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Inhibition of fungal growth in the cultural isolation of mycobacteria.

Antifungal antibiotics were compared to determine their usefulness in primary mycobacterial cultures. Amphotericin B was found to be more effective in preventing fungal growth from bovine fecal specimens than were cycloheximide, nystatin, and tetracycline. Amphotericin B did not affect the growth rate of the following Mycobacterium species: M. avium, M. bovis, M. intracellulare, M. paratuberculosis, M. phlei, or M. tuberculosis, but it inhibited the growth of M. fortuitum. There was no observable effect on numbers of colonies of M. paratuberculosis on primary isolation from fecal specimens. It is recommended that, for the primary isolation of pathogenic mycobacteria from specimens likely to contain fungi, the inoculum should be pretreated with benzalkonium chloride, followed by mixing with amphotericin B or inoculation onto media containing amphotericin B.

Amphotericin B↗

Surface-bonded antimicrobial activity of an organosilicon quaternary ammonium chloride.

The hydrolysis product of 3-(trimethoxysilyl)-propyldimethyloctadecyl ammonium chloride exhibited antimicrobial activity against a broad range of microorganisms while chemically bonded to a variety of surfaces. The chemical was not removed from surfaces by repeated washing with water, and its antimicrobial activity could not be attributed to a slow release of the chemical, but rather to the surface-bonded chemical.

Acetates↗

Algicidal activity of a surface-bonded organosilicon quaternary ammonium chloride.

The hydrolysis product of a quaternary amine-containing organosilicon salt, 3-(trimethoxysilyl)-propyldimethyloctadecyl ammonium chloride, was found to exhibit algicidal activity while chemically bonded to a variety of substrates. Six representative species of Chlorophyta, Cyanophyta, and Chrysophyta were used to evaluate the algicidal activity. Substrate-bonded (14)C-labeled organosilicon quaternary ammonium salt when attached to nonwoven fibers was durable to repeated washings, and algicidal activity could not be attributed to slow release of the chemical.

Ammonium Chloride↗

Comparison of six methods for isolating mycobacteria from swine lymph nodes.

Six laboratory methods were compared for isolating acid-fast bacteria. Tuberculous lymph nodes from each of 48 swine as identified by federal meat inspectors were processed by each of the methods. Treated tissue suspensions were inoculated onto each of eight media which were observed at 7-day intervals for 9 weeks. There were no statistically significant differences between the number of Mycobacterium avium complex bacteria isolated by each of the six methods. Rapid tissue preparation methods involving treatment with 2% sodium hydroxide or treatment with 0.2% zephiran required only one-third to one-fourth the processing time as a standard method. There were small differences in the amount of contamination among the six methods, but no detectable differences in the time of first appearance of M. avium complex colonies.

Alkanes↗

Chemical disinfection of holding-tank sewage.

A number of chemical disinfectants were evaluated for their bactericidal and virucidal effectiveness in holding-tank sewage. It was found that the disinfection efficiencies of formaldehyde, benzalkonium chloride, cetylpyridinium chloride, and methylene blue were markedly improved if the pH of the sewage was raised from 8.0 to 10.5. When formaldehyde, benzalkonium chloride, and methylene blue were tested with either 2-week holding times with no sewage additions or 10-day holding times with daily sewage additions, disinfection effectiveness was maintained as long as the sewage pH was kept at 10.5 and the disinfectant concentration was kept at 100 mg/liter or more. Calcium hypochlorite, zinc sulfate, and phenol were found to be relatively ineffective disinfectants for holding-tank sewage.

Bacteria↗

Studies on disinfection of clinical thermometers. II. Oral thermometers from a tuberculosis sanatorium.

A study was made of the chemical disinfection of oral thermometers used by patients with active pulmonary tuberculosis. Only 10% of these thermometers were found to be contaminated with acid-fast bacilli. Because of this small number, the use of a phenol coefficient type test with Mycobacterium tuberculosis was suggested as an alternative method for evaluating tuberculocidal activity. These data, in conjunction with data from Part I of these studies dealing with disinfection of oral thermometers from a general hospital, were the criteria used to judge the efficacy of the disinfectants. It was concluded that 70% ethyl alcohol, 2% phenolic no. 1, and 3% phenolic no. 3 were reliable disinfectants for thermometers. Fifty per cent ethyl alcohol, 2% phenolic no. 2, 2% iodophor (300 ppm available iodine), and 0.1% benzalkonium chloride, aqueous or tincture, were unreliable.

