LAB 304 Final. Lecture \ 4 Lecture \ 4 _ المحاضرة 4 بالكامل

LAB 304Final

Lecture \ 4 بالكامل 4المحاضرة _    

Samples

Blood culture

• Blood culture : is a microbiological culture of blood. It is employed to detect infections that are spreading through the bloodstream (such as bacteremia or septicemia amongst others). This is possible because the bloodstream is usually a sterile environment.• N.B : blood does not have a normal microbial flora .

Blood culture

• Whenever possible blood should be collected before antimicrobial treatment has started .

1- when the patient has recurring fever collect the blood as the temperature begins to rise .

2- for other patients collect the blood as soon as possible after receiving the request .

* To increase the chance of isolating a pathogen it is usually recommended that at least two specimens are collected at different times.

Urine collection

• Untimed urine sample (random) ( single sample )• Timed urine sample ( 24 H sample )• First Morning Specimen• Midstream Clean Catch Specimen• Catheter Collection Specimen• Pediatric Specimen

Urine collection

• This is the specimen most commonly sent to the laboratory for analysis, primarily because it is the easiest to obtain and is readily available.• This specimen is usually submitted for urinalysis

and microscopic analysis, although it is not the specimen of choice for either of these tests.• Random specimens can sometimes give an

inaccurate view of a patient's health if the specimen is too diluted and analytic values are artificially lowered.

1 -Random Specimen

Urine collection

• As the name implies, the random specimen can be collected at any time. Although there are no specific guidelines for how the collection should be conducted, avoiding the introduction of contaminants into the specimen is recommended. This requires explicit instructions to patients so that they do not touch the inside of the cup or cup lid.

1 -Random Specimen

Urine collection

• Among the most commonly performed tests requiring timed specimens are those measuring creatinine, urine urea nitrogen, glucose, sodium, potassium and other analytes that are affected by diurnal variations.• A timed specimen is collected to measure the

concentration of these substances in urine over a specified length of time.

2 -Timed Collection Specimen

Urine collection

• You should collect every drop of urine during each 24-hour period. It does not matter how much or little urine is passed each time, as long as every drop is collected.• Begin the urine collection in the morning after you

wake up, after you have emptied your bladder for the first time.•Urinate (empty the bladder) for the first time and

flush it down the toilet. Note the exact time (e.g, 5:00 AM). You will begin the urine collection at this time.

2 -Timed Collection Specimen

Urine collection

• Collect every drop of urine during the day and night in an empty collection bottle. Store the bottle at room temperature or in the refrigerator.• If you need to have a bowel movement, any urine

passed with the bowel movement should be collected.• Finish by collecting the first urine passed the next

morning, adding it to the collection bottle. This should be within ten minutes before or after the time of the first morning void on the first day (which was flushed). In this example, you would try to void between 4:50 and 5:10 on the second day.

2 -Timed Collection Specimen

Urine collection

• It is not recommended that the patient void directly into the 24 hour collection container due to the preservative acid content inside the container.• The patient is encouraged to void into

a separate (beaker style collection with pour spout ) cup and pour the contents into the 24 hour collection container during the collection process.

2 -Timed Collection Specimen

Urine collection

• This is the specimen of choice for urinalysis and microscopic analysis, since the urine is generally more concentrated (due to the length of time the urine is allowed to remain in the bladder) .• Also called an 8-hour specimen, the first morning

specimen is collected when the patient first wakes up in the morning, having emptied the bladder before going to sleep.

3 -First Morning Specimen

Urine collection

• This is the preferred type of specimen for culture and sensitivity testing because of the reduced incidence of cellular and microbial contamination.• Patients are required to first cleanse the urethral

area with soap . The patient should then void the first portion of the urine stream into the toilet. These first steps significantly reduce the opportunities for contaminants to enter into the urine stream. The urine midstream is then collected into a clean container . This method of collection can be conducted at any time of day or night.

4 -Midstream Clean Catch Specimen

Urine collection

• This assisted procedure is conducted when a patient is bedridden or cannot urinate independently. The healthcare provider inserts a Foley’s catheter into the bladder through the urethra to collect the urine specimen.

5 -Catheter Collection Specimen

Urine collection

• For infants and small children, a special urine collection bag is adhered to the skin surrounding the urethral area. Once the collection is completed, the urine is poured into a collection cup or transferred directly into an evacuated tube with a transfer straw.

6 -Pediatric Specimen

• Specimen required is From the lower respiratory tract expectorated by deep coughing .• Sputum specimen collection can be either self-

expectorated or mechanically obtained.• Sputum samples should be collected in the morning

before breakfast if possible , because sputum collects during the night.

