Micro

The hyaline saprobic fungus that has microscopic features similar to the mold form of Coccidioides immitis is: The correct answer is highlighted below Malbranchia species Geotrichum species Trichosporon species Microsporum canis

C. immitis and malbranchia look alike with their alternate staining!!!......... Feedback Malbranchia species share the production of alternate staining arthroconidia as a common feature with the mold form of Coccidioides immitis. Both Geotrichum species and Trichosporon species produce rectangular-shaped arthroconidia; however, they are regularly rather than alternately staining. Additionally, the arthroconidia of Geotrichum may produce germ tubes from one corner and the arthroconidia of Trichosporon species may produce blastoconidia from adjacent corners, features not shared by either Malbranchia species or Coccidioides immitis. The hyphae of Microsporum canis, as seen in direct KOH mounts of skin scales, may break up into arthroconidia; however, they are much narrower in dimension and do not share the alternate staining characteristics.

E. coli O157:H7

Clear colonies on MAC sorb sorbitol neg lac pos lysine decarboxylase pos zero h2s

A 67 year-old man was seen in the emergency room complaining of cough, fever, and piercing right posterior chest pain. X-ray of the chest revealed consolidation of the right middle lobe of the lung. A sputum culture grew the bacterial species shown in the upper photograph. The lower photomicrograph illustrates a gram-stain of the sputum specimen. The most likely cause of the pneumonia is: Klebsiella pneumoniae Enterococcus faecalis Staphylococcus intermedius Streptococcus pneumoniae

Klebsiella pneumoniae = lobar pna, mucoid, GNB Enterococcus faecalis = lobar pna LESS LIKELY, may form gpdc NOT mucoid Staphylococcus intermedius = necrotizing bronchopneumonia, not MUCOID, gpc in clusters not pairs Streptococcus pneumoniae= lobar pna, mucoid, alpha hem, gram POS diplococci

if asked about being lactose fermenter or nonfermenter think of TSI slants....

L SD........ then use your brain

Along with Mycobacterium tuberculosis, all of the ff mycobacterium species can cause tuberculosis of those EXCEPT: M. bovis M. Africanum M. kansasii M. microti

M. kansasii

Mycobacterium kansasii Mycobacterium tuberculosis Mycobacterium simiae Mycobacterium chelonei Mycobacterium avium/intracellulare Mycobacterium marinum mycobacterium leprae

Mycobacterium kansasii= slow growth, photochromogenic, may cause chronic lung infxn similar to TB

Pseudomonas aeruginosa Pseudomonas stutzeri Pseudomonas acidovorans Pseudomonas alcaligenes

P. aeruginosa and P. stutzeri are OXIDIZERS; P. acidovorans and P. alcaligenes are ASSACROLYTIC

All of the following may cause systemic mycoses EXCEPT: The correct answer is highlighted below Actinomyces Israeli Nocardia brasiliensis Coccidioides immitis Nocardia asteroides Piedraia hortai

Piedraia hortai does not cause systemic mycosis, instead it causes a condition known as black piedra. This disease is characterized by formation of brown/black nodules which are attached to the hair shaft. Scalp hair is the most frequently infected area.

strep pneumo is BILE SOLUBLE

YES, SHIT a drop of 10% deoxycolate

Flavobacterium (Chryseobacterium) INDOLogenes

a WEAK indole producer since there is not a lot of indole, the indole must be extracted using xylene. Then, erline's reagent, a more sensitive test, is used to detect presence of indole.

Oxidative/fermentative (OF) dextrose tubes (one is covered with mineral oil, the other tube is not [in other words, is exposed to air]

acid production only in the oxygen exposed, uncovered tube = oxidizer yellow pigmentation in both, covered and uncovered, tubes = fermenter no color change (in other words, tubes remain green) = non fermenter or non oxidizer (aka carb is not utilized by either mode of metabolism)

cobweb colonies (fuzzy looking) + takes longer incubation =

dimorphic fungi know the different types

organisms that cause pitting

diptheroids eikenella

rabbit fever

f. tularensis

Strep moniliformis vs yersinia pestis vs erysipelothrix rhusiopathiae vs Anaerobispirillum succinoproducans

first 3 are r/t animal bites last one does not cause human infxn and NOT r/t animal bite strep moni = GNB yersinia pestis = short cocobacilli e. rhus = gram POSitive Bacilli

keratitis

fusarium Fusarium can be found as A COMMON SAPROBE and as a cause of keratitis. Fusarium colonies are most commonly fast-growing and may or may not have a cottony aerial mycelium. Fusarium typically produce both macroconidia and microconidia from thin phialides. Macroconidia and microconidia are both hyaline. Chlamydoconidia may or may not be present.

m. fortuitum

grows on modified Macconkey (crystal violet removed)

cobweb

histoplasmos

Procedures that may enhance the recovery of beta hemolytic, group A streptococci from throat cultures include: Extraction of streptococcal grouping antigen Incorporation of sulfamethoxazole and trimethoprim in the culture media Incubation under anaerobic conditions Use of culture media with increased concentrations of glucose

(1) Incorporation of sulfamethoxazole and trimethoprim in the culture media (2) Incubation under anaerobic conditions Feedback For the optimum recovery of group A streptococci from throat cultures, the specimen should be inoculated to a 5% sheep blood agar plate containing sulfamethoxazole and trimethoprim, and incubated under anaerobic conditions for 48 hours (Pacific et al, Relative value of selective group A streptococcal agar incubated under different atmospheres. J Clin Microbiol 33:2480-2482, 1995). Although the extraction of streptococcal grouping antigen is a sensitive method for detecting Group A streptococci in throat cultures, it has no effect on the cultural recovery of the organism. Although direct detection methods using antigen extraction may provide a rapid diagnosis of streptococcal pharyngitis, culture is still the most sensitive method for detection of the organisms and remains the "gold standard". Media with increased concentrations of glucose (such as Columbia base media, for example) tend to squelch the hemolytic reactions making detection more difficult.

rat bite fever

-aka Haverhill fever -caused by STREPTOBACILLUS MONILIFORMIS a fastidious (will only grow when specific ingredients are in the diet), pleomorphic (can alter shape and size in reaction to environment..) , gram negative bacillus

c. perfringens

-anaerobe -produce toxins that cause a form of necrotizing enteritis known as Darmbrand ("fire bowels") in Germany or "Pig bel" in New Guinea -double zone of hemolysis (beta hemolytic and lecithinase activity - ingestion of food contaminated with enterotoxin-producing strains of Clostridium perfringens (poorly cooked pork, excessive eating of foodds rich in trypsin inhibitors (sweet potatoes and peanut)). Bacillus cereus does produce toxin-related enteritis; HOWEVER, is an AERobe and produces only a SINGLE zone of hemolysis on blood agar.

List in descending order, the names of the bacterial species from most to least anaerobic (highest to the lowest oxygen-reduction potential Eh): Bacteroides fragilis Eubacterium lentum Clostridium tertium Clostridium novyi

3 2 4 1 Feedback Clostridium novyi is one of the most oxygen susceptible anaerobes, with cells being killed within 10 minutes of exposure to atmospheric air. This species is often used as a quality control strain to indicate an adequate anaerobic environment in anaerobe tents and jars. On the other side of the spectrum, Clostridium tertium, although classified as an anaerobe, is aerotolerant and can survive in the presence of atmospheric air. Between these two extremes, Eubacterium lentum has a lower oxygen reduction potential than Bacteroides fragilis, the latter surviving oxygen exposure after colonies have been grown in an anerobic environment.

