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Biomedical subjects

M J Ferraro

Publications and source records attributed to M J Ferraro.

At least 37 records · Page 2Linked to original sources
PubMed1996

Emergence of high rates of antimicrobial resistance among viridans group streptococci in the United States.

Three hundred fifty-two blood culture isolates of viridans group streptococci obtained from 43 U.S. medical centers during 1993 and 1994 were characterized. Included were 48 isolates of "Streptococcus milleri," 219 S. mitis isolates, 29 S. salivarius isolates, and 56 S. sanguis isolates. High-level penicillin resistance (MIC, > or = 4.0 micrograms/ml) was noted among 13.4% of the strains; for 42.9% of the strains, penicillin MICs were 0.25 to 2.0 micrograms/ml (i.e., intermediate resistance). In general, amoxicillin was slightly more active than penicillin. The rank order of activity for five cephalosporins versus viridans group streptococci was cefpodoxime = ceftriaxone > cefprozil = cefuroxime >> cephalexin. The percentages of isolates resistant (MIC, > or = 2 micrograms/ml) to these agents were 15, 17, 18, 20, and 96, respectively. The rates of resistance to erythromycin, tetracycline, and trimethoprim-sulfamethoxazole were 12 to 38%. Resistance to either chloramphenicol or ofloxacin was uncommon (i.e., < 1%). In general, among the four species, S. mitis was the most resistant and "S. milleri" was the most susceptible.

Anti-Bacterial Agents↗
PubMed1996

Development of interpretive criteria and quality control limits for macrolide and clindamycin susceptibility testing of Streptococcus pneumoniae.

A six-laboratory collaborative study was conducted to develop MIC and zone diameter quality control limits and interpretive criteria for antimicrobial susceptibility testing of Streptococcus pneumoniae with azithromycin, clarithromycin, dirithromycin, and clindamycin. The MICs of all of the agents plus erythromycin for 302 clinical isolates of pneumococci that had been selected with an emphasis on resistant strains were determined by use of the National Committee for Clinical Laboratory Standards (NCCLS)-recommended broth microdilution procedure. The zone diameters of the isolates were also determined for the same agents except erythromycin by the NCCLS disk diffusion test procedure. Repeated testing of S. pneumoniae ATCC 49619 with different sources and lots of media and disks allowed development of MIC and zone diameter quality control ranges for these agents. Interpretive criteria for the MIC of azithromycin were established and were as follows: susceptible, < or = 0.5 microgram/ml; intermediate, 1 microgram/ml; and resistant, > or = 2 micrograms/ml. The interpretive criteria advocated for the MICs of clarithromycin and clindamycin were as follows: susceptible, < or = 0.25 microgram/ml; intermediate, 0.5 microgram/ml; and resistant, > or = 1 microgram/ml. Comparison of MICs and disk diffusion zone diameters led to the development of interpretive criteria for the zone diameters for azithromycin, clarithromycin, and clindamycin that correlated well with these MIC breakpoints. Testing of this organism collection also led to the reestablishment of the erythromycin MIC breakpoints as being identical to those of clarithromycin, which resulted in equivalent cross-susceptibility and cross-resistance for the three macrolides that are currently marketed in the United States. Thus, the susceptibility of pneumococci to azithromycin and clarithromycin can be predicted accurately by testing only erythromycin in clinical laboratories. This recommendation, as well as the interpretive and quality control criteria that are described, have been accepted by NCCLS and are included in the latest NCCLS susceptibility testing guidelines.

Anti-Bacterial Agents↗
PubMed1995

Performance of the Gen-Probe amplified Mycobacterium tuberculosis direct test in a laboratory that infrequently isolates Mycobacterium tuberculosis.

The performance of the Gen-Probe Mycobacterium tuberculosis direct (MTD) test was assessed in a laboratory whose specimens were derived from a population with a low prevalence (1.3%) of tuberculosis. A total of 339 specimens from 113 patients were included in the study. Nine of 10 MTD positive samples were culture positive (smear positive, n = 7; smear negative, n = 1; smear not ordered, n = 2). The 10th MTD-positive sample, which was smear and culture negative, was from a patient whose two other study specimens were smear and culture positive and who had a clinical history consistent with tuberculosis. Prior to and following resolution of discrepant results, the sensitivities and specificities of the MTD test relative to culture were 100 and 99.7% and 100 and 100%, respectively.

