infection and therapy

8/6/2019 Infection and Therapy

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Infection


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Infection - Definition The lodgment & multiplication of a parasite in or on

the tissues of a host


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Introduction to Microorganisms Bacteria- They are unicellular prokaryotes

Fungi - Fungi includes multicellular or unicellularorganisms.

Viruses- Viruses do not fall in the category of

unicellular microorganisms as they do not possessa cellular organization. It contains only one type ofnucleic acid, either DNA or RNA


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Bacteria


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Classification according to ShapeCocci - spherical likee.g. Streptococci( pneumonia)

Bacilli - rodshaped likee.g. Lactobacilli

Vibrio -comma shaped

e.g Vibrio cholerae (cholera)

Spirochetesspiral forms e.g.Treponema pallidum ( syphillis)

Filamentouse. . actinom ces infec. Lun s


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Nutrition & Oxygen RequirementHeterotrophs

saprophytes parasites

Symbiosis

Oxygen Requirements

Aerobic

Anaerobic


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Gram staining Important feature used to classify bacteria

Gram's stain will highlight peptidoglycan (acomponent of the cell wall)

Bacteria that are Gram-positive are stained violet

by Gram staining, in contrast to Gram-negativebacteria which are stained pink in colour


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Overview : Bacterial Infections If bacteria make it past our immune system

(protective system) and start reproducing inside our

bodies, they cause disease.

Certain bacteria produce chemicals that damage ordisable parts of our bodies.

Antibiotics/antimicrobials work to kill bacteria.

Antibiotics/antimicrobials are specific to certain

bacteria and disrupt their function.


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Antibiotics- " Magic Bullets" Antibiotic is the substances produced by various

species of microorganisms: bacteria, fungi,

actinomycetes, to suppress the growth of othermicroorganisms and to destroy them. An antibiotic is a selective poison. It has been chosen so that it will kill the desired

bacteria, but not the cells in your body.

Each different type of antibiotic affects different bacteriain different ways.

Today the term antibiotic extends to include syntheticagents killing bacteria (Antimicrobials) : sulfonamidesand quinolones.


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Antibacterial : Modes of Action

Cell wall synthesis inhibitors: Natural penicillins,Semisynthetic penicills, Cephalosporins Carbapenems,

monobactams, Isoniazide etc.Proteinsynthesis inhibitors: Macrolides,Aminoglycosides, tetracyclines, chloramphenicol etc.

Plasma membrane disruptors: polymyxin B,

Bacitracin.

Nucleic acidsynthesis impairment: Quinolones,nalidixic acid, Fluoroquinolones

Metabolite mimic: Sulphonamides, co-trimoxazole etc.


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Upper Respiratory Tract Infection


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Background Upper respiratory tract infection (URTI) represents

the most common acute illness evaluated in the

outpatient setting. URTIs range from the common cold, typically a mild,

self-limited, catarrhal syndrome of the nasopharynx,to life-threatening illnesses such as epiglottitis.

Viruses account for mostURTIs.

Bacterial primary infection or superinfection mayrequire targeted therapy.


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URTI The upper respiratory tract includes the sinuses,

nasal passages, pharynx, and larynx, which serve as

gateways to the trachea, bronchi, and pulmonaryalveolar spaces.

Rhinitis, pharyngitis, sinusitis, epiglottitis, laryngitis,and tracheitis are specific manifestations ofURIs.


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Common URI terms are defined

as follows: Rhinitis - Inflammation of the nasal mucosa

Rhinosinusitis or sinusitis - Inflammation of the

nares and paranasal sinuses, including frontal, ethmoid,maxillary, and sphenoid

Nasopharyngitis (rhinopharyngitis or thecommon cold) - Inflammation of the nares, pharynx,

hypopharynx, uvula, and tonsils

Pharyngitis - Inflammation of the pharynx,hypopharynx, uvula, and tonsils


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Epiglottitis (supraglottitis) - Inflammation of thesuperior portion of the larynx and supraglottic area

Laryngitis - Inflammation of the larynx Laryngotracheitis - Inflammation of the larynx,

trachea, and subglottic area

Tracheitis - Inflammation of the trachea and

subglottic area Otitis media is an infection or inflammation of the

middle ear. This inflammation often begins wheninfections that cause sore throats, colds, or otherrespiratory or breathing problems spread to the

middle ear.


