Biomedical subjects

A L Baltch

Publications and source records attributed to A L Baltch.

At least 55 records · Page 3Linked to original sources

PubMed1989

Susceptibility of Legionella pneumophila to eight antimicrobial agents including four macrolides under different assay conditions.

A comparison of agar dilution and microdilution susceptibility testing for eight antimicrobial agents, including roxithromycin, was performed against 48 isolates of Legionella pneumophila. For agar dilution tests, charcoal free agar (BSYE) and charcoal supplemented agar (BCYE) were used. In general, BSYE agar produced lower MICs than BCYE agar, except for imipenem. Microdilution testing data fell between the data obtained for the two agar media. The MBCs were two to sixteen fold higher than the MICs. Prolongation of the incubation time from 48 h to 72 h or growth in 5% CO2 did not influence the results. As tested by the microdilution method, an increase in the inoculum from 10(5) to 10(7) was associated with a two-fold increase in the MIC. Roxithromycin and two other investigational macrolides (A-56268 and rosaramicin) demonstrated better in-vitro activity than erythromycin.

Anti-Bacterial Agents↗

PubMed1989

Oropharyngeal and fecal carriage of Pseudomonas aeruginosa in hospital patients.

This prospective study was designed to determine the incidence of rectal and/or oropharyngeal colonization rates of patients with Pseudomonas aeruginosa upon admission to a general hospital and the risk of becoming colonized while hospitalized. Consecutive 186 admissions (180 patients) to one medical ward, one surgical ward, and the intensive care unit were studied over a period of 5 months. Rectal and oropharyngeal swabs for P. aeruginosa were obtained on admission, weekly thereafter, and/or upon discharge. Forty-two patients (22.6%) were colonized on admission, 20 patients (10.8%) acquired P. aeruginosa during hospitalization. Colonization on admission was observed twice as frequently on the surgical ward and in the intensive care unit as on the medical ward. Positive rectal cultures were more frequent than oropharyngeal cultures throughout the study (P less than 0.01). For patients admitted culture positive or culture negative, the probabilities of remaining culture positive or culture negative, respectively, remained at 44 and 72% after 35 days of hospitalization. The most common P. aeruginosa serotypes were 1, 6, and 10, and pyocin types 1, 3, and 10 were predominant. There was no statistical difference in the serotypes or pyocin types detected on admission or acquired during hospitalization. Except for two hospital-acquired first isolates which were resistant to moxalactam, all first isolates were susceptible to the four antibiotics tested. During the study, one isolate became resistant to azlocillin, gentamicin, and tobramycin, while two isolates became resistant to moxalactam. A statistical analysis was performed for 13 risk factors for all colonized and noncolonized patients. Colonization detected at the time admission was positively associated with age ( > 65 years), previous surgery of the gastrointestinal tract for neoplasm, and anemia ( P< 0.05). In contrast, for patients who entered the study culture negative, none of the analyzed 13 risk factors was associated with an increased probability for colonization. This observation included the administration of antimicrobial agents singly or in combination or both.

Carrier State↗

PubMed1988

Bacteremia in patients undergoing oral procedures. Study following parenteral antimicrobial prophylaxis as recommended by the American Heart Association, 1977.

The type and rate of bacteremia following dental extractions, dental cleaning, or other dental/oral surgical procedures were studied in 124 patients with valvular heart disease following parenteral antibiotic prophylaxis (penicillin G potassium with or without streptomycin sulfate, or vancomycin hydrochloride) as recommended by the American Heart Association in 1977. Generally, under penicillin G prophylaxis with or without streptomycin, detection of bacteremia in blood culture media containing no penicillinase was low (14.7% to 16.1% at five minutes and 3.1% to 9.0% at 30 minutes after the procedure). The number and types of organisms recovered from patients who received penicillin prophylaxis alone or with streptomycin were similar. Anaerobes were recovered twice as frequently as aerobes. Polymicrobial bacteremia was rare and only one patient had streptococci detected in the blood culture. Addition of penicillinase to one blood culture medium, however, and comparing it with a similar medium without penicillinase was accompanied with a sixfold greater recovery from patients of both aerobic and anaerobic bacteria, including six patients with streptococcal bacteremia. Vancomycin prophylaxis was accompanied with bacteremia in only one patient.