Match the name of the bacterial species listed with its most likely associated infectious disease syndrome listed. B. cereus d. congloensis corynebacerium ureolyticum norcadia brasilensis

B. cereus = food poisoning/enteritis Dermatophylus congloensis= foot rot or pitted karyolysis from soil or animal dander or hair corynebacterium ureolyticum = UTI and alkaline crusted CYSTITIS due to rapid hydrolysis of urea Nocardia brasiliensis is one of the more common agents of actinomycotic mycetomas of the subcutaneous tissues.

legionella

BCBYE agar (charcoal)

Bacillus anthrasis Yersinia pestis Francisella tularensis Brucella species

Bacillus anthrasis = large, GPB with SQUARED ENDS appearing in single and short chains. Yersinia pestis = FAT gram-negative rod in SINGLE or SHORT chains with bipolar staining. Francisella tularensis =VERY TINY, WEAKLY stained gram-negative coccobacilli(AKA may look like gram pos when they're really not) and it is difficult to see individual cells. Brucella species is a VERY VERY small, gram-negative coccobacilli that may stain gram-positive. The individual cells are evident.

The lecithin hydrolysis, on egg yolk agar plate, may be produced by each of the following Bacillus species except: Bacillus cereus Bacillus subtilis Bacillus mycoides Bacillus anthracis

Bacillus subtilis

Bacteroides fragilis Fusobacterium nucleatum Porphyromonas asaccharolytica Prevotella intermedia

Bacteroides fragilis -most commonly recovered from human infections, particularly those that occur "below the diaphragm"/abscesses. - grows readily on anaerobic blood agar in an anaerobic atmosphere -small, gram negative bacilli with rounded ends biles salt pos esc pos (black is positive) Prevotella species and Porphyromonas species are BOTH bile salt neg, esc neg AND both produce colonies with black pigment that fluoresce red when viewed with a Wood lamp Difference: Prevotella bivia is saccharolytic while Porphyromonas assacharolyticus is Assacharolytic. Duh Fusobacterium nucleatum can also be associated with intra abdominal cavity abscesses; however, the bacterial cells are slender and tapered and bile salt neg, and esc neg but the indole reaction is positive.

aka aspiration pna

Bifidobacterium dentium debilitating and necrotizing

Enteorococcus faecalis Streptococcus group D Enterococcus casseliflavus Micrococcus luteus

Enteorococcus faecalis (esc pos, bile salt growth. esc will be black, bile salt will be yellow) Streptococcus group D do a OF test to distinguish strep from staph strep utilizes carbohydrate by fermenting, staph is oxidative ( STREP will show acid production or yellowing in the open tube) Enterococcus casseliflavus motility positive Micrococcus luteus (esc neg, bile salt NO growth = esc will be black, bile salt will be red blue)

QUESTION 62 MICRO Reading from left to right, illustrated are sodium citrate, Christensen's urea, esculin agar and phenylalanine agar. Match the label of the bacterial species with the agar slant showing the biochemical reaction most helpful in its identification: Enterobacter aerogenes Bordetella bronchiseptica Enterococcus faecalis Oligella urethralis

Enterobacter aerogenes sodium cit pos (super blue) Bordetella bronchiseptica strong urease reaction (super pink) Enterococcus faecalis ESC POS (black) Oligella urethralis phenylalanine deaminase pos (green is pos?)

C. neoformans Failure to produce germ tubes Urease positive Produced brown pigment on bird seed agar The correct answer is highlighted below Candida albicans Candida pseudotropicalis Cryptococcus neoformans Torulopsis glabrata Saccharomyces cerevisiae

Failure to produce germ tubes Urease positive Produced brown pigment on BIRD SEED AGAR an ENCAPSULATED yeast may use INDIA INK to visualize capsule

Illustrated in this photomicrograph of a gastric biopsy specimen are a few thin, curved and S-shaped bacteria (arrows). This picture is suspicious for Helicobacter pylori. An additional test helpful in confirming this identification is: The correct answer is highlighted below Indoxyl acetate Rapid urease Hippurate hydrolysis Growth at 42°C

Feedback The ability of H. pylori to rapidly hydrolyze urea not only allows it to maintain residence in the highly acid gastric mucosa (production of NH4 to neutralize the acid ions) but also provides the basis for the CLO test commonly used in GI clinics and microbiology laboratories. The CLO test is based on the rapid red conversion of the plug of urea agar after inoculation with bits of biopsy material. H. pylori reacts negatively in both the indoxyl acetate and hippurate hydrolysis tests, and most strains are incapable of growing at 42°C.

The saccharolytic anaerobe that produces red fluorescing colonies when illuminated with a Wood's lamp, as shown in this photograph, is: Porphyromonas asaccharolyticus Prevotella bivia Bacteroides distasonis Fusobacterium nucleatum

Feedback The production of colonies with black pigment, that also fluoresce red when viewed with a Wood's lamp, are characteristics by which Prevotella species and Porphyromonas species are separated from other anaerobic bacteria, particularly the closely related Bacteroides species. Prevotella species, which produce acids from several sugars (saccharolytic) are separated from Porphyromonas species which are asaccharolytic. Therefore, the correct response in this exercise is Prevotella bivia. None of the Bacteroides nor Fusobacterium species produce colonies with black pigment, nor do they fluoresce.

sensitive to BACITRACIN

Group A Streptococcus

pos phenylalanine reaction (green slant) seen in the ff:

Proteus vulgaris Morganella morganii Providencia stuartii Oligella urethralis Phenylalanine deaminase is a key reaction for the presumptive identification of members of the Proteus/Providencia genera of the Family Enterobacteriaceae. Members of the genus Morganella, formerly classified in the genus Proteus, also possess this capability. Therefore, of the responses in this exercise, only Serratia marcescens does not have the capability of converting phenylalanine to phenylpyruvic acid.

confirmation test for H1N1

RT-PCR

S low lactose fermenter

S erratia marcescens

TSIA . . . . . . . . . . . . . . . . . . . K/A, Gas (+), H2S (+) Citrate . . . . . . . . . . . . . . . . . Positive Indole . . . . . . . . . . . . . . . . . Negative Lysine . . . . . . . . . . . . . . . . . POSITIVE Ornithine . . . . . . . . . . . . . . Positive Motility . . . . . . . . . . . . . . . . Positive Phenylalanine. . . . . . . . . . . .NEGATIVE

Salmonella

The Quellung test

Serological typing of Streptococcus pneumoniae

Salmonella enterica VS Shigella infections

Shigella ONLY infect humans while Salmonella is found in many animals ONLY shigella produces exotoxin ONLY salmonella can animals serve as a reservoir of infxn Both have diarrhea as a major symptom. Endotoxin is produced by all gram negative bacteria.

streptokinase vs. streptolysin S

Streptokinase Hydrolysis ( "-ase" BREAKS DOWN) of fibrin clots Streptolysin S Leucotoxic ASSASINS phagocytes

All mycobacterium are acid fast. t or f

TRUE!

Shigella

TSIA . .. . . . . . .K/A, no gas, no H2S Citrate . . . . . . . NEGATIVE Lysine . . . . . . . .Negative Ornithine. . . . . . .Positive Indole. . . . . . . . . Negative

wow Which statements about melt curve analysis are TRUE? (Choose all that apply.) The melting temperature of double stranded DNA depends on its base composition and length. When hybridization probes are utilized, the temperature is incrementally decreased while fluorescence is monitored. All PCR products for a specific primer pair should have the same melting temperature. At the melting point, the probe separates from the target strand and fluorescence rapidly decreases.

The melting temperature of double stranded DNA depends on its base composition and length. All PCR products for a specific primer pair should have the same melting temperature. At the melting point, the probe separates from the target strand and fluorescence rapidly decreases. Feedback The melting temperature of double stranded DNA depends on its base composition and its length. All PCR products for a specific primer pair should have the same melting temperature, unless there is contamination, primer-dimer pairs, or some other problem. During melt curve analysis, the temperature is incrementally increased. At the melting point, the probe separates from the target strand, and the fluorescence rapidly decreases. The temperature at which the peak rate of change occurs is the Tm, and can be compared to known controls or established ranges to identify the PCR product.