Benzalkonium Compounds↗

Bacterial decontamination and antileukemic therapy of AKR mice.

Four nonabsorbable antibiotics (streptomycin, neomycin, bacitracin, and amphotericin B) and a germicidal dip solution (Zephiran chloride/water) were used to eliminate all the detectable bacteria from conventional AKR mice. Control mice were not decontaminated and were used as such. When antibiotic-decontaminated and control mice developed clinical manifestations of spontaneous lymphatic leukemia, each was treated for the disease with an antitumor drug (cyclophosphamide [CP]) at weekly intervals. With the decontamination procedure, mice of each of the two groups became bacteria-free after 16 weeks of continuous oral administration of the antibiotics and two separate germicidal dippings. All decontaminated mice remained free of bacteria throughout the experiment. The bacterial flora of the control mice remained unaltered. With CP therapy, the mean survival time of the female decontaminated mice was 65 days, whereas that of male mice was 218 days. The average survival time of the CP-treated control leukemic mice was 51 days. Untreated decontaminated or control mice usually died of leukemia within 7 days after the onset of symptoms of leukemia. Although CP therapy was not curative, it did prolong the life expectancy of the decontaminated mice significantly.

Amphotericin B↗

Antimicrobial actions of hexachlorophene: release of cytoplasmic materials.

Intracellular solutes were released from growing or resting cells of Bacillus megaterium as a consequence of hexachlorophene treatment. The effect was dose dependent, with the optimum at a concentration about sevenfold greater than the minimal lethal dose. The effects of pH and temperature on the leakage process also were inconsistent with the killing effects of the drug. The types of materials released appeared to be the same with or without hexachlorophene treatment. The released materials were small molecules which apparently derived from preexisting ribonucleic acid and protein, but not from deoxyribonucleic acid. Compared to the effects of other representative surface-active agents and other bis-phenols, hexachlorophene was superior in ability to cause leakage of intracellular materials. Different microorganisms varied in their susceptibility to hexachlorophene, with Pseudomonas aeruginosa and a paracolon isolate the most resistant of the vegetative cells examined. It was concluded that the release of intracellular solutes was an effect secondary to the lethal event and presumably arose from hexachlorophene-mediated stimulation of degradative enzymes.

Bacillus megaterium↗

Ultrastructural alterations associated with the growth of resistant Pseudomonas aeruginosa in the presence of benzalkonium chloride.

Cells of Pseudomonas aeruginosa resistant to benzalkonium chloride (BC) underwent unique ultrastructural reorganizations when they were grown in the presence of 1 mg of BC/ml. The resistant cells usually contained a single, centrally positioned pseudovacuole. The pseudovacuole was surrounded by a diffuse substance that spread irregularly throughout the cytoplasm. The presence of the pseudovacuole seemed to cause a physical compartmentalization of the cytoplasm into random pockets of ribosomes and nuclear material. Contained within the pseudovacuole was a horseshoe-shaped, electron-dense body which was bounded by a trilaminar membrane 5.2 nm in width. These bodies averaged 77 nm when measured through the long axis. The surfaces of resistant cells were covered by an additional layer not found in sensitive cells. Thin sections of sensitive cells which had been treated with 1 mg of BC/ml showed little or no lysis. The cytoplasm appeared to be deeply stained and coagulated. Ribosomes were no longer distinctly visible. Although the cell wall remained intact, the cell membrane was dissolved and fragmented. BC-grown resistant cells could not be successfully stained by standard techniques; however, details were demonstrated with the aid of a combination of 1.5% glutaraldehyde, 1% osmium tetroxide, and 1% phosphotungstic acid prepared in 0.1 m sodium dimethylarsonate buffer (pH 6.8).

Benzalkonium Compounds↗

Reduced virulence of Pseudomonas aeruginosa grown in the presence of benzalkonium chloride.