Anti-Bacterial Agents↗

PubMed1988

Comparative in-vitro activities of A-56268 (TE-031) and erythromycin against 306 clinical isolates.

The inhibitory (MIC) and bactericidal (MBC) activities of a new macrolide A-56268 (TE-031) against 306 clinical aerobic bacterial isolates was compared with that of erythromycin. The MIC90/MBC90 ratios for A-56268 were: Campylobacter jejuni 4/16, Haemophilus influenzae 8/8-16, H. parainfluenzae 8/8-16, Legionella pneumophila 0.06/0.5, methicillin-sensitive isolates of Staphylococcus aureus 0.5/1, and coagulase negative staphylococci 1/8, methicillin resistant isolates of Staph. aureus and coagulase negative staphylococci greater than 16/ greater than 16, Streptococcus pneumoniae 0.06/0.125, streptococcus Group A 0.06/2-4, streptococcus Group B 0.06/8- greater than 16, streptococcus Groups C and G 0.125/8 and Str. faecalis 4/64. Compared with erythromycin, A-56268 had greater inhibitory and bactericidal activity against isolates of L. pneumophila, with an MIC90 16-fold less and an MBC90 eight-fold less than that of erythromycin. Except for enterococci, A-56268 showed inhibitory activity equal to or greater than that of penicillin G against isolates of streptococci and an MIC two-fold less than that of erythromycin. For other strains tested, the inhibitory and bactericidal activities of A-56268 and erythromycin were similar. The clinical importance of the differences between these two macrolides will depend on the pharmacokinetic and tissue penetration properties of the new compound.

Bacteria, Aerobic↗

PubMed1988

Human granulocyte activity against moxalactam-induced filamentous forms of Pseudomonas aeruginosa.

The purpose of this investigation was to study the kinetics of human granulocyte (polymorphonuclear leukocyte) phagocytosis and bactericidal activity against beta-lactam antibiotic (moxalactam)-induced filamentous bacterial forms of Pseudomonas aeruginosa. Ultrastructural observations of rod and filamentous forms of P. aeruginosa and their interaction with polymorphonuclear leukocytes are presented. Growth of P. aeruginosa 1348A in the presence of 4 micrograms of moxalactam per ml (one-fourth the MIC) resulted in filamentous forms. Phagocytosis of 75Se-radiolabeled filaments was more efficient than that of rods during the first 20 min of the assay; subsequently, phagocytosis of both forms was equal. The polymorphonuclear leukocyte bactericidal activities against both forms, which were standardized to equal bacterial particle and viable-cell counts, were equivalent. Considering the greater size and mass of filaments compared with those of rods, we concluded that filaments are more susceptible to both phagocytosis and killing than are bacillary forms.

Blood Bactericidal Activity↗

PubMed1988

In vitro activities of PD 117,596 and reference antibiotics against 448 clinical bacterial strains.

