clinical microbiology review - asclsga.org

Tera Webb, MS, MLS(ASCP)CM

Clinical and Diagnostic Sciences

[email protected]

Clinical Microbiology Review

© UAB. All Rights Reserved.

• Beta- Lactams

• Glycopeptides

• Polymyxins

• Quinolones

• Rifamycin

• Aminoglycosides

• Tetracylines

• Macrolides or MLS

• Sulfa

• Trimethoprim

• Nitrofuratonine

Antibiotic Targets

TARGET

Cell Wall

DNA and RNA

Synthesis

Metabolic Pathways

Protein Synthesis

Cell Membrane


• Blood agar plates (BAP)

• Chocolate agar (CHOC)

• Thayer-Martin agar (TM)

• HBT (Human Blood Tween Bilayer)

• CIN (cefsulodin-irgasan-novobiocin)

• NYC (New York City)

• HE (hektoen enteric)

• XLD (xylose lysine deoxycholate)

• TCBS (Thiosulfate-citrate-bile sucrose)

• SS (Salmonella-Shigella)

• Regan Lowe

• Bordet-Gengou

Culture Plates

• CVA (cefoperazone, vancomycin, amphotericin B)

• CCFA (cycloserine cefoxitin fructose agar)

• SMAC (Sorbitol MacConkey)

• BBE (Bacteriodes Bile Esculin)

• EYA (Egg Yolk Agar)

• LKV (Kanamycin-Vancomycin-Laked Blood)

• Tomato Juice Agar

• Mueller Hinton

• McCoy

• Middlebrook 7H11

• CIN

• Cystine glucose blood agar

3


• Most common pathogen

• Media

• Microscopic

Staphylococcus

• Staphylococcus aureus

• Staphylococcus epidermidis

• Staphylococcus saprophyticus

• Staphylococcus lugdunersis

4


• Gram Stain• GPC in clusters

• Colony Morphology• Round, smooth, creamy, yellow to white colonies with beta- hemolysis

• Biochemical tests• Catalase• Coagulase

• Pathology

• Virulence Factors• Enterotoxins• Cytolytic toxins• Extracellular Enzymes• Protein A

Staphylococcus aureus


• Gram Stain

• GPC in clusters

• Colony Morphology

• Round, smooth, creamy, yellow to white colonies with no hemolysis

• Biochemical Tests

• Catalase

• Coagulase

• Pathology

Staphylococcus epidermidis


• Staphylococcus saprophyticus

• Add’l Biochemical: Novobiocin

• Pathology:

• Staphylococcus lugdunensis

• Add’l Biochemical: PYR

• Pathology:

Other Coag-Negative Staphylococci


• Abnormal susceptibility patterns

• Beta-lactam resistance

• MRSA• Screening vs Diagnostic

• Treatment with vancomycin

• VISA and VRSA• Limitations to disk diffusion & automated methods

• Macrolide resistance• Resistance to clindamycin may not be obvious

• D test - Use erythromycin and clindamycin disks

• Inducible resistance is growth between disks but not on side of clindamycin disk

Staphylococcus - Antimicrobial Susceptibility 8


Streptococci and Enterococci are speciated based on hemolysin production and biochemical properties.

• α-Hemolysis

• RBCs are partially lysed, resulting in a greening of the area around the colony

• β-Hemolysis

• RBCs are completely lysed, resulting in a clear area around the colony

• γ-Hemolysis (nonhemolytic)

• RBCs are not lysed, so there is no change in agar color

Hemolysis


• Streptococcus pyogenes

• Streptococcus agalactiae

• Streptococcus pneumoniae

• Streptococcus bovis

• Viridians Streptococcus

• Enterococcus faecalis

• Enterococcus faecium

Streptococcus 10

• Lancefield groupings

• Brown’s classification

• Media

• Microscopic


• Gram Stain• GPC in chains

• Colony Morphology• Small, white, transparent, smooth colony with well-defined zone beta-hemolysis

• Biochemical Tests• Catalase• Strep Grouping

• Pathology• Infections• Post-streptococcal sequelae

• Virulence Factors

Streptococcus pyogenes



• Colony Morphology• Small, greyish-white, transparent, smooth colony with small zone beta- hemolysis

