Re: intracellular SA protected from abx in experimental infection

[Guest guest]

:-( Sounds about right. Also about right that the only way we learn much about staph is from the dairy industry. double :-( penny <usenethod@...> wrote: J Dairy Res. 1984 Nov;51(4):513-23. Related Articles, Links Phagocytosis of Staphylococcus aureus by bovine mammary gland macrophages and intracellular protection from antibiotic action in vitro and in vivo.Craven N,

JC.Macrophages isolated from the involuted bovine mammary gland were cultured in vitro. Phagocytosis of opsonized Staphylococcus aureus occurred rapidly, but intracellular killing of bacteria was slow. Many intracellular staphylococci survived for up to 4 d exposure to extracellular cloxacillin and emerged from within the macrophages to multiply extracellularly when the antibiotic was inactivated. Rifampicin was significantly more efficient than cloxacillin in killing intracellular S. aureus after 18 h incubation, but it too failed to sterilize the cultures within 3 d. Staphylococci, which had remained viable within macrophages during 20 h incubation with extracellular cloxacillin, showed an increased sensitivity to dilute lysostaphin on subsequent exposure. A 3 d course of intramammary therapy with cloxacillin, commencing simultaneously with an infecting inoculum of approximately 10(8) colony forming

units (c.f.u.) S. aureus, apparently eliminated the infection from one quarter of the udders of each of three lactating cows, but bacteria were re-isolated from two cows after a delay of several days. However, when other quarters of the same cows were infected with approximately 10(8) c.f.u. S. aureus which had been phagocytosed by autologous mammary macrophages, similar simultaneous antibiotic therapy failed to affect these infections. The in vitro and in vivo findings indicate the significance of intracellular survival of S. aureus as a factor contributing to failure of antibiotic therapy.PMID: 6569065 [PubMed - indexed for MEDLINE]

[Guest guest]

The thing about some of these experiments is that there a pre-

determined amount of days for the sensitivity tests- Ususally it's 24

to 48 hrs (and that's pretty much understood, and/or reported in the

Meterials and Methods section of the paper.)

Some of the efficacy of therapeutic doses of abx have been found to

take longer than 48 hrs (even in vitro)... found by accident I guess

when an experimenter left the plates alone longer than 48 hrs..

SO it makes you wonder- what would have happened if they'd just

let it go another couple of days.

Barb

> J Dairy Res. 1984 Nov;51(4):513-23. Related Articles,

Links

>

> Phagocytosis of Staphylococcus aureus by bovine mammary gland

> macrophages and intracellular protection from antibiotic action in

> vitro and in vivo.

>

> Craven N, JC.

>

> Macrophages isolated from the involuted bovine mammary gland were

> cultured in vitro. Phagocytosis of opsonized Staphylococcus aureus

> occurred rapidly, but intracellular killing of bacteria was slow.

> Many intracellular staphylococci survived for up to 4 d exposure to

> extracellular cloxacillin and emerged from within the macrophages

to

> multiply extracellularly when the antibiotic was inactivated.

> Rifampicin was significantly more efficient than cloxacillin in

> killing intracellular S. aureus after 18 h incubation, but it too

> failed to sterilize the cultures within 3 d. Staphylococci, which

had

> remained viable within macrophages during 20 h incubation with

> extracellular cloxacillin, showed an increased sensitivity to

dilute

> lysostaphin on subsequent exposure. A 3 d course of intramammary

> therapy with cloxacillin, commencing simultaneously with an

infecting

> inoculum of approximately 10(8) colony forming units (c.f.u.) S.

> aureus, apparently eliminated the infection from one quarter of the

> udders of each of three lactating cows, but bacteria were re-

isolated

> from two cows after a delay of several days. However, when other

> quarters of the same cows were infected with approximately 10(8)

> c.f.u. S. aureus which had been phagocytosed by autologous mammary

> macrophages, similar simultaneous antibiotic therapy failed to

affect

> these infections. The in vitro and in vivo findings indicate the

> significance of intracellular survival of S. aureus as a factor

> contributing to failure of antibiotic therapy.

