PROFESSOR PETER M. HAWKEY

Health Protection Agency West Midlands Public Health Laboratory, Heart of England

NHS Foundation Trust, B5 9SS

The University of BirminghamEdgbaston, B15 2TT

p.m.hawkey@bham.ac.uk;peter.hawkey@heartofengland.nhs.uk

Treatment Options for Multiple Resistant Gram Negative

Infections

BSAC Spring MeetingTuesday 7th April 2009

International Convention Centre, Birmingham

Some antibiotic resistance genes that threaten treatment of Gram -ve infections

“Mobile” ampC

Carbapenemases blaOXA blaKPC blaIMP / blaVIM

ESBL’s blaCTX-M blaSHV / blaTEM / blaPER

“Intrinisically resistance bacteria”

Acinetobacter / Pseudomonas / Stenotrophomonas

Topoisomerase mutants (gyrA / parC)

Plasmid borne quinolone resistance (qnr/aac6’-cr)

Efflux genesAminoglycoside inactivating enzymes

Effect of genetic location of resistance genes

• CHROMOSOMAL – All isolates carry resistance most will express depending on expression controle.g.

• L1/L2 β-lactamase Stenotrophomonas maltophilia • AmpC β-lactamase in Enterobacter spp.

• ACQUIRED – variable rates of carriage, commonly gives multiple resistancee.g.

• CTX-M, KPC, TEM plasmid mediated β-lactamases• AAC – 6’ – cr, APH3’ aminoglyside inactivating

enzymes

Meta-analysis of mortality in ESBL-producing versus non-ESBL-producing Enterobacteriaceae bacteraemia

Schwaber & Carmelli, 2007, J Antimicrob Chemother, 60: 913-20

Meta-analysis of delay in effective therapy in in ESBL-producing versus non-ESBL-producing Enterobacteriaceae bacteraemia

Schwaber & Carmelli, 2007, J Antimicrob Chemother, 60: 913-20

Mortality rates (21 day) in 97 ESBL-BSI patients treated with antimicrobial agents to which the infecting organism displayed in vitro susceptibility

Tumbarello, M., 2007, Antimicrob Agents Chemother 51: 1987-94

Use of cephalosporins to treat ESBL in China - but all CTX-M 14/3 no OXA-1 so....

22 cases of bacteremia Survival %

ceftazidime (7) 86imipenem/cilastatin (8) 86cefoperazone/sulbactam (7) 72

Cao, et al, Diag. Micro. & ID (2006) 56:351-7

Things are bad quite close to home....

A. baumannii bacteremiaGreece 83%, Spain 48% (ImiR)

Klebsiella sppGreece 46% (ImiR) 58% (Quin) 63% (3GC)

Pseudomonas aeruginosa Greece 51% (ImiR)

CARBAPENEM ANTIBIOTICS...

Resistance mechanisms to carbapenems

• Intrinsic carbapenemases L1 • Loss of porin D2• Efflux pumps MexEF-OprN,MexXY • Class A&D KPC-2, OXA-23,OXA-46• Class B carbapenemase IMP,VIM

C.youngae(01) IMP-4 P.aeruginosa (01) IMP-9

K.pneumoniae(00) IMP-5, 8 P.aeruginosa(00) VIM-2,3

P.aeruginosa(01) IMP-7

K.pneumoniae (00) IMP-1 P.aeruginosa (01) OXA-27 P.pudita (02) VIM-6

Acinetobacter(00) IMP-4

>12 species (91-) IMP-1,3,6,10,11

Pseudomonas(01) VIM-1

P.aeruginosa(02) OXA-23

Pseudomonas (01) S.marcesence(01) VIM-2

P.aeruginosa(02) GES-2

P.aeruginosa (02) IMP-7

S.marcesence(82) SME-1

E.cloacae(84) IMI-1

S.marcesence(00) SME-2,3

P.aeruginosa (00-01) IMP-2 VIM-1,2, 5

Acinetobacter(01) IMP-1, OXA-27

K.pneumoniae(01) KPC-1/2

Acinetobacter(00) IMP-5

P.aeruginosa (01-02) VIM-2, VIM-4

Acinetobacter (00-02) OXA-24, 25,40

Acinetobacter (01) OXA-26

Global spread of carbapenem resistance

Endemic KPC Sporadic cases of KPC

Distribution of KPC in 2009

Temocillin

Matagne, et al, Biochem 1993, 293, 607-11

Temocillin• Developed and marketed by Beechams in

1980’s• 6 x methoxy derivative of ticarcillin → +++ β-

lactamase stability• Stable to serine activated β-lactamase e.g.

CTX-M, TEM, SHV, ESBLs• No selection for depressed AmpC production• Probably little C. difficile selection• Burkholderia cepacia susceptible (mode MIC

32 mg/L)

But....

• Withdrawn because of low sales• Temocillin has no activity against

Pseudomonas anaerobes or Gram positive bacteria

• Better with continuous infusion – serum levels ≥ 16 mg/L

• Most experience in UTI, but also BelgiumVAP (non Pseudomonas spp)

Effect of temocillin against KPC producing bacteria from 2 states in USA

MIC Temocillin mg/L

8 16 32 64 1281 x 104 K. pneumoniae (30) 12 15 3

E. coli (3) 1 21 x 106 K. pneumoniae (30) 1 3 15 10 1

E. coli (3) 1 1 1

Adams-Haduch, et al, AAC (2009) epub 30th March

Tetracyclines

•Discovered by Benjamin Duggar in 1945 (aureomycin)