• Biochemical Tests• Catalase• Strep Grouping • Hippurate• CAMP

• Pathology• Neonatal sepsis• Neonatal meningitis

Streptococcus agalactiae


• Gram Stain• GPC in pairs (lancet- shaped)

• Colony Morphology• Small, round, glistening, mucoid, dome -shaped colony with alpha - hemolysis

• Biochemical Tests• Catalase• Optochin (P) • Bile solubility

• Pathology• Pneumonia, sinusitis, otitis media, bacteremia, meningitis

Streptococcus pneumoniae


• Gram Stain

• GPC in chains


• Small, round, colony with alpha -hemolysis

• Biochemical Tests

• Catalase

• Optochin (P)

• Pathology

• Normal flora, opportunistic, subacute bacterial endocarditis

Viridians Streptococcus



• Colony Morphology• Small, greyish, smooth colony with gamma-hemolysis

• Biochemical Tests• Catalase• PYR• Bile Esculin• NaCl

• Pathology• Opportunistic

Streptococcus bovis



• Colony Morphology• Small, greyish, smooth colony with gamma-hemolysis

• Biochemical Tests• Catalase• PYR• Bile Esculin• NaCl

• Pathology• UTIs, Wounds, endocarditis, etc

Enterococcus spp.


• Streptococus• Penicillin is drug of choice

• Group B – typically resistant to tetracyclines

• Vancomycin and linezolid resistance has not been observed

• E. faecalis• Usually susceptible to ampicillin and penicillin.

• Can acquire resistance to vancomycin.

• Occasionally produce beta- lactamase.

• E. faecium• Often resistant to ampicillin and penicillin.

• Can acquire resistance to vancomycin.

• E. gallinarum and E. casseliflavus• Have intrinsic low level vancomycin resistance

Streptococcus -Antibiotic Susceptibility 17


• A beta hemolytic streptococcus was recovered from a throat swab. Based on the following tests, what is the identification of this organism?

• Bacitracin susceptible and SXT resistant

• A. Group A

• B. Group B

• C. Other Beta-hemolytic Streptococcus

• D. Abiotrophia

• E. Granulicatella

Question


• Gram Stain• Pleomorphic Gram positive rods • Often palisading • Can be club-shaped

• Colony Morphology• White, non-hemolytic, opaque colonies

• Biochemical Tests• Catalase

• Pathology• Considered normal skin flora or contaminant

Corynebacterium spp. aka Diphtheroids


• Gram Stain• Pleomorphic Gram positive rods • Often palisading • Can be club-shaped

• Colony Morphology• White, non-hemolytic, opaque colonies

• Biochemical Tests• Catalase• Nitrate positive• Glucose positive• Maltose positive • Sucrose negative • Urease variable

• Virulence Factor

Corynebacterium diphtheriae


• Gram Stain• Small Gram positive rods (can be coccobacilli)

• Colony Morphology• Grayish white colony, small zone beta-hemolysis

• Biochemical tests• Catalase• Esculin hydrolysis• Hippurate hydrolysis• Motility• Wet prep =• 25°C semisolid media =

• Pathology• Pregnant women: premature labor, spontaneous abortion• Neonates: sepsis, meningitis• Immunocompromised

Listeria monocytogenes


• Gram Stain• Large gram positive rods• Can see spores (if organism is stressed)

• Colony Morphology• “Ground glass appearance,” Large colonies, rough edges, beta- hemolytic

• Biochemical tests• Catalase• Motility

• Pathology• Considered a contaminant, endophthalmitis, food poisoning (B. cereus)

Bacillus species


• Gram Stain• Large gram positive rods• Can see spores (if organism is stressed)

• Colony Morphology• “Ground glass appearance,” Large colonies, rough edges, NON- hemolytic