Bacteriological Techniques↗
PubMed1995

Clostridium difficile colitis: correlation of CT findings with severity of clinical disease.

Clinical records and abdominal CT scans from 64 patients with documented Clostridium difficile disease were reviewed to determine if any correlation existed between CT findings of colitis and severity of clinical disease. Clostridium difficile disease was documented with stool toxin titre levels and CT scans were performed within 3 days of stool sample. Clinical disease severity was estimated by tabulating the degree of fever, WBC count, frequency and duration of diarrhoea. Thirty-nine of 64 patients showed CT evidence of colitis of which 28/39 showed evidence of focal colitis and 11/39 had pancolitis. CT findings suggesting colitis included colonic wall thickening (39 patients), nodular mucosal thickening (11 patients), the 'accordion pattern' (3 patients), pericolonic oedema (27 patients) and ascites (10 patients). Twenty-five of 64 patients showed no CT evidence of colitis. The clinical severity of disease did not statistically differ (P < 0.05) between patients with CT evidence of colitis and those without colitis. The only CT finding that correlated with clinical severity of disease was nodular mucosal thickening which was found with significantly (P < 0.05) more frequency in patients with a WBC count > 11,000 mm3. CT changes with Cl. difficile disease correlate poorly with the clinical severity. This and negative findings do not exclude the disease.

Adult↗
PubMed1995

Pathogenesis and prevention of early pancreatic infection in experimental acute necrotizing pancreatitis.

OBJECTIVE: The authors test antibiotic strategies aimed at either mitigating bacterial translocation from the gut or delivering antibiotics specifically concentrated by the pancreas for prevention of early secondary infection after acute necrotizing pancreatitis. BACKGROUND: Infection currently is the principal cause of death after severe pancreatitis. The authors have shown that the risk of bacterial infection correlates directly with the degree of tissue injury in a rodent model of pancreatitis. Bacteria most likely arrive by translocation from the colon. METHODS: Severe acute necrotizing pancreatitis was induced in rats by a combination of low-dose controlled intraductal infusion of glycodeoxycholic acid superimposed on intravenous cerulein hyperstimulation. At 6 hours, animals were randomly allocated to five treatment groups: controls, selective gut decontamination (oral antibiotics and cefotaxime), oral antibiotics alone, cefotaxime alone, or imipenem. At 96 hours, surviving animals were killed for quantitative bacterial study of the cecum, pancreas, and kidney. RESULTS: The 96-hour mortality (35%) was unaffected by any treatment regimen. Cecal gram-negative bacteria were significantly reduced only by the oral antibiotics. Pancreatic infection was significantly reduced by full-gut decontamination and by imipenem, but not by oral antibiotics or by cefotaxime alone. Renal infection was reduced by both intravenous antibiotics. CONCLUSIONS: Early pancreatic infection after acute necrotizing pancreatitis can be reduced with a full-gut decontamination regimen or with an antibiotic concentrated by the pancreas (imipenem) but not by unconcentrated antibiotics of similar spectrum (cefotaxime) or by oral antibiotics alone. These findings suggest that 1) both direct bacterial translocation from the gut and hematogenous seeding interplay in pancreatic infection while hematogenous seeding is dominant at extrapancreatic sites and 2) imipenem may be useful in clinical pancreatitis.

Acute Disease↗
PubMed1995

Multilaboratory evaluation of screening methods for detection of high-level aminoglycoside resistance in enterococci. National Committee for Clinical Laboratory Standards Study Group on Enterococci.