Sputum collection

PROCEDURE

1- Wash hands thoroughly 2- Assemble necessary equipment.3- Confirm the patient’s identity using two patient

identifiers.4- Tell the patient that : * you will collect a specimen of sputum (not saliva)

and explain the procedure. * The cup is very clean. So Don’t open it until you

are ready to use it.

Sputum collection

PROCEDURE

5- Instruct the patient to sit in a chair or at the edge of the bed. If the patient cannot sit up place him in high Fowler’s position.

* Place the head of the bed at 30° for semi-Fowler's, 45° to 60° for Fowler's, and 90° for high Fowler's

Sputum collection

PROCEDURE

6- Ask the patient to rinse his/ her mouth with water (avoid mouthwash solution or toothpaste).

7- Tell patient to cough deeply and expectorate directly into the specimen container. At least 15 ml is needed to identify the causative organism.

8- Cap the container and if necessary, clean its exterior.

Sputum collection

• Purpose :For the detection of the causative agent of pneumonia,

bronchitis, lung abscess or tuberculosis .Examples of common causative agents of bacterial

pneumonia:• Streptococcus pneumoniae,• Haemophilus influenzae,• Staphylococcus aureus,• Klebsiella pneumoniae,• Escherichia coli, and• Pseudomonas aeruginosa.

Sputum collection

Fecal sample

• Collect the stool in a dry, clean, leak-proof container.• Make sure no urine, water, soil or other material gets in

the container.• Insure that the specimen containers are sealed well.

Reinforce with parafilm or other suitable material.• Insert the container in a plastic bag.• Certain drugs and compounds will render the stool

specimens unsatisfactory for examination. The specimens should be collected before these substances are administered, or collection must be delayed until after the effects have passed.

Lecture \ 5بالكامل 5المحاضرة _    

Swabs

Throat swabProcedure

1- With the patient’s head tilted back and the throat well illuminated, depress the tongue so that the back of the throat can be seen.

Throat swabProcedure

2- Rub the swab up and down the back of the throat and against any white patches in the tonsillar area. Avoid the tongue and the cheeks.

Throat swabProcedure

3- Replace the swab in the transport tube .4- Seal tube tightly and label with patient’s

information, and date .5- Send the specimen to the laboratory .

• Gargling to clear the throat or treatment with antibiotics will affect culture results and may make identification of the bacteria impossible. The patient should not gargle immediately before the swab.

Throat swabPrecautions

• Definition : A throat culture is a microbiological procedure for

identifying disease-causing bacterial organisms in material taken from the throat. A throat swab will capture the causative organism in most cases and the culture will allow the specific organism to be grown in the microbiology laboratory under certain conditions. The bacteria can then be identified .

Throat swabCulture

• Purpose : 1- identify the specific bacterial organisms that are

causing a sore throat or throat infection 2- a correct diagnosis is important to prevent unnecessary

use of antibiotics for viruses that do not respond to them. 3- the bacteria identified are used to determine antibiotic

sensitivity, allowing physicians to select the most appropriate and effective antibiotic to treat a specific infection.• It is common for physicians to order culture and

sensitivity tests at the same time. ( c/s test )

Throat swabCulture

Vaginal swab

• Vaginal swabs are the specimens of choice when screening for :

1- Trichomonas vaginalis

Vaginal swab

2- candida species

Candida albicans

Vaginal swab

3- Gardnerella vaginalis with anaerobes .

Vaginal swabProcedure

1- Place the patient in dorsal position, supported by a pillow

2- ask her to bring her heels together, 3- bend her legs and then draw her heels towards

her bottom.4- Open the swab package

Vaginal swabProcedure

5- Remove the swab; do not touch the soft tip or lay the swab down.

6- Hold the swab as shown

Vaginal swabProcedure

7- Insert the swab into the lower part of the vagina (about two inches ).

8- Gently but firmly rotate the swab for 10 to 30 seconds in the vagina.

vagina

Vaginal swabProcedure

9- Withdraw the swab without touching the skin. 10- Place the swab into the test tube so that the tip

of the swab is visible below the tube label .11- Ensure that the swab is labeled accurately and

place, with the completed request form 12- transport bag to the Department of Medical

Microbiology.

Cervical swab

• Also it is called : Papanicolaou test ,Pap smear, Pap test, cervical smear, or smear test .• A sample of cells from the patient's cervix is

collected and spread (smeared) on a microscope slide. The cells are examined under a microscope in order to look for pre-malignant (before-cancer) or malignant (cancer) changes.• Changes can be treated, thus preventing cervical

cancer, and cancer can be detected early.