• Biochemical tests• Catalase positive• Non- motile

• Pathology• Causes anthrax

Bacillus anthracis


• Gram Stain• Gram positive rods in chains

• Colony Morphology• Alpha hemolytic colonies

• Biochemical tests• Catalase negative

• Pathology• Normal female urogenital flora

Other Gram Positive Rods

• Gram Stain• Gram negative rod

• Direct smear: Clue cells

• Colony Morphology• Tiny transparent colonies

• Biochemical tests• Catalase negative

• Pathology• Bacterial vaginitis

• Lactobacillus sp. • Gardnerella vaginalis


• Utilization of Glucose

• Ferment “F”, oxidize “O” or inactive

• Oxidase

• Positive or negative

• Ability to grow on MacConkey agar

• Some GNRs that grow on BAP are unable to grow on MacConkey agar

Differentiation of Major GNR Genera


• All ferment glucose• All reduce nitrate to nitrites• All grow on MAC• All are oxidase negative

• Except Plesiomonas

• Majority motile• Gram-negative coccobacilli or rods

• Not very useful in identification other than ruling out other organisms

• Facultatively anaerobic• Culture morphology

• Large moist, gray colonies• Some mucoid

Family: EnterobacteriaceaeGeneral Characteristics


• Colony Morphology• Most beta-hemolytic

• Biochemical tests• Oxidase• Indole• Motility

• Pathology• Normal colon flora• Cause UTIs, septicemia, neonatal septicemia and meningitis and several GI tract diseases

• Traveller’s diarrhea (ETEC)• Dysentary (EIEC)• Diarrhea and Vomiting (EPEC)• Hemolytic colitis (EHEC)

Lactose-FermentersEscherichia coli


• Biochemical tests• Oxidase• Indole

• K. pneumoniae =• K. oxytoca =

• Urea• Citrate• Motility

• Polysaccharide capsule• Pathology

• UTIs, pneumonia

Lactose-FermentersKlebsiella


• Biochemical tests

• Oxidase

• Indole

• Urea

• Citrate

• Motility

Lactose-FermentersEnterobacter


• Biochemical tests• Oxidase• Indole• H2S

• Motility• Pathology

• Opportunistic

Slow-Lactose FermentersCitrobacter


• Colony Morphology• Colonies have a salmon red pigment



• Opportunistic

Slow-Lactose FermentersSerratia


Proteus species• Colony Morphology

• Swarming motility


• Proteus vulgaris =• Proteus mirabilus =

• H2S


• Cause UTI’s• Opportunistic

ProteeaePhenylalanine deaminase & Urea positive

ProteeaePhenylalanine deaminase & Urea positive

Providencia• Biochemical tests

– Oxidase– Indole– Citrate

• Motility

Morganella• Biochemical tests

– Oxidase– Indole– Citrate

• Motility



• Oxidase

• Indole

• H2S

• Motility

• Pathology

• Diarrhea

• Septicemia

Obligate PathogensSalmonella



• Oxidase

• Motility

• Pathology

• Diarrhea

Obligate PathogensShigella


• Coccibacilli; bipolar staining


• Oxidase negative

• Indole negative

• Motile

• Pathology

• Plague (Y. pestis)

• Diarrhea (Y. enterolitica)

Obligate PathogensYersinia


• Ferment Glucose

• Ferment Lactose

• Motile @ body temp

• Citrate

• H2S Producers

• Deaminate phenylalanine

• KIA: K/A no H2S

• KIA: A/A no H2S

• KIA: K/K no H2S

• KIA: K/A H2S

• KIA: A/A H2S

Enterobacteriaceae

• P. vulgaris vs. P. mirabilis

• Morganella vs. Providencia

• Enterobacter vs. Klebsiella

• K. pneumoniae vs. K. oxytoca

• E. coli vs. K. oxytoca

• E. aerogenes vs. E. cloacae

• Salmonella vs. Shigella

• Non-fermenting E.coli vs. Edwardsiella

• Providencia vs. Proteus

• Edwardsiella vs. Salmonella

37

• Groupings • Differentiation


• Gram Stain• Gram negative rod

• Colony Morphology• Beta-hemolytic; flat, spreading colony with fruity, grape-like smell• Growth at 42oC

• Biochemical tests• Glucose• Oxidase

• Pathology• Pneumonia and wounds

Pseudomonas aeruginosa


• Gram Stain• Gram Negative Rod

• Non-motile• Biochemical tests

• Catalase• Oxidase• Nitrate

• Acinetobacter baumannii• Glucose• Grows at 42°C

• Acinetobacter lwoffii• Glucose • No growth at 42°C

Acinetobacter species


• Gram negative rod

• Oxidase negative

• Glucose “O”

