Bacterial Infections of the Upper Respiratory Tract; Streptococcal

Pharyngitis

Group 4

UPPER RESPIRATORY TRACT INFECTIONS

• Rhinitis• Sinusitis• Nasopharyngitis(common

cold)• Laryngitis

• Pharyngitis• Epiglottis• Laryngotracheatis• Tracheatis

Members• Orimoloye Philip Oluwafemi 110705136• Akinlotan Elizabeth 120705715• Imaguezegie Grace Ese 120705739• Onochie Martins 110705134• Cole Oluwafunke 110705036• Adelakun Davidson 120705706• Dauda Adebisi 100705065• Shote Olaitan B. 100705154• Bello Mariam Y. 120701709

Members• Ariahu Nonso 110705052• Balogun Abdulkhalil 110705055• Agboola Tomilola 110705026• Amusa Omolabake R. 110705046• Toriola Temilola 110705156• Adeyemi Barbara 120705708• Ogidan Lucky 110705109• Ugboke Joshua O. 110705158• Odulaja Ayobami O. 120705751

Members

• Oladotun Oluwafunmbi O. 120701737• Faminu Akin E. 110701016• Ndifon Minka 110705101• Mokwenye Sylvester 120701718• Awosika Oluwakorede I. 120705722

INTRODUCTION

• The upper respiratory tract consists of the sinuses, nasal passages, pharynx, larynx which serve as a gateway for air to move into trachea, bronchi and pulmonary alveolar spaces.

• The respiratory tract is the most common site with infections by pathogens.• URTIs is a non specific term used to describe acute infections involving the

nose, paranasal sinuses, pharynx, larynx, trachea and bronchi.• A wide range of organisms can infect the respiratory tract including

VIRUSES, BACTERIA , FUNGI AND PARASITES.• Viruses cause most URTIs with rhinovirus, parainfluenza, coronavirus,

adenovirus, respiratory syncytial virus. Coxsackie virus, human metapneumovirus and influenza virus accounting for most cases.

• It represent the most common acute illnesses evaluated in outpatient settings.

• It ranges from common colds-typically self limited, catarrhal syndrome of the nasopharynx to the life threatening epiglottis.

Bacteria that cause upper respiratory tract infections

• Group A beta haemolytic streptococcus• Group C beta haemolytic streptococcus• Corynebacterium diphtheriae• Neisseria gonorrhoea• Arcanobacterium haemolyticum• Chlamydophilia pneumoniae• Mycoplasma pneumoniae• Haemophilus influenza• Moraxella catarrhalis• Bordetella pertussis• Bordetella parapertussis

MODE OF TRANSMISSION

• Transmission of organisms causing URTIs occurs by aerosols, droplets from coughing and sneezing or direct hand to hand contact with infected secretions with subsequent passage to the nares or eyes.

• These infections occur more frequently in cold seasons or weather and crowded areas.

• After inhalation or contact with the organism, there is direct invasion of the respiratory epithelium resulting in symptoms corresponding to the areas involved.

GENERAL SIGNS AND SYMPTOMS

• There is significant overlap in the clinical manifestations of the different URTIs.• Onset of symptoms occurs 1-3 days after exposure to the pathogens.• Generally, the symptoms of URTIs result from the toxins released from the

pathogens as well as the inflammatory response mounted by the immune system to fight the infections.

• Common symptoms of the URTI’s include

Nasal congestion

Runny nose (rhinorrhoea)

Nasal Discharge( may change from clear to white to green)

Nasal Breathing

Sneezing

Sore throat or scratchy throat

painful swallowing(odynophagia)

cough(from laryngeal swelling and post nasal drip)

malaise and

fever( more common in children)

• Other less common symptoms may include

Foul breath

Poor smelling sensation (hyposmia)

Headache

Shortness of breath

Sinus pain

Itchy and watery eye(conjunctivitis)

Nausea and vomiting

Diarrhoea

Body aches• Symptoms last between 3-14 days; if symptoms last longer than that

alternative diagnosis should be considered.

GENERAL DIAGNOSIS OF URTIs

• The diagnosis of URTIs is typically made based on REVIEW OF SYMPTOMS, PHYSICAL EXAMINATION and OCCASIONALLY LABORATORY TESTS.

