scholarly journals Bactericidal Action of Gatifloxacin, Rifampin, and Isoniazid on Logarithmic- and Stationary-Phase Cultures of Mycobacterium tuberculosis

2005 ◽  
Vol 49 (2) ◽  
pp. 627-631 ◽  
Author(s):  
C. N. Paramasivan ◽  
S. Sulochana ◽  
G. Kubendiran ◽  
P. Venkatesan ◽  
D. A. Mitchison
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Stationary Phase ◽  
Bactericidal Activity ◽  
Bactericidal Action ◽  
Duration Of Treatment ◽  
Stationary Phase Culture ◽  
Treatment Regimens ◽  
Phase Culture ◽  
Bactericidal Activities ◽  
Strain H37rv

ABSTRACT The bactericidal activity of gatifloxacin, alone and in combination with isoniazid and rifampin, was studied on both exponential- and stationary-phase cultures of Mycobacterium tuberculosis strain H37Rv. On log-phase cultures, the bactericidal activity of gatifloxacin at 4 μg/ml was rapid and was very similar to that of isoniazid. At concentrations of 0.25 and 4 μg/ml, gatifloxacin enhanced the activity of isoniazid. Killing of the stationary-phase culture was biphasic. During the first 2 days, gatifloxacin at 4 μg/ml slightly increased the limited bactericidal activities of isoniazid and rifampin. However, no further additional bactericidal activity was found during further incubation with isoniazid alone or when gatifloxacin was added to either isoniazid or rifampin. This suggested that the stationary-phase culture contained a mixture of occasionally dividing bacilli that were killed during the first 2 days and true static persisters in the residual population that mimicked those in human lesions. In view of the failure of gatifloxacin to add to the sterilizing activity of isoniazid or rifampin during days 2 to 6 of exposure in the stationary-phase culture, it is unlikely to be a sterilizing drug that can be used to shorten the duration of treatment appreciably when it is added to present treatment regimens.

scholarly journals Bactericidal action of ofloxacin, sulbactam-ampicillin, rifampin, and isoniazid on logarithmic- and stationary-phase cultures of Mycobacterium tuberculosis.

1996 ◽  
Vol 40 (10) ◽  
pp. 2296-2299 ◽  
Author(s):  
D Herbert ◽  
C N Paramasivan ◽  
P Venkatesan ◽  
G Kubendiran ◽  
R Prabhakar ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Stationary Phase ◽  
Bactericidal Activity ◽  
Exponential Phase ◽  
Drug Combinations ◽  
Bactericidal Action ◽  
Level Of Activity ◽  
Susceptible Isolate ◽  
Emergence Of Resistance

The bactericidal actions of ofloxacin and sulbactam-ampicillin, alone and in combination with rifampin and isoniazid, on exponential-phase and stationary-phase cultures of a drug-susceptible isolate of Mycobacterium tuberculosis were studied in vitro. In exponential-phase cultures, all drugs were bactericidal, with the higher concentrations of ofloxacin (5 micrograms/ml) and sulbactam-ampicillin (15 micrograms of ampicillin per ml) being as bactericidal as 1 microgram of isoniazid per ml or 1 microgram of rifampin per ml. In two-drug combinations, both drugs increased the levels of activity of isoniazid and rifampin and were almost as bactericidal as isoniazid-rifampin; they also appeared to increase the level of activity of isoniazid-rifampin in three-drug combinations. In contrast, ofloxacin and sulbactam-ampicillin had little bactericidal activity against stationary-phase cultures and were less active than isoniazid or rifampin alone. Furthermore, in two-drug or three-drug combinations, they did not increase the level of activity of isoniazid, rifampin, or isoniazid-rifampin. These findings suggest that ofloxacin and sulbactam-ampicillin are likely to be most useful in the early stages of treatment and in preventing the emergence of resistance to other drugs but are unlikely to be effective as sterilizing drugs helping to kill persisting lesional bacilli.

Action of Fluoroquinolones and Linezolid on Logarithmic- and Stationary-Phase Culture of Mycobacterium tuberculosis

Chemotherapy ◽  
2004 ◽  
Vol 50 (5) ◽  
pp. 211-213 ◽  
Author(s):  
A. García-Tapia ◽  
J.C. Rodríguez ◽  
M. Ruiz ◽  
G. Royo
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Stationary Phase ◽  
Stationary Phase Culture ◽  
Phase Culture

scholarly journals Artemisia annua and Artemisia afra extracts exhibit strong bactericidal activity against Mycobacterium tuberculosis

2020 ◽  
Author(s):  
Maria Carla Martini ◽  
Tianbi Zhang ◽  
John T. Williams ◽  
Robert B. Abramovitch ◽  
Pamela J. Weathers ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Bactericidal Activity ◽  
Artemisia Annua ◽  
Multidrug Resistant ◽  
Mycobacterium Abscessus ◽  
Major Barrier ◽  
Treatment Regimens ◽  
Tb Treatment ◽  
Emergence Of Resistance