• No growth at 42°C; Sometimes can develop a lavender-green to light purple pigment

Stenotrophomonas maltophila


• Three major groups:• V. cholerae O1• V. cholerae O129• V. cholerae non-O1

• Virulence factors• Cholera toxin—Causes mucosal cell hypersecretion of water• Others—Enterotoxins (zonula occludens toxin [ZOT] and accessory cholera enterotoxin [ACE]); O1 and O139

antigens • Spectrum of disease

• Cholera• Profuse, watery diarrhea leading to dehydration (“rice-water” stool)• Hypotension

• Nonepidemic diarrhea, associated with non-O1 group• Vibrio Identification

• Oxidase• 6.5% NaCl• Vibrostatic compound O/129• String test• Sucrose

Vibrio cholerae

41


• Gram negative rods

• Beta-hemolytic on BAP

• Grows on MAC

• Oxidase positive

• Glucose “F”

Aeromonas hydrophilia


• Curved Gram negative rod

• Grows at both 37°C & 42°C in 10% CO2 (microaerophilic)


• Darting motility on wet prep

• Hippurate hydrolysis positive

Campylobacter jejuni


• Curved Gram negative rod

• Urease positive


Helicobacter pylori


• Gram negative coccobacilli• Fastidious (agar, factors, CO2)• Porphyrin test• Pathology

• H. influenzae: Meningitis, epiglottitis, pneumonia, otitis media• H. aegyptius: conjunctivitis• H. ducreyi: STD - chancoid

Haemophilus species


• Gram Stain

• Gram-negative rods


• Nonhemolytic colonies

• Pathology

• Colonize the URT

Other Gram-negative Rods Eikenella corrodens


• Gram-negative bacilli• Require an increased CO2 (5%-10%) environment• Significant cause of endocarditis• Usual flora of the oral cavity• Thus are pathogens associated with human bite wounds causing septicemia and subacute

endocarditis• Opportunists in immunocompromised hosts

• H – Haemophilus spp. (Now Aggregatibacter aphrophilus)• A – Actinobacillus actinomycetemcomitans (Now Aggregatibacter actinomycetemcomitans)• C – Cardiobacterium hominis• E – Eikenella corrodens• K – Kingella spp.

HACEK GroupGeneral Characteristics


• Gram Stain

• Gram-negative coccibacilli

• Zoonotic infection acquired from animals or animal products

• Most common species for human brucellosis

• B. mellitensis (most common isolate), B. abortus, B. canis, B. suis

• Pathology

• Brucellosis or undulant fever

Brucella species

CO2 Urease H2S Inhibition Thionine

Inhibition

Fuchsin

B.abortus +/- 2 hrs + + (S) - (R)

B.melitensis - V - - (R) - (R)

B.suis - 15 min +/- - (R) + (S)

B.canis _ 15 min - - (R) + (S)


• Gram Stain

• Gram-negative coccibacilli

• Facultative intracellular parasite

• Strict aerobe

• Pathology

• Zoonotic infection

• Causes tularemia

• Acute febrile, granulomatous disease with rapid onset and flulike symptoms

Francisella species


• Intracellular parasite of cells• Enter and multiply within host cells• Particularly bronchoalveolar macrophages• Legionella pneumophila

• Legionnaires’ disease• Pontiac fever

• Sources• Present in environmental water sources• Air conditioning systems

• Detection• Culture: BCYE agar• Antigen in the urine: Sensitive• Direct fluorescent antibody staining• Serology

Legionella Species


• Major pathogens• Bordetella pertussis• Bordetella parapertussis• Bordetella bronchiseptica

• Highly contagious disease• Exposure and incubation period of 1-2 weeks• Initially cold or flulike symptoms, sneezing, runny nose• Catarrhal phase 1-2 weeks (highly contagious)

• Paroxysmal phase: Sudden severe repetitious coughing• Convalescent phase

• Begin recovery about 4 weeks after initial symptoms• Decrease in bouts of coughing but may take weeks or months for complete resolution

• Pathology• Causes ____________________• B. bronchiseptica - Opportunistic pathogen involved in pneumonia and wound infections