Resistant cells of Pseudomonas aeruginosa ATCC 9027 which were grown in the presence of 1 mg of benzalkonium chloride (BC) per ml caused only a mild conjunctivitis when they were dropped onto the scratched corneas of rabbits. In contrast, cells of the BC-sensitive parent strain induced a severe keratoconjunctivitis. In addition, the BC-grown cells also had a reduced capacity to produce kidney infections in mice as compared to the parent strain. BC-grown cells acted as weak complex antigens which conferred slight protection against lethal doses of BC-grown cells. No cross-protection to cells of the parent strain occurred. The data indicate that growth in the presence of BC results in cells with reduced virulence.

Animals↗

Nosocomial transmission of Serratia marcescens in a veterinary hospital due to contamination by benzalkonium chloride.

During a 1-year period, Serratia marcescens was isolated from 50% of all contaminate intravenous catheters from dogs and cats in a large veterinary hospital. S. marcescens was also isolated from respiratory tracts, genitourinary tracts, skin, and other sites in hospitalized animals. A total of 55% of the clinical isolates and 66% of the intravenous catheter isolates had the same API biochemical profile. The source of the S. marcescens was determined to be aqueous benzalkonium chloride (0.025%) sponge pots located in the intensive care unit, surgery rooms, and outpatient clinic areas of the hospital. Of the 11 S. marcescens isolates submitted to the Centers for Disease Control for serotyping (6 from aqueous benzalkonium chloride sponge pots, 5 from intravenous catheters), 8 were identified as serotype O10:H11. All S. marcescens isolates tested for antibiotic susceptibilities were multiply resistant; isolates were most frequently resistant to streptomycin, cephalothin, and ampicillin. This study demonstrates that improper use of disinfectants plays an important role in the nosocomial transmission of S. marcescens.

Animals↗

Effects of physiol and chemical factors on the viability of Mycobacterium paratuberculosis.

Alternative methods of storing bovine fecal specimens for delayed culture of Mycobacterium paratuberculosis was studied. Significant (P less than 0.05) losses of viability were sustained by storage at 23 degrees C for 10 days and by treatment with 0.03 Zephiran for 4 and 10 days. Losses were moderate after storage at -70 degrees C for 15 weeks but significant (P greater than 0.05) after storage at 23 degrees C for 4 days. The alternative methods were compared with the standard method of processing specimens upon receipt and after 2 days in transit. Fecal specimens from 18 cattle were cultured.

Animals↗

Effect of decontamination procedures on recovery of Nocardia spp.

Exposure to 0.5% N-acetyl-L-cysteine (NAC), 2% NaOH-NAC, or benzalkonium chloride in trisodium phosphate (Zephiran-TSP) was toxic for Nocardia isolates. The number of viable Nocardia cells in a standardized suspension was reduced by 10(2) to 10(6) after a 30-min exposure to 2% NaOH-NAC and by 10(4) or more after a 30-min treatment with Zephiran-TSP.

Acetylcysteine↗

Epidemic septic arthritis caused by Serratia marcescens and associated with a benzalkonium chloride antiseptic.

During a 6-week period, 10 patients were admitted to a hospital for treatment of knee or shoulder joint infections due to Serratia species. Isolates from eight patients were identified as Serratia marcescens with identical biochemical characteristics and antibiotic susceptibility patterns. Before the onset of infections, all patients had been treated by two orthopedic surgeons who shared an office. Studies revealed that infections were associated with previous joint injections (P = 4.44 X 10(-5] of methylprednisolone and lidocaine. Environmental cultures revealed that a canister of cotton balls soaked in aqueous benzalkonium chloride and two multiple-dose vials of methylprednisolone previously used by office personnel were contaminated with the epidemic strain of S. marcescens. The canister may have served as a potential reservoir for contamination of sterile solutions and equipment used for joint injections, of skin at the injection site, and of hands of personnel. No further cases occurred after the use of aqueous benzalkonium chloride was discontinued.

Adult↗

Inactivation of human immunodeficiency virus type 1 in tissue culture fluid and in genital secretions by the spermicide benzalkonium chloride.

