12. Antimicrob Chemotherapy PART 2_v2_Mech of action and resist_Dr. FB_09Dec2024.pdf

Hematological principles

1. Antimicrobial Chemotherapy

Mechanism of Action / Resistance in Bacteria

PART 2

Dr. Freddie Bwanga

M.B;Ch.B, M. Med (Microb) Ph.D.

2. Contents

3. Multidrug-resistant bacteria are bacteria that are

resistant to three or more chemical classes of
antimicrobial drugs

4. Due to production of carbapanamase enzymes
encoded by various genes e.g.

vim
IMP_A
IMP_C
IMP_B

OXA_48
KPC

NDM_1

5. MDR Gram Negative Bacterial Clinical Isolates
from Bugando Univ. Hospital Mwanza, TZ studied for
Carbapenem Resistance genes

Frequency

6. % Resistance of the MDR GM Neg. Isolates studied

‘Tape 3: Resistance pattern of bacteria species used in the study

Isolate AMP AMC CRO CAZ CN CP SXT ERT MEM
A. baumannii (10) 100.0% 100.0% 90.0% 90.0% 80.0% 40.0% 90.0% 40. 10.0%
dit (15) 100.0% 100.0% 60.0% 80.0% 80.0% 26.7% 86.7% 133% 0.0%

E. coli (56) 100.0% 100.0% 840% 821% 44 964% 19.6% 89%
Enterobacter (5) 100.0% 100.0% 20.0% 40.0% 60.0% 20. 100.0% 20.0% 0.0%
K. oxytoca (8) 100.0% 100.0% 100.0% 1000% 10.0% 625 100.0 125% 0.0%
K. pneumoniae (68) 100.0% 985% 84.0% 79.4% 83.8% 33.8% 971% 16.2% 15%
M. morganti (3) 100.0% 100.0% 333% 33.3% 33.3% 0.0% 100.0% 0.0% 0.0%
P aeruginosa 100.0% 975% 2% 53.7% E 171% 92.7% 561% 195%
P. mirabilis (2 100.0% 100.0% 100.0% 100.0% 100.0% 50.0% 0.0%
P vulgaris (7) 100.0% 85.7% % 429% 5 143% 857% 143% 0.0%
$. marcescens 100.0% 100.0% 7 66.7% 444% 1000% 0.0% 0.0%
Salmonel 3 100.0% 100.0% 100.0% 1000% 100.0% 0.0% 100.0% 0.0% 0.0%
Total 100.0% 98.7% 0% 74.0% 656% 95.2% 6.6%

AMP AMC, CAZ, CRO, CN, CIP, SXT, ERT, and MEM stand for ampicillin, amoxicillin/clavulanic acid, ceftazidime, gentamicin, ciprofloxacin, trimethoprim-
sulfamethoxazole, ertapenem, and meropenem, respectively

Ref. Mushi F. Martha, Stephen E. Mshana, Can Imirzalioglu and Freddie Bwanga.
Carbapenemase Genes among Multidrug Resistant Gram Negative Clinical Isolates from
a Tertiary Hospital in Mwanza, Tanzania. Hindawi Publishing Corporation BioMed Research International Volume 2014, Article ID 303104.

7. Study 1 findings

OVERALL:

80 of 227 MDR-GNB isolates (35%) were positive for one or
more of the carbapenem resistance determining genes

Frequency Percentage
(n=227) (%)

28 12.33
18 7.93
17 7.49
14 6.17
4.85
3.52

3.01

8. Which Gram negative bacteria harbored
carbapenem resistance determining genes?

Bacteria species

9. Research Article
Carbapenemase Genes among Multidrug
Resistant Gram Negative Clinical Isolate:
a Tertiary Hospital in Mwanza, Tanzania

Martha E. Mushi,"? Stephen E. Mshana,! Can Imirzalioglu,™ and Freddie Bwanga?

ht 0201 Manba
proper

nc of erbpeneman
species in a rar Psp Ms

D OXA en re poste or on r mon ca
roma gene bellowed by VIN, 9 (21508) snd 3 (2%) ses topetingy. Catbapenase
NB paca len inet

ye B-lactamases with capacty to hyuroya

10. Drug Resistant H. pylori

11. H. Pylori Resistance to Fluor
and to Clarithromycin, 2013

based on Genotype HelicoDR PCR test
(Hain Life Sciences Nehren, Germany) Sia] Sitges)
| Genotype HelicoDf

test
31 samples

+ Angol Denish
Calmax, Freddie

Bwanga,
Ponsiano Ocama

+ June 2013 data

12. Hindawi

BioMed Research Internat

‘Volume 2017, Article .
hip doiorg/10.1155/2 2

Hindawi

Research Article

Helicobacter pylori from Peptic Ulcer Patients in
Uganda Is Highly Resistant to Clarithromycin and
Fluoroquinolones: Results of the GenoType HelicoDR
Test Directly Applied on Stool