The tube coagulase test, shown in this image (upper tube positive), should be performed on all S. aureus-suspicious isolates giving a negative slide coagulase reaction. True False

True Feedback The slide coagulase test measures for "bound" coagulase; the tube test for "free" coagulase. Most strains produce both types; rare strains may produce only free coagulase. These uncommon strains therefore will only be detected by performing the tube test, which should be performed on all clinically significant, slide test-negative isolates. The tube test should be read within four hours to detect an early positive reaction before lysis occurs; but if negative, read again in 24 hours to detect weak, delayed coagulase activity.

aspergillus niger

black in the middle, yellowish fuzzy ring on the outside

bordetella pertussis agar (name all 3)

bordet regan lowe potato

m. marinum VS m. kansaii difference

both are the only 2 photochromogens (colony turns yellow when exposed to light) but m. marinum does NOT grow in 35 C and is A FAST grower kansaii CAN grow in 35C and is a SLOW grower

c. dipth and c. ulcerans are preety much the same....

both biochemically (differing only by failing to reduce nitrates or hydrolyze urea) and culturally (by producing the black colonies on tellurite agar as illustrated in the photograph)

PCN

common contaminant rapid grower (from white to bluish-green to very powdery...etc)

m. xenopi

hot water systems able to grown even in 42 C

m. avium

in nonpigmented and color doesn't change whether or not exposed to light

lobar pna (2)

klebsiella pna and legionella

aka walking pna

m. pneumoniae has symptoms of cold but not enough to impede activities does NOT have cell wall

vancomycin-resistant Enterococcus faecium and Enterococcus faecalis FROM other Enterococcus species

non motility

kingella...

osteomyelitis

actinobacillus

periodontis

positive VP rxn (red pigment) is caused by a reaction between Alpha naphthol and diacetyl

true that

Key tests in species ID Optochin susceptible = S. pneumoniae resistant = s. viridans, alpha hemolytic Group D streptococci Indoxyl acetate hydrolyzed by = campylobacter jejuni and campylobacter spp. CANNOT BE hydrolyzed by helicobacter spp. Niacin accumulation - Mycobacterium tuberculosis; most commonly identified by nucleic acid probe assays. Phenylalanine deaminase =used to ID Proteus and Providencia species.

yep

bipolar staining

yersinia pasteurella francisella

Based on the reactions observed in the tubes shown in the photograph (including open and closed OF dextrose and a positive nitrate reaction only after addition of zinc dust, as shown in the right tube of this pair), the most likely identification is: Bordetella bronchiseptica Flavobacterium odoratum Moraxella osloensis Oligella ureolytica

Based on the reactions observed in the tubes shown in the photograph (including open and closed OF dextrose and a positive nitrate reaction only after addition of zinc dust, as shown in the right tube of this pair), the most likely identification is: The correct answer is highlighted below Bordetella bronchiseptica urease pos, nitra reduced to nitrites, Flavobacterium odoratum urease pos Moraxella osloensis Oligella ureolytica urease pos, nitrates reduced to nitri The red pigment only appears in the second tube after the addition of zinc dust. The zinc reduces nitrates to nitrites, confirming that nitrates were still unchanged in the original tube. None of the Moraxella species hydrolyze urea.

