Prepared & Presented by:

GERRY A. BERNAS

Senior Lab Tech

SQH

i. Definition

ii. Factors resulting to the rise of NCI

iii. Routes of transmission

iv. Sites of infection

v. Occurrence of NCI

vi. Consequences of NCI

vii. Pathological agents

viii. Examples of MDRO.

ix. Bacterial Identification

x. Mechanism of resistance

xi. Role of clinical microbiology lab.

xii. Determining drug resistance.

xiii. Prevention NCI.

Nosocomial Infection (NCI)

Any infection causing illness that was not present

when the patient was admitted to the hospital or

received treatment in OPD.

Infection considered nosocomial if they first appear

48 hrs or more after admission or within 30 days

after discharge.

MDRO ( Multi- drug resistant organism)

Defined as organisms that are resistant to different

classes of anti-microbial agents also called as

antibiotics.

WHO notes that the rate of nosocomial infections

will continue to rise as a result of:

1. Emergence of MDRO.

2. Crowded hospital condition.

3. Increasing number of immunocompromised

patients

4. Appearance of new microorganisms.

1. Contact - Direct physical transfer of

microorganism between a host and

susceptible person.

2. Airborne/droplet. Generated by

coughing, sneezing or respiratory

procedures such as bronchoscopy or suction

- Tiny droplets nuclei ( < 5 microns) remain

suspended in the air.

Con’t..

3. Vector- transmitted through insect bites.

Mosquito bites can transmit malaria and

dengue fever.

4. Common vehicle of transmission

transmitted indirectly by material contaminated

with infectious agents

a. contaminated blood products.

b. contaminated instrument.

c. contaminated food and water.

- Urinary tract 40%

- Surgical wound 15 %

- Respiratory tract 15%

- Skin 10%

- Blood (Bacterimia) 10%

- Others 10%

1. Presence of microorganism in hospital

environment.

2. Immunocompromised patient or any

susceptible host.

3. Transmission of pathogen between staff and

patient or among patient.

1. Additional suffering of patient.

2. Prolong hospital stay.

3. Increased cost of care.

4. Increased morbidity and mortality rate-

death.

MDRO related nosocomial infection has a

mortality rate of more than 50%

1. Bacteriaa. Commensal bacteria – found in the normal

flora of healthy people as skin, nose, axilla, groin, throat. They have lesser virulence but can cause I.V infection and bacterimia.

Ex. Staph epidermidis

Strept viridans

a. Pathogenic bacteria – they have greater virulence and cause infection ( sporadic or endemic)

- They can colonise a healthy person without causing infection and can transmit to another person and will cause them infection.

- some strains develop resistance to

antibiotic and some are highly resistant

(MDRO)

2. Viruses

a. Hepatitis virus (HBV, HCV)

b. HIV

3. Fungi

a. Candida albicans

B. Aspergillus spp

C. Cryptosporidium

1. MRSA (methicillin- resistant staph aureus)

- staph aureus causes a wide variety of

infection and common cause of hospital

acquired infection like wound infection

(abcess), UTI, pneumonia, endocarditis,

osteomyelitis and food poisoning (entero-

toxin).

- MRSA is staph aureus that are resistant to

certain antibiotics called beta-lactams

includes methicillin, oxacillin, penicillin

and amoxicillin.

BIOCHEMICAL TEST STAPH AUREUS OTHER STAPH

SPP/EPIDERMIDIS

CATALASE + +

COAGULASE + _

DNASE + _

Con’t…

- This is because of their ability to produce the

enzyme beta lactamase which breakdown the

drug and render it ineffective.

- Vancomycin is considered the only effective

antibiotic against MRSA.

2. ESBL ( EXTENDED – SPECTRUM BETA-

LACTAMASE)

- ESBL is an enzyme which built up a form of

resistance of community use antibiotics the

extended spectrum cephalosporins (

cefotaxime, cefriaxone, ceftazidime and

monobactams).

- ESBL develops co-resistance with antibiotics

aminogycosides, septrin ( sulfomethoxazole-

trimthoprim), flouroquinolones, tetracycline

and chloramphenicol.

- ESBL enzyme is produced by gram negative

enterobacteriaceae, the most common are E.Coli

and klebsiella pneumoniae.

- Enterbacteriaceae are group of enteric bacteria

that found in intestinal tract of normal individual.

However, they can cause severe infection like

septicemia, UTI, wound infection and pneumonia.

- Patients who are colonized or infected with ESBL

bacteria can spread to other patients through direct

contact, poor hygiene and by contaminated

equipment or via hands of health care workers.