Since the early 1970s, the synergistic activity of an aminoglycoside with a cell wall-active agent has been predicted by determining the ability of an enterococcus to grow in the presence of high levels of the aminoglycoside (usually > or = 2,000 micrograms/ml). However, a variety of media and concentrations of aminoglycosides has been used for this screening procedure. In the present study, we sought to optimize the agar dilution, broth microdilution, and disk diffusion tests used to detect high-level gentamicin and streptomycin resistance in enterococci. For dilution tests, brain heart infusion agar or broth gave the best growth and performance. For agar dilution, 500 micrograms of gentamicin per ml, 2,000 micrograms of streptomycin per ml, and an inoculum of 1 x 10(6) CFU/ml were optimal, while for broth microdilution, 500 micrograms of gentamicin per ml, 1,000 micrograms of streptomycin per ml, and an inoculum of 5 x 10(5) CFU/ml were best. Growth of more than one colony in the agar dilution test was determined to be the best indicator of high-level resistance. For disk diffusion, Mueller-Hinton agar, 120-micrograms gentamicin disks, and 300-micrograms streptomycin disks with breakpoints of no zone for resistance and > or = 10 mm for susceptibility gave the best sensitivity and specificity if results for strains with zones of 7 to 9 mm are considered inconclusive, indicating that a broth or agar test should be performed to determine susceptibility or resistance.

Anti-Bacterial Agents↗
PubMed1995

Molecular characterization and multilaboratory evaluation of Enterococcus faecalis ATCC 51299 for quality control of screening tests for vancomycin and high-level aminoglycoside resistance in enterococci.

Studies were conducted to validate the use of Enterococcus faecalis ATCC 51299 (which is vancomycin resistant and resistant to high levels of gentamicin and streptomycin) and E. faecalis ATCC 29212 (which is susceptible to vancomycin and against which gentamicin or streptomycin and cell wall-active agents have synergistic kill activity) as controls in an agar screening test for vancomycin resistance and high-level streptomycin and gentamicin resistance and a broth microdilution screening test for high-level streptomycin and gentamicin resistance. Both organisms performed as expected in these tests and will serve as appropriate controls. However, E. faecalis ATCC 29212 was occasionally noted to produce light growth on the vancomycin screening plate with certain lots of agar. Quality control ranges for disk diffusion tests with disks with large amounts of streptomycin (300 micrograms) and gentamicin (120 micrograms) were established for E. faecalis ATCC 29212; zone limits are 16 to 22 mm for gentamicin and 14 to 19 mm for streptomycin. No zones for inhibition were seen when E. faecalis ATCC 51299 was tested with these high-content disks.

Aminoglycosides↗
PubMed1994

Time course of bacterial infection of the pancreas and its relation to disease severity in a rodent model of acute necrotizing pancreatitis.

BACKGROUND: Bacterial infection of pancreatic necrosis is thought to be a major determinant of outcome in acute necrotizing pancreatitis. The determinants and possibilities for prophylaxis are unknown and difficult to study in humans. OBJECTIVE: The time course of bacterial infection of the pancreas in a rodent model of acute necrotizing pancreatitis was characterized. The authors ascertained if there is a correlation with the degree of necrosis. METHODS: Acute pancreatitis (AP) of graded severity was induced under sterile conditions by an intravenous infusion of cerulein (5 micrograms/kg/hr) for 6 hours (mild AP), or a combination of intravenous cerulein with an intraductal infusion of 10-mM glycodeoxycholic acid (0.2 mL for 2 min for moderate AP, 0.5 mL for 10 min for severe AP). Sham-operated animals (intravenous and intraductal NaCl 0.9%) served as controls. Ninety-six hours after induction, animals were killed for quantitative bacterial examination and histologic scoring of necrosis. In addition, groups of animals with severe AP were investigated at 12, 24, 48, 96, and 144 hours. RESULTS: No significant pancreatic necrosis was found in control animals (0.3 +/- 0.1) or animals with mild AP (0.6 +/- 0.1) killed at 96 hours. Necrosis scores were 1.1 +/- 0.2 for animals with moderate AP and 1.9 +/- 0.2 for animals with severe AP. Control animals did not develop significant bacterial infection of the pancreas (> or = 10(3) CFU/g). At 96 hours, the prevalence of infection was 37.5% in animals with mild AP and 50% in animals with moderate AP. In animals with severe AP, infection of the pancreas increased from 33% in the first 24 hours to 75% between 48 and 96 hours (p < 0.05). The bacterial counts and the number of different species increased with time and was maximal (> 10(11) CFU/g) at 96 hours. CONCLUSION: Bacterial infection of the pancreas in rodent AP increases during the first several days, and its likelihood correlates with the severity of the disease. This model, which closely mimics the features of human acute pancreatitis, provides a unique opportunity to study the pathogenesis of infected necrosis and test therapeutic strategies.

