Susceptibility testing of anaerobic bacteria

Finegold, Sydney M.; Rolfe, Rial D.

doi:10.1016/0732-8893(83)90030-5

Cited by 30 publications

(29 citation statements)

References 26 publications

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“…Colistin or polymyxin B lacks activity against gram-positive anaerobes and many Bacteroides species (10). Metronidazole is active against most all anaerobic organisms except some gram-positive species (10). The activities of other antimicrobial agents are less predictable and, therefore, less useful as indicators of cell wall type.…”

Section: Discussionmentioning

confidence: 99%

“…The most useful agents for this are vancomycin, colistin or polymyxin B, and metronidazole. Vancomycin is very active against most gram-positive anaerobes but not against gram-negative organisms (10). Colistin or polymyxin B lacks activity against gram-positive anaerobes and many Bacteroides species (10).…”

Section: Discussionmentioning

confidence: 99%

“…For some antimicrobial agents, anaerobes have a pattern of susceptibility that has been used as a general indicator of cell wall type (10,38). The most useful agents for this are vancomycin, colistin or polymyxin B, and metronidazole.…”

Section: Discussionmentioning

confidence: 99%

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Cell Wall Characteristics of Mobiluncus Species

Carlone

Thomas

Arko

et al. 1986

International Journal of Systematic Bacteriology

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The three type strains and a reference strain of Mobiluncus examined in this study had a gram-positive type of cell walls. All four strains were susceptible to vancomycin and resistant to colistin, and the overall susceptibility patterns with other antimicrobial agents were consistent with those of gram-positive microorganisms. Strains of Mobiluncus mulieris were lysed by 3% potassium hydroxide, and strains of Mobiluncus curtisii were not. However, all of the strains examined had intermediate levels of Limulus amebocyte-lysate reactivity that was not lipopolysaccharide associated. Lipopolysaccharide was not detected when whole-cell lysates were digested with proteinase K, separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and silver stained. In addition, 2-keto-3-deoxyoctulosonic acid and heptose were not detected by gas chromatography of 0-methyloxime acetate derivatives of whole-cell carbohydrates. Saponification and gas chromatography of whole-cell fatty acids showed that none of the four strains examined had detectable levels of hydroxylated fatty acids. Hydroxylated fatty acids or aldehyde fatty acids were not detected in acid hydrolysates of crude cell membrane preparations. (1,4,17,27,30,35,37,39,41,45,48), although the taxonomic position of members of this genus is still unresolved (15,43).The genus Mobiluncus has been tentatively assigned to the family Bacteroidaceae (43), which includes obligately anaerobic straight, curved, or helical gram-negative and gram-positive rod-shaped bacteria (18). The Gram reactions of strains of Mobiluncus are typically gram negative or variable (15, 43), although electron micrographs show that structurally these organisms have gram-positive cell walls (41, 43) and lack an outer membrane. Likewise, anaerobic curved rod-shaped organisms belonging to the genera Butyrivibrio, Lachnospira, and Acetivibrio (B), which are also members of the family Bacteruidaceae, stain gram negative but are structurally gram positive. Among anaerobic curved rods consistent with Mobiluncus, fatty acid aldehydes (presumably from plasmologens) have been detected, while hydroxlated fatty acids (found predominately in gram-negative bacteria) have not been found (39). Mobiluncus species are resistant to some antimicrobial agents which traditionally inhibit gram-negative microorganisms and are susceptible to some antimicrobial agents which inhibit gram-positive microorganisms (1,8,15,42,43,44). Limulus amebocyte lysate (LAL) reactivity, an indicator of gram-negative endotoxin, has also been reported (29).In this study, we compared characteristics of the type * Corresponding author.strains and a reference strain of Mobiluncus since previous reports have included organisms of undetermined taxonomic position which resemble members of this genus. We examined four strains of Mobiluncus for the following characteristics which are indicative of cell wall type: cell lysis, lipopolysaccharide (LPS), endotoxin reactivity, fatty acid content, antimicrobial agent susceptibility, and carbohyd...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Cell Wall Characteristics of Mobiluncus Species

Carlone

Thomas

Arko

et al. 1986

International Journal of Systematic Bacteriology

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“…Routine susceptibility testing of anaerobes is generally not required (6,47). Exact identifications and susceptibility results generated days after therapy has been initiated are likely to be of less use to the clinician than presumptive identification of the likely pathogens.…”

Section: Needmentioning

confidence: 99%

Susceptibility testing of anaerobic bacteria: myth, magic, or method?

Wexler

1991

Clin Microbiol Rev

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The demand for susceptibility testing of anaerobes has increased, yet consensus as to procedure and interpretation in this area has not been achieved. While routine testing of anaerobic isolates is not needed, certain isolates in specific clinical settings should be tested. Also, laboratories may monitor their local antibiograms by doing periodic surveillance batch testing. The National Committee for Clinical Laboratory Standards has published a protocol of methods approved for susceptibility testing of anaerobic bacteria. Both agar and broth microdilution are included; however, the broth disk elution method is no longer approved by the National Committee for Clinical Laboratory Standards because of method-related interpretive errors. A number of newer methods are undergoing evaluation and seem promising. Clinicians and microbiologists reviewing susceptibility reports should be aware of sources of variability in the test results. Variables in susceptibility testing of anaerobes include the media and methods used, organisms chosen for testing, breakpoints chosen for interpretation, antibiotic, and determination of endpoint. Clustering of MICs around the breakpoint may lead to significant variability in test results. Adherence of testing laboratories to approved methods and careful descriptions of the method and the breakpoints used for interpretation would facilitate interlaboratory comparisons and allow problems of emerging resistance to be noted. A variety of resistance mechanisms occurs in anaerobic bacteria, including the production of beta-lactamase and other drug-inactivating enzymes, alteration of target proteins, and inability of the drug to penetrate the bacterial wall. Antimicrobial resistance patterns in the United States and abroad are described.

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“…The B. fragilis species unexplainably remains more susceptible to many antimicrobial agents than the other species within the group (1,7,17). It is therefore important, especially in the choice of empirical therapy, that sufficient susceptibility data from sufficient numbers of isolates be available for local or regional isolates.…”

mentioning

confidence: 99%

In Vitro Susceptibilities of the Bacteroides fragilis Group Species: Change in Isolation Rates Significantly Affects Overall Susceptibility Data

Aldridge

O’Brien

2002

J Clin Microbiol

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A comparison of antimicrobial susceptibility data of species of the Bacteroides fragilis group for 1989-1990 and 1998-1999 studies showed statistically significant increases or decreases in in vitro activity. Overall significant increases in resistance were noted for ampicillin-sulbactam and clindamycin, while significant decreases in resistance were noted for ertapenem and cefoxitin. Susceptibilities to piperacillin-tazobactam, imipenem, meropenem, and trovafloxacin remained virtually the same for the two studies. Importantly, a change in the rates of isolation of the various species showed the B. fragilis species comprised 58% of the isolates in 1989 to 1990 and 45% of the isolates in 1998 to 1999. This change in rates of isolation of B. fragilis versus non-B. fragilis species had an overall effect on susceptibility data.

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Susceptibility testing of anaerobic bacteria

Cited by 30 publications

References 26 publications

Cell Wall Characteristics of Mobiluncus Species

Cell Wall Characteristics of Mobiluncus Species

Susceptibility testing of anaerobic bacteria: myth, magic, or method?

In Vitro Susceptibilities of the Bacteroides fragilis Group Species: Change in Isolation Rates Significantly Affects Overall Susceptibility Data

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