The in vitro activity of PD 117,596, a new fluoroquinolone antibiotic, was tested against 448 bacterial isolates (15 genera) by agar dilution (inoculum, 10(4) CFU per spot). The activity of PD 117,596 was compared with that of 15 antibiotics against 327 gram-negative strains and with that of 8 other antibiotics against 121 gram-positive strains. PD 117,596 demonstrated the best activity against Klebsiella spp., Enterobacter spp., Acinetobacter spp., Serratia marcescens, and Branhamella catarrhalis (MICs for 90% of the isolates [MIC90S], 0.008 to 0.25 microgram/ml). PD 117,596 (MIC90, 0.25 microgram/ml) was at least twofold more active than ciprofloxacin against Pseudomonas aeruginosa and Pseudomonas spp. PD 117,596 and ciprofloxacin were similar in activity against Escherichia coli, Proteus mirabilis, Haemophilus influenzae, H. parainfluenzae, Neisseria gonorrhoeae, Legionella pneumophila, and Campylobacter jejuni (MIC90, 0.002 to 0.125 microgram/ml). PD 117,596 was more active than ciprofloxacin against streptococcal groups A, B, C, and G, S. pneumoniae, and enterococci (MIC90S, 0.06 to 0.125 microgram/ml). Against Staphylococcus aureus, including methicillin-resistant isolates, PD 117,596 (MIC90S, 0.03 to 0.06 microgram/ml) was 4- to 16-fold more active than ciprofloxacin and was most active against Corynebacterium spp. PD 117,596 appears to be the most active fluoroquinolone to date, with excellent activity against gram-positive bacteria and enhanced activity against gram-negative aerobic-facultative bacteria.

Anti-Bacterial Agents↗

PubMed1988

Azlocillin and mezlocillin concentration in human prostatic tissue.

The concentrations of azlocillin and mezlocillin in human prostatic tissue obtained by transurethral resection or enucleation were measured after two 2.0-gram doses of either drug. The average plasma concentration of azlocillin and mezlocillin at time of tissue sampling was 64.9 and 36.3 micrograms/ml, respectively, and tissue concentration at the time of sampling was 22.9 micrograms/g for azlocillin and 9.4 micrograms/g for mezlocillin. The plasma/tissue concentration ratio for mezlocillin was 0.25 and for azlocillin 0.35. Concentrations of mezlocillin in tissue obtained by transurethral resection were similar to those obtained by enucleation. Azlocillin and mezlocillin in appropriate doses achieve a concentration in human prostatic tissue above the inhibitory concentration for common bacterial pathogens.

Aged↗

PubMed1988

Nosocomial Mycobacterium fortuitum colonization from a contaminated ice machine.

Between October 15 and November 18, 1985, 5 patients on a medical ward of the Albany VA Medical Center (Ward 8A) became colonized with Mycobacterium fortuitum. Because other patients in Ward 8A were at risk of developing disease with M. fortuitum, microbiologic surveillance to identify colonization in sputum was begun. By February 15, 1986, 30 colonized patients had been identified in this ward but none in another ward with a comparable patient population, which suggests a source unique to Ward 8A. Because water has been recognized as a source of opportunistic mycobacterial pathogens, we conducted a retrospective case-control study using a telephone survey questionnaire to examine a number of water exposures in 10 patients and 20 control subjects. Exposure to ice from the Ward 8A ice machine, but not to potable water, was associated with colonization with M. fortuitum. Large-volume water samples from a variety of sources were cultured for acid-fast bacilli. M. fortuitum was isolated only from the ice machine in Ward 8A. The ice machine was disconnected, and no additional patients became colonized. Although ice machines are infrequently implicated in nosocomial outbreaks, they represent a potential source for pathogens that survive or replicate in water.

Cross Infection↗

PubMed1988

Sensory motor neuropathy associated with AIDS.

Clinical, laboratory, and pathologic observations in six patients with sensory motor peripheral neuropathy associated with the acquired immunodeficiency syndrome (AIDS) are presented. Blood and urine testing failed to reveal other causes for peripheral neuropathy. Distinctive CSF findings included elevated human immunodeficiency virus-specific indices. Peripheral nerve pathology confirmed the results of electrodiagnostic studies and revealed axonal loss and demyelination. Epineurial and endoneurial mononuclear infiltrates were present in three patients, and in one with early neuropathy, retroviral-like particles were present in peripheral nerve axoplasm. The findings indicate that in some patients with AIDS, neuropathy may be the direct result of a viral insult, although the causes are likely multifactorial.

