WEEK 11: AEROBIC GRAM-POSITIVE BACILLI Flashcards
Non-spore formers can be divided into two, smaller groups
as:
non-branching catalase-positive bacilli and non
branching catalase-negative bacilli
frequently isolated from urogenital specimens from women
and are incubated aerobically but they are aerotolerant
anaerobes
Lactobacillus
Frequently isolated in clinical laboratory but are typically
considered contaminants or commensals:
Bacillus and
Corynebacterium
A large diverse group of bacteria that includes animal and
human pathogens as well as saprophytes and plant
pathogens
CORYNEBACTERIUM
closely related to
mycobacteria and nocardiae On the basis of 16S ribosomal ribonucleic acid (rRNA)
sequencing,
corynebacteria
CORYNEBACTERIUM CAN BE DIVIDED INTO
- Can be divided into nonlipophilic and lipophilic species
- Lipophilic corynebacterial:
o Considered fastidious and grow slowly on
standard culture media
o incubated for at least 48 hours
o Growth is enhanced if lipids are included in the
culture medium
Slightly curved, gram-positive rods with
nonparallel sides and slightly wider ends, producing the
described “club shape”
CORYNEBACTERIUM
The term diphtheroid, meaning “diphtheria-like,” is
sometimes used in reference to this Gram staining
morphology
CORYNEBACTERIUM
The classification of corynebacteria is not well
characterized. It is not possible to identify 30% to 50% of
coryneform-like isolates to the species level without
16S
rRNA gene sequencing.
Most significant pathogen of the group CORYNEBACTERIUM
C. diphtheriae
CORYNEBACTERIUM DIPTHERIAE
IS CLASSIFIED INTO
Classified into biotypes (mitis, intermedius, and gravis)
according to colony morphology, as well as into lysotypes
based upon corynebacteriophage sensitivity
WHAT IS NEEDED FOR OPTIMAL GROWTH OF C. DITHERIAE??
- Most strains require nicotinic and pantothenic acids for growth; some also require thiamine, biotin, or pimelic acid
- For optimal production of diphtheria toxin, the medium should be supplemented with amino acids and must be deferrated
Virulence factor of c diptheriae
- diptheria toxin
- fragment a and b
he major virulence factor and a protein
of 62,000 daltons (Da)
Diphtheria toxin
__________and _______ which belong to the
“C. diphtheriae group,” can also produce the toxin when
they become infected with the tox-carrying β-phage____
C. ulcerans and C. pseudotuberculosis
when is diptheria toxin toxic?
Toxin is exceedingly potent and is lethal for humans in
amounts of 130 ng/kg body weight
is responsible for the cytotoxicity
fragment a
binds to receptors on human cells
and mediates the entry of fragment A into the
cytoplasm
Fragment B
diptheria toxin is caused by and secreted by
- The toxicity is caused by the ability of diphtheria toxin to
block protein synthesis in eukaryotic cells. - The toxin is secreted by the bacterial cell and is nontoxic
until exposed to trypsin.
cleaves the diptheria toxin into the two fragments,
which are held together by a disulfide bridge
Trypsinization
splits nicotinamide adenosine dinucleotide to form nicotinamide and adenosine diphosphoribose
(ADPR).
Fragment A
binds to and inactivates elongation factor 2 (EF-2),
an enzyme required for elongation of polypeptide chains on
ribosomes.
ADPR
Production of the diptheria toxin in vitro depends on numerous
environmental conditions:
o Alkaline pH (7.8 to 8.0)
o Oxygen
o Iron concentration in the environment (most
important)
diseases cause dby c diptheria
2 different form of disease in humans
Respiratory diptheria
Cutaneous diphtheria = nonhealing ulcer and dirty gray membrane
Begins gradually and is characterized by low-grade fever, malaise, and a mild sore throat
Most common site of infection is the tonsils or the pharynx
The symptoms of diphtheria include pharyngitis, fever, swelling of the neck or area surrounding the skin lesion
Combination of cell necrosis and exudate forms a tough gray-to-white pseudomembrane, which attaches to the tissues.
diphtheritic lesion
diphtheritic lesion
Cardiac failure
Asymptomatic nasopharyngeal carriage
how to diagnose c diptheria
Toxigenicity is identified by a variety of in vitro (e.g., gel
immunodiffusion, tissue culture) or in vivo (e.g., rabbit skin test, guinea pig challenge) methods
In vivo toxin testing is rarely done because the in vitro
methods are reliable, less expensive, and free from animal
use.
appearance of c diptheria
- pleomorphic
- palisades, sharp angles with v and L formation
- club shaped swelling and beads
- babes ernst granules
- irregular stain esp with meth blue
accumulation of polymerized polyphosphates.
Babès-Ernst granules
accumulation of
nutrient reserves and differs with the type of medium and the metabolic state of the individual cells.
Babès-Ernst granules
temp for c diptheriae
FA
Grows best under aerobic conditions and has an optimal growth temperature of 37° C, although multiplication occurs within the range of 15° to 40° C.
WHAT AGAR MEDIUM IS BEST FOR C DIPTHEIRA
Grows on nutrient agar, better growth is usually obtained on a medium containing blood or serum, such as Loeffler serum or Pai agars
LOEFFLER = KITANG KITA
SBA = SMALL ZONE OF B HEMOLYSIS
CTBA - BLACK/BROWN COLONY DUE TO REDUCED TELLURITE
is useful for differentiating corynebacteria because
only C. diphtheriae, C. ulcerans, and C. pseudotuberculosis
form a brown halo as a result of cystinase activity
CTBA
CTBA is useful for differentiating corynebacteria because only____________________ form a brown halo as a result of cystinase activity
CTBA is useful for differentiating corynebacteria because
only C. diphtheriae, C. ulcerans, and C. pseudotuberculosis
form a brown halo as a result of cystinase activity
1distinguishes C. diphtheriae
from c. ULCERANCE AND C PSEUDOTUBERCULSOSIS
Lack of urease production
Identification of an isolate as C. diphtheriae does not mean that the patient has diphtheria
t or f
trueeeeeee
elek test what bacteria and explain procedure
c. diptheria
o Requires reagents and antisera be carefully
controlled and titrated
o Organisms (controls and unknowns) are streaked
on medium of low iron content.
o Each organism is streaked in a single straight line
parallel to each other and 10 mm apart.
o A filter paper strip impregnated with diphtheria
antitoxin is laid along the center of the plate on a
line at right angles to the inoculum lines of control
and unknown organisms
o The plate is incubated at 35° C and examined after
18, 24, and 48 hours.
o Lines of precipitation are best seen by transmitted
light against a dark background.
o The white precipitin lines start about 4 to 5 mm
from the filter paper strip and are at an angle of
about 45 degrees to the line of growth.
If an isolate is positive for toxin production and it is
placed next to the positive control, the toxin line of
the positive control should join the toxin line of the
positive unknown to form an arch of identity
what else can be used to diagnose c diptheria
Rapid enzyme-linked immunosorbent assays and
immunochromatographic strip assays: Available for the
detection of diphtheria toxin.
* PCR - for tox gene
Toxoid vaccine-formalin-treated diphtheria toxin is part of
trivalent diphtheria, tetanus, and pertussis vaccine
preventing disease but not infection
Antimicrobial agents have no effect on the toxin that is
already circulating, but they do eliminate the focus of
infection and prevent the spread of the organism.
c diptheria
treatment of diptheria
- Drug of choice is penicillin
- Erythromycin is used for penicillin-sensitive individuals.
- Most patients do not develop immunity after infection;
therefore, vaccination should be administered after
recovery
C. Amycolatum
- normal skin microbiota
- prosthetic joint infection and has been
reported to cause bloodstream infection and endocarditis - flat and dry, have a matte or
waxy appearance, and are nonlipophilic. - MDR:β-lactams, fluoroquinolines, macrolides, clindamycin, and
aminoglycosides
C. jeikeium
- NORMAL SKIN MICROBIOTA
- LIMITED TO IMMUNOCOMPOROMISED, HAD INVASIVE PROCEDURE OR THOSE WITH CENTRAL LINE CATHETER OR PROSTHETIC DEVICE
- Most common cause of Corynebacterium-associated
prosthetic valve endocarditis in adults. - Causes septicemia, meningitis, prosthetic joint infections,
and skin complications, such as rash and subcutaneous
nodules. - Lipophilic
- MDR: Cephalosporins, aminoglycosides.
- SUS: VANCOMYCIN
C. pseudodiptheriticum
- Part of the normal biota of the human nasopharynx, is an infrequent cause of infection.
- Associated with respiratory tract infections in
immunocompromised or patients with other
underlying diseases, such as chronic obstructive pulmonary disease or diabetes mellitus - Respiratory tract infection can mimic respiratory diphtheria.
- Cause endocarditis, urinary tract infections (UTIs), and
cutaneous wound infections in immunocompromised
patients. - NOT PLEOMORPHIC
- EVEN STAIN
C. pseudotuberculosis
- Veterinary pathogen
- Human infections typically have been associated with
contact with sheep and are rare - Causes a granulomatous lymphadenitis in humans.
C. striatum
- Part of the human skin and the nasopharynx
- commensal, contaminant, nosocomial
- device-related infection and has been reported in cases of endocarditis, septic arthritis, meningitis, and pneumonia.
- Nonlipophilic
- Pleomorphic
- Produces small, shiny, convex colonies in about 24 hours.
- Resistant: Penicillins and other β-lactams, macrolides,
fluoroquinolones, daptomycin (reported recently) - Susceptible: Vancomycin. Resistance to daptomycin has been reported recently.
C. ulcerans
- Isolated from humans with diphtheria-like illness, and a significant number of isolates produce the diphtheria toxin.
- veterinary pathogen, causing mastitis in cattle and
other domestic and wild animals - Isolated from skin ulcers and exudative pharyngitis.
C. urealyticum
- Most commonly associated with UTIs.
- Presumptive identification can be made for urine isolates with pinpoint, nonhemolytic, white colonies
- Christensen urea slant
- Resistant: β-lactams, trimethoprimsulfamethoxazol,
macrolides, and tetracycline. - Drug of choice: Vancomycin
Linked to bacteremia, endocarditis, pneumonia, and other
infections.
R. MUCILAGINOSA
R. DENTOCARIOSA
- Normal human oropharyngeal microbiota
- Found in saliva and supragingival plaque.
- Isolated from patients with endocarditis.
- Resembles coryneform bacilli
o Branching filaments that resemble filaments of
facultative actinomycetes.
o However, when placed in broth, the species
produces
coccoid cells, a characteristic
differentiating it from actinomycetes.
R. DENTOCARIOSA
is widespread in the environment and has been recovered from:
o Soil
o Water
o Vegetation
o Animal products: Raw milk, cheese, poultry, and
processed meats
LISTERIA MONOCYTOGENES
- can also be in git
- Isolated from crustaceans, flies, and ticks.
- Known to cause illness in many species of wild and
domestic animals, including sheep, cattle, swine, horses,
dogs, cats, rodents, birds, and fishes - Can be isolated from both human and animal asymptomatic carriers.
Has the highest mortality rate secondary to its unique
virulence factors
L. monocytogenes
is recognized as an uncommon but serious
infection primarily of neonates, pregnant women, older
adults, and immunocompromised hosts. Infection may also
occur in healthy individuals
Listeriosis
Virulence Factors of listeria monocytogenes
- Hemolysin (Listeriolysin O (LLO))
- catalsew=
- superoxide dismutase
-Phosphatidylinositol-specific phospholipase C (PI-PLC)
- Intracellular mobility via actin polymerization (ActA)
- Surface protein (p60)
- hemolysis
- Intracellular mobility via actin polymerization (ActA)
- