Haemophilus and Other Fastidious Gram-Negative Rods

How are many of these organisms isolated?

Due to bite wounds, insect bites or transmission from animals.

This group has what rate with immuncompromised patients?

High morbidity/mortality

Pasteurella species general characteristics?

Colonizes mucous membranes of the upper respiratory tract and gastrointestinal tracts of mammals and birds

Pasteurella species human infections occur how?

From bites and scratches inflicted by animals, primarily felines

Results in a localized, pus- producing infection

Can cause life-threatening systemic disease

Most common isolate of Pasterurella?

P. multocida

P. multocida culture characteristics?

Growth on 5% blood or chocolate shows small, smooth, grayish,convex colonies

Non-hemolytic

"Musty" or earthy odor

No growth on MacConkey agar

P. multocida microscopic examination?

Very small gram-negative rods

Bipolar staining with Giemsa or methylene blue

"Safety-pin" appearance

P. multocida biochemicals?

Oxidase positive

Indole positive

Nonmotile

Catalase positive

Glucose fermenter

Bartonella spp. characteristics?

Facultative

Intracellular gram negative cocco-bacillus

Transmitted by direct contact or blood-sucking arthropods

Infect RBCs and vascular endothelial cells in the host leading to circulatory system infections

Most isolates are identified by Molecular or serological techniques.

Bartonella species clinical infections?

Cat Scratch disease

What is cat scratch disease caused by?

B. henselae

Cat scratch disease?

Patient has history of a scratch or bite or other contact with an infected cat or kitten

Patient has swelling of the lymph nodes of head, neck and upper limbs.

May see a papule at the site of the inoculation. Not always.

¢Hard to diagnose.

What is B. quitana associated with?

Trench fever

What is trench fever?

Patient has a persistant relapsing fever

Transmitted by the body louse

Hard to diagnose: general malaise, bone pain, large spleen, joint pain.

Most often seen with homeless and urban areas. Unsanitary conditions living close to one another.

Lab ID of Bartonella?

Slightly curved gram negative rods

Grow on blood and chocolate in CO2

Grow VERY Very Slow. 9- 40 days.

You can see why molecular and serology techniques are best.

Most often seen on a biopsy of a lymph node.

Afipia?

Very similar to Bartonella

Once thought to cause Cat Scratch fever

Important to differentiate this from Bartonella

Very RARE

what does B. pertussis cause?

Whooping cough

What is whooping cough?

Highly communicable disease of children

Strict human pathogen, spread by airborne droplets

Lives in ciliated epithelium of URT

Produces toxins and virulence factors

Whooping cough vaccine?

Required vaccination (DTaP)

Bordetella specimen collection, transport, and processing?

Nasopharyngeal swab or aspirate is the specimen of choice.

Swabs should be calcium alginate or dacron polyester

Specimen should be plated at the bedside and a smear made OR placed in casamino acid for transport

Regan-Lowe is recommended for transport

What agars are used with Bordetella?

Bordet-Gengou agar

Regan-Low agar

Bordet-Gengou agar?

Cough plate

Appears slightly beta hemolytic smooth, shiny, resembling a mercury droplet

Regan-Lowe agar?

Domed and shiny with a white mother of pearl opalescence

BAP & MAC: no growth

Organism is a fastidious obligate aerobe

Bordetella gram stain?

Gram stain: small faint staining GN coccobacilli

Can increase counterstain of safranin to 2 minutes for improved visibility

Bordetella biochemical?

Oxidase positive

Nonmotile

Bordetella serologic ID?

Direct fluorescent antibody

Slide agglutination tests

Nucleic Acid Detection by PCR

Growth requirements of Capnocytophaga sp.?

Capnophilic

Facultative anaerobe

Normal flora of Capnocytophaga?

Humans, dogs and cats

Capnocytophaga causes?

Cause periodontal disease, sepsis

Can be seen in endocarditis, arthritis and septicemia.

Capnocytophaga must be ruled out if specimen is not a an animal bite? T/F

True

ID of Capnocytophaga?

Long, thin pointed ends, can sometimes be cocci

Fastidious, slow growing , will grow on blood, chocolate but NOT on MacConkey agar. Only in C02.

Slow growing must keep at least 48 hours.

Blood cultures should be kept up to 7 days.

Non-hemolytic and produces a yellow/orange pigment.

Streptobacillus Moniliformis causes what?

Rat bit fever

Rat bit fever?

Normal flora of the respiratory tract of rodents

Can acquire infection from food contaminated with bacteria from rats.

Causes Haverhill fever (food poisoning)

Brucella species causes?

Infection in cattle (zoonosis)

How is Zoonosis acquired?

Acquired through aerosol, percutaneous and oral routes of exposure

Brucellosis in humans?

Primarily seen with animal handlers and those who handle animal products

Also known as Malta or undulant fever

How can Brucellosis be transmitted?

Through unbroken skin

Category b biological agent?

Easy to disseminate and cause moderate morbidity, but low mortality.

B. abortus?

Cattle

B. suis?

Pigs

B. meletenis?

Goats

B. canes?

Dogs

What is Brucella considered?

Considered a bioterrorism agent therefore must be reported if isolated.

Colony morph of Brucella?

Small, smooth, convex, nonhemolytic

May require holding culture for 21 days

Gram stain of Brucella?

Small gram-negative coccobaccilli

Biochemicals of brucella?

Nonmotile

Aerobic

Oxidase positive

Catalase positive

Urease positive (Blood red and quickly turns positive)

Francisella Tularensis is transmitted how?

Through unbroken skin, bite from an insect, direct contact with infected animals or inhalation of aerosols

F. tularensis spread how?

Spread from person to person or disseminated, high mortality rates

Where is the F. tularensis is an infection in?

Rabbits, sheep, squirrels and ticks

Zoonotic infections in humans?

Tularemia

Etiological agent of tularemia is?

A disease also known as glandular fever, tick fever, rabbit fever.

F. tularensis is a reportable organisms? T/F

True

How does the infection (F. Tularensis) occur?

By contact with contaminated air, water, soil or vegetation. Handling ill or dead animals. Bites by infected insects.

Four subspecies of F. tularemia?

Subspecies tularensis is the most virulent and is acquired by the bite of a tick or deerfly.

Six forms of tularemia?

Ulceroglandular

Glandular

Oculoglandular

Oropharyngeal

Pneumonic

Typhoidal

Ulceroglandular?

Ulcer at the site of inoculation

Glandular?

Lymph node involvement

Oculoglandular?

Enters the eye

Oropharyngeal?

Pharynx usually following ingestion of the organism.

Pneumonic?

Direct inhalation of the organism

Typhoidal?

Septicemia

Tularemia can be a potential?

Bioterrorism agent

Colony morph of F. tularensis?

BAP = No growth

MAC = No growth

Choc = Small, smooth, gray gncb at 2-5 days

Requires special media (BCYE or MTM)

Biochemicals of F. tularensis?

Oxidase: negative

Catalase: negative- weak positive

Ferments glucose

X and V negative

NOTE: Usually identified by DFA or direct agglutination tests due to risk of lab acquired infection

Legionella species habitat?

Aquatic sources

Cooling towers, condensers

Ubiquitous gram-negative rods

Legionella is acquired in humans how?

Primarily through inhalation of aerosols

Legionella species general characteristics?

Can survive a wide range of temperatures. 0-64 degrees.

Colonize hot water tanks.

Associated with biofilms

Can multiply within free living organisms.

Legionella Virulence factors?

Endotoxin

Flagella

Pili

Cytotoxin production

Intracellular pathogen

Some antibiotics are ineffective once the organism penetrates the cell.

Legionnaire's disease?

Disease with pneumonia and extrapulmonary involvement

Malaise, rapid onset of dry cough and fever

Illness is fatal in 15-30% of cases not treated

Pontiac fever?

Influenza-like

Fever, headache, malaise

Not fatal- short lived (2-5 days)

Legionella species handling and processinf?

BAL, bronchial washings, lung biopsy and pleural fluid are appropriate specimens

Avoid aerosolization & transport ambient temperature

Buffered Charcoal Yeast Extract (BCYE) most widely used

Organism requires cysteine & iron salts for growth

Incubate at 35o C in 5-10% CO2 with increased humidity for 10 days

Slow growth (2-4 days)

BCYE

Nonselective buffered charcoal yeast extract

Biochemical with Legionellas?

Oxidase positive

Catalase Positive

Motile by polar flagella

Gram stain Legionella?

Short, thin GNR, may be faint staining

Preferred stain is carbofusal due to faint staining with gram stain.

ID of Legionella pneumophila?

Rapid Methods for Identification

Urine Antigen test-most common test

Direct Fluorescent Antibody test (DFA)

DNA Detection

Serological tests (IFA)

Legionella spp treatment?

Susceptibility testing not routinely performed

Erythromycin alone or Rifampin used to treat

Organisms that lack cell walls?

Mycoplasma

Ureaplasma urealyticum

Mycoplasma?

Does not possess a cell wall ( not gram stainable)

Can be grown on complex culture media

Immunological and molecular procedures most used to identify

Common cause of pneumonia

Patient will present with a cold agglutinin

Ureaplasma Urealyticum?

Common inhabitant of the genitourinary tract mucus membranes

Differentiate from Mycoplasma by the ability to hydrolyze urea

identified by immunological or molecular methods.