Infection PDF

Infection Chain of infection  Vertical Infection (Vertical transmission) Toxoplasma gondii, other (listeria monocytogenes, Treponema pallidium, Parvovirus, HIV, Varicella zoster virus), Rubella, Cytome...

Infection Chain of infection  Vertical Infection (Vertical transmission) Toxoplasma gondii, other (listeria monocytogenes, Treponema pallidium, Parvovirus, HIV, Varicella zoster virus), Rubella, Cytomegalovirus (CMV), and Herpesviruses (HSV) 1 and 2. (TORCH) Tests used to Diagnose Infection Pyrexia of unknown origin (PUO) Pyrexia of unknown origin (PUO) was classically defined as a temperature above 38.0°C on multiple occasions for more than 3 weeks, without diagnosis, despite initial investigation in hospital for 1 week. The definition has been relaxed to allow for investigation over 3 days of inpatient care, three outpatient visits or 1 week of intensive ambulatory investigation. Subsets of PUO are described as HIV-1 related, immune-deficient or nosocomial. Infection (30%) Connective TD (15%) Miscellaneous(30%) Malignancy (20%) Idiopathic (15%) Fever - Sweating Bacterial Infection Gram film appearances of bacteria on light microscopy (×100). Covid -19 4-14 days Incubation periods of important infections Incubation periods of important infections Incubation periods of important infections History-taking in suspected infectious disease Normal flora Human non-sterile sites and normal flora in health. Staphylococcal infections Staphylococci are usually found colonizing the anterior nares and skin. Traditionally , staphylococci were divided into two groups according to their ability to produce coagulase, an enzyme that can converts fibrinogen to fibrin in rabbit plasma, causing it to clot. Staph. aureus is the main cause of staphylococcal infections. Staph. Intermedius is another coagulase positive staphylococcus, which causes infection following dog bites. Among coagulase-negative organisms, Staph. Epidermidis is the, predominant commensal organism of the skin,& can cause severe infections in those with central venous catheters , implanted prosthetic materials or IV canulae. Infections caused by Staphylococci Skin infections Staphylococcal infection can cause : ecthyma, folliculitis, furuncles, carbuncles bullous, impetigo and the scalded skin syndrome. They may also be involved in necrotizing infection of the skin and subcutaneous tissues. Ecthyma folliculitis Furuncle Carbuncle Scalded skin infection  Wound Infections Many wound infections caused by staphylococci which may significantly prolong post-operative hospital stays.. Prevention involve careful hand hygiene, skin preparation and aseptic technique, and the use of topical and systemic antibiotic prophylaxis. Treatment is by drainage of any abscesses plus adequate dosage of anti-staphylococcal antibiotics. These should be instituted early, particularly if prosthetic implants of any kind have been inserted.  Cannula related infection Staphylococcal infection associated with cannula sepsis and thrombophlebitis is an important and, unfortunately, extremely common reason for morbidity following hospital admission.. Staphylococci have a predilection for plastic, rapidly forming a biofilm which remains as a source of bacteraemia as long as the plastic is in situ. Cannula removal and antibiotic treatment with flucloxacillin (or a glycopeptide if MRSA is suspected) are necessary if there is any suggestion of spreading infection. Meticillin-resistant staph. aureus Resistance to meticillin, due to a penicillin-binding protein mutation, has been recognised in Staph. aureus for more than 30 years. The recognition of resistance to vancomycin/teicoplanin (glycopeptides) in either glycopeptide intermediate Staph. Aureus (GISA) or, rarely, vancomycin-resistant (VRSA) strains threatens the ability to manage serious infections produced by such organisms.. Treatment should always be based on the results of antimicrobial susceptibility testing, since resistance to all these agents occurs. Milder MRSA infections may be treated with clindamycin, tetracyclines or co- trimoxazole. Glycopeptides, linezolid and daptomycin are reserved for treatment of more severe infections.  Streptococcal infections Streptococci are nasopharyngeal and gut commensals, which appear as Gram-positive cocci In chains. They are classified by the haemolysis they produce on blood agar and by their serotypes. Skin presentations of streptococcal infections group A streptococci (GAS) are the major cause of cellulitis, erysipelas and impetigo. Groups C and G streptococci cause cellulitis, in elderly, diabetic or immunocompromised patients in particular. Group B streptococcal (GBS) infection is an increasing problem at the extremes of age. Impetigo Erysipelas cellulitis Streptococcal scarlet fever Group A (or occasionally groups C and G) streptococci causing pharyngitis , tonsillitis or other infection may lead to scarlet fever, if the infecting strain produces a streptococcal pyrogenic exotoxin. Common in school age children, scarlet fever can occur in young adults who have contact with young children. A diffuse erythematous rash occurs, which blanches on pressure, classically with circumoral pallor. The tongue initially coated ,becomes red and swollen(strawberry tongue). The disease lasts about 7 days, then rash dissappearing in 7- 10 days, followed by a fine desquamation. Residual petechial lesions in the antecubital fossa may be seen(Pastia’s sign).. Treatment with susceptible antibiotics(Pencillin) , which can beneficial to prevent rheumatic fever but not Poststreptococal Glomerulo - nephritis ,which may need follow up(GUE)for microscopic haematuria. Pressure blanch strawberry tongue Pastia’s sign Questions and Answers