Presentation on theme: "REVIEW OF MEDICAL MICROBIOLOGY"— Presentation transcript:
1REVIEW OF MEDICAL MICROBIOLOGY Infections ofRespiratory tractCardiovascular systemGastrointestinal tractSkin and soft tissueCentral nervous systemGenitourinary tract
2Upper Respiratory Tract THE RESPIRATORY TRACTUpper Respiratory TractPharyngitis (mostly 2 years through adolescence)AdenovirusesGroup A Streptococci (S. pyogenes)Potential for rheumatic feverChlamydophila pneumoniaeNeisseria gonorrhoeaeCorynebacterium diphtheriaeMycoplasma pneumoniae
3Otitis media (infants and young children) Streptococcus pneumoniae THE RESPIRATORY TRACTOtitis media (infants and young children)Streptococcus pneumoniaeHaemophilus influenzaeStaphylococcus aureusGroup A streptococcusMoraxella catarrhalisFormerly “Branhamella”Gram-negative cocciOpportunistic pathogen
4Staphylococcus aureus Pseudomonas aeruginosa Group A Streptococcus THE RESPIRATORY TRACTOtitis externaStaphylococcus aureusPseudomonas aeruginosaGroup A StreptococcusMalignant otitis externa• In diabetics, elderly & immunocompromised• Can lead to osteomyelitis and meningitis
5Streptococcus pneumoniae Haemophilus influenzae Staphylococcus aureus THE RESPIRATORY TRACTSinusitisStreptococcus pneumoniaeHaemophilus influenzaeStaphylococcus aureusChlamydophila pneumoniaeMoraxella catarrhalisGroup A StreptococcusPseudomonas aeruginosaVirusesOral anaerobic bacteria
6Streptococcus pneumoniae Group B Streptococcus Viridans Streptococcus THE RESPIRATORY TRACTConjunctivitisStreptococcus pneumoniaeGroup B StreptococcusViridans StreptococcusStaphylococcus aureusHaemophilus influenzaeMoraxella catarrhalis
7Conjunctivitis (contd) Pseudomonas aeruginosa Corynebacterium species THE RESPIRATORY TRACTConjunctivitis (contd)Pseudomonas aeruginosaCorynebacterium speciesFrancisella tularensisAdenovirusesChlamydia trachomatis
8Rhinocerebral mucormycosis • Life-threatening THE RESPIRATORY TRACTRhinocerebral mucormycosis• Life-threatening• Most common in diabetics• The fungi Mucor and Rhizopus invade bloodvessels, resulting in necrosis of bone andthrombosis of the cavernous sinus and internalcarotid artery
9Bacterial epiglottitis Life-threatening Haemophilus influenzae type b THE RESPIRATORY TRACTBacterial epiglottitisLife-threateningHaemophilus influenzae type bStreptococcus pneumoniaeStaphylococcus aureus
22A 40-year-old male with multisystem failure secondary to bilateral pneumonia was transferred to our hospital via helicopter.He had presented to his local physician 3 days previously complaining of fever, malaise, and vague respiratory symptoms.He was given amantadine for suspected influenza. His condition became progressively worse, with shortness of breath and a fever to 40.5˚C.From: “Cases in Medical Microbiology and Infectious Disease”
23He was admitted to an outside hospital 24 h prior to transfer. A laboratory examination revealed abnormal liver and kidney function.Therapy with Timentin (ticarcillin-clavulanic acid) and trimethoprim-sulfamethoxazole was begun.He underwent pronchoscopic examination which revealed mildly inflamed airways containing thin, watery secretions.
24A Gram-stain of bronchial washings and culture results are shown in the figure. Based on these findings, he was begun on appropriate antimicrobial therapy.
25Which organisms are common causes of community-acquired bacterial pneumonia?
26Streptococcus pneumoniae Haemophilus influenzaeMycoplasma pneumoniaeStaphylococcus aureus(frequently following an influenza infection)Klebsiella pneumoniae(elderly & alcoholics)Legionella pneumophilaChlamydophila pneumoniae
27On the basis of the Gram-stain of bronchial washings, and the patient’s presentation, what is the most likely cause of this patient’s catastrophic infection?Why must the laboratory be notified if this organism is considered in the differential diagnosis?
