Broth microdilution testing of susceptibilities to 30 antimicrobial agents of Mycobacterium avium strains from patients with acquired immune deficiency syndrome

Yajko, D M; Nassos, P S; Hadley, W K

doi:10.1128/aac.31.10.1579

Cited by 54 publications

(44 citation statements)

References 15 publications

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“…avium is a radiometric broth macrodilution method (BACTEC), which is regarded to be more reliable and rapid than an agar-based method. 31,44,45 A controversial aspect of this method involves careful preparation of the inoculum. 46,47 An optimal inoculum size for broth macrodilution is 10 4 to 10 5 CFU/ml.…”

Section: Discussionmentioning

confidence: 99%

Growth, Congo Red Agar Colony Morphotypes and Antibiotic Susceptibility Testing of Mycobacterium avium subspecies paratuberculosis

Parrish¹,

Ko²,

Dick³

et al. 2004

Clinical Medicine & Research

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OBJECTIVEMycobacterium avium subspecies (subsp.) paratuberculosis (MAP) is the causative agent of Johne's disease in ruminants and has been associated with Crohn's disease in humans. We sought to test growth rates and susceptibilities of various strains of MAP in two available growth media. METHODSUsing the BACTEC macrobroth radiometric growth system and Congo Red-staining agar media, we determined inherent differences in growth characteristics of three bovine and two human strains of MAP and compared susceptibility results obtained in each growth system. RESULTSSignificant differences were observed in growth rate as well as mycobactin J dependence between strains and between a laboratory-adapted isolate of the same strain in the macrobroth system. Similarly, colonial morphology and Congo Red staining on agar media were observed. Two strains, one human and one bovine, demonstrated a 100% rough transparent colony with white coloration on Congo Red agar, while one bovine isolate exclusively grew as a smooth opaque colony with red coloration on Congo Red agar. The remaining strains exhibited mixtures of these two colonial morphotypes on agar media. Comparative susceptibility results between the BACTEC radiometric macrobroth method and the agar proportionality method showed good correlation for most antibiotics/inhibitors tested. However, erratic or poor growth in the macrobroth system prevented minimal inhibitory concentration determinations for two bovine strains by this method. CONCLUSIONThis study demonstrates the variability in the colonial morphology of MAP on Congo Red agar as well as the correlation of antibiotic susceptibility results between the BACTEC macro broth method and the agar proportionality method. This study also emphasizes the need for the development of improved, standardized culture and susceptibility test methods for MAP.

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Section: Discussionmentioning

confidence: 99%

Growth, Congo Red Agar Colony Morphotypes and Antibiotic Susceptibility Testing of Mycobacterium avium subspecies paratuberculosis

Parrish¹,

Ko²,

Dick³

et al. 2004

Clinical Medicine & Research

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“…In the study described here we compared the data obtained by use (43). Plates were incubated for 14 days and were examined for growth; the MIC was defined as the lowest concentration of drug at which no bacterial growth could be visually discerned.…”

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confidence: 99%

“…Existing treatment regimens are primarily based on early results in the field in which multiple clinical isolates were tested for their in vitro susceptibilities to a wide variety of drugs, with the two most widely used methods being the broth microdilution method (43) and the radiometric BACTEC method (15,21). In both of these methods, the antimicrobial agent is added directly to broth cultures, and hence is in direct contact with the bacilli.…”

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confidence: 99%

A bone marrow-derived murine macrophage model for evaluating efficacy of antimycobacterial drugs under relevant physiological conditions

Skinner

Furney

Jacobs

et al. 1994

Antimicrob Agents Chemother

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Even though the macrophage is the host cell for the intracellular bacterial parasite Mycobacterium avium, macrophages have undergone only limited evaluation as models for determining the capacities of antimycobacterial drugs to inhibit the growth of M. avium within this relevant intracellular environment. In the present study, we demonstrated that a panel of M. avium isolates could actively infect homogeneous monolayers of murine bone marrow-derived macrophages. A number of established and experimental antimycobacterial drugs were then added to these cultures at a range of concentrations, and their effects on the numbers of surviving bacilli were determined 8 days later. By plotting such numbers versus drug concentrations it was then possible to clearly distinguish between compounds with bactericidal activity (such as rifabutin and PD 125354) and those with bacteriostatic effects (such as clarithromycin), even though several of these compounds had very similar MICs. In addition, an estimate of the potential therapeutic efficiency of each drug could be made by determining the concentration needed to destroy an arbitrary percentage of the inoculum (in this case, the bactericidal concentration destroying 99%o of the inoculum). Such values were considerably in excess of the MICs and may more realistically reflect the concentrations in serum required to electively reduce the bacterial burden in vivo.