Cervical swab

• The best time for screening is between 10 and 20 days after the first day of menstrual period .• For about two days before testing, the patient

should avoid douching or using spermicidal foams, creams, or jellies or vaginal medicines (except as directed by a physician). These agents may wash away or hide any abnormal cervical cells.

Cervical swabProcedure

1- Place the patient in dorsal position, supported by a pillow

2- ask her to bring her heels together, 3- bend her legs and then draw her heels towards

her bottom.

Cervical swabProcedure

4- Moisten the speculum with warm water and insert into the vagina to separate the vaginal walls. Wipe away any excess cervical mucus with a tissue. Using a blue top Trans tube swab sample as high as possible into the vault.

5- Gently but firmly rotate the swab (a cervical brush)

Cervical swabProcedure

6- Withdraw the swab without touching the skin. 7- Remove speculum and wipe vaginal / vulvar area

with a tissue .8- Place the swab into the test tube so that the tip of

the swab is visible below the tube label .9- Ensure that the swab is labeled accurately and

place, with the completed request form 10- transport bag to the Department of Medical

Microbiology.

Lecture \ 6المطلوبة ) (6المحاضرة _     الشرائح كالتالي

·        4·        5 causes of sample rejection

مشطوب 10        · الغير·        11/ 12

مشطوب   22 / 21 / 20        · الغير·        29

مشطوب   32 / 31 / 30        · الغير·        33

Results andResult Reporting

Results reporting• Reference values should be mentioned in the result

report .• Reference range : it is the interval between and

including two reference limits ( upper & lower ) for the specific test .• The test should be repeated if the results are out of

range

Results reporting• Causes of sample rejection?

1. Q.N.S sample. (Quantity of specimen not sufficient)2. Clotted sample.3. Hemolysed sample.4. Sample collected in wrong tube.5. Test N/A ( not available )6. Specimen not labeled.7. Incomplete request's information.

Normal ranges Conventional Unit Analyte

4500-11000/ µL WBC

13.5-16.5 g/dl HGB MALE

12.0-15.0 g/dl HGB FEMALE

150-350 x10³/ µL PLT

HGB: Hemoglobin PLT: platelets

Result interpretation

INTERPRET Increased Type of Cell

Primary & secondary polycythemia polycythemia RBC

leukocytosis WBC

bacterial infection & acute inflammation neutrophilia NEU

Allergic disorders & Parasitic infections eosinophilia EOS

myeloproliferative disorders & Allergic disorders basophilia BAS

acute viral infections , chronic intracellular bacterial infections (TB) & some protozoal infections (TOXO) lymphocytosis LYMPH

chronic inflammation. monocytosis MONO

Inflammation , Surgery , Anemia or hemorrhage thrombocytosis PLT

INTERPRET decreased Type of Cell

Decreased production in the bone marrow , Increased destruction & Medications

erythroblastopenia RBC

leukopenia WBC

neutropenia NEULeukocytosis with eosinopenia can be a predictor of bacterial infection eosinopenia EOS

Urticaria basopenia BAS

a recent infection e.g. common cold lymphocytopenia LYMPH

glucocorticoids monocytopenia MONOVitamin B12 or folic acid deficiency, Decreased production of thrombopoietin in liver failure & thrombocytopenic purpura

thrombocytopenia PLT

Aplastic anemia , Leukemia , SLE , Severe Folate or vitamin B12 deficiency , HIV , Pernicious anemia & Medications

pancytopenia ALL CELL

Result interpretationInterpret Conventional Unit Analyte

Increased in diabetes and severe illness; decreased in insulin overdose or hypoglycemia

70-110 mg/dl GLUGLU: Glucose

Interpret Conventional Unit Analyte

Increased in dehydration and diabetes insipidus; decreased in overload of IV fluids, burns,diarrhea, or vomiting

136-142 mEq/l NA

Increased in renal failure, extensive cell damage, and acidosis; decreased in vomiting, diarrhea, and excess administration of diuretics or IV fluids

8-23 mg/dl K

Interpret Conventional Unit Analyte

Increased in excess parathyroid hormone production and in cancer; decreased in alkalosis, elevated phosphate in renal failure, and excess IV fluids

8.2-10.2 mg/dl Ca

Critical values

• PROCEDURE :1- A critical value result should be confirmed by

repeating the test for a second time.2- If the result is similar to the previous one, the

comment code or footnote: CPR (Consistent with the Previous Result) is written by the lab technician.

3- If the result is critical and no history of pervious critical value for this test, the result is confirmed, and the doctor is called.