Acute Disease↗
PubMed1994

Comparative activities of piperacillin and tazobactam against clinical isolates of Legionella spp.

We evaluated the in vitro activity of piperacillin alone or in combination with the beta-lactamase inhibitor tazobactam against clinical isolates of Legionella species. At an inoculum of approximately 10(4) CFU, tazobactam, piperacillin, and the 8:1 combination had equivalent activities against Legionella spp. At an approximately 10-fold higher inoculum, the following results were obtained, expressed as MICs for 50 and 90% of strains tested (MIC range): piperacillin, 4 and 16 (0.25 to 32) micrograms/ml; tazobactam, 0.5 and 1 (0.125 to 2) micrograms/ml; and piperacillin-tazobactam (expressed in terms of MIC of piperacillin) 0.5 and 1 (0.03 to 2) micrograms/ml. Tazobactam alone and the combination with piperacillin were more active than piperacillin alone at the higher inoculum.

Drug Synergism↗
PubMed1994

Activity of fleroxacin alone and in combination with clindamycin or metronidazole in experimental intra-abdominal abscesses.

To assess the potential efficacy of fleroxacin in combination with clindamycin or metronidazole in mixed aerobic and anaerobic infections, we used a rat model of intra-abdominal abscesses in which the inoculum consisted of pooled rat feces mixed with BaSO4. Two hours after bacterial challenge, antimicrobial therapy was begun intravenously with regimens designed to stimulate human pharmacokinetics. A combination of clindamycin and gentamicin was included as an established treatment regimen. After 8.5 days of therapy, final bacterial counts in abscesses showed that fleroxacin alone or combined with metronidazole or clindamycin effectively eradicated Escherichia coli, with bacterial densities of < or = 2.84 +/- 0.1, < or = 2.9 +/- 0.1, and < or = 2.9 +/- 0.1 (mean +/- standard error of the mean) log10 CFU/g, respectively. The addition of either clindamycin or metronidazole to fleroxacin substantially enhanced the effectiveness of the regimens against Bacteroides fragilis, with bacterial counts of < or = 3.0 +/- 0.1 or < or = 2.9 +/- 0.1 log10 CFU/g, respectively, versus 9.2 +/- 0.2 log10 CFU/g for fleroxacin alone. The combination of metronidazole and fleroxacin also resulted in a significantly greater reduction of peptostreptococci and Bacteroides thetaiotaomicron than fleroxacin alone (< or = 2.9 +/- 0.1 versus 6.1 +/- 0.9 log10 CFU/g and 3.3 +/- 0.4 versus 8.3 +/- 0.1 log10 CFU/g, respectively). Except for those of B. fragilis, counts of other anaerobes were reduced to a greater extent by metronidazole plus fleroxacin than by clindamycin plus fleroxacin, although differences were not always significant. Metronidazole plus fleroxacin was at least as active a clindamycin plus gentamicin against all species and was significantly more active against Clostridium spp. No regimen effectively eradicated enterococci from the abscesses. These results suggest that the addition of either metronidazole or clindamycin would effectively enhance the spectrum of fleroxacin for treatment of mixed aerobic and anaerobic infections.

Abdomen↗
PubMed1994

Comparison of Vibrio cholerae O139 with V. cholerae O1 classical and El Tor biotypes.