Denish Calmax Angol,'” Ponsiano Ocama,' Tess Ayazika Kirabo,'
Alfred Okeng,' Irene Najjingo,' and Freddie Bwanga'*

13. Antimicrobial Resistance in H. pylori (2023 study)
Based on Culture and sensitivity testing with Etest

R (%) S (%)
45 (97.8) 4 (2.2)
44 (95.7) 2 (43)
44 (95.7) 2 (4.3)
35 (76.1) 11 (23.9)
32 (69.6) 14 (30.4)
24 (62.2) 22 (47.5)

Ref:
Emmanuel Aedeke, Freddie Bwanga (October 2023 study data)
Patients: Symtoms of dyspepsia, for endoscopy at Nsambya Hospital Kampala.
Methods: Stomach Bx tissues collected at upper Gl endoscopy were cultured and tested using Etest fo MICs

14. Drug Resistance in
Salmonella

(cause of Typhoid)

15. Antibiotic Susceptibility of Salmonella isolates recovered from Blood
cultures at (32 Isolates) and
(19 isolates) January & Feb 2015

Ampicillin Ceftrioxon TRM-SXT Chloramphenicol
(n=51) (n=51) (n=50) (n=51)
38 (74%) 46 (90%) 44 (88%) 43 (84%)

9 (18%) 3 (6%) 6 (12%) 8 (16%)

4 (8%) 2 (4%)

51 51 50 51
(100%) (100%) (100%) (100%)

Freddie Bwanga, Emmannuel Aboce, Simon Dembe Kasango, Hannington Baluku,
jjuka, Henry Kajumbula

16. Drug Resistant Fungi

Mugisha evelyne, Freddie Bwanga, Kakaire Othman May
2013 data

17. HVS Fungal species studied
Antenatal Clinic Mulago Hospital, 2013

70 64

Species

18. % resistance in candida species

Species

Percentage Resistance

Econazol
e

Miconazo
le

Clotrimazo
le

Nystati
n

Ketoconaz
ole

Fluconazol
e

C. albicans

18%

18%

6%

14%

16%

17%

C. glabrata

6%

6%

14%

26%

14%

64%

C. krusei

0%

0%

50%

0%

50%

100%

C. pseudotropicalis

C. tropicalis

Candida spp

20. [Drug

Mechanism of action

Genes affected by
resistant-determing
mutations

First line drugs (Oral)
Isoniazid (H)

Tnhibits mycolic acid synthesis

KaïG, inhA, oxyR

Rifampicin (RJ Binds to RNA polymerase inhibiting RNA synthesis rpoB
Pyrazinamide [Z) Activated to pyrazinoic acid - bacterialcidal in phagolysosome pnoA
Ethambutol (E) Tnhibits cell wall synthesis. EABC
[Second ine drugs
a) Injectable drugs
Streptomycin (S) Binds to ribosomal proteins and Inhibits protein synthesis ITS, rpsT
[Amikacin (Am) [Disrupts ribosomal function and Inhibits protein synthesis TTS, (pst
Kanamycin (Km) Binds fo 30S ribosomal subunit, Hibiting protein synthesis TTS, rpsT
Tapreomycın (Cm) ımilar to aminoglycosides TTS, [pst
b) Fluoroquinolones
Ciprofloxacin (Cx) Disrupts the DNA-DNA gyrase complex blocking DNA synthesis OVA, gyrB
Ofloxacin (Of)

evofloxacın

foxifloxacin
Gatifloxacin [GX]
c) Oral bacteriostatic anti-TB agents (second-line)
Cycloserine (Cs) Inhibits cell wall synthesis =
Ethionamide (Eto) Inhibits oxygen dependent mycolic acid synthesis =
P-aminosalicylic acid (PAS) | Disrupts folic acid metabolism -
Rıfabufin Binds to RNA polymerase Hibiting RNA synthesis rpoB

Thioacetazone (Th)

d) Anti-TB agents with unclear efficacy

Clofazimine (Cizy

|Amoxicilin/Clavulanate [Amx/Clv) =

Clarithromycin (Cir)

Linezolid (Lzd)

21. Types of Drug resistance in MTB

Mono resistance: resistance to one anti-TB drug
MDR-TB: resistance to at least isoniazid (INH) and rifampicin (Rif)

XDR-TB: MDR-TB with resistance to a fluoroquinolone and
to at least one of the injectable second line drugs
(Kanamycin, Amikacin or Capreomycin)

