates as follows: paraffin agar (PA), gelatin agar (GA), urea agar (UA), PA-gelatin (PG), and PA-urea (PU). The growth rates of Nocardia spp. on BA, PA, PU, and PG were similar; but 3-day-old colonies were larger on BA for 20 (45%) isolates. After longer incubations (7 to 14 days), some Nocardia colonies were larger on PA, PG and PU than they were on BA. Despite variable morphologies on BA, colonies on PA, PG, and PU were consistently smooth, creamy, and raised. Compared with growth on BA, the growth of mycobacteria was much slower on PA, PG, and PU, with poor growth on UA and GA. The growth of Streptomyces spp. was greatly enhanced on GA, PG, UA, and PU and was poorest on PA. Twelve sputum specimens seeded with Nocardia asteroides (10(4) CFU/ml) were inoculated onto BA and all chemically defined media. Nocardiae were recovered from 6 to 12 specimens grown on BA, GA, and UA; 11 of 12 specimens grown on PG; and 12 of 12 specimens grown on PA and PU. Only PA was able to suppress the growth of other microorganisms that were present in sputum specimens. These results suggest that chemically defined media containing PA may be useful for the selective isolation of Nocardia spp. from contaminated clinical specimens.

Culture Media↗
PubMed1989

Detection of piluslike structures on clinical and environmental isolates of Vibrio vulnificus.

Twenty clinical isolates of Vibrio vulnificus were compared with 10 environmental strains by using electron microscopy and agglutination assays with human erythrocytes, guinea pig erythrocytes, and Saccharomyces cerevisiae. In addition, the isolates were tested for ability to adhere to the human epithelial cell lines HEp-2 and A549. When examined by electron microscopy, 16 (80%) of the 20 clinical isolates demonstrated the presence of piluslike structures; the composition of the bacterial populations ranged from 0 to 68% piliated cells. In contrast, only 3 (30%) of the 10 environmental isolates were piliated, with a range from 0 to 16% piliated cells. A significant association between the presence of piliated cells and the isolate source was found (P less than 0.05). None of the 30 strains agglutinated erythrocytes or yeast cells. V. vulnificus adherence results obtained with HEp-2 cells showed 10 (50%) of 20 clinical isolates and 0 (0%) of 10 environmental isolates with averages of greater than 10 adherent bacteria per cell, demonstrating a correlation between attachment and the isolate source (P less than 0.05). Selected strains were tested to determine whether methyl alpha-D-mannopyranoside, fructose, or alpha-L-(-)-fucose would inhibit bacterial adherence to HEp-2 cells. Multiple patterns of adherence inhibition were observed. Adherence to A549 cells showed 8 (40%) of 20 clinical isolates and 0 (0%) of 10 environmental strains with averages of greater than 10 adherent bacteria per cell. A statistical association between attachment and the isolate source was demonstrated (P less than 0.05). These data suggest that the presence of piluslike structures and the ability to adhere to human epithelial cell lines may be more closely associated with V. vulnificus isolates from clinical specimens than with environmental strains.

Agglutination Tests↗
PubMed1987

Multiple drug-resistance in Shigella flexneri isolated from a patient with human immunodeficiency virus.

Persistent shigellosis, due to Shigella flexneri resistant to multiple antibiotics, developed in a 40-yr-old homosexual man with human immunodeficiency virus infection. The Shigella strain demonstrated resistance to ampicillin, tetracycline, and trimethoprim-sulfamethoxazole. Although Shigella flexneri isolates resistant to trimethoprim-sulfamethoxazole are uncommon in the United States, laboratories should monitor resistance patterns through routine in vitro susceptibility testing.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Protein fingerprinting for the determination of relatedness in Acinetobacter calcoaceticus subspecies anitratus isolated from patients in a surgical intensive care unit.

The use of protein fingerprinting for the establishment of relatedness among isolates of Acinetobacter calcoaceticus subspecies anitratus, isolated from patients in a surgical intensive care unit was examined. Polyacrylamide gel electrophoresis was used to analyze the cellular proteins from whole cell lysates of 14 intensive care unit A calcoaceticus subspecies anitratus isolates and 11 control strains. Antimicrobial susceptibilities and plasmid profiles were also determined for all isolates. All intensive care unit A calcoaceticus subspecies anitratus isolates exhibited identical cellular protein fingerprints, no detectable plasmids, and minimum inhibitory concentrations within +/- 1 log2 dilution of the mode value for each of the antimicrobial agents tested. The other clinical isolates demonstrated a range of antimicrobial susceptibilities, various numbers and sizes of plasmids, and distinctly different protein fingerprints. These data indicate that protein fingerprinting may be useful as an epidemiologic tool in A calcoaceticus subspecies anitratus outbreaks and this method deserves further study.

Acinetobacter↗