Some Critical valuesConventional Unit

AnalyteHigh Low

>500 mg/dL <40 or 45mg/dL Glucose

>160 mEq/L <120 mEq/L NA

>6.0 mEq/L <2.5 mEq/L K

Conventional UnitAnalyte

High Low>13.0 mg/dL <7.0 mg/dL Ca

Conventional UnitAnalyte

High Low≥ 30 x 109/L ≤ 2.0 x 109/L WBC

> 60% < 20% HCT-hematocrit-

> 1,000 x 10-9/L < 20 x 10-9/L PLT

> 200 g/L ≤ 80 g/L HGB

Some of Critical values

• Positive blood culture• Positive CSF (gram stain, culture)• Positive AFB smear (new patient)• Positive smear for P. Falciparum• Positive Meningococcus (smear or culture)• Positive new MRSA• Positive salmonella or shigella and campylobacter• Positive Clostredium perfringens• Positive HIV, HEP B , HEP C , CMV • Positive Respiratory Virus (RSV, Adeno, Inf…)

Lecture \ 7بالكامل  Urinalysisمحاضرة ) ) ))

التالية الشرائح عدا·        7 , 16 , 17 , 25

Urinalysis

1

2

3

1- Physical examination

• Color• Appearance• Volume• Specific gravity (SG)

NORMAL COLOR

• Including color and clarity• Normal urine color ranges from pale yellow to deep

amber

ABNORMAL COLOR

Abnormal color : some drugs and urinary tract infection cause color

changes 1. reddish urine: hematuria, hemoglobinuria

2. yellow-brown or green-brown urine: bilirubin cause : obstructive jaundice 3- greenish urine : infection

• Other abnormal colors : blue ,orange ,purple

Appearance

• Clarity: normally, clear Abnormal appearance:

POSSIBLE CAUSE APPEARANCE

BACTERIAL URINARY INFECTION CLOUDY

1- URINARY SCHISTOSOMIASIS2- BACTERIAL INFECTION DUE TO RBC RED & CLOUDY

1- ACUTE VIRAL HEPATITIS2- OBSTRUCTIVE JAUNDICE DUE TO BILIRUBIN YELLOW-BROWN OR

GREEN-BROWN

1 -HAEMOLYSIS2 -HEPATOCELLULAR JAUNDICE

DUE TO UROBILIN YELLOW-ORANGE

Urine volume

• The average adult : 1000ml to 2000ml/24h• Increased POLYURIA---more than 2500ml of urine in 24 hours 1. physiological states: water intake, some drugs ( diuretics ), intravenous solutions 2. pathologic states: diabetes mellitus, diabetes insipidus

Urine volume

• Decreased OLIGURIA : less than 400ml of urine in 24 hours ANURIA : less than 100ml of urine in 24 hours 1. pre-renal: hemorrhage, dehydration, congestive heart failure 2. post-renal: obstruction of the urinary tract (may be stones, carcinoma)

Specific gravity (SG)

• Reflect the density of the urine • Range of 1.001 to 1.040• Increased: Dehydration , Fever , Vomiting , Diarrhea ,

Diabetes Mellitus

(urine volume↓ and SG↑) • Decreased: diabetes insipidus (urine volume↑ and SG ↓)

2-Chemical examination

• Urine PH• Protein• Glucose• Ketones• Occult blood• Bilirubin • Urobilinogen • Nitrites

Urine PH

• Normal PH The average is about 6 Range from 5~7 (depends on diet)• Higher PH---alkaline urine ( 7.8 – 8 .0 ) 1.drugs: sodium bicarbonate 2.vegetarian 3.alkalosis (metabolic or respiratory) 4. urinary tract infection• Lower PH---acid urine ( 4.5 – 5.5 ) 1. drugs: ammonium chloride 2. diabetes 3. acidosis (metabolic or respiratory)

Protein in urine

• Reference value Qualitative method: negative Quantitative method: ＜ 150mg of protein in 24

hours• Urine proteins come from plasma proteins e.g. albumin and Tamm-Horsfall (T-H) glycoprotein

Protein in urine

• The two most common risk factors for proteinuria are:1. Diabetes2. hypertension

• Proteinuria---- ＞ 150 mg /24 hours or qualitative test is positive

• Proteinuria quantification (amount of protein ) heavy proteinuria---- ＞ 4 g/24 hours moderate proteinuria----1 - 4 g/24 hours minimal proteinuria---- ＜ 1 g/24 hours

Protein in urine

TYPE PATHOPHYSIOLOGIC FEATURES CAUSE

Glomerular glomerular capillary permeability to protein

Primary or secondary glomerulopathy e.g. IgA nephropathy, lupus nephritis

Tubular tubular reabsorption of proteins in glomerular filtrate

Tubular or interstitial disease due to:Uric acid nephropathyHeavy metals, NSAIDs

Overflow production of low-molecular-weight proteins Monoclonal gammopathy, leukemia