• Laboratory testing is generally not recommended in the evaluation of URTIs because most are are caused by viruses hence specific testing is not recommended.

• Some important situations where specific testing is required includes: suspected strep throat Possible bacterial infection Prolonged symptoms Evaluation of allergens and asthma Enlarged lymph node and sore throat that may be caused by Epstein Barr

Virus(mononucleosis) Testing for swine flu if suspected.

Introduction• The Upper respiratory tract consists of the

nose and nasal passages, paranasal sinuses, the pharynx and the portion of the larynx above the vocal cords.

• Pharyngitis is the inflammation of the Pharynx, hypopharynx, uvula and tonsils.

• Streptococcal pharyngitis is mainly caused by Streptococcus pyogenes. It could also be caused by a group of species called Streptococcus dysgalactiae

Introduction

• Although humans can be asymptomatic nasopharyngeal or perineal carriers of S pyogenes, the organism should be considered significant if it is detected by culture or other means.

• The ultimate source of group A streptococci is a person harboring these organisms.

• The individual may have a clinical or subclinical infection or may be a carrier distributing streptococci directly to other persons via droplets from the respiratory tract or skin.

• The nasal discharges of a person harboring S pyogenes are the most dangerous source for spread of these organisms.

Aetiology

• Group A streptococcus (Streptococcus pyogenes) is the leading cause of pharyngitis and cellulitis.

• It is also an important cause of impetigo, necrotizing fascilitis and streptococcal toxic syndrome.

• It is also the inciting factor of two immunologic diseases: RHEUMATIC FEVER AND ACUTE GLOMERULONEPHRITIS

• Streptococcus are gram positive cocci arranged in

chains or pairs.• All streptococci are CATALASE NEGATIVE.

CLASSIFICATION OF STREPTOCOCCI

Based on the type of hemolysis

1. Alpha hemolytic streptococcus

2. Beta hemolytic streptococcus

3. Peptostreptococcus

ALPHA HEMOLYTIC STREPTOCOCCI

• Form green zone around their colonies as a result of incomplete lysis of Red Blood cells in the agar.

• The green color is formed when hydrogen peroxide produced by the bacteria oxidizes hemoglobin (Red) to biliverdin (Green).

• The principle organisms in this group are Streptococcus pneumonia and Streptococcus viridans group (S. sanguis, S .mutas)

• Streptococci pneumonia growth is inhibited by OPTOCHIN and its colonies dissolve when exposed to bile while the viridans group doesn’t exhibit these characteristics.

• Inflammation is thought to be the major way pnemococcus causes disease.• Viridans streptococci are part of the normal flora of the human pharynx

and intermittently reach the blood stream to cause endocarditis.• Some viridans group are non hemolytic.

BETA HEMOLYTIC STREPTOCOCCI• Form a clear zone around their colonies because of complete lysis of red cells

occur.• Beta hemolysis is due to production of enzymes (hemolysins called streptolysin o

and streptolysin s).

Antigens used in beta hemolysis

1. C- carbohydrate: determines the group, located in the cell wall and its specificity is determined by an amino sugar.

2. M-protein: most important virulence factor and determines the type of Group A hemolytic streptococci. It protrudes from the outer surface of the cell and interferes with ingestion of phagocytes (i.e antiphagocytic). Antibody to M protein provides type specific immunity.

• Approximately 80 serotypes based on M protein• The type of M protein produced by the strain of S. pyogenes determines if it will

primarily cause rheumatic fever or acute glomerulonephritis.• Beta hemolytics are arranged into groups A-H and K-U (Lancefield groups)

based on the antigenic difference of the M protein.

Group A streptococcus (Streptococcus pyogenes)

• Major bacterial cause of pharyngitis and common cause of other skin infections (impetigo).

• They adhere to pharyngeal epithelium via pili composed of lipoteichoic acid and M protein.

• Infection may be invasive (more severe and less common) or non-invasive.

• Growth of S. pyogenes in the lab is inhibited by the antibiotic Bacitracin (an important diagnostic criteria).

• Additional complications may be caused by GAS namely: acute rheumatic fever and acute glomerulonephritis.

