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Biomedical subjects

R H Eng

Publications and source records attributed to R H Eng.

At least 73 records · Page 4Linked to original sources
PubMed1986

Use of D-lactic acid measurements in the diagnosis of bacterial infections.

This study explored the use of D-lactic acid as a marker for bacterial infections. D-Lactic was produced by frequently encountered human bacterial pathogens under anaerobic growth conditions; Bacteroides fragilis produced the largest amount. Orally administered D-lactic acid was absorbed from the intestines of rats and later found in measurable quantities in the blood and urine. Eunephric and anephric rats that received D-lactic acid intravenously showed similar quantities of this metabolite in the blood. These quantities are consistent with the distribution of D-lactic acid to total body water. Isolated liver and lung tissues from rats did not metabolize or produce D-lactic acid. Rats with experimentally induced, sublethal klebsiella peritonitis had D-lactic acidemia of 0.2 mM and 25.6 mM at 0 and 6 hr of infection, respectively. In a normal human, D-lactic acid was detected in the urine and blood after a subcutaneous injection of D-lactic acid, and pharmacokinetics of elimination similar to those of rats were found.

Anaerobiosis↗
PubMed1986

The effect of ciprofloxacin on methicillin-resistant Staphylococcus aureus.

Ciprofloxacin exhibited good in-vitro activity for methicillin-resistant Staphylococcus aureus with a MIC90 of 0.5 mg/l. The postantibiotic effect was 2.16 h. When ciprofloxacin was evaluated in combination studies with an aminoglycoside, none of the strains met the criterion of synergy as defined by FIC or FBC interaction indices of less than or equal to 0.25. However, killing kinetic experiments indicated that the combination of ciprofloxacin was synergistic for two of 12 strains with gentamicin and three of 12 strains with amikacin. Although the inoculum size had no effect on the rate of killing by ciprofloxacin, an increase in turbidity was noted when a high inoculum was tested. This increase in turbidity was due to the swelling of the staphylococci to several times their normal size and the formation of clusters of multicellular, incompletely divided staphylococci. If a high inoculum is used for susceptibility testing, this increase in turbidity could be misinterpreted as bacterial growth and could result in a false report of an elevated MIC.

Anti-Bacterial Agents↗
PubMed1986

In-vitro emergence of beta-lactam-resistant variants of Pseudomonas aeruginosa.

The frequency with which resistant variants could be found in Pseudomonas aeruginosa ATCC 27853 during growth in media with and without antibiotics was determined for ticarcillin, piperacillin, cefotaxime, latamoxef, cefoperazone, ceftriaxone, ceftazidime, aztreonam and imipenem. The resistance frequency was highest for ceftriaxone, cefotaxime, cefoperazone and piperacillin (up to 2 X 10(-4)) and lowest for ticarcillin, latamoxef, ceftazidime, aztreonam and imipenem (less than 10(-8)). The resistant variants showed cross-resistance to all of the beta-lactam antibiotics tested with the exception of imipenem. The MIC profiles of all variants were similar regardless of which antibiotic the cultures had been exposed to previously. Although all resistant variants produced and excreted cephalosporinases, increased resistance was demonstrated to both cephalosporinase-susceptible and cephalosporinase-stable beta-lactam antibiotics.

Anti-Bacterial Agents↗
PubMed1986

Failure of vancomycin prophylaxis and treatment for Actinobacillus actinomycetemcomitans endocarditis.

Reported is a case of Actinobacillus actinomycetemcomitans endocarditis which developed after dental prophylaxis with vancomycin and erythromycin. In vitro results indicated that this isolate and 20 additional isolates were resistant to vancomycin and that potentially useful bactericidal antibiotics for the prophylaxis and treatment of A. actinomycetemcomitans infections included gentamicin, sulfamethoxazole-trimethoprim, cefotaxime, and ciprofloxacin.

Actinobacillus↗
PubMed1986

Yield of bone marrow culture in the diagnosis of infectious diseases in patients with acquired immunodeficiency syndrome.

The yield in cultures of bone marrow aspirations or biopsies was determined in 50 patients with acquired immunodeficiency syndrome. Most patients were febrile and had no identifiable source of infection. Concurrent stool, urine, and blood samples were also cultured. The bone marrow aspiration and biopsy procedures produced no complications and enabled a microbiological diagnosis to be made in 42% of the cases. Granuloma formation was not seen in any of the infected bone marrow specimens despite the fact that mycobacteria were seen in abundance in some. Bone marrow culture is a valuable low-morbidity invasive procedure in the evaluation of febrile patients with acquired immunodeficiency syndrome.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Detection of bacterial antigens in body fluids by the Phadebact system.