ABSTRACTEthnopharmacological relevanceEmergence of drug-resistant and multidrug-resistant Mycobacterium tuberculosis (Mtb) strains is a major barrier to tuberculosis (TB) eradication, as it leads to longer treatment regimens and in many cases treatment failure. Thus, there is an urgent need to explore new TB drugs and combinations, in order to shorten TB treatment and improve outcomes. Here, we evaluate the potential of two medicinal plants, Artemisia annua, a natural source of artemisinin (AN), and Artemisia afra, as sources of novel antitubercular agents.Aim of the studyOur goal was to measure the activity of A. annua and A. afra extracts against Mtb as potential natural and inexpensive therapies for TB treatment, or as sources of compounds that could be further developed into effective treatments.Materials and MethodsThe minimum inhibitory concentrations (MICs) of A. annua and A. afra dichloromethane extracts were determined, and concentrations above the MICs were used to evaluate their ability to kill Mtb and Mycobacterium abscessus in vitro.ResultsPrevious studies showed that A. annua and A. afra inhibit Mtb growth. Here, we show for the first time that Artemisia extracts have a strong bactericidal activity against Mtb. The killing effect of A. annua was much stronger than equivalent concentrations of pure AN, suggesting that A. annua extracts kill Mtb through a combination of AN and additional compounds. A. afra, which produces very little AN, displayed bactericidal activity against Mtb that was substantial but weaker than that of A. annua. In addition, we measured the activity of Artemisia extracts against Mycobacterium abscessus. Interestingly, we observed that while A. annua is not bactericidal, it inhibits growth of M. abscessus, highlighting the potential of this plant in combinatory therapies to treat M. abscessus infections.ConclusionOur results indicate that Artemisia extracts have an enormous potential for treatment of TB and M. abscessus infections, and that these plants contain bactericidal compounds in addition to AN. Combination of extracts with existing antibiotics may not only improve treatment outcomes but also reduce the emergence of resistance to other drugs.

scholarly journals Bactericidal activities of combinations of new drugs against Mycobacterium leprae in nude mice.

1996 ◽  
Vol 40 (2) ◽  
pp. 393-399 ◽  
Author(s):  
B Ji ◽  
E G Perani ◽  
C Petinom ◽  
J H Grosset
Keyword(s):  
Nude Mice ◽  
Bactericidal Activity ◽  
Mycobacterium Leprae ◽  
New Drugs ◽  
Daily Treatment ◽  
Intermittent Treatment ◽  
Duration Of Treatment ◽  
Bactericidal Effects ◽  
Bactericidal Activities ◽  
Multibacillary Leprosy

The bactericidal activities of 12 regimens with various combinations of new drugs (clarithromycin [CLARI], minocycline [MINO], and ofloxacin [OFLO]) and the standard antileprosy drugs, especially rifampin (RMP), were compared in nude mice with established Mycobacterium leprae infection. The longest duration of treatment was 24 weeks for intermittent (once every 4 weeks) therapy and 8 weeks for daily therapy. Bactericidal effects were monitored by titrating the proportion of viable M. leprae isolates by subinoculating the organisms into the footpads of immunocompetent and nude mice. The results indicate that RMP was more bactericidal than any combination of the new drugs. A single dose of CLARI-MINO, with or without OFLO, displayed bactericidal activity as great as that of 4 weeks of daily treatment with dapsone (DDS) plus clofazimine (CLO); thus, intermittent CLARI-MINO, with or without OFLO, may replace DDS and CLO of the standard multidrug regimen, and these will become regimens that can be administered monthly and under full supervision. Additional evidence that this may be the case is provided by the finding that intermittent RMP-CLARI-MINO or RMP-CLARI-MINO-OFLO administered for 12 or 24 weeks was as active as the standard multidrug regimen. While the intermittent treatment always displayed significantly greater bactericidal activity than the same number of doses of daily treatment, daily treatment with CLARI-MINO and CLARI-MINO-OFLO were more active than the drugs given as intermittent treatment for the same duration; therefore, unless these combinations are to be administered together with intermittent RMP, they should be given daily, especially for the treatment of RMP-resistant cases of infection. Finally, 12 weeks of daily treatment with DDS-CLO was more bactericidal than had been expected, suggesting that it may not be necessary to administer the standard multidrug regimen for multibacillary leprosy for as long as 24 months in order to minimize the risk of developing RMP resistance.