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Pathophysiology URIs involve direct invasion of the mucosa lining the

upper airway.

Person-to-person spread of viruses accounts for mostURIs.

Patients with bacterial infections may present insimilar fashion, or they may present with asuperinfection of a viral URI.

Inoculation by bacteria or viruses begins whensecretions are transferred by touching a handexposed to pathogens to the nose or mouth or bydirectly inhaling respiratory droplets from an infectedperson who is coughing or sneezing.


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Pathophysiology Most symptoms ofURIs, including local swelling,

erythema, edema, secretions, and fever, result from

the inflammatory response of the immune system toinvading pathogens and from toxin production frompathogens.

An initial nasopharyngeal infection may spread toadjacent structures, resulting in sinusitis, otitis

media, epiglottitis, laryngitis, tracheobronchitis, andpneumonia.


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Bacterial pharyngitis History alone is rarely a

reliable differentiator

between viral andbacterial pharyngitis.

If symptoms persistbeyond 10 days orprogressively worsenafter the first 5-7 days,a bacterial illness issuggested.


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Bacterial pharyngitis Pharyngeal symptoms: Sore or scratchy throat,

odynophagia, or dysphagia Secretions Cough

Foul breath

Headache

Fatigue or malaise

Fever: While usually slight or absent, temperaturesmay reach 38.9C (102F) in infants and youngchildren.


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Bacterial Rhinosinusitis The presentation of rhinosinusitis is often similar to

that of nasopharyngitis Acute bacterial rhinosinusitis is not common in

patients whose symptoms have lasted fewer than 7days.

Symptoms: Nasal discharge Hyposmia or anosmia

Facial or dental pressure or pain Oropharyngeal symptoms Halitosis Cough Fever Fatigue or malaise


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Laryngotracheitis Nasopharyngeal symptoms

Hoarseness or loss of voice

Posttussive gagging or emesis Dyspnea

Other symptoms like fever, chills, nonproductivecough, and headache


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Otitis Media Otitis media is an

inflammation of the

middle ear (the cavitybetween the eardrumand the inner ear).

Otitis media that fails toclear up after threemonths or more iscalled chronic otitismedia.


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Symptoms of Otitis Media Acute otitis media causes

sudden, severe earache

deafness, and tinnitus (ringing or buzzing in the ear)

sense of fullness in the ear irritability

fever

headache

fluid leaking from the ear,

nausea and difficulty in speaking and hearing

Occasionally, the eardrum can burst, which causes adischarge of pus and relief of pain.


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Medical Therapies Antibiotics

Amoxicillin Cefadroxil Erythromycin Co-amoxiclav Cefaclor Cefuroxime Ceftriaxone Azithromycin

Anti-histaminics NSAIDs Anti-tussives Nasal Decongestants


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Lower Respiratory tract Infections


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Community Acquired Pneumonia


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Background Community-acquired pneumonia (CAP) is one of the

most common infectious diseases addressed by

clinicians.

CAP is an important cause of mortality and morbidityworldwide.

CAP is usually acquired via inhalation or aspiration ofpulmonary pathogenic organisms into a lung segmentor lobe.


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M pneumoniae

1%6%

C pneumoniae

4%6%

H influenzae

3%10%

Others

3%i10%

Viruses

2%15%

Legionella spp

2%8%

S pneumoniae

20%60%

S aureus

3%5%

1. Bartlett JG, Mundy LM. NEngl J Med. 1995;333:16181624.

Respiratory pathogens in CAP


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Symptoms Patients with bacterial CAP typically present with

variable degrees of fever, usually with a productive

cough and often with pleuritic chest pain.

The clinical presentation ofCAP due to atypicalpathogens is usually less acute than CAP due totypical bacterial pathogens.

CAP due to atypical pathogens may have one ormore extrapulmonary features, which is a clue totheir presence.


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Treatment measures Patients with CAP who are moderately to severely ill

should be hospitalized.

Patients with severe CAP require admission to anintensive care unit (ICU). Oxygen and/or ventilatorysupport may be required.