150 infected patients from 2 study centers had body fluids examined for presence of bacterial antigens (group B streptococcus, Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae type b) using the Pharmacia Phadebact system. The rates of detection of the pneumococcal antigens in the urine or serum of the patients with pneumococcal pneumonia, pneumococcal bacteremia and pneumococcal meningitis were 0.38, 0.47 and 0.5, respectively. The overall detection rate for H. influenzae infections was 0.92 and for group B streptococcal infections 0.87. Serum and urine from 100 non-infected patients were also tested for the presence of group B streptococcus, S. pneumoniae, N. meningitidis and H. influenzae type b antigens with only 1 false positive (H. influenzae type b).

Antigens, Bacterial↗
PubMed1985

Rifampin resistance. Development during the therapy of methicillin-resistant Staphylococcus aureus infection.

The incidence of methicillin-resistant staphylococcal infections, for which vancomycin hydrochloride remains the only active cell-wall antibiotic therapy, is rising. Some physicians have been combining other antibiotics with vancomycin in hopes of obtaining a more effective regimen for the therapy of these infections. Rifampin has been advocated as a concurrent second antibiotic because of its extraordinary potent bactericidal activity for Staphylococcus aureus. When rifampin is used in combination with a cell-wall antibiotic, suppression of the development of rifampin resistance has been thought possible. We report a case of infection caused by a methicillin-resistant S aureus in which the rifampin resistance occurred during therapy with vancomycin and rifampin. The rifampin resistance was stable and was present after ten serial broth and agar passages. Physicians are cautioned against the indiscriminant or routine use of rifampin as a second antibiotic in combination with vancomycin for the therapy of infections caused by S aureus.

Adult↗
PubMed1985

Effectiveness of antibiotic removal by the antibiotic-binding blood culture systems.

The effectiveness of antibiotic removal by the BACTEC aerobic resin-containing blood culture medium (16B) and the Antimicrobial Removal Device (ARD) was compared for 12 antibiotics: ampicillin, cephalothin, cefoperazone, cefotaxime, moxalactam, nafcillin, gentamicin, tobramycin, azlocillin, mezlocillin, piperacillin, and ticarcillin. The ability to recover eight commonly encountered species of bacteria from antibiotic-containing serum by these two systems showed that recovery of antibiotic-exposed bacteria was dependent not only upon the amount and rate of the antibiotic removal but also upon the kinetics of bacterial killing by the antibiotic(s). The 16B medium had difficulty recovering organisms exposed to ticarcillin and moxalactam, whereas the ARD had difficulties with moxalactam and sometimes with cefotaxime and cefoperazone. Although neither system was able to recover all species of microorganisms tested, these in vitro results suggest that to use optimally these new culture systems, knowledge of the suspected pathogen(s), the amount and kind of antibiotic(s) administered, and the rate of bacterial killing by the antibiotic(s) is required.

Adsorption↗
PubMed1985

Recovery of blood-borne bacteria from human urine.

Recovery from the urine of organisms causing bacteraemia may depend on the bacterial species involved. The survival of the more common species of bacteria which cause bacteraemia was examined in human urine, serum and normal saline. All species survived well or grew in serum. Haemophilus influenzae, Streptococcus pneumoniae, Streptococcus sanguis and group A streptococci were killed in all urine samples. The number of colony-forming units of Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus saprophyticus and group B streptococci either remained the same or increased in the urine, while the numbers of Escherichia coli and Klebsiella pneumoniae increased rapidly. These data suggest that the observed differences in recovery from urine of these bacterial species that cause bacteraemia are related to the viability of the species in human urine.

Bacteria↗
PubMed1985

Differences in ability of cell-wall antibiotics to suppress emergence of rifampicin resistance in Staphylococcus aureus.

Rifampicin resistance developed easily in methicillin-susceptible and methicillin-resistant strains of Staphylococcus aureus during an overnight incubation in broth containing 0.1 mg/l of rifampicin. Incubation of methicillin-susceptible Staph. aureus and 0.1 mg/l of rifampicin with 1 mg/l of nafcillin reduced the emergence of rifampicin resistance with only 5 of 50 strains (10%) becoming rifampicin-resistant. However, incubation of the methicillin-susceptible or methicillin-resistant strains with 0.1 mg/l of rifampicin and 1 mg/l of vancomycin did not prevent the development of rifampicin resistance. Rifampicin resistance developed in 25 of 50 (50%) of methicillin-susceptible and 32 of 50 (64%) methicillin-resistant Staph. aureus strains tested. These data would suggest that differences exist in the abilities of nafcillin and vancomycin to suppress the development of rifampicin resistance in Staph. aureus (P less than 0.01). Caution should be exercised when the combination of vancomycin and rifampicin is used for infections caused by Staph. aureus and Staph. aureus isolates recovered during therapy should be monitored for the development of rifampicin resistance.

Anti-Bacterial Agents↗
PubMed1985

Activity of ciprofloxacin against methicillin-resistant Staphylococcus aureus.