Identification of immunoreactive secretory proteins from the stationary phase culture of Burkholderia pseudomallei

2010 ◽  
Vol 32 (2) ◽  
pp. 310-320 ◽  
Author(s):  
Kumutha Malar Vellasamy ◽  
Vanitha Mariappan ◽  
Onn H. Hashim ◽  
Jamuna Vadivelu
Keyword(s):  
Stationary Phase ◽  
Burkholderia Pseudomallei ◽  
Secretory Proteins ◽  
Stationary Phase Culture ◽  
Phase Culture

scholarly journals Autolysis of Lactococcus lactis Is Influenced by Proteolysis

1998 ◽  
Vol 180 (22) ◽  
pp. 5947-5953 ◽  
Author(s):  
Girbe Buist ◽  
Gerard Venema ◽  
Jan Kok
Keyword(s):  
Cell Wall ◽  
Stationary Phase ◽  
Lactococcus Lactis ◽  
Deletion Mutant ◽  
Stationary Phase Culture ◽  
Intracellular Proteins ◽  
Phase Culture ◽  
A Cell ◽  
Zymographic Analysis ◽  
High Level

ABSTRACT The autolysin AcmA of Lactococcus lactis was shown to be degraded by the extracellular lactococcal proteinase PrtP. Autolysis, as evidenced by reduction in optical density of a stationary-phase culture and concomitant release of intracellular proteins, was greatly reduced when L. lactis MG1363 cells expressed the cell wall-anchored lactococcal proteinase PrtP of the PI-type caseinolytic specificity (PI). On the other hand, lactococcal strains that did not produce the proteinase showed a high level of autolysis, which was also observed when the cells produced the secreted form of PI or a cell wall-anchored proteinase with PIII-type specificity. Autolysis was also increased when MG1363 expressed the cell wall-anchored hybrid PI/PIII-type proteinase PIac. Zymographic analysis of AcmA activity during stationary phase showed that AcmA was quickly degraded by PI and much more slowly by PrtP proteinases with PIII-type and intermediate specificities. Autolysis of L. lactis by AcmA was influenced by the specificity, amount, and location of the lactococcal proteinase. No autolysis was observed when the various proteinases were expressed in an L. lactis acmAdeletion mutant, indicating that PrtP itself did not cause lysis of cells. The chain length of a strain was significantly shortened when the strain expressed a cell wall-anchored active proteinase.

scholarly journals Possible odour-mediated attraction of flies to Bacillus subtilis NRS-762 stationary phase culture

2015 ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Bacillus Subtilis ◽  
Stationary Phase ◽  
Volatile Compound ◽  
Stationary Phase Culture ◽  
Phase Culture ◽  
A Cell ◽  
Short And Long Term ◽  
Orbital Shaker

Signalling helps connects different organisms in the biosphere. This research note describes the possible concentration-dependent odour mediated attraction of flies to stationary phase aerobic liquid cultures of Bacillus subtilis NRS-762 cultivated on an open orbital shaker at 25 oC. Greater odour pungency correlated with more intense “foraging” attempts, which suggested the compounds’ possible behaviour modifying effects. Additionally, co-occurrence of optical density decline and increase in odour pungency suggested volatile compound(s) secretion might be a cell survival response mediated by a cell density-based signalling mechanism. Flies were not attracted to odourous stationary phase cultures of other common bacteria (Escherichia coli DH5α, Pseudomonas aeruginosa PRD-10, and Pseudomonas protegens Pf-5, which suggested species-specificity of the volatile compound(s)). Altogether, volatile compound(s) might serve as interkingdom messengers to enlist flies for dispersing B. subtilis to habitats with more favourable conditions in coping with possible irreversible decline in habitability, and operate in parallel with other in situ mechanisms such as cannibalism and sporulation that help B. subtilis ride out short- and long-term environmental fluctuations, respectively. Interested researchers are invited to build upon the preliminary findings.

scholarly journals Possible odour-mediated attraction of flies to Bacillus subtilis NRS-762 stationary phase culture

2015 ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Bacillus Subtilis ◽  
Stationary Phase ◽  
Volatile Compound ◽  
Stationary Phase Culture ◽  
Phase Culture ◽  
A Cell ◽  
Short And Long Term ◽  
Orbital Shaker

Signalling helps connects different organisms in the biosphere. This research note describes the possible concentration-dependent odour mediated attraction of flies to stationary phase aerobic liquid cultures of Bacillus subtilis NRS-762 maintained on an open orbital shaker at 25 oC. Greater odour pungency was observed to correlate with more intense “foraging” attempts, which suggested the compounds’ possible behaviour modifying effects. Additionally, co-occurrence of optical density decline and increase in odour pungency suggested volatile compound(s) secretion might be a cell survival response mediated by a cell density-based signalling mechanism. Flies were not attracted to odourous stationary phase cultures of other common bacteria (Escherichia coli DH5α, Pseudomonas aeruginosa PRD-10, and Pseudomonas protegens Pf-5, which suggested species-specificity of the volatile compound(s). Altogether, volatile compound(s) might serve as interkingdom messengers to enlist flies for dispersing B. subtilis to habitats with more favourable conditions in coping with possible irreversible decline in habitability, and operate in parallel with other in situ mechanisms such as cannibalism and sporulation that help B. subtilis ride out short- and long-term environmental fluctuations, respectively. Interested researchers are invited to build upon the preliminary findings.

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