ESBL detection method:

Inhibitor potentiated diffusion test

This test performed by placing two sensitivity discs

on a mueller- hinton sensitivity plate inoculated

with a bacteria suspected ESBL.

One of the discs is impregnated with ESBL inhibitor

like clavulanic acid.

It is then incubated at 37oC and the minimal

inhibitory concentration is measured the next day.

Fig. 1. Phenotypic confirmation test of an ESBL producing strain showing

zone size of more than 5 mm in the disk with ceftazidime and clavulanic

acid (CAC) as compared to Ceftazidime (CA).

3. CRE: carbapenem resistant

enterobacteriaceae

- carbapenem (impenem, meropenem) are class

of antibiotics considered to be the drug of last

resort.

- CRE in general were become resistant to

almost all antibiotic and it can be very difficult

to treat.

- nosocomial infection due to CRE has a

mortality rate of more than 50%.

- like ESBL, the enterobacteriaceae, a group

of gram negative enteric bacilli develops

resistance to carbapenem example E.Coli and

Klebs pneumoniae.

- CRE are also named as superbug, patients

whose care require ventilators, urinary

catheter, IV catheter are the most high risk

of infection.

- Colistin and Tigecycline are the drugs of

choice for CRE infection.

Mechanism of resistance of CRE:

- CRE has different types of carbapenemase

enzymes.

1. Klebsiella pneumonia carbapenemase (KPC)

2. New Delhi Metallo beta-lactamase (NBL)

3. Verona Integron-Encoded metallo beta-

lactamase (VIM)

4.Imipenemase metallo beta-lactamase (IMP)

4. Acinetobacter baumannii

- is aerobic gram negative bacilli

- non lactose fermenter on Mcconkey agar.

- Multi drug resistant acineto.baumannii is a

rapidly known pathogen in health care facilities.

Its ability to survive in a long period of time on

surfaces makes it a major cause of nosocomial

infection and outbreaks.

- it can be found in

curtains, laryngeoscope, cupboard, door

handle, mops, keyboard, telephone etc.

- it has ability to colonize healthy individuals as

well as patients without causing infection.

- immunocompromised patients are of high risk of severe infection because it can be resistant to almost all drugs except Tigecycline (glycylcycline) and colistin (polymixin E).

- infection includes bacteremia, pneumonia, meningitis, UTI and wound infection.

Mechanism of resistance of A. baumannii

-Resistance is due to its impermeable membrane and it posses wide array of enzyme lactamases that hydrolyse penicillin, cephalosporins and carbapenems.

5. Other MDRO

A. Pseudomonas aeroginosa and stenotrophomonas

maltophilia.

- Aerobic, gram negative bacilli

- Non lactose fermenting colony on mcconkey agar.

- They closely related bacteria, can be found in soil,

water, sewage, hospital environment

- they exhibit resistance to most potent antibiotics

cephalosporins, carbapenem etc, and they are

opportunistic human pathogen infecting

immunocompromised patients.

B. VRE. Vancomycin resistant entercocci.

C. XDR –TB . Extensive drug resistant TB.

API SYSTEM: API 20E and API 20NE

-Standardized, miniaturized microtubes

system consist of series of biochemical test

used for identification of gram-negative

bacteria.

-Microtubes are reconstituted with

bacterial suspension and then incubated at

37’C for 18-24 hrs.

-Identification of bacteria is based on

seven digit profile of Analytical Profile Index

(API).

1. Drug inactivation by enzymatic

degradation of antibiotic (beta-

lactamase enzyme)

2. Mutation of binding site

3. Decreased permeability of bacteria cell

membrane.

4. Efflux pumps

5. Transduction of genes.

1. Disc-diffusion method (Kirby-bauertechnique)

-This is a drug sensitivity test, a semi-quantitative test where petri dish filled with sensitivity media (mueller-hinton agar) is completely inoculated and covered with pure culture of bacteria , then small disc saturated with specific antibiotic over the surface and incubated over night at 37o C. the zone of inhibition is measured and compared to the present standard to determine the antibiotic sensitivity.

Kirby-Bauer sensitivity technique in Mueller-Hinton Agar

2. E.Test

It is consist of a predefined gradient of antibiotic

concentration on a plastic strip and it is used to

determine minimum inhibitory concentrations

(MIC) of antibiotics.

The clinical laboratory has important role in

controlling hospital-acquired infection by

accurately identifying nosocomial pathogens

and detecting unexpected MDRO to prevent

outbreaks.

1. Isolation

2. Sterilization

3. Hand washing

4. Wearing personal protective equipment

- gloves

- apron

- mask

5. Proper waste disposal

WASH NOW!!!

Thank You