Ciprofloxacin, a carboxy quinolone antibiotic with a broad spectrum of activity, was tested against 54 strains of methicillin-resistant Staphylococcus aureus. The ciprofloxacin MICs for 50 and 90% of the isolates were 0.25 and 0.5 micrograms/ml, respectively, and its MBC for 90% of the isolates was 1.0 microgram/ml. Killing kinetic studies were conducted in vitro with ciprofloxacin and vancomycin individually and in combination. The results of these studies showed that ciprofloxacin at 2 micrograms/ml and vancomycin at 10 micrograms/ml decreased the number of organisms by approximately 1.5 log10 after 6 h. The combination of ciprofloxacin plus vancomycin did not alter the rate of killing over that achieved by ciprofloxacin alone. The in vitro killing of resistant staphylococci was rapid, and the potential use of ciprofloxacin for infections caused by methicillin-resistant S. aureus should be further explored.

Anti-Bacterial Agents↗
PubMed1985

Inoculum effect of beta-lactam antibiotics on Enterobacteriaceae.

Seven beta-lactam antibiotics were studied for both their antimicrobial activity and the degree to which they produced inoculum effect on Escherichia coli, Klebsiella pneumoniae, and Salmonella typhimurium. Aztreonam, cefoperazone, and ceftazidime were poorly bactericidal, caused marked bacterial filamentation, and exhibited a large inoculum effect on E. coli, K. pneumoniae, and S. typhimurium. Cefotaxime and ceftriaxone were more rapidly bactericidal, caused only a moderate amount of filamentous forms, and exhibited a modest inoculum effect, while cefoxitin and imipenem both were rapidly bactericidal and exhibited only a minimal-to-no-inoculum effect. The inoculum effect did not correlate with drug stability during incubation with the bacteria. Inoculum effect on these species of the family Enterobacteriaceae appears to be a manifestation of increase in optical density secondary to the development of filamentous bacterial forms with an increase in bacterial mass during exposure to antibiotics which are not rapidly bactericidal. These observations have a clear significance for the susceptibility testing of beta-lactam antibiotics when turbidity is used as a parameter to determine presence of bacterial growth.

Anti-Bacterial Agents↗
PubMed1985

Pseudomonas mesophilica infections in humans.

Reported here is the case of a patient with metastatic adenocarcinoma of the lung who had bacteremia involving Pseudomonas mesophilica. Of the common laboratory media tested at 35 degrees C, buffered charcoal yeast extract agar and nutrient agar provided the best growth; however, other media supported growth at lower temperatures. Since blood cultures are routinely subcultured onto chocolate agar and then incubated at 35 degrees C, awareness of the characteristics of P. mesophilica and of the isolation techniques as outlined may enhance the recovery of this and related bacterial species.

Adult↗
PubMed1985

Salmonella infections in patients with acquired immunodeficiency syndrome.

Salmonella infections occurred in six patients with acquired immunodeficiency syndrome (AIDS) and one patient with probable AIDS. The immune system defects increase the susceptibility of patients with AIDS to salmonella infections. Recognition of salmonellosis in patients with AIDS is important because of a high propensity of this organism to invade the bloodstreams of these patients, and because, unlike other infections in patients with AIDS, this infection can be easily treated.

Acquired Immunodeficiency Syndrome↗
PubMed1984

Cefmenoxime therapy of serious bacterial infections.

The efficacy and safety of cefmenoxime was evaluated in 50 patients with serious bacterial infections. These included 26 pneumonias, 18 urinary tract infections, 2 soft tissue infections, 2 bacteremias, 1 renal abscess, and 1 peritonitis. A satisfactory clinical response was seen in 47 patients (94%). Eosinophilia and thrombocytosis were seen in several patients but were generally mild and transient.

Bacterial Infections↗
PubMed1984

Inoculum effect of new beta-lactam antibiotics on Pseudomonas aeruginosa.

The degree of the inoculum effect shown by the new beta-lactam antibiotics with Pseudomonas aeruginosa was investigated, and the antibiotics were divided into three groups based upon the observations. The group 1 antibiotics (cefotaxime, moxalactam, cefoperazone, azlocillin, piperacillin, and aztreonam) demonstrated a large inoculum effect, were poorly bactericidal, produced aberrant, elongated bacilli, and did not inhibit the increase in turbidity of high inocula during an 18-h incubation. The group 2 antibiotics (ceftazidime and ticarcillin) were slowly bactericidal, caused minimal formation of aberrant, elongated bacilli, and slowly decreased the turbidity of high inocula. The group 3 antibiotics (imipenem and gentamicin) were bactericidal, did not cause the formation of elongated bacilli, and decreased the turbidity of high inocula rapidly. Data are presented which suggest that the inoculum effect seen with the group 1 beta-lactam antibiotics is related to (i) the poor intrinsic antibactericidal activity of these antibiotics for P. aeruginosa at the inocula tested and (ii) failure of these antibiotics to inhibit the formation of aberrant and filamentous bacilli, which can result in increased bacterial mass and turbidity.

Amino Acids↗