Vibrio cholerae O139 is a recently identified non-O1 V. cholerae strain responsible for outbreaks of epidemic cholera in India, Bangladesh, and Thailand in the past 2 years. Other workers have demonstrated the presence of the cholera toxin genetic element in V. cholerae O139, unlike the situation for other non-O1 V. cholerae strains. We sought to compare further this strain with strains of V. cholerae O1, classical and El Tor biotypes, by classic microbiologic methods, Southern blot analysis for restriction fragment length polymorphisms with probes for iron-regulated genes of V. cholerae O1, and comparisons of outer membrane protein profiles. Our results were similar for V. cholerae O139 and the El Tor biotype of V. cholerae O1, with the exception of the constitutive expression in V. cholerae O139 of OmpS, an outer membrane protein that was maltose inducible in comparison strains of V. cholerae O1.

Bacterial Outer Membrane Proteins↗
PubMed1994

Use of induced sputum specimens for microbiologic diagnosis of infections due to organisms other than Pneumocystis carinii.

The optimal diagnostic approach to pneumonia provides a rapid microbiologic identification of pulmonary pathogens by the least invasive means. The technique of sputum induction has been useful in the evaluation of patients with Pneumocystis carinii or mycobacterial pneumonia. It is not known whether induced sputum samples are preferable for the detection of pathogens other than P. carinii or mycobacteria. Microbiologic yields were evaluated from identically processed induced and conventional sputum samples collected from 509 consecutive patients. No statistically significant differences were found between the microbiologic yields of induced and spontaneous sputum samples. Bacterial pathogens were isolated in 19.6% of induced and 23.5% of routine specimens. Mycobacteria were cultured from 13.1% of routine and 9.4% of induced specimens. Non-Candida albicans fungi grew from 24% of routine and 20% of induced specimens. The process of sputum induction with aerosolized hypertonic saline did not alter either the purulence or the bacterial quantitation of Gram-stained sputum specimens. Sputum induction has been useful for the cytologic diagnosis of malignancy, for the diagnosis of pneumocystosis and tuberculosis, and in patients unable to spontaneously produce sputum samples. The use of induced sputum samples for the diagnosis of other infections may not be necessary when routine sputum specimens are available.

Bacteria↗
PubMed1994

Detection of penicillin and extended-spectrum cephalosporin resistance among Streptococcus pneumoniae clinical isolates by use of the E test.

Increasing penicillin resistance and the initial recognition of resistance to extended-spectrum cephalosporins among Streptococcus pneumoniae isolates have placed greater emphasis on accurate methods for susceptibility testing of clinical isolates. This study has evaluated the use of the E test (AB Biodisk NA, Piscataway, N.J.) for the detection of penicillin and cefotaxime resistance among 147 pneumococcal clinical isolates in three geographically separate laboratories. These included 42 penicillin-resistant (MIC, > or = 2 micrograms/ml) and 14 cefotaxime-resistant (defined here as an MIC of > or = 2 micrograms/ml) isolates. E test strips were applied to the surface of Mueller-Hinton sheep blood agar plates and incubated at 35 degrees C in 5% CO2 for 20 to 24 h. E test MICs were compared with MICs determined with lysed horse blood-supplemented Mueller-Hinton broth in a microdilution format as recommended by the National Committee for Clinical Laboratory Standards. Penicillin MICs agreed within one log2 dilution for 136 of 147 (92.5%) isolates, and cefotaxime MICs agreed within one log2 dilution for 142 of 147 (96.6%) isolates. No very major or major interpretive errors occurred with either penicillin or cefotaxime E test MIC results. There were 9.5 and 5.4% minor interpretive category errors with penicillin and cefotaxime E test MICs, respectively. These data indicate that the E test represents a convenient and reliable method for the detection of penicillin or cephalosporin resistance in pneumococci.

Air↗
PubMed1994

Development of interpretive criteria and quality control limits for broth microdilution and disk diffusion antimicrobial susceptibility testing of Streptococcus pneumoniae.