>

> PMID: 6569065 [PubMed - indexed for MEDLINE]

>

[Guest guest]

Thats a good point indeed. For one example pyrazinamide is one of the

best killers of dormant Mtb. (In fact it is the only drug known to

kill a dormant bacteria slightly better than the active form.) But it

kills very very slowly.

> The thing about some of these experiments is that there a pre-

> determined amount of days for the sensitivity tests- Ususally it's

24

> to 48 hrs (and that's pretty much understood, and/or reported in

the

> Meterials and Methods section of the paper.)

>

> Some of the efficacy of therapeutic doses of abx have been found to

> take longer than 48 hrs (even in vitro)... found by accident I

guess

> when an experimenter left the plates alone longer than 48 hrs..

>

> SO it makes you wonder- what would have happened if they'd just

> let it go another couple of days.

>

> Barb

>

>

>

>

>

>

> > J Dairy Res. 1984 Nov;51(4):513-23. Related Articles,

> Links

> >

> > Phagocytosis of Staphylococcus aureus by bovine mammary gland

> > macrophages and intracellular protection from antibiotic action

in

> > vitro and in vivo.

> >

> > Craven N, JC.

> >

> > Macrophages isolated from the involuted bovine mammary gland were

> > cultured in vitro. Phagocytosis of opsonized Staphylococcus

aureus

> > occurred rapidly, but intracellular killing of bacteria was slow.

> > Many intracellular staphylococci survived for up to 4 d exposure

to

> > extracellular cloxacillin and emerged from within the macrophages

> to

> > multiply extracellularly when the antibiotic was inactivated.

> > Rifampicin was significantly more efficient than cloxacillin in

> > killing intracellular S. aureus after 18 h incubation, but it too

> > failed to sterilize the cultures within 3 d. Staphylococci, which

> had

> > remained viable within macrophages during 20 h incubation with

> > extracellular cloxacillin, showed an increased sensitivity to

> dilute

> > lysostaphin on subsequent exposure. A 3 d course of intramammary

> > therapy with cloxacillin, commencing simultaneously with an

> infecting

> > inoculum of approximately 10(8) colony forming units (c.f.u.) S.

> > aureus, apparently eliminated the infection from one quarter of

the

> > udders of each of three lactating cows, but bacteria were re-

> isolated

> > from two cows after a delay of several days. However, when other

> > quarters of the same cows were infected with approximately 10(8)

> > c.f.u. S. aureus which had been phagocytosed by autologous

mammary

> > macrophages, similar simultaneous antibiotic therapy failed to

> affect

> > these infections. The in vitro and in vivo findings indicate the

> > significance of intracellular survival of S. aureus as a factor

> > contributing to failure of antibiotic therapy.

> >

> > PMID: 6569065 [PubMed - indexed for MEDLINE]

> >

>

[Guest guest]

Something to remember when we hang on every word of an abstract.

It's probably at least a component of why invito is so oftem way off

from in vivo.

Barb

> > > J Dairy Res. 1984 Nov;51(4):513-23. Related Articles,

> > Links

> > >

> > > Phagocytosis of Staphylococcus aureus by bovine mammary gland

> > > macrophages and intracellular protection from antibiotic action

> in

> > > vitro and in vivo.

> > >

> > > Craven N, JC.

> > >

> > > Macrophages isolated from the involuted bovine mammary gland

were

> > > cultured in vitro. Phagocytosis of opsonized Staphylococcus

> aureus

> > > occurred rapidly, but intracellular killing of bacteria was

slow.

> > > Many intracellular staphylococci survived for up to 4 d

exposure

> to

> > > extracellular cloxacillin and emerged from within the

macrophages

> > to

> > > multiply extracellularly when the antibiotic was inactivated.