Match the name of each of the bacterial species listed with its most likely associated clinical condition. Enterobacter sakasakii Morganella morganii Klebsiella ozaenae Yersinia pseudotuberculosis

Enterobacter sakasakii Neonatal meningitis Morganella morganii Alkaline cysitits Klebsiella ozaenae Atrophic rhinitis Yersinia pseudotuberculosis Mesenteric adenitis Feedback Klebsiella ozaenae, along with the closely related K. rhinoscleromatis, cause infections primarily limited to the nasal passages. K. ozaenae produces an offensive smelling, purulent infection of the nasal mucous membrane called ozena. Of the species listed in this exercise, E. sakasakii is most commonly associated with neonatal meningitis (Muytjens, et al, analysis of 8 cases of neonatal meningitis and sepsis, J Clin Microbiol 18:115-120, 1983; and, Biering et al, report of 3 cases of neonatal meningitis related to contaminated powdered milk, J Clin Microbiol 27:2054-2056, 1989). Y. pseudotuberculosis is one of the bacterial species recovered in cases of mesenteric adenitis in children, a disease simulating acute appendicitis. Morganella morganii is a bacterial species associated with urinary tract infections. The active urease activity results in a markedly alkaline urine and ammonium phosphate crystaluria.

The appropriate media for the isolation of anaerobic bacteria from any source would normally include all of the following EXCEPT: sheep blood agar MacConkey's agar phenyl ethyl alcohol agar (PEA) Kanamycin Vancomycin agar (KVA) Thioglycollate media

Feedback MacConkey's agar would not be ideally suited for the isolation of anaerobic bacteria from any source. Each of the other types of media could, however, help in the isolation of anaerobic bacteria from any source.

Leuconostoc species are streptococcus-like bacteria used in the dairy and pickling industries that have recently caused opportunistic infections in humans. The need to make the laboratory identification is compounded because these bacteria are intrinsically resistant to vancomycin. The characteristics most helpful in separating Leuconostoc species from other streptococcus like organisms is: Gas from glucose in MRS broth Leucine aminopeptidase (LAP) activity Ability to grow in 6.5% NaCl (salt tolerance) Ability to grow at 10°C

Gas from glucose in MRS broth Feedback Leuconostoc species may be misidentified as pneumococci, species of viridans streptococci or lactobacilli (Buu-Hoi, et al: Antimicrob Agents Chemother 28:458-460, 1985). The detection of gas from glucose in Mann, Rogosa and Sharpe (MRS) broth (available from Difco Laboratories) overlaid with petrolatum is the one characteristic that differentiates Leuconostoc species from the other streptococcal like organisms. All of the other characteristics listed in this exercise are either variable for Leuconostoc species or are shared by other streptococcal like organisms and therefore are not discriminatory tests.

Of the dimorphic fungal species that are listed below, the one with the longest time of recovery in primary culture is: Coccidioides immitis Histoplasma capsulatum Sporothrix schenckii

H. capsulatum = 10 days c. immitis = 5 sporotrhix schenckii= 1-2 days

MAC does not have...

PCN

mariner's wheel

Paracoccidioides brasiliensis para dako ug Braso

This member of the Enterobacteriaceae is shown on triple sugar iron agar, lysine iron agar, urea agar, citrate agar, phenylanine deaminase agar, and motility indole ornithine agar. The most likely identification would be: Escherichia coli Salmonella spp. Shigella sonnei Providencia spp.

Shigella sonnei Shigella sonnei is the correct answer because it is a sucrose and lactose non-fermenter, H2S negative, lysine negative, urea negative, citrate negative, phenylalanine negative, ornithine positive, indole negative, and non-motile. Salmonella is positive for H2S, lysine decarboxylase positive, and is motile. Escherichia coli would ferment lactose and sucrose, decarboxylase lysine, is motile and is indole positive. Providencia spp. is citrate positive, phenylalanine deamination positive, indole positive, and is motile.

Bordetella bronchiseptica Haemophilus influenzae Moraxella catarrhalis Klebsiella pneumoniae

b. bronchiseptia= is a cocobacilli like h. influenzae. HOWEVER, it's only seen in animals, rarely in humans. moraxella is associated with chronic bronchitis but is GNDCocci klebsiella pna is more associated with lobar pna and not chronic bronchitis.