Group B streptococcus(Streptococcus

agalactiae)• Colonizes the genital tract of women and causes neonatal meningitis and

sepsis. • It increases the risk of premature rupture of membrane during pregnancy

and transmission of the organism to the infant.• They are Bacitracin resistant. • They hydrolyze (break down) Hippurate (an important diagnostic criteria).

Group C streptococcus (S. equi and S. zooepidemicus)• S. equi causes strangles in horses.• S. dysgalactiae is also a member that causes pharyngitis and other

pyogenic infections similar to group A streptococci.

Group D streptococcus• ENTEROCOCCI (e.g. E. faecalis and E. faecium) - Members of the normal flora of the colon and are noted to cause

URINARY, BILIARY and CARDIOVASCULAR INFECTIONS.- They are very hardy organisms; they can grow in hypertonic (65%), saline

or bile and are not killed by Penicillin G.- Hence synergistic combination of penicillin and aminoglycoside (e.g.

gentamicin) is required to kill enterococci.- Vancomycin can be used but vancomycin-resistant enterococci (VRE) have

emerged and become an important and much feared cause of life-threatening nosocomial infection.

• NON ENTEROCOCCI (S.bovis)- Cause similar infection but are inhibited by 6.5% sodium chloride and are

killed by penicillin.

Groups E, F, G, H, K – U rarely/infrequently cause human infections.

PEPTOSTREPTOCOCCI• Grow under anaerobic or microaerophilic

conditions and produce variable hemolysis.• Members of the normal flora of the gut, mouth

and female genital tract.• Participate in mixed aerobic infections

(infections caused by multiple bacteria: aerobes and facultative).

• Peptostreptococci and viridans streptococci (members of the normal oral flora are found in brain abscesses after dental surgery.

MODE OF TRANSMISSION• Most streptococci are part of the normal flora of the human

body but produce disease when they get access to blood and body tissues.

• Viridans and S. pneumoniae are found in the pharynx and oropharynx.

• S. pyogenes is found in the skin and oropharynx.• S. galactiae is found in the vagina and the colon.• Enterococci and anaerobic streptococci are found in the colon.

• GAS (Streptococci pyogenes is transmitted through large respiratory droplets or direct contact with infected persons or carriers.

• Outbreak of streptococcal infection may occur as a result of ingestion of contaminated foods such as milk, meat produce and eggs.

Morphology and Identification• Individual cocci are spherical or ovoid and are

arranged in chains.• Streptococci are gram positive but as culture

ages, they die and lose their gram positivity and appear as gram negative

• They produce capsules composed of hyaluronic acid which phagocytosis

• Their cell wall contains proteins (M, T, R antigens), carbohydrates and peptidoglycans

Morphology and identification• S pyogenes is Beta Hemolytic• They grow poorly on solid media or in broth,

unless enriched with blood or tissue fluids.• Growth and hemolysis are aided by incubation

in 10% Carbon dioxide.• They grow best at 37oC• They are facultative anaerobes and grow under

aerobic and anaerobic conditions

Morphology and Identification

• S pyogenes give rise to either matte or glossy colonies.

• Matte colonies consist of organisms that produce much M protein and generally are virulent.

• The S pyogenes in glossy colonies tend to produce little M protein and are often not virulent.

Pathogenesis

• When the organism enters the upper respiratory tract, it attaches itself to the epithelium lipoteichoic acid which is in the hair-like projections.

• M protein and hyaluronic acid in the capsule of the bacteria inhibits phagocytosis. thus increasing it's virulence.

• Thus causing inflammation (pharyngitis).

Clinical Features

• Sore throat• Fever with sudden onset (greater than 38.3

degrees C)• Tonsilar exudates• Cervical adenopathy• Swollen uvula• Palatal petechiae• Scarlatiniform rash

The above two are less common and highly specific.

Differential Diagnosis

Viral Pharyngitis• Absence of cough• Absence of Conjunctivitis• Nasal discharge• Diarrhea

Complications

• Acute rheumatic fever• Scarlet fever• Streptococcal toxic shock syndrome• Glomerulonephritis• Peritonsilar abscess• Cervical lymphadenitis• Mastoiditis

DIAGNOSIS

• There is broad overlap between the signs and symptoms of streptococcal and nonstreptococcal (usually viral) pharyngitis, and the ability to identify streptococcal pharyngitis accurately on the basis of clinical grounds alone is generally poor.