Poly-resistance: resistance to more than one anti-TB drug,
other than both INH and Rif

Totally drug resistant TB - resistance to all first-line anti-TB
drugs (FLD) and second-line anti-TB drugs (SLD)

22. Development of Resistance in M. tuberculosis

Due to sequential accumulation of spontaneously emerging point
mutations in the drug target genes, then natural selection of the

resistant mutants, which then multiply to form a new clone
Wild type INH-Monoresistant INH+Rif Resist (MDR) MDR+Ofx+Km Resist (XDR)

IN! Rif Ofx, Km

Since prior exposure to anti-TB drugs can select for the mutants, drug resistance to
antiTB drugs is 10 times more common in previously treated patients (Treatment
failures, Relapses, Defaulters) than in new TB cases

In Africa first line drugs are commonly in use,
thus MDR-TB is the main concern!!

23. Dangers of MDR-TB?

MDR-TB treatment is difficult
2nd line drugs must be used - quinolones and aminoglycosides
Disadvantages

1. Less efficacious drugs than Rif & INH,
2. More toxic drug: Renal toxicity, Ototoxicit

3. Some are injectable only (Injection safety, nurses, cost, social
issues)

4. Expensive: 100 times more costly than treating susceptible
TB (Drugs 50%, Hospital costs, Lab tests, social care)

\ 5. Long Rx Duration: 6. Poor Cure rate:
| Up to 2 years of treatment Only around 50-60%

6
7. If untreated: May infects 15 — 20 people/year; and Virtual death sentence

24. MDR-TB Burden

Settings

MDR-TB Prevalence

New cases

Retreatment
cases

Ref

1. Global estimates, (who 2010)

3%

15%

WHO DR survey
report 4 (2008)

2. African* countries, 2005-7

1- 4%

417%

Wright A et al
Lancet. 2009 May
30:373(9678):1861-73

4. Uganda, (DR survey, 1997)

0.5

4%

WHO, 2009

5. Kampala DR survey, 2009

1.5

12%

Kampala drug
survey 2008

6. National drug survey 2010

1

12%

NTRL

7. TB Center, Mulago Hosp 2009

19%

(Bwanga F et al
2009).

Cote d'Ivoire, Ethiopia, Madagascar, Rwanda, and Senegal

DR = Drug resistance

25. Vancomycin-resistant Staphylococcus aureus

» With the increase of staphylococcal resistance to
methicillin, vancomycin (or another glycopeptide
antibiotic, teicoplanin) is often a treatment of choice in
infections with methicillin-resistant S. aureus (MRSA)

Three classes of vancomycin-resistant S. aureus:
— Vancomycin-intermediate S. aureus (VISA)
— Heterogenous vancomycin-intermediate S. aureus (hVISA) andl

— High-level vancomycin-resistant S. aureus (VRSA) - vanA gene
mediated

Treatment options: Trimethoprim/Sulfamethoxazole, Linezolid,
quinupristin/dalfopristin and daptomycin

26. > Enterococci live as normal flora in the gut & female genital tract
> Resistance to vancomycin is mediated by the vanA, vanB, vanC
genes

Who is at risk of VRE infections?
Previously treated with vancomycin
Hospitalized patients esp with weakened immunity - intensive
care units, cancer or post-transplant
Post-abdominal or chest surgery
In-dwelling Medical devices that stay in for some time such as
urinary catheters or central intravenous (IV) catheters.
Colonized with VRE

Treatment options: Combinations of penicillin & aminoglycosides
might help

27. MRSA (Methicillin resistant staphylococcus aureus )
ESBL-GNB (Extended Spectrum B-lactamase
producing gram negative bacteria) e.g. E. coli, K.
pneumoniae

VISA (vancomycin intermediate Staphylococcus aureus )

VRE (vancomycin Resistant Enterococcus )
FQ-R P. aeruginosa
MDR-TB (Multidrug tuberculosis )

XDR-TB (Extensively drug resistant tuberculosis )

28. May 2014: Sixty-seventh World Health Assembly tasked the Director-
General to develop a draft global action plan to combat antimicrobial
resistance

May 2015: Sixty-eighth World Health Assembly adopted the global action
plan on antimicrobial resistance

Strategy 2: to strengthen the evidence base through enhanced global
surveillance and research on the burden of AMR to support local, national
and global strategies

However, ltd ongoing surveillance data on AMDR in Uganda

Uganda (MOH) has drafted a national strategy against AMR

29. Global Antimicrobial Resistance
Surveillance System (GLASS)

y By

oo N Organisms and Samples Targeted in
4 Y e GLASS surveillance
Global Antimicrobial À

7
Resistance Surveillance K
System 4

; y

$

=~
Al

World Health
2,9 Organization