Bordetella Species


• Gram Stain• Gram negative diplococci• Kidney bean shaped

• Colony Morphology• On modified Thayer- Martin (MTM) agar:• Small, gray, translucent, raised

• Biochemical tests• Catalase• Oxidase• Carbohydrate utilization ->

• Pathology• N. gonorrhea: Cervicitis, urethritis, conjunctivitis• N. meningitidis: meningococcemia

• Antimicrobials• Penicillin is drug of choice• Resistance observed- Perform beta-lactamase

Pathogenic Neisseria

Organism Glucose Maltose Lactose Sucrose

Neisseria gonorrhoeae

Neisseria meningitidis

Neisseria lactamica Positive Positive Positive Negative

Nonpathogenic Neisseria Positive Positive Negative Positive

Moraxella catarrhalis


• Anaerobic organism• Gram Stain

• Large gram positive rods• Blunt, rounded ends (“boxcar” shaped)• Can see spores (if organism is stressed)


• Biochemical tests• Catalase

• Pathology• Gas gangrene, food poisoning

Clostridium perfringens


• Clostridium difficile

• Clostridium tetani

• Clostridium botulium

Other Clostridium


• Main group of anaerobes isolated

• Consists 13 species

• Most common – B. fragilis, B. thetaiotamicron

• Natural habitat

• Predominant NF colon

• Also found oropharynx, female genital tract

• Clinical significance

• Mainly infections below diaphragm (intraabdominal, liver abscesses, other)

• GS- pale-staining neg rod, rounded ends, vacuoles, pleomorphic

• Colonies- white-gray, translucent or semi-opaque, NH

B. fragilis group5

5


Acid –Fast Stains• Ziehl-Neelson

• Kinyoun

Media• Lowenstein-Jensen

• Middlebrook Medium

• Mycobacterium culture bottles

Specimens• Respiratory

• Urine

• Blood & bone marrow

• Tissue & body fluids

Lipid-Mycolic Acid WallsMycobacterium

• M. tuberculosis

• M. bovis

• M. ulcerans

• M. avium

• M. kansasii

• M. xenopi

• M. lepreae

56

Pathogens


• Highly fastidious

• Very small cell size (0.3 x 0.8 μm)

• No cell wall

• Two mycoplasma species are known human pathogens• Mycoplasma pneumoniae• Mycoplasma hominis

• Ureaplasma urealyticum

Cell-Wall Deficient Bacteria

57


Any Questions? 58

SCHOOL OF HEALTH PROFESSIONS

• www.TeraWebb.comWebsite

• www.linkedin.com/in/terawebb LinkedIn

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• [email protected]


• Growth Rate• Rapid, intermediate, slow growers

• Incubation conditions

• Colony Morphology• Hyaline or dematiaceous• Pigment, texture, topography, etc

• Microscopic Morphology (natural growth state)• Hyphae • Type of Sporulation

• Mold to yeast conversion

• Cycloheximide resistance

Criteria for ID of Molds 59

Superficial Mycosis

• Malassezia furfur– Patchy lesions or scaling of varying pigmentation

• Usually on chest, trunk, abdomen

– May be cause of dandruff– Skin scrapings in KOH prep

• Yellow fluorescence with Wood’s lamp

– Spaghetti and meatballs microscopic morphology

• Piedraia hortae– Black piedra

• Hairs of scalp - Black gritty nodules

– Tropical Africa, Asia, and Latin America

• Trichosporum– White piedra on hair shaft– Opportunistic pathogen

• Endemic in tropical South America, Far East, and Pacific– Grow rapidly on primary media

• Smooth colonies cream colored and yeastlike– Some wrinkling upon maturation

• Utilization of potassium nitrate, urease positive

• Hortaea (Phaeoannellomyces) werneckii– Tinea nigra

• Brown to black nonscaly macule - Palms of hands and soles of feet• No inflammation or reaction to fungus