Acquired Immunodeficiency Syndrome↗

PubMed1987

The effect of diabetes mellitus on chemotactic and bactericidal activity of human polymorphonuclear leukocytes.

We studied the bactericidal activity (against P. aeruginosa) and chemotactic ability of polymorphonuclear leukocytes from 26 diabetic patients in three treatment groups (oral hypoglycemic, daily insulin, and continuous insulin infusion). Patients were studied before entry into intensified management protocols, and after intensified management in 11 of the 26 patients. Diabetic serum had a persistent inhibitory effect on both diabetic and normal white cells, but normal serum was unable to fully correct diabetic white cell killing to control values. After intensified management of diabetes, there was an improvement in bactericidal function of diabetic patient white cells, but not in the effect of diabetic serum. Diabetic serum, and to a lesser extent diabetic white blood cells, are defective mediators of killing of P. aeruginosa. Chemotaxis was normal in all patient groups. These findings confirm the earlier work of others showing that some patients with diabetes mellitus have a defect in host defense against infection with bacteria.

Adult↗

PubMed1987

In-vitro antimicrobial activity of enoxacin in combination with eight other antibiotics against Pseudomonas aeruginosa, Enterobacteriaceae and Staphylococcus aureus.

Susceptibilities of 28 strains of Pseudomonas aeruginosa, 32 strains of Enterobacteriaceae and 24 strains of Staphylococcus aureus were tested against combinations of enoxacin with either cefsulodin, piperacillin, or amikacin, enoxacin with either aztreonam, latamoxef or amikacin, and enoxacin with either oxacillin, clindamycin or vancomycin, respectively. Synergy was detected by the agar dilution technique and was defined as a four-fold decrease in the inhibitory concentration of both drugs (sigma FIC less than or equal to 0.5). Against Ps. aeruginosa, synergy occurred in 28.5% of the strains for enoxacin plus cefsulodin, 17.6% for enoxacin plus piperacillin, and 3.7% for enoxacin plus amikacin. Against the Enterobacteriaceae, synergy was detected with enoxacin plus aztreonam, latamoxef or amikacin in 9.3%, 3.1% and 0% of strains, respectively. Against Staph. aureus, no synergy was demonstrable with enoxacin plus oxacillin, clindamycin or vancomycin. No antagonism was detected for any combination tested. Selected strains demonstrating synergy by the agar dilution method for enoxacin plus cefsulodin or piperacillin failed to show synergy in kinetic studies.

Amikacin↗

PubMed1987

The effect of Pseudomonas aeruginosa cytotoxin and toxin A on human polymorphonuclear leukocytes.

After exposure to cytotoxin or toxin A of Pseudomonas aeruginosa, the ultrastructure of resting and phagocytosing human polymorphonuclear leukocytes (PMNL) and of cells of P. aeruginosa strain 1348A was studied by transmission (TEM) and scanning (SEM) electronmicroscopy, and by light microscopy (LM) after histochemical staining of cytoplasmic granules. Cytotoxin caused marked clumping and destruction of PMNL, pyknotic nuclear changes with bleb formation, and release of cytoplasmic granules; phagocytosis was markedly diminished. In contrast, after exposure to toxin A, PMNL phagocytosed actively, but their cytoplasmic pseudopodia were markedly irregular and their nuclei pyknotic. Colloidal-gold-labelled cytotoxin showed an affinity for the cytoplasmic membranes, nuclei and granules of PMNL. Cytotoxin had no apparent effect on cells of P. aeruginosa strain 1348A but there was polar separation of the cytoplasmic membrane in bacteria exposed to toxin A. Cytotoxin and toxin A appear to be important in the pathogenesis of infections caused by P. aeruginosa.

ADP Ribose Transferases↗

PubMed1987

Production of cytotoxin by clinical strains of Pseudomonas aeruginosa.