Because the severity ofCAP frequently is due tounderlying severe cardiopulmonary disease, directmedical efforts at supporting cardiopulmonaryfunction while administering antibiotics for CAP.


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Medical Treatment Antibiotic therapy

Beta-lactam group of drugs including carbapenem

Beta-lactam / beta-lactamase inhibitor combination Tetracyclin

Quinolones

Macrolides

Other supportive treatment


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AECB

Acute Exacerbation ofChronic Bronchitis


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Background Chronic bronchitis belongs to a larger family of

medical conditions known as chronic obstructive

pulmonary disease (COPD

).

The term COPD is given to any condition thatcauses difficulty in breathing as a result of constantblocking of the airways.


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Bronchitis Bronchitis: When the airways

in the lungs (bronchial tubes)

become partly clogged withlarge amounts of mucus andbecome narrowed due toinflammation and swelling.

chronic bronchitis : Whencough and sputum havebeen present for more thanthree months in each of two

consecutive years


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AECB When breathing suddenly becomes more difficult for

a person with chronic bronchitis, he or she may be

experiencing an acute exacerbation of chronicbronchitis (AECB).

During an acute exacerbation, breathing becomesmuch more difficult because of further narrowing ofthe airways and secretion of large amounts of mucusthat is often thicker than usual.


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Causes Allergens (e.g., pollens, wood or cigarette smoke,

pollution), toxins (a variety of different chemicals), oracute viral or bacterial infections.

Extra mucus in the airways of a person with chronicbronchitis provides a good place for viruses andbacteria to grow.

Bacterial infections are usually associated with mucusthat turns a yellow or greenish colour and is typicallymuch thicker than usual.


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Symptoms and Complications Increased frequency & severity of coughing, and is

often accompanied by worsened chest congestionand discomfort.

If the acute exacerbation is due to a bacterialinfection, the sputum may be slightly streaked withblood and coloured yellow or green.

In many cases of AECB, shortness of breath andwheezing are present.

Malaise, fever and chills might be presents


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Medical Treatment Anti-tussive

Bronchodilator

Antibiotics Steroids


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Urinary Tract Infections


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Background A urinary tract infection, or

UTI, is an infection that canhappen anywhere along the

urinary tract. The urinarytract includes the:

Kidneys

Ureters -- the tubes that take

urine from each kidney to thebladder

Bladder

Urethra -- the tube thatempties urine from the bladder

to the outside


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UTI Urinary tract infections (UTIs) have different names,

depending on where the infection is located.

Cystitis: a common condition, is an infection of thebladder. It is usually caused by bacteria entering theurethra and then the bladder. This leads toinflammation and infection in the lower urinary tract.

Pyelonephritis: is an infection of one or bothkidneys and the surrounding area.


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Symptoms The symptoms of a bladder infection include:

Cloudy urine

Foul or strong urine odour

Frequent or urgent need to urinate

Low fever (not everyone will have a fever)

Need to urinate at night

Pain or burning with urination Painful sexual intercourse

Pressure in the lower pelvis


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Symptoms If the infection spreads to the kidneys, symptoms

may include: Chills and shaking

Fatigue Fever above 102 degrees Fahrenheit, which lasts for more

than 2 days

Flank (side) pain

Flushed, warm, or reddened skin

General ill feeling Mental changes or confusion (in the elderly, these

symptoms often are the only signs of an UTI)

Nausea and vomiting

Severe abdominal pain (sometimes)


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Treatment Commonly used antibiotics include:

Beta-lactam group of drugs Cephalosporins Doxycycline (should not be used under age 8) Nitrofurantoin Sulfa drugs (sulfonamides) Trimethoprim-sulfamethoxazole Quinolones (should not be used in children)

to relieve the burning pain and urgent need tourinate, and to decrease bacteria in your urine:

Acidifying medications such as ascorbic acid to lower theconcentration of bacteria in the urine

Phenazopyridine hydrochloride (Pyridium) to reduce urgencyand burning with urination


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Pyrexia ofUnknown Origin


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Background Fever of unknown origin (FUO) was defined in 1961

by Petersdorf and Beeson as the following:

(1) a temperature greater than 38.3C (101F) onseveral occasions,

(2) more than 3 weeks' duration of illness, and

(3) failure to reach a diagnosis despite one week ofinpatient investigation


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Pathophysiology FUOs are caused by

infections (30-40%),

neoplasms (20-30%),

collagen vascular diseases (10-20%), and

numerous miscellaneous diseases (15-20%)

The literature also reveals that between 5 and 15%

ofFUO cases defy diagnosis, despite exhaustivestudies.