We have shown that the spermicidal agent benzalkonium chloride can exert a direct inhibitory effect on the viral reverse transcriptase activity of human immunodeficiency virus type 1 (HIV-1) when utilized at concentrations of 0.05% and higher. Exposure of HIV-1 to this disinfectant at concentrations of more than 0.05% was able to completely destroy viral infectivity, as assessed on susceptible target cells. We have further shown that HIV-1, which is present in both seminal and genital secretions, can be inactivated in such fluids by direct exposure to benzalkonium chloride.

Antiviral Agents↗

Comparison of four decontamination methods for recovery of Mycobacterium avium complex from stools.

The presence of Mycobacterium avium complex (MAC) in stool specimens may be a predictor of disseminated MAC infection, yet the methods for decontaminating stools have not been evaluated for their usefulness in recovering MAC organisms. In the present study, four decontamination methods commonly used to recover acid-fast bacteria from respiratory specimens were compared for their utility in recovering MAC from stool specimens. Ten strains of MAC were used at a level of 10(4) to 10(6) CFU to seed the stool specimens. Specimens were divided into four portions and were decontaminated by using the following treatments: (i) N-acetyl-L-cysteine-sodium hydroxide (NALC-NaOH), (ii) cetylpyridinium chloride-sodium chloride (CPC-NaCl), (iii) oxalic acid, or (iv) benzalkonium chloride-trisodium phosphate (BC-TSP). The specimens were then plated onto a total of five pieces of selective and nonselective egg- and agar-based media. The oxalic acid method yielded the greatest number of MAC CFU from seeded stool samples; this was followed by NALC-NaOH, BC-TSP, and CPC-NaCl. The difference between the oxalic acid method and each of the other methods was statistically significant (analysis of variance at the 95% significance level). Although more MAC CFU was recovered from seeded stool samples by using oxalic acid than NALC-NaOH, no difference in culture positivity rates was observed when the two methods were used to test 368 clinical stool specimens processed with either oxalic acid (164 specimens) or NALC-NaOH (204 specimens) (P = 0.07) or 67 specimens processed by both methods (P = 0.77). The oxalic acid and NALC-NaOH decontamination methods both appear to be useful for the recovery of MAC organisms from stool specimens.

AIDS-Related Opportunistic Infections↗

Adaptive resistance to biocides in Salmonella enterica and Escherichia coli O157 and cross-resistance to antimicrobial agents.

The mechanisms by which bacteria resist killing by antibiotics and biocides are still poorly defined, although repeated exposure to sublethal concentrations of antibacterial agents undoubtedly contributes to their development. This study aimed both to investigate the potential of Salmonella enterica and Escherichia coli O157 for adaptive resistance to commonly used biocides and to determine any cross-resistance to antibiotics. Strains were repeatedly passaged in media containing increasing concentrations of a biocide or antibiotic until adaptive resistance was obtained. A wide panel of antimicrobial agents was then screened by using the adapted strain to determine cross-resistance, if any. Adaptive resistance was readily achieved for both S. enterica and E. coli O157. Cross-resistance in adaptively resistant S. enterica varied with the serotype; Salmonella enterica serovar Enteritidis expressed cross-resistance to chloramphenicol, whereas Salmonella enterica serovar Typhimurium expressed cross-resistance to chlorhexidine. Benzalkonium chloride-resistant Salmonella enterica serovar Virchow showed elevated resistance to chlorhexidine; however, chlorhexidine-resistant Salmonella serovar Virchow did not demonstrate reciprocal cross-resistance to benzalkonium chloride, suggesting specific rather than generic resistance mechanisms. E. coli O157 strains acquired high levels of resistance to triclosan after only two sublethal exposures and, when adapted, repeatedly demonstrated decreased susceptibilities to various antimicrobial agents, including chloramphenicol, erythromycin, imipenem, tetracycline, and trimethoprim, as well as to a number of biocides. These observations raise concern over the indiscriminate and often inappropriate use of biocides, especially triclosan, in situations where they are unnecessary, whereby they may contribute to the development of microbial resistance mechanisms.

Adaptation, Physiological↗