Presence of cytotoxin was studied in extracts of 57 strains of Pseudomonas aeruginosa (46 bacteremia, 4 environmental, and 7 Fisher immunotype), 10 Pseudomonas species, and 7 nonpseudomonas isolates. Cytotoxin was identified by Western immunoblot in extracts of all P. aeruginosa isolates. None of the Pseudomonas species or nonpseudomonas isolates were shown to produce this protein. No immunologic cross-reactivity was observed between cytotoxin antibody and P. aeruginosa alkaline protease, toxin A, or elastase. In partially purified extracts of two bacteremia strains and PA 158 (parent strain for cytotoxin production), detection of cytotoxin by Western immunoblot was correlated with biological activity, as measured by the cell swelling assay. Cytotoxin appears to be produced by all strains of P. aeruginosa and biological activity can be demonstrated in extracts of the strains tested. This biological activity is neutralized by specific antibody. Because of its known marked cytotoxic effect on most eukaryotic cells, P. aeruginosa cytotoxin might be an important factor in the pathogenesis of P. aeruginosa infections.

Cytotoxins↗

PubMed1986

Efficacy of pneumococcal vaccine in high-risk patients. Results of a Veterans Administration Cooperative Study.

We conducted a randomized, double-blind, placebo-controlled trial to test the efficacy of the 14-valent pneumococcal capsular polysaccharide vaccine in 2295 high-risk patients (patients with one or more of the following: age above 55 years and the presence of chronic cardiac, pulmonary, renal, or hepatic disease, alcoholism, or diabetes mellitus). Seventy-one episodes of proved or probable pneumococcal pneumonia or bronchitis occurred among 63 of the patients (27 placebo recipients and 36 vaccine recipients). Vaccine-serotype Streptococcus pneumoniae strains were recovered in association with 11 infections in the placebo group and 14 infections in the vaccine group. Pneumococcal infections occurred most frequently among patients with chronic pulmonary, cardiac, or renal diseases. Among vaccine recipients who subsequently had vaccine-type pneumonia or bronchitis, the majority did not make or sustain serum antibodies against their infecting organism in concentrations that were twice as high as the base-line values, or more than 400 ng of antibody nitrogen per milliliter, although their base-line levels were higher than those in subjects in whom infection did not develop. We were unable to demonstrate any efficacy of the pneumococcal vaccine in preventing pneumonia or bronchitis in this population. Our data suggest that chronically ill patients, who are most susceptible to infection, may have an impaired immune response to the pneumococcal vaccine.

Antibodies, Bacterial↗

PubMed1986

Effects of storage and incubation conditions on human granulocyte phagocytic, bactericidal, and chemotactic functions.

This study was undertaken to determine the effects of different incubation conditions on human granulocyte (PMN) bactericidal, phagocytic, and chemotactic functions. Specifically, (1) how long may a patient's blood be held before assay and maintain original PMN function, and (2) how long may isolated PMNs be incubated for the purpose of exposure to various agents and still maintain original function? PMNs isolated following storage of whole heparinized blood at 4 degrees C for 24 and 48 hr phagocytized as well as fresh cells and their bactericidal activity was 96 and 85% of control values after 24 and 48 hr, respectively. Chemotaxis decreased to 62% of control after 24 hr. The bactericidal capacity of isolated PMNs stored at 4 degrees C for 24, 48, and 72 hr decreased to 85, 81, and 78% of controls, respectively. Phagocytosis after 24 hr storage was equal to controls. Chemotaxis was decreased to 59 and 34% of controls after 24 and 48 hr, respectively. Isolated PMNs incubated at 37 degrees C demonstrated impairment in phagocytic capacity after only 4 hr.

Blood Preservation↗

PubMed1986

Antibiotic-resistant isolates of Streptococcus pneumoniae from clinical specimens: a cluster of serotype 19A organisms in Brooklyn, New York.