28The patient has Legionella pneumophila. Renal and hepatic dysfunction and thin watery secretions are characteristic of this infection.Patients with bacterial pneumonia due to most other bacterial agents have thick, purulent secretions.The laboratory needs to be informed because the organism requires a specific growth medium, buffered charcoal yeast extract (BCYE) agar.
29What techniques other than culture can be used to detect this organism within 24 h?
39THE CARDIOVASCULAR SYSTEM MyocarditisCorynebacterium diphtheriaeClostridium perfringensGroup A StreptococcusBorrelia burgdorferiNeisseria meningitidisStaphylocccus aureus
40Five days prior to admission she had developed a cough and rhinitis. The patient was a 4-month-old female who was admitted to the hospital in March with sever respiratory distress.Five days prior to admission she had developed a cough and rhinitis.Two days later she began wheezing and was noted to have a fever.She was brought to the emergency room when she became lethargic.From: “Cases in Medical Microbiology and Infectious Disease”
41One sibling was reported to be coughing, and her father had a “cold”. On examination she hada fever of 38.9˚Ctachycardia with a pulse of 220/mintachypnea with respirations of 80/minHer throat was clear.
42A chest X-ray revealed interstitial infiltrates. She was put in respiratory isolation in the pediatric intensive care unit, and was subsequently intubated.Blood and nasopharyngeal cultures were sent to the bacteriology and virology laboratories.A rapid diagnostic test was positive and specific antiviral therapy was begun.
43She was also given a bronchodilator (aminophylline) to treat the bronchospasm which was resulting in her wheezing.She was extubated 5 days later and discharged home on day 8.1. What are the possible causes for this patient’s pneumonia?
44Parainfluenza virusInfluenza A and BRespiratory syncytial virusMycoplasma pneumoniaeBordetella pertussis
462. What other techniques could one use to identify this microorganism?
47Direct Fluorescence Antibody “Shell Vial Assay”Fibroblasts grown on coverslips in a shell vialClinical specimens a centrifuged onto the cell monolayerIncubation for 1-2 daysThe monolayer is stained with a fluorescent monoclonal antibody specific for an RSV antigen
49RSV is spread by large droplets and on fomites Can be spread via contaminated handsOccurs primarily in winter months
503. What is the pathophysiologic basis for wheezing?
51RSV is tropic for bronchial epithelium Edema and necrosis can lead to collapse and obstruction of a child’s small bronchioles
524. What specific therapy should be given after the antigen test gives the diagnosis?
53Only one antiviral agent is available for treatment of RSV in infants Aerosolized ribavirin(oral administration can result in hepatic or bone marrow toxicity)The American Academy of Pediatrics recommends its use in children with congenital heart disease, cystic fibrosis, immunodeficiency or severe illness.
545. What infection control measures should be taken?
55Patients should be put on respiratory isolation Gowns and gloves should be used during contact
57Inactivated RSV vaccine did not work and exacerbated the disease Immune globulin can be used in children at greatest risk
58THE GASTROINTESTINAL SYSTEM Two basic mechanisms of diarrheal disease:Enterotoxin-induced fluid lossCholera toxinDirect damage to the intestinal epitheliumCytotoxinEntamoeba histolyticaInvasion of epitheliumSalmonella spp.Shigella spp.Campylobacter spp.Yersinia enterocolitica
59THE GASTROINTESTINAL SYSTEM Infectious dosesHundreds of thousands to millionsSalmonella spp.Vibrio choleraeLess than 100Shigella spp.