– Skin scraping in 10%-20% KOH• Septate hyphae and budding cells

– Culture• Shiny, moist, yeastlike colonies brown to olive or greenish black

Cutaneous Mycosis

• Epidermophyton floccosum– Colony morphology

• Yellow to yellow tan

– Microscopically• Macroconidia & macroconidia

– 3-5 cells with thin smooth walls– Look like beaver tails

• Microsporum canis– Colony

• Initially white and silky • Reverse developing a lemon yellow pigment on reverse

– Microscopically• Spindle-shaped, multicelled macroconidia and scattered

microconidia• Pointed and slightly turned at one tip• Thick spiny (echinulate) wall

• Microsporum gypseum– Colony morphology

• Flat initially white turning light brown to reddish-brown on maturity

• Sugary or granular appearance

– Microscopically• Macroconidia

– Abundant with long and rounded tips

• Echinulate wall with less thick septations• Clublike macroconidia

• Microsporum audouinii– Slow-growing anthropomorphic dermatophyte

• Used to be leading cause of tinea capitis

– Rare conidia• Some isolates produce terminal chlamydoconidium-like

swellings

– Colonies• Cottony and white with little to no pigment on reverse

Cutaneous Mycosis

• Trichophyton mentagrophytes– Macroscopically

• Downy to granular based on number of microconidiapresent

– Microscopically• Microconidia form loose grapelike clusters (en grappe)

– Globose to tear shaped• Macroconidia present in very low numbers or absent

– Thin smooth cigar-shaped four to five cells separated by parallel cross-walls

• Trichophyton rubrum• Colony morphology

– Initially white with cottony, velvety, or granular colonies– Key observation

• Water soluble wine-red pigment on the reverse of the colony

• Microscopically– Microconidia are tiny clavate or peg shaped and

distributed on either side of the hyphal strands• “Birds on a fence”

– Macroconidia similar to T. mentagrophytes• Elongated and pencil shaped• Rare

• Trichophyton tonsurans– Colony morphology

• Granular buff surface with deep radial rugae on maturation

– Microscopically• Microconidia vary in size

– Elongated – Club shaped– Balloon shaped forms with small tear-shaped microconidia


• Involve deeper skin layers• Generally dissemination through the blood does not occur

• Clinical features• Chromoblastomycosis - Dematiaceous molds

• Chronic infection: Nonhealing ulcers• Eumycotic mycetoma - P. boydii (Scedosporium boydii)

• Draining sinus tracts

• Lymphocutaneous infection that may become systemic• Sporothrix schenckii

• Mold• Yeast: cigar-shaped

Subcutaneous Mycoses

Systemic Mycosis

Coccidioides immitis

• Coccidioidomycosis• Endemic to Southwestern United States

– Soil

• Colony morphology– Cobweb-like, with gray-white mycelium– Highly infectious

• Microscopically– Mold form

• Hyphae are delicate and break up into barrel-shaped arthroconidia that are separated by empty spaces when stained (every other one)

– Spherule form (do not form yeast)• Observed in tissue sections

Histoplasma capsulatum

• Commonly found in the North American river basins– St. Lawrence, Ohio, Mississippi, Missouri, river valleys – Soil rich in organic content (bird and bat excreta)

• Colony morphology– Mold

• Mycelium initially white but turning gray or gray-brown– Yeast

• Typically smooth, yellow-white, and glistening with pasty consistency

• Microscopically– Yeast

• Single bud connected by a delicate filament• In tissue, yeast cells are clustered in macrophages

surrounded by clear space (looks pseudoencapsulated)

Blastomyces dermatitidis

• Soil mold– Found in KY, MS, AR, NC, TN, LA, IL, WI

• Colony morphology– Gray-white or light buff colored with delicate, silky,

hairlike, mycelium

• Microscopically - mold– Delicate hyphae 1-2 μm in diameter hyline, and

septate– Oval or pyriform conidia Form “lollipop-like” structure

• Yeast (35° C) on enriched agar– Colony morphology

• Small, slightly convex, smooth off yellow or buff pigmentation

– Microscopically• Single bud attached by a broad base• Can be confused with C. immitis

Penicillium marneffei

• Infections in immunocompromised patients• Resembles H. capsulatum


• Zygomycota• Multinucleate molds, most are saprobes• Nonseptate fungi• Mucor, Absidia, Rhizopus, Rhizomucor