•Produced by Streptomyces aureofaciens

•Inhibitors of protein synthesis

•Bacteriostatic antibacterial activity

Tigecycline: Glycylcycline Class

NH2

O

OH

OO OHOH

N

N(CH3)2

OH

N

O

H

N(CH3)2

H3C

H3C

CH3

H9

87

Tigecycline

•Developed to evade the classic mechanisms of resistance

•Inhibitor of protein synthesis

•Generally bacteriostatic

•Binds with 5x greater avidity

Tygacil binding to 30S subunitComparison of Tetracycline and Tigecycline docking

tetracyclinetetracycline

tigecyclinetigecycline

Side chain results in 5x increase in binding strength

Tetracycline blocked from binding

Tetracycline pumped out of cell

Tigecycline is still able to bind to ribosome

Tigecycline cannot be pumped out of cell

Ribosomal protection

Efflux Pump Protection

Efflux pump

Efflux pump

Tigecycline is Active Against a Broad Spectrum of Clinically Relevant Pathogens

• Escherichia coli• Klebsiella pneumoniae• Klebsiella oxytoca• Citrobacter freundii• Citrobacter diversus• Enterobacter cloacae• Enterobacter aerogenes• Salmonella spp.

• Shigella spp.• Stenotrophomonas

maltophilia• Acinetobacter baumannii• Haemophilus influenzae• Moraxella catarrhalis• Neisseria gonorrhoeae• Eikenella corrodens• Pasteurella multocida

Gram-Negative

Comparative in vitro activity of tigecycline andβ-lactam antimicrobials against A.baumanii (USA)

0.004

0.015

0.06

0.25 1 4

16 6425

6

020406080

100

Tigecycline

Ampicillin

Amox/ClavPip/Taz

Ceftazidime Ceftriaxone

Cefepime

MIC (mg/L)

% ofisolates

n=762

Comparative in vitro activity of tigecycline andβ-lactam antimicrobials against Multidrug-Resistant Acinetobacter spp. (USA)

0.004

0.015

0.06

0.25 1 4

16 6425

6

020406080

100

TigecyclineAmpicillin

Amox/ClavPip/Taz

Ceftazidime

Ceftriaxone

Cefepime

MIC (mg/L)

% ofisolates

n=42

Tigecycline for Acinetobacterspp infections review

• 22 microbiological studies of 2,384 isolates (1906 Acb)

• 90% susceptibility (MIC ≤ 2mg/L)• Efficacy 42 severely ill patients (31 resp.

Infections, 8 bacteremia)• Tigecycline used in combination in 28/42

patients – effective in 32/42

Karageorgopoulos, et al, JAC (2008); 62:45-55

Resistance to tigecycline

• No resistance reported for MRSA• Acinetobacter baumannii upregulation of

RND pump AdeABC important1

• Pseudomonas aeruginosa MexXY-OprM• Enterobacteriacae AcrAB2

1AAC (2007)51:2065-92CMI(2006)13:354-62

Polymyxins

Polymyxins (A-E) – Colistin (A-B)• Mixtures of cyclic peptides –

colistimethate for i.v. use.• Variation in potency of different

preparations, hydrolysed to colistin variably in patient.

• Colomycin (Forest Labs) 240-480 mg colistimethate/day (Usually 2 doses)

• Renal toxicity seen particularly if prior damage,neurotox as well.

Landman, et al, Clin Micro Revs (2008) 21: 449-65

Colistin mode of action

• Cationic agent that binds to anionic components of outer membrane e.g. peptidoglycan- displaces Mg++/Ca++

leading to membrane leakage• Moct GNB sensitive except

Proteus/Providencia Burkholderia cepacia & Chromobacterium

Resistance to colistin• Resistance in Proteus due to linkage of 4’-

PO4++ with 4-amino-4deoxy-L-

arabinopyranosea in Lipid A leads to reduced binding(also seen in other species with acquired resistance)

• Genetically stable resistance in Pseudomonas due to extra OMP H1, ? Replaces divalent cations in outer membrane

aSidorczyk et al.Eur.J. Microbiol.137:15-22

Colistin resistant K. pneumoniae in Greek ICUs

• Heavy empirical use of colistin• 18 isolates from 13 patients over 16/12• Long stay (median: 69 days),

Old (mean: 70 yrs)Long course colistin (median: 27 days)

• 2 bacteraemia, 1 VAP, 2 cSSTI

Antoniadou, et al, JAC (2007) 59: 786-90

Sulbactam

• Has intrinsic activity against A. baumannii

• Early studies showed high rates of susceptibility a- declined recently b

• Has been used in pneumonia with moderate effect

a CID (1996) 22:1026b JAC (2007) 59:583

Odds & Sods

Nitrofuratonin FosfomycinAmikacinMecillinam (± clavulanic acid)

Future Approaches• Trinem (Tricyclic carbapenem) – most

discontinued but LK-157 structureal analogue.• Inhibits Class A & C β-lactamase but not

stable to carbapenemases.

LK-157

Paukner, et al, AAC (2009) 505-11

NXL 104 - Novexel

• Non – β‐lactamase inhibitor of serine activated Ambler class A enzymes e.g. CTX‐M, KPC, OXA‐48

• Could be combined with ceftazidime for specific GNB cover or ceftaroline for broad spectrum activity (including MRSA) or a monobactam for cabapenemase producers

Livermore, et al, JAC 2008, 62, 1053-56

Beta-lactamase bingo cardAmp Pip/

TazCRD CXN CTX CPM AZT IMI

A TEM1/SHV1 R S R S S S S STEM3/CTX-M R S R R R R R S

A CMY/FOXKPC

RR

RS

RR

RR

RR

RR

RR

SR

B(Zn++)

VIM/IMP R R R R R R S R

C Chromosomal (hyperproducer)

R R R R R S R S

D OXAOXA (carbapenemase)

RR

RR

RR

RR

SS

SS

SS

SR

e.g. AcinetobacterOXA-23, OXA-51