Electron Microscopic Study of the Action of Nafcillin on Staphylococcus aureus

Warren, George H.; Stasny, J.T.

doi:10.1159/000220569

Cited by 7 publications

(3 citation statements)

References 7 publications

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“…A wider septum but a normal surrounding cell -rnn,trni . P n i c i i n U wall has been observed after exposure to subins---... Loridine hibitory concentrations of penicillin (34 1053 VOL. 9,1976 on May 10, 2018 by guest http://aac.asm.org/ served in Bacillus megaterium grown in the presence of penicillin (9).…”

Section: Discussionmentioning

confidence: 99%

Effects of Subinhibitory Concentrations of Antibiotics on Cross Walls of Cocci

Lorian

Atkinson²

1976

Antimicrob Agents Chemother

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Cultures ofStaphylococcus aureus, Neisseria gonorrhoeae, and Streptococcus bovis were incubated on membrane filters on agar containing antibiotics at onethird to one-fourth the minimal inhibitory concentration for the particular bacterial strain. S. aureus was grown in the presence of oxacillin, cephaloridine, or lincomycin. N. gonorrhoeae and S. bovis were grown in the presence of penicillin. The membranes were then incubated in drug-free agar, after which viability was determined and the cells were examined by electron microscopy. S. aureus exposed to oxacillin and cephaloridine grew into cells two to seven times larger than normal that contained thick multiple cross walls. S. aureus exposed to lincomycin grew into cells 1.5 to 2 times larger than normal, with multiple thick cross walls and periheral cell walls twice the normal thickness. N. gonorrhoeae cells exposed to penicillin were slightly larger than normal and had cross walls that were up to eight times thicker than normal. After transfer to drugfree agar, cells became smaller, and some normal organisms could be seen. S. bovis incubated in the presence of penicillin grew into filaments that contained no cross walls. Two hours after the return to drug-free agar, filaments with cross walls as well as normal cells were observed. Exposure to subinhibitory concentrations of penicillin did not affect the growth of the peripheral cell wall of S. aureus, N. gonorrhoeae, or S. bovis, but appeared to inhibit lysis of cross walls in S. aureus and N. gonorrhoeae and to inhibit the synthesis of cross walls in S. bovis; that is, the rates of peripheral and cross wall formation differed in their susceptibility to penicillin. These facts suggest that peripheral growth and cross wall formation in cocci are separable processes.During bacterial growth there is an equilibrium between synthesis and lysis within the cell wall (24, 29). Cross wall growth at the equatorial plane is probably the only site of cell wall growth in gram-positive cocci (1, 5). During division, the cell wall of cocci grows inward and eventually forms a transverse cross wall (septum).Cross wall cleavage before cell separation is carried out by one or more autolytic enzymes (16,17,31,33). Subinhibitory concentrations of penicillin have appeared to inhibit cross wall lysis in Staphylococcus aureus (22). This paper reports changes in cross wall structure in three cocci species grown in the presence of subinhibitory concentrations of various antibiotics.MATERIALS AND METHODS Strain FDA 209P (ATCC 6538P) ofStaphylococcus aureus and a clinical isolate of Streptococcus bovis (8) were grown in Trypticase soy broth (BBL) for 20 h at 37 C. A clinical isolate ofNeisseria gonorrhoeae (21) was grown on brain heart agar (Difco) with 5% horse blood and IsoVitalex (BBL) (BHASI) for 24 h at 37 C in a 10% CO2 atmosphere.Trypticase soy agar (BBL) and BHASI plates with and without antibiotics were prepared. Penicillin G (Squibb), oxacillin (Bristol), cephaloridine (Lilly), and lincomycin (Upjohn) were used. Drug concentr...

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Section: Discussionmentioning

confidence: 99%

Effects of Subinhibitory Concentrations of Antibiotics on Cross Walls of Cocci

Lorian

Atkinson²

1976

Antimicrob Agents Chemother

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“…After a relatively short exposure of susceptible staphylococci to concentrations equal to or greater than the minimal inhibitory concentration, the septum showed loss in density and irregularity of shape, and the peripheral cell wall was markedly thin (10). A wider septum but a normal surrounding cell wall has been observed after exposure to subinhibitory concentrations of penicillin (18).…”

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confidence: 98%

Some Effects of Subinhibitory Concentrations of Penicillin on the Structure and Division of Staphylococci

Lorian

1975

Antimicrob Agents Chemother

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“…Staphylococci grown in the presence of a sub-MIC of penicillin or nafcillin have shown a thickening in their cross walls (8,27) and an increased susceptibility to phagocytosis (1,5 …”

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confidence: 99%

Killing of oxacillin-exposed staphylococci in human polymorphonuclear leukocytes

Lorian¹,

Atkinson²

1980

Antimicrob Agents Chemother

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Twelve strains of Staphylococcus aureus isolated from patients and two collection strains were grown on membranes placed on agar containing subminimal inhibitory concentrations of oxacillin. Clusters of staphylococci held together by thick cross walls resulted. These organisms, as well as the same strains grown in the same way on drug-free medium (control), were eluted from the membranes and were incubated with human polymorphonuclear leukocytes (PMNs) from various donors. Phagocytosis was comparable for both staphylococci exposed to oxacillin and control staphylococci, but the killing effect was different. The staphylococci grown on membranes in the presence of oxacillin were less susceptible to killing than the control staphylococci. After 0.5 and 1 h of incubation with PMNs, the killing rates for oxacillin-grown versus control staphylococci were 52 and 70% and 65 and 85%, respectively (P < 0.01). After 2 and 3 h of incubation, the killing was similar. Most clusters of staphylococci contain a few individual cells that are located in the center of the cluster and are surrounded by other staphylococci; therefore, they are protected from adverse agents in the environment. This could explain why the phagocytized clusters are less susceptible than control staphylococci to the killing effect of PMNs during the first hour of incubation. Oxacillin does not penetrate into PMNs and in the absence of the drug the cross walls lyse, liberating the constituent staphylococci. This coincides with the increase in the percentage of cluster killing by PMNs after 2 and 3 h of incubation.

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Electron Microscopic Study of the Action of Nafcillin on Staphylococcus aureus

Cited by 7 publications

References 7 publications

Effects of Subinhibitory Concentrations of Antibiotics on Cross Walls of Cocci

Effects of Subinhibitory Concentrations of Antibiotics on Cross Walls of Cocci

Some Effects of Subinhibitory Concentrations of Penicillin on the Structure and Division of Staphylococci

Killing of oxacillin-exposed staphylococci in human polymorphonuclear leukocytes

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