• Therefore, except when obvious viral clinical and epidemiological features are present, a laboratory test should be performed to determine whether GAS is present in the pharynx

• Selective use of diagnostic studies for GAS on the basis of clinical features increases not only the proportion of positive test results but also the proportion of patients who have positive test results and who are truly infected rather than mere carriers of streptococcus

Clinical diagnosis

• The modified Centor criteria may be used to determine the management of people with pharyngitis

• Based on 5 clinical criteria, it indicates the probability of a streptococcal infection

• One point is given for each of the criteria:– Absence of cough– Swollen and tender cervical lymph nodes– Temperature >38.0 degree celcius– Tonsillar exudate or swelling– Age less than 15 (a point is subtracted if age

>44)

Modified Centor scorePoints Probability

Of StrepManagement

1 orfewer

<10% N0 antibiotic orCulture needed

2 11-17% Antibiotic based onCulture or RADT

3 28-35% Antibiotic based onCulture or RADT

4 or 5 52% Empiric antibiotics

Laboratory diagnosis

Throat Culture– Culture of a throat swab on a sheepblood agar

plate has been the standard for the documentation of the presence of GAS pharyngitis in the upper respiratory tract and for the confirmation of the clinical diagnosis of acute streptococcal pharyngitis .

– If performed correctly, culture of a single throat swab on a blood agar plate is 90%–95% sensitive for detection of GAS pharyngitis

Rapid antigen detection test (RADT).– A major disadvantage of throat cultures is the

delay (overnight or longer) in obtaining results.

– RADTs have been developed for the identification

of GAS pharyngitis directly from throat swabs, with shorter turnaround time.

– A negative RADT should be accompanied by a follow-up or back-up throat culture in children and adolescents, while this is not necessary in adults under usual circumstances

Treatment• Untreated streptococcal pharyngitis usually

resolves within a few days. • The primary reason for treatment with

antibiotics is to reduce the risk of complications such as rheumatic fever and retropharyngeal abscesses and they are effective if given within 9 days of the onset of symptoms

Treatment

Analgesics• Analgesics such as non-steroidal anti-inflammatory

drugs (NSAIDs) and paracetamol(acetaminophen) help significantly in the management of pain associated with strep throat.

• Viscous lidocaine may also be useful. While steroids may help with the pain, they are not routinely recommended.

• Aspirin may be used in adults but is not recommended in children dueto the risk of Reye's syndrome

TreatmentAntibiotics

• The antibiotic of choice in the United States for streptococcal pharyngitis is penicillin V due to safety, cost, and effectiveness.

• Amoxicillin is preferred in Europe. In India, where the risk of rheumatic fever is higher, intramuscular benzathine penicillin G is the first choice for treatment.

• Appropriate antibiotics decrease the average 3–5 day duration of symptoms by about one day, and also reduce contagiousness. They are primarily prescribed out of a motivation to reduce rare complications such as rheumatic fever and peritonsillar abscess.

• The arguments in favor of antibiotic treatment should be

balanced by the consideration of possible side effects, and it is reasonable to suggest that no antimicrobial treatment be given to healthy adults who have adverse reactions to medication.

• Antibiotics are prescribed for strep throat at a higher rate than would be expected from its prevalence. Erythromycin and other macrolides or clindamycin are recommended for people with severe penicillin allergies.

• First generation cephalosporins may be used in those with less severe allergies and some evidence supports cephalosporins as superior to penicillin.

• Streptococcal infections may also lead to acute glomerulonephritis; however, the incidence of this side effect is not reduced by the use of antibiotics.

Prevention• Tonsillectomy may be a reasonable preventive

measure in those with frequent throat infections (more than three a year).

• The benefits are, however, small and episodes typically lessen in time regardless of measures taken. Recurrent episodes of pharyngitis which test positive for GAS may also represent a person who is a chronic carrier of GAS who is getting recurrent viral infections.

• Treating people who have been exposed but who are without symptoms is not recommended. Treating people who are carriers of GAS is not recommended as the risk of spread and complications is low.

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