Classification of Proteinuria

Glucose in urine

• Reference value Qualitative method: negative• Glycosuria--- qualitative test is positive 1. with hyperglycemia ( most common ): diabetes

mellitus, Cushing’s syndrome 2. without hyperglycemia (Renal glycosuria ): renal

tubular dysfunction, such as pyelonephritis

Ketones in urine

• Including three ketone bodies: 1. acetone 2% 2. acetoacetic acid 20%3. β-hydroxybutyric acid 78%• The products of fat catabolism ( breakdown )• Reference value: qualitative method: negative• Ketonuria--- qualitative test is positive

Ketones in urine• Ketonuria

1. diabetic ketonuria :

I. Poorly controlled diabetes

II. Diabetic ketoacidosis (DKA)

2. nondiabetic ketonuria:

III. Acute or severe illness

IV. Burns

V. Fever

VI. Hyperthyroidism

VII. Pregnancy & lactation

VIII. Abnormal food or nutrition intake due to:

Anorexia, fasting, high protein or low carbohydrate diets, starvation,

vomiting over a long period of time

Microscopic examination

• ExaminationA- Cells B- Bacteria C- CrystalsD- Casts

Microscopic examination

A- Cells :1- White Blood Cells (pus cell)Normal <2/ HPF in men and <5/ HPF in women• Few : up to 10/ HPF• Moderate : 11-40 / HPF• Many : > 40 / HPF• HPF = high power field

Microscopic examination

2- Red Blood Cells : smaller and more refractile than white cells

Normal <3/ HPF• Dysmorphic RBCs suggest glomerular disease

Microscopic examination

3- Epithelial cells : 3 types1. Transitional epithelial cells are normally present

Microscopic examination

2. Squamous epithelial cells suggest contamination

Microscopic examination

3. Renal tubule epithelial cells suggest renal disease

Microscopic examination

B- Bacteria : Diagnostic for Urinary Tract Infection• Men: Any bacteria• Women: 5 or more bacteria per HPF

Microscopic examination

C- Crystals1- Calcium oxalate crystals (square envelope shape)

Microscopic examination

2- Triple phosphate crystals (coffin lid shape)• Associated with increased Urine pH (alkaline)• Associated with Proteus Urinary Tract Infection

Microscopic examination

3- Uric Acid crystals (diamond shape)

Microscopic examination

D- Casts1- Epithelial cell casts of renal tubule

Microscopic examination

2- Red Blood Cell casts

Microscopic examination

3- White Blood Cell casts

Microscopic examination

4- Hyaline or mucoprotein casts

Microscopic examination

5- Granular casts

Microscopic examination

6- Waxy casts

Microscopic examination

7- Fatty casts

Oval fat bodies ( OFB )

N

Hospital infection Controlبالكامل _     الباقيتان المحاضراتان

n

Nosocomial infections (hospital –acquired infection):

An infection acquired in [a] hospital by a patient who was admitted

for a reason other than that infection.

OR:

An infection occurring in a patient in a hospital or other health care

facility in whom the infection was not present or incubating at the

time of admission.

N

As a general timeline, infections occurring more than 48

hours after admission are usually considered nosocomial.

Frequency of infection:

Nosocomial infection occurs worldwide and affects both

developed and poor countries.

According to studies conducted by WHO, 8.7% of

hospitalized patients had nosocomial infection.

Factors influencing the development of nosocomial infection:1-The microbial agents and antibiotic-resistance ability: -Patients are exposed to a variety of microorganisms during a hospital stay: A- Endogenous microbes: Part of a patient’s own flora.

B- Exogenous microbes: -Patients, and Visitors.

-Medical staff (doctor, nurse, physiotherapist, technician). -Instruments (Endoscopy, catheter, surgical instruments) -Fluids, blood, or food. -Dust, and Insect bite.

N

Hospital-dwelling microbes:Bacteria:

Staphylococcus aureus (MRSA), coagulase-negative

Staphylococci, Enterococci (VRE), and Enterobacteriaceae

species.

Viruses:Hepatitis B and C, Rotaviruses, and Enteroviruses.

Fungi:Candida albicans.

N

Hospital-dwelling bacteria could develop antibiotics

resistance ability due to conjugation process.

Conjugation: Transfer of bacterial plasmid from one

bacterium to another by sex pili.

Plasmid: Extracircular supercoiled DNA that carry some

important gene such as the reporter genes (CAT gene).

N

2. Patient susceptibility: Important patient factors influencing acquisition of infection are:

1-Age : infancy and old age. 2-Immune status: chronic diseases like malignant tumor, diabetes, renal failure immunosuppressive therapy and AIDS. 3-Underlying disease : injuries to skin (burn, wound), ischemia.

4-Malnutrition.5-Diagnostic and therapeutic interventions:

biopsies, catheterization, I.V. cannulation, endoscopic examination,

incubation/ventilation.

n

3. Environmental Factors: -Different factors play a role in establishment of Nosocomial infections: 1-Crowded conditions. 2-Frequent transfer of patients from one unit to another. 3-Concentration of susceptible patients: (newborn infants, burn patient, intensive care). 4-Microbial flora may contaminate objects, devices that may come in susceptible site of the patient.

Sources of Hospital-acquired Infections:Nimer

CONTAMINATED HOSPITAL ENVIRONMENT

Instruments, Fluids, Food, Air, Medications

Patient Normal flora

Cutaneous, GIT, Genitourinary,

Respiratory

Invasive medical devices : Iatrogenic

Urinary Catheter, Intravenous catheter, Endotracheal tubes,

Endoscopes

Medical Personnel: Colonized, Infected, Transient, Carriers.

Plasmid transfer

Common Nosocomial Infections:1. Urinary tract infections (UTI):This is the most common nosocomial infection it account for 40 % of hospital acquired infections; 80% of infections are associated with the use of an indwelling catheter.Organisms :

E.coli, multi-resistant Klebsiella, Pseudomonas aeruginosa,

Enterobacter and Candida albicans. Source:

Endogenous flora or exogenous from other patients, health

care provider, instrument, etc.

N

Diagnosis:

positive urine culture (1 or 2 species) with at least 105

bacteria/ ml, with or without clinical symptoms.Prevention:1-Remove the indwelling urinary catheter as soon as possible. 2-Use aseptic technique for inserting or manipulating the catheter.3-Maintain an unobstructed urinary flow.4-Ensure that the patient is taking sufficient amount of fluids per day (3-4 L).5-Give proper antibiotic therapy for proper course.

N

2.Nosocomial Pneumonia:

Nosocomial pneumonia is the second most common

nosocomial infection accounting for 15 % of all nosocomial

infections.

It is associated with mortality rates that range from

20-50 %.

It occurs in several patient groups, the most important are

patients on ventilator in intensive care units (ICU), where

the Incidence rate of pneumonia is 3% per day.

N

Organisms:

Staph aureus, Pseudomonas , Enterobacter, Klebsiella

pneumoniae, Candida albicans and Haemophilus

influenzae.

Source: endogenous from upper air way, and exogenous

from contaminated respiratory equipment, patients,

visitors, etc.

Diagnosis: isolation of microbe from clinical specimens,

and presence of signs and symptoms of infect.

n

Prevention:

1-Wear gloves; for contact with respiratory

secretions.

2-Wash hands after contact with respiratory secretions,

even if gloves have been worn.

3-Maintain open airway.

4-Isolate patient with potentially transferred

respiratory infections.

N

Other hospital-acquired infections:

1-Surgical site infections: Staphylococcus aureus,

Staphylococcus epidermidis (Intravenous catheter).

2-Nosocomial Bacteremia.

3-Skin and soft tissue infections:

Open sores (ulcers, burns and bedsores).

4-Gastroenteritis : The most common nosocomial infection in the children, where rotavirus is a chief pathogen.

N

5-Nosocomial Bloodborne diseases: A-Hepatitis B virus: -Transmission rate was 25%, reduced due to application of vaccination, the practice of not recapping needle, and Hepatitis B surface antigen screening test.

B-Hepatitis C: Rate is 3%. Anti-viral drugs at first 8 hrs reduce the infection by 60%. C-HIV: Rate is 0.3%

Infection Control :

-Biological safety precautions.

-Hand hygiene.

-Clean & contaminated area.

-Management of blood & body fluid spillage.

-Immunization of health care workers.

-Post exposure management for health care

workers.

Biological safety precautions:

1-All clinical specimens should be considered as

potentially hazardous.

2-Wear Lab coat, gloves, shoes (Protective purpose).

3- Remove gloves when using the telephone or

photocopier.

4- Skin cuts on the hands, must be covered with a

waterproof dressing prior to start working.

n

5-Never perform any action which may bring your hands

into contact with your face, eyes or mouth, such as

eating, smoking or adjusting contact lenses.

6-Remove laboratory coat and

gloves and wash hands

before leaving your

working area.