> > > Rifampicin was significantly more efficient than cloxacillin in

> > > killing intracellular S. aureus after 18 h incubation, but it

too

> > > failed to sterilize the cultures within 3 d. Staphylococci,

which

> > had

> > > remained viable within macrophages during 20 h incubation with

> > > extracellular cloxacillin, showed an increased sensitivity to

> > dilute

> > > lysostaphin on subsequent exposure. A 3 d course of

intramammary

> > > therapy with cloxacillin, commencing simultaneously with an

> > infecting

> > > inoculum of approximately 10(8) colony forming units (c.f.u.)

S.

> > > aureus, apparently eliminated the infection from one quarter of

> the

> > > udders of each of three lactating cows, but bacteria were re-

> > isolated

> > > from two cows after a delay of several days. However, when

other

> > > quarters of the same cows were infected with approximately 10

(8)

> > > c.f.u. S. aureus which had been phagocytosed by autologous

> mammary

> > > macrophages, similar simultaneous antibiotic therapy failed to

> > affect

> > > these infections. The in vitro and in vivo findings indicate

the

> > > significance of intracellular survival of S. aureus as a factor

> > > contributing to failure of antibiotic therapy.

> > >

> > > PMID: 6569065 [PubMed - indexed for MEDLINE]

> > >

> >

>

[Guest guest]

****** This is a prime example of what I've said before-

> occurred rapidly, but intracellular killing of bacteria was slow.

> Many intracellular staphylococci survived for up to 4 d exposure to

> extracellular cloxacillin and emerged from within the macrophages

to

> multiply extracellularly when the antibiotic was inactivated.

***** This is because the in vitro part of the experiment only lasted

4 days... what if it had gone on for 14 days- would conclusions be

different?

>A 3 d course of intramammary

> therapy with cloxacillin, commencing simultaneously with an

infecting

> inoculum of approximately 10(8) colony forming units (c.f.u.) S.

> aureus, apparently eliminated the infection from one quarter of the

> udders of each of three lactating cows,

******** A 3 day course of abx? No surprise alot of intracellular

bacteria survived.

And this paper is a 1984 paper. As faras I know abx experiments are

STILL being run between 2 to 4 days. Very very few are run longer.

Barb

>

> J Dairy Res. 1984 Nov;51(4):513-23. Related Articles, Links

>

>

> Phagocytosis of Staphylococcus aureus by bovine mammary gland

> macrophages and intracellular protection from antibiotic action in

> vitro and in vivo.

>

> Craven N, JC.

>

> Macrophages isolated from the involuted bovine mammary gland were

> cultured in vitro. Phagocytosis of opsonized Staphylococcus aureus

> occurred rapidly, but intracellular killing of bacteria was slow.

> Many intracellular staphylococci survived for up to 4 d exposure to

> extracellular cloxacillin and emerged from within the macrophages

to

> multiply extracellularly when the antibiotic was inactivated.

> Rifampicin was significantly more efficient than cloxacillin in

> killing intracellular S. aureus after 18 h incubation, but it too

> failed to sterilize the cultures within 3 d. Staphylococci, which

had

> remained viable within macrophages during 20 h incubation with

> extracellular cloxacillin, showed an increased sensitivity to

dilute

> lysostaphin on subsequent exposure. A 3 d course of intramammary

> therapy with cloxacillin, commencing simultaneously with an

infecting

> inoculum of approximately 10(8) colony forming units (c.f.u.) S.

> aureus, apparently eliminated the infection from one quarter of the

> udders of each of three lactating cows, but bacteria were re-

isolated

> from two cows after a delay of several days. However, when other

> quarters of the same cows were infected with approximately 10(8)

> c.f.u. S. aureus which had been phagocytosed by autologous mammary

> macrophages, similar simultaneous antibiotic therapy failed to

affect

> these infections. The in vitro and in vivo findings indicate the

> significance of intracellular survival of S. aureus as a factor

> contributing to failure of antibiotic therapy.

>

> PMID: 6569065 [PubMed - indexed for MEDLINE]

>