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“…Numerous studies have been performed either in vitro (25,28,36,49) or on macrophages (46) and in animal models (6,21,34,38,39) with classic or more recent antituberculous agents (ciprofloxacin, sparfloxacin, azithromycin, and clarithromycin) alone or in combi-…”

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confidence: 99%

“…Treatment is difficult because of the weakened immune defense system of the host and the resistance of MAC strains to many classic antituberculous agents. Moreover, the phenotypes of resistance of these strains are very heterogeneous (25,26,49).Experimental infection models involving animal or human macrophage cultures and acute or chronic infections in the mouse have been developed to assess the activities of antiinfectious agents against MAC (32). Numerous studies have been performed either in vitro (25,28,36,49) or on macrophages (46) and in animal models (6,21,34,38,39) with classic or more recent antituberculous agents (ciprofloxacin, sparfloxacin, azithromycin, and clarithromycin) alone or in combi-…”

mentioning

confidence: 99%

Pharmacokinetics, toxicity, and efficacy of liposomal capreomycin in disseminated Mycobacterium avium beige mouse model

Conte¹,

Gallou²,

Potel³

et al. 1994

Antimicrob Agents Chemother

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Capreomycin was incorporated into multilamellar vesicles of pure dipalmitoylphosphatidylcholine. The pharmacokinetics and nephrotoxicity of capreomycin in the free and liposomal forms were studied in normal mice. The efficacies of the two forms were evaluated by using the Mycobacterium avium complex beige mouse model. Approximately 107 viable M. avium cells were injected intravenously. Seven days later, treatment with either liposomal or free capreomycin at 60 or 120 mg/kg of body weight was administered daily for 5 days. Mice were sacrificed 5 days after the end of treatment, and the viable bacteria in liver, spleen, lungs, and blood were counted. After 5 days of treatment with dosages of 60 or 120 mg/kg/day, the level of blood urea nitrogen increased in the group treated with free capreomycin but not in the group treated with liposomal capreomycin. After intravenous injection of 120 mg/kg, liposomes enhanced the diffusion of capreomycin in the spleen, lungs, and kidneys and increased the half-life in serum. The 120-mg/kg dose of liposomal capreomycin significantly reduced the number of viable mycobacteria in the liver, spleen, and blood compared with those in the controls. Although these results are promising, further studies are needed to assess the efficacy of liposomal capreomycin for the treatment of M. avium complex infections.Since the appearance of the human immunodeficiency virus (HIV), the incidence of Mycobacterium avium complex (MAC) infections has increased considerably and has involved between 18 and 50% of HIV-infected patients (17,24,33). Treatment is difficult because of the weakened immune defense system of the host and the resistance of MAC strains to many classic antituberculous agents. Moreover, the phenotypes of resistance of these strains are very heterogeneous (25,26,49).Experimental infection models involving animal or human macrophage cultures and acute or chronic infections in the mouse have been developed to assess the activities of antiinfectious agents against MAC (32). Numerous studies have been performed either in vitro (25,28,36,49) or on macrophages (46) and in animal models (6,21,34,38,39) with classic or more recent antituberculous agents (ciprofloxacin, sparfloxacin, azithromycin, and clarithromycin) alone or in combi-

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Broth microdilution testing of susceptibilities to 30 antimicrobial agents of Mycobacterium avium strains from patients with acquired immune deficiency syndrome

Cited by 54 publications

References 15 publications

Growth, Congo Red Agar Colony Morphotypes and Antibiotic Susceptibility Testing of Mycobacterium avium subspecies paratuberculosis

Growth, Congo Red Agar Colony Morphotypes and Antibiotic Susceptibility Testing of Mycobacterium avium subspecies paratuberculosis

A bone marrow-derived murine macrophage model for evaluating efficacy of antimycobacterial drugs under relevant physiological conditions

Pharmacokinetics, toxicity, and efficacy of liposomal capreomycin in disseminated Mycobacterium avium beige mouse model

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