64THE GASTROINTESTINAL SYSTEM BacteriaAbdominal abscessBacteroides fragilisGangrenous lesions of bowel or gall bladderClostridium perfringensEnterohemorrhagic colitisEnterohemorrhagic E. coli
65THE GASTROINTESTINAL SYSTEM VirusesAcute, self-limited hepatitisHepatitis AAcute and chronic hepatitisHepatitis BHepatitis C
66THE GASTROINTESTINAL SYSTEM VirusesDiarrheaEnterovirusRotavirusNorwalk agent (calicivirus)VomitingNorwalk agent (“24-hour flu”)
67THE GASTROINTESTINAL SYSTEM VirusesInfantsRotavirus A (most common cause)Adenovirus 40, 41Coxsackie A24 virusInfants, children, and adultsNorwalk agent (“24-hour flu”)CalicivirusReovirus
68Rocky Mountain spotted fever Meningococcemia Entereoviral infection SKIN AND SOFT TISSUEDiffuse erythematous macular rash may be a manifestation of systemic diseaseRocky Mountain spotted feverMeningococcemiaEntereoviral infectionToxic shock syndromeScarlet feverMeaslesGerman measles
69Vesicular skin lesions Varicella Zoster virus SKIN AND SOFT TISSUEErythema migransLyme diseasesVesicular skin lesionsVaricella Zoster virusMacular, papular or pustular, but not vesicular, skin lesionsSecondary syphilis
70Important to treat superficial skin infections SKIN AND SOFT TISSUEImportant to treat superficial skin infectionsFolliculitis caused by Staphylococcus aureusCellulitis caused by Streptococcus pyogenesDelay in treatment may result in invasion of the deeper structures (e.g necrotizing fasciitis)
72Diphtheria and wound diphtheria Corynebacterium diphtheriae Cellulitis SKIN AND SOFT TISSUEDiphtheria and wound diphtheriaCorynebacterium diphtheriaeCellulitisGroup A streptococci (S. pyogenes)Group B streptococci (S. agalactiae)Pasteurella multocidaStaphylococcus aureusCryptococcus neoformans
73Skin infection in burn patients Pseudomonas aeruginosa Thrush SKIN AND SOFT TISSUESkin infection in burn patientsPseudomonas aeruginosaThrushCandida albicansCandida spp.Cutaneous infectionBlastomyces dermatitidis
74Infection of keratinized tissue Epidermophyton floccosum SKIN AND SOFT TISSUEInfection of keratinized tissueEpidermophyton floccosumMicrosporum spp.Trichophyton spp.Ulcerative skin lesionsLeishmania tropica
75Human herpesvirus type 6 Oral infections Herpes simplex virus Warts SKIN AND SOFT TISSUEExanthem subitumHuman herpesvirus type 6Oral infectionsHerpes simplex virusWartsHuman papillomavirus
76CENTRAL NERVOUS SYSTEM The most frequent infections areMeningitisEncephalitisAbscessSeptic: caused by bacteriaCSF cloudy (>1,000 white blood cells/µl)Aseptic: Viruses, fungi, MTBCSF clear ( cells/µl)
77CENTRAL NERVOUS SYSTEM Neonatal meningitis (newborn - 2 months)Group B streptococci (most common cause)Listeria monocytogenesE. coliKlebsiella pneumoniaeCitrobacter diversus Citrobacter koseriTreponema pallidum
78CENTRAL NERVOUS SYSTEM Meningitis (2 months - 5 years)Haemophilus influenzae type bStreptococcus pneumoniaeNeisseria meningitidis (all ages)Meningitis (Patients with head trauma )Coagulase-negative staphylococciStaphylococcus aureusPseudomonas aeruginosa
79CENTRAL NERVOUS SYSTEM Aseptic meningitisEchovirusCoxsackievirusHerpes simplex virusFungal meningitis(primarily in the immunocompromised)Cryptococcus neoformans (in AIDS patients)
81CENTRAL NERVOUS SYSTEM EncephalitisToxoplasma gondiiTaenia solium (“cysticercosis”; from pork)MeningoencephalitisCerebral malariaNaegleria fowleri (an amoeba)Citrobacter diversus
82CENTRAL NERVOUS SYSTEM Brain abscessesExtension from a contiguous siteHematogenous spread from another site (endocarditis or lung abscess)Septic emboli (blood clots containing an infectious agent)In immunocompetent individualsS. aureusviridans streptococciActinomyces spp.Anaerobic bacteria