A five-center collaborative study was undertaken to develop quality control and specific interpretive criteria for susceptibility testing of Streptococcus pneumoniae against 12 antimicrobial agents. MICs were determined for 248 pneumococcal clinical isolates (with an emphasis on resistant strains) by use of the National Committee for Clinical Laboratory Standards (NCCLS)-recommended broth microdilution procedure incorporating lysed horse blood-supplemented Mueller-Hinton broth. NCCLS disk diffusion testing was also performed for each isolate by using Mueller-Hinton sheep blood agar incubated in 5% CO2. Repetitive testing of S. pneumoniae ATCC 49619 with different sources and lots of media and disks allowed development of quality control ranges which encompassed approximately 95% of MIC and zone size values observed in the study. Good intra- and interlaboratory reproducibilities were seen with these testing methods and all of the drugs examined. On the basis of the results of this study, MIC interpretive criteria are proposed for 11 agents. Comparisons of MICs and disk diffusion zone sizes allowed disk diffusion zone size interpretive criteria to be proposed for five drugs and confirmed the use of the oxacillin disk test for prediction of penicillin susceptibility among pneumococci. Excessive numbers of minor-category interpretive errors precludes recommendation at this time of the disk diffusion method for testing of pneumococci against five of the drugs. Use of these proposed quality control and interpretive criteria should provide for reproducible test results and allow recognition of recently emerging resistance among pneumococcal clinical isolates.

Diffusion↗
PubMed1994

Detection of Klebsiella pneumoniae and Escherichia coli strains producing extended-spectrum beta-lactamases.

Plasmids encoding extended-spectrum beta-lactamases of the TEM, SHV, and AmpC families were introduced into common Escherichia coli and Klebsiella pneumoniae hosts to create a homogeneous panel for evaluating the abilities of five test systems to detect resistance to eight beta-lactam antibiotics. Although MICs, as determined by agar dilution or E test strips, were increased and disk diffusion zone diameters were diminished, breakpoints for resistance were often not reached, and neither approach was sensitive in detecting resistance to oxyimino-beta-lactams. The MicroScan 18-h microdilution or Vitek rapid automated procedures were similarly insensitive. Ceftazidime was the best single test antibiotic for detecting extended-spectrum beta-lactamase production. beta-Lactamases TEM-7 and TEM-12 were particularly difficult to detect. Because of such difficulties, the prevalence of extended-spectrum beta-lactamases is likely to be greater than is currently appreciated.

Drug Resistance, Microbial↗
PubMed1994

Comparison of fecal lactoferrin latex agglutination assay and methylene blue microscopy for detection of fecal leukocytes in Clostridium difficile-associated disease.

The fecal lactoferrin assay was more sensitive (75%) than methylene blue microscopy (40%) for the detection of leukocytes in Clostridium difficile toxin-positive fecal samples. Although limited sensitivity and specificity precludes its use as a laboratory screening test, it may be a more useful initial test in an algorithm for clinically suspected C. difficile-associated disease.

Bacterial Proteins↗
PubMed1994

Development of a standardized screening method for detection of vancomycin-resistant enterococci.

The incidence of vancomycin resistance among enterococci is increasing in the United States and elsewhere in the world, but automated susceptibility testing methods have difficulty detecting resistance expressed by certain strains. The agar screening method described by Willey et al. (B. M. Willey, B. N. Kreiswirth, A. E. Simor, G. Williams, S. R. Scriver, A. Phillips, and D. E. Low, J. Clin. Microbiol. 30:1621-1624, 1992) has been proposed as a reliable method for confirming vancomycin resistance. In this study, we investigated various parameters associated with the agar screening method and, on the basis of the findings, established optimum testing conditions for the method. First, to evaluate media and vancomycin concentrations, one laboratory used Mueller-Hinton and brain heart infusion agars supplemented with 4, 6, and 8 micrograms of vancomycin per ml to test 100 genetically characterized enterococcal strains. On the basis of the results obtained, brain heart infusion agar supplemented with 6 micrograms of vancomycin per ml was selected for further study. Subsequently, eight laboratories used the medium to test both reference and clinical isolates. There was very good performance with the reference strains and, among 158 clinical isolates tested, the method demonstrated sensitivity and specificity of 100% and from 96 to 99%, respectively.

Culture Media↗