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Causes Bacterial diseases

Abscesses

Tuberculosis

Urinary tract infections

Others which are rare: e.g. endocarditis etc.

Viral diseases e.g. HIV

Fungal infections

Parasitic infections

Others like autoimmune disorders, drug fever etc.


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Medical Care Treatment should be directed toward the underlying

cause, as needed, once a diagnosis is made.

The medications used depend on the etiology of thefever of unknown origin (FUO).


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SSSI


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Introduction Dermatologists treat a variety of uncomplicated skin

and skin structure infections (uSSSIs) such asfolliculitis,

impetigo,

erysipelas,

cellulitis,

furuncles,

Carbuncles Abscess

Most uSSSIs are caused by Staphylococcus aureusand Streptococcus pyogenes.


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Impetigo Contagious skin infection affecting mainly

infants and children.

The causative organisms: hemolyticstreptococci or staphylococci .

The eruption consists of small red spots orblisters that rupture, discharge, andbecome encrusted.

The infection is easily spread over the skinby fingernails because of its symptomaticitching; it can also be spread bycontaminated linen, clothing, or otherobjects.


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Cellulitis Cellulitis is an acute inflammation of the connective

tissue of the skin, caused by infection withstaphylococcus, streptococcus or other bacteria

Most common on the lower legs and the arms orhands, although other areas of the body maysometimes be involved. If it involves the face

(erysipelas), medical attention is urgent.


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Symptoms Localized skin redness or inflammation that

increases in size as the infection spreads Tight, glossy, "stretched" appearance of the

skin

Pain or tenderness of the area Skin lesion or rash (macule):

Sudden onset Usually with sharp borders Rapid growth within the first 24 hours

Warmth over the area of redness Fever Other signs of infection:

Chills, shaking Fatigue Muscle aches, pains (myalgias) General ill feeling (malaise) Warm skin, sweating


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Erysipelas Skin infection typically caused by

group A beta-hemolytic streptococci,although other streptococcal groups

are occasionally causative agents. Erysipelas is a febrile illness with

dermatological findings, characterizedby an abrupt onset of illness with

initial fever and chills followed by apainful rash occurring 1-2 days later

Muscle & joint pain, nausea,headache, skin discomfort and othersystemic manifestations of an

infectious process is noted.


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Furuncle (Boil) A skin infection involving an entire

hair follicle and nearby skin tissue.

Furuncles are very common.Furuncles are generally caused byStaphylococcus aureus, but theymay be caused by other bacteria orfungi found on the skin's surface.

May occur in the hair folliclesanywhere on the body, but mostcommon on the face, neck, armpit,

buttocks, and thighs.


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Carbuncle skin infection that often

involves a group of hairfollicles. The infected material

forms a lump, called mass,which occurs deep in theskin.

When you have more thanone carbuncle, the conditionis called carbunculosis.

Most carbuncles are causedby the bacteriastaphylococcus aureus. Theinfection is contagious andmay spread to other areas of

the body or other people.


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Carbuncle A carbuncle is made up of several skin boils

(furuncles). The infected mass is filled with fluid, pus,and dead tissue. Fluid may drain out of thecarbuncle, but sometimes the mass is so deep that itcannot drain on its own.

Carbuncles may develop anywhere, but they are

most common on the back and the nape of the neck.Men get carbuncles more often than women.


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Abscess An abscess is a cavity containing pus

and surrounded by inflamed tissue,formed as a result of a localized

infection Common sites include the breast, gums

and peri-rectal area

Common bacteria, such as staphylococci

cause abscess on the skin Fungal infections sometimes cause

abscesses, while amoebae (single-celledprotozoal parasites) are an importantcause of liver abscesses.


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Treatment Depending upon the organisms involved, Antibiotics

are chosen

Other supportive treatment is given

infection and therapy

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