Ten of 294 isolates of Streptococcus pneumoniae from patients enrolled in a Veterans Administration Cooperative Studies Program trial of pneumococcal vaccine efficacy were moderately resistant or resistant to penicillin. Nine of these organisms were serotype 19A isolated from patients at the Brooklyn (New York) V.A. Medical Center over an 18-month period (March 1983-November 1984). The minimal inhibitory concentration of penicillin for these pneumococci ranged from 1.0 to 2.0 micrograms/ml by the agar dilution technique and from 4.0 to 8.0 micrograms/ml by tube dilution. These organisms were resistant also to other beta-lactam antibiotics and to tetracycline, chloramphenicol, and trimethoprim-sulfamethoxazole. They were sensitive to erythromycin, clindamycin, vancomycin, and rifampin. The epidemiological source of these isolates was not discovered. However, it is possible that a focus of multiple antibiotic-resistant serotype 19A S. pneumoniae is present in Brooklyn.

Drug Resistance, Microbial↗

PubMed1986

Comparative antimicrobial activity of enoxacin, ciprofloxacin, amifloxacin, norfloxacin and ofloxacin against 177 bacterial isolates.

The in-vitro antimicrobial activity of five new quinolones, enoxacin (CI-919, AT-2266), ciprofloxacin (Bay o 9867), amifloxacin (WIN 49375) norfloxacin (MK 0366), and ofloxacin (ORF 18489), was compared against 104 strains of Enterobacteriaceae, 51 Pseudomonas species, 7 Acinetobacter calcoaceticus var. anitratus, and 15 enterococci. In general the quinolones tested were active against most bacterial strains. Ciprofloxacin was the most active with MIC90 for all genera tested ranging from 0.03 to 4.0 mg/l. The range of MIC90 for enoxacin and amifloxacin was 0.06 to 16.0 mg/l, for ofloxacin 0.25 to 8.0 mg/l, and for norfloxacin 0.06 to 32.0 mg/l. All strains of P. aeruginosa tested were resistant to amikacin (MIC greater than or equal to 16 mg/l); those resistant by virtue of inactivating enzyme production were less susceptible to ciprofloxacin, ofloxacin, and norfloxacin than those strains exhibiting decreased uptake of amikacin. Susceptibility to enoxacin and amifloxacin was not affected by the mechanism of aminoglycoside resistance. Of 65 strains tested with four quinolones using log and lag phase bacterial growth, the MICs in log phase growth were one to two dilutions higher for 42% of strains tested with amifloxacin, 33% of those tested with norfloxacin, and 23% for those tested with enoxacin and ciprofloxacin.

Anti-Bacterial Agents↗

PubMed1986

Comparison of the effect of three adrenal corticosteroids on human granulocyte function against Pseudomonas aeruginosa.

The effect of hydrocortisone, methylprednisolone, and dexamethasone on the phagocytic and bactericidal capabilities of normal human granulocytes (PMN) was studied under previously described optimal conditions for Pseudomonas aeruginosa, PA 1348A. At hydrocortisone and methylprednisolone concentrations of 1,000 micrograms/ml, delayed phagocytosis was clearly observed, whereas dexamethasone 400 micrograms/ml had no effect on phagocytosis. The bactericidal effect of PMN on PA 1348A was significantly reduced by all three corticosteroids at highest concentrations (p less than 0.05). However, the effect of methylprednisolone was greatest and that of dexamethasone was least evident, 25% and 10% reduction in PMN bactericidal activity, respectively. Following exposure to the highest concentrations of corticosteroids, TEM observations correlated well with the PMN functional assays. While the observations of PMN and bacteria in controls, hydrocortisone, and dexamethasone preparations were similar, evidence for incomplete phagocytosis, lack of vacuole coalescence, minimal disruption of bacterial cell walls, and dividing bacteria in phagosomes were evident in methylprednisolone preparations. These PMN functional and TEM observations suggest that of the three corticosteroids studied, methylprednisolone appears most deleterious to the PMN phagocytic and bactericidal activity.

Adrenal Cortex Hormones↗