• Aspergillus• Several species

• A. fumigatus• A. flavus• A. terreus• A. niger

• Penicillium

Opportunistic Mycosis 66


• Candida albicans• Thrush leading to systemic infections• Yeast infections

• Candida glabrata• Aggressive infections and difficult to treat

• Cryptococcus neoformans• Opportunistic infection

• Meningitis, pneumonia, and septicemia• Characteristics

• Mucoid appearance due to capsule• India ink test

• Black background with clear halos around organism• Being replaced by latex agglutination

• Blastoconidia only

Agents of Yeast Infections


• P. jiroveci• Most infections occur by 2-4 years old

• Asymptomatic in healthy immunocompetent individuals

• Symptoms• Fever, nonproductive cough, and difficulty breathing

• Chest radiographs may show interstitial infiltrates

• Life cycle• Nonfilamentous fungus• Three stages

• Trophozoite• Multiply by binary fission

• Precyst

• Cyst• Infective stage

• Diagnosis• Biopsy and aspirates of the lung• Calcofluor white

• Blue-white color when stained and viewed under UV light

Pneumocystis


• Adenoviridae

• Mostly respiratory illness

• May cause gastroenteritis, conjunctivitis, cystitis, rashes

• Hepadnaviridae

• Hepatitis B

• Herpesviridae• Herpes simplex 1 and 2• Varicella-zoster

• Papillomaviridae• Warts• Possibly cervical carcinomas

DNA Viruses


• Parvoviridae• Only one causes human disease: B19

• Others cause disease in animals

• Poxviridae• Largest viruses• Causative agent of smallpox

DNA Viruses 70


• Orthomyxoviridae

• Include influenza A, B, and C viruses

• Type A—most virulent in humans

• Coronaviridae

• Respiratory and enteric disease

• Picornaviridae

• Important pathogens, include Enterovirus, Rhinovirus, Hepatovirus, Aphthovirus, Parechovirus, Erbovirus, Kobuvirus, Teschovirus

• Large family, smallest RNA viruses

• Hepeviridae

• Paramyxoviridae

• Filoviridae & Bunyaviridae

• Hemorrhagic Fevers

RNA Viruses 71


• Rhabdoviridae• Infect plants, insects, fish, birds, mammals, including humans

• Rabies virus belongs to this group

• Reoviridae• Rotavirus: gastroenteritis—common in children— accounts for approximately 50% of all cases of

diarrhea in children requiring hospitalization

• Retroviridae• Oncovirinae, Lentivirinae, Spumavirinae• Example: HIV

• Togaviridae• Alphaviruses, Rubivirus—rubella virus

• Flaviviruses• Yellow fever, West Nile virus

RNA Viruses 72


• Defined by three common characteristics

• They are eukaryotes

• They are single-celled

• They lack a cell wall

• Majority are motile due to cilia, flagella, and/or pseudopodia

• Two distinctive forms

• Trophozoites

• Cysts

Protozoans 73


• Amebas

Move by pseudopods

• Entamoeba histolytica

• Entamoeba coli

• Acanthamoeba

• Naegleria fowleri

Protozoan Parasites


• Flagellates

• Simple

• Giardia

• Trichomonas

• Several life-cycle forms

• Typanosmona cruzi

• Typanosoma brucei

• Leishmania

Protozoan Parasites


• Ciliates

• Balantidium coli

• Apicomplexa

Intracellular

• Plasmodium

• Toxoplasma

• Pneumocystis

• Cryptosporidium

Protozoan Parasites


• Often found in blood, feces, and urine

• Must be distinguished from microbes

• Many parasitic helminths spend much of their life cycle in mammalian host

• Most of the ones affecting humans belong to flatworms and roundworms

• Adult animals usually large enough to be seen with the naked eye

• Eggs and larvae—microscopic

Helminths 77


• Trematodes a.k.a. flukes

• Schistosoma

• Cestodes a.k.a. tapeworms

• Taenia saginata

• Taenia solium

• Hymenolepis nana

Helminth Parasites


• Nematodes a.k.a. roundworms

• Necator

• Ascaris

• Enterobius

• Loa Loa

• Filiariasis

• Wuchereria

• Brugia

Helminth Parasites

clinical microbiology review - asclsga.org

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