Hand hygiene:

When Do We Need to Wash Our Hands?-Before eating-Before starting work-Before and after any patient contact-After contact with potentially contaminated materials like blood, urine, CSF.

-Before wearing gloves.-After removing gloves.-Before and after performing any medical procedure-Before leaving work.

Types of Hand Hygiene (Decontamination):

1-Routine care (minimal): -Hand washing with non antiseptic soap. -Or quick hygienic hand disinfection by rubbing with alcoholic solution.2-Antiseptic hand cleaning (moderate) – aseptic care of infected patients: -Hygienic hand washing with antiseptic soap. -Quick hand disinfection by rubbing with alcoholic solution.

3-Surgical scrub (surgical care):Surgical hand and forearm washing with antiseptic soap and sufficient time and duration of contact (3 – 5 minutes).

Clean & contaminated area:

Control of spreading of infection could be achieved by classifying hospital environment into one of four zones:Zone A: no patient contact. Normal cleaning . (e.g. administration, library).

Zone B: Care of patients, who are not infected and not highly susceptible. Wet disinfection with detergent.

Zone C: infected patients (isolation wards). Clean with a detergent/disinfectant solution, with separate cleaning equipment for each room.

N

Zone D: High–susceptible patient (protective isolation) or protected areas such as: Operating room, delivery rooms, intensive care units, premature baby units, and haemodialysis unit.

-Clean using a detergent/disinfectant solution and separate cleaning equipment.

Blood and body fluid spillage, and contaminationmanagement :

PURPOSE: To protect healthcare workers, patients and

visitors from unnecessary exposures to bloodborne

pathogens and other potentially infectious body fluids.

Three types:

1-Low grade disinfection:

Quaternary ammonium: Bactericidal effect.

used for low amount- blood spillage.

N

2-Intermediate grade disinfection: Phenol and 70-90% alcohol ;Bactericidal and Virucidal effect. Used for low amount -blood spillage (less than 50ml).

3-High grade disinfection: Formaldehyde ,Glutaraldehyde, Sodium hydrochlorite , and hydrogen peroxide. : Sporicidal ,Mycobactericidal, Fungicidal, and bactericidal effect. Used for: high blood spillage (more than 50ml), and fungal decontamination.

NOSOCOMIAL INFECTION SURVEILLANCE:

The development of a surveillance is an essential first step

to identify local problems , and evaluate the effectiveness

of the infection control activity.

Objectives:

The purpose of surveillance program is to detect, record,

and report hospital acquired infection aiming to reduce

them and their costs.

N

2. Strategy of Surveillance: A surveillance system must meet the following criteria:Simplicity: to minimize costs and work load, and promote

unit participation by feedback.Flexibility: to allow changes when appropriate.

Acceptability: Evaluated by ICC according to data analysis.

Consistency: use standardized definitions and methodology

Sensitivity. Specificity.

Infection Control Committee:1-Management2-Epidemiologist 3-Physicians4-Other health care workers(Laboratory, or Nurse).5-Clinical microbiologist 6-Pharmacy 7-Central supply 8-Maintenance

Tasks (most important) of the committee -To review and approve a yearly program of activity for surveillance and prevention.

-To review epidemiological surveillance data and identify areas for intervention.

Role of the physician:1-Direct patient care using practices which minimize infection.2-Appropriate practice of hygiene: (hand washing, and isolation).3-Supporting the infection control team.

4-Protecting their own patients from other infected patients and from hospital staff who may be infected.

5-Obtaining appropriate microbiological specimens when an infection is present or suspected.

Stool Analysis

بالكامل _     الباقيتان المحاضراتان

Stool analysis is a series of tests done on stool (feces) samples for differential diagnosis of certain diseases of digestive system.

Clinical significance of stool analysis:• Diagnosis of digestive system infections: Bacteria, parasites, virus,

and fungi. • Diagnosis of pancreas disorders (inflammation); malabsorption of

nutrients (fat).• Primary screening test for some types of digestive system

malignancy such as: colon cancer (occult blood). • Primary screening for peptic ulcer disease, and some types of

anemia (occult blood).

Which patients need urgent stool analysis?• Patients with diarrhea.• Patients with abdominal pain.• Patients with anemia.Other patients for whom stool analysis is non-

urgently required: Patients who is too thin or do not grow well. Patient with stool color that is changed to

abnormal color.

Stool analysis procedure is divided into:•Physical examination:• Color• Consistency

•Chemical examination:• PH• Sugar content.• Fat content.• Occult blood.

•Microscopic examination.

Physical Examination: Color: Normal feces is dark brown color (bilirubin in the presence of bacteria is oxidized to urobilinogen which is reduced to stercobilin which gives the stool its color).Abnormal Color:

• Black color: blood of upper GIT origin.

• Red color: blood of lower GIT origin. • White color: yeast fermentation (Candida).• Very pale color: biliary obstruction or barium (swallow or enema).

N

Consistency:• Normal feces is solid to semi-solid depending on the type of diet.• Liquid stool indicates diarrhea (gastroenteritis). • A ribbon like fecal specimen could indicate irritable bowl

syndrome or GIT obstruction. • Fatty stool indicates mal-digestion; Vitamins deficiency (A,D,E,K).

Chemical Examination: The pH: The pH of the stool is 7.0-7.5 (low PH indicate

carbohydrate malabsorption). Sugar contents: The stool contains less than 0.25 grams per deciliter (g/dL) or less than 13.9 millimoles per liter (mmol/L) of sugars.Elevated sugar indicates (more than 0.5g/dl): Lactose intolerance.

Fat contents: The stool contains 2-7 grams of fat /24h.

High levels of fat in the stool may be caused by diseases such as pancreatitis, cystic fibrosis, or celiac disease (autoimmune allergy to gluten protein in wheat).

Test: add 95% ethanolic-Sudan black-II stain or acetic acid to the specimen: 60 red droplets of neutral fats on HPF is considered fat malabsorption (steatorrhea).

N

Occult blood: Stool guaiac test : • Stool applied to a paper surface with phenolic compound alpha-

guaiaconic acid.• Hydrogen peroxide is then added • H2O2 oxidizes guaiaconic acid to dark-blue color within two

seconds. • Heme is a catalyst of this reaction.

N

Patients should be instructed to avoid eating red meat, horse- radish, aspirin, or vitamin C as they interfere with the test by their catalases and peroxidases .Clinical significance of the test:- Diagnosis of colorectal cancer.- Diagnosis of ulcerative hemorrhoids.- Invasive gastroenteritis.

Microscopic Examination: • Fecal leukocytes, especially neutrophils are associated with

dysentery. They can be detected by stool smears stained with gram stain.

• Parasites: o Wet-mount smear (0.9% saline) or Iodine stained.

• Wet mount smear: Show the motility of active Protozoa.

• Iodine smear: Show the nucleus and karyosome of protozoa.

Protozoa: cysts and trophozoite• Entamoeba histolytica.• Giardia lamblia.• Balantidium coli.Helminths:• Ova ‘egg’:• Schistosoma mansoni.• Taenia worms• Ascaris lumbricoides.• Hook worms.• Trichuris trichiura.• Enterobius vermicularis.

• Larva: Strongyloides stercoralis.

Amoebic dysentery: Entamoeba histolytica

(Rhizopoda)- Offensive stool.- Macroscopic: Feces mixed with blood and mucus.- Microscopic: RBCs, pus, mucus, and Entamoeba histolytica cyst or/and trophozoite (central karyosome).- Trophozoite show motility in one direction.

Entamoeba cyst (infective and diagnostic stage)

Entamoeba trophozoite (diagnostic stage)

Entamoeba histolytica life cycle:N

Giardia intestinalis Gastrointestinal Mastigophora. Habitat: Small intestine especially in duodenum. Disease: Fatty diarrhea especially in children. Morphology:

• Trophozoite: four pairs of flagella.• Cyst.

Giardia cyst (infective and diagnostic)

Giardia trophozoite (diagnostic stage).

Balantidial dysentery: Balantidium coli:

- Ciliophora. - Kidney-shaped macronucleus and small micronucleus.- Ingestion of food and water contaminated by the cysts.

Helminths: Schistosoma mansoni:- Trematoda.- Intestinal bilharziasis.- Diagnosis: finding of ova with lateral spine in the stool.

Taenia (Cestoda) infection:• Taenia saginata (beef tapeworm). • Taenia solium (pork tapeworm).Diagnostic stages:o Gravid segments. o Hexacantho-embryonated ova.

N

Ascaris lumbricoides: (Nematoda)Diagnostic stage: • un-fertilized ova, fertilized, or embryonated ova.• Adult stage.

unfertile ova

embryonated ovaFertile ova

Ascaris lumbricoides life cycle:

N

N

Hook worms: - Ancylostoma duodenale.- Nematoda. - Diagnostic stage: 4-8 cell embryonated ova.

N

Enterobius vermicularis: -Nematoda.

Diagnostic stage: D-shaped ova.

D-Shaped Ova

n

Trichocephalus trichiuris:

barrel shaped-egg with two polar plugs

N

Strongyloides stercoralis: -Free-living Nematoda.-Diagnostic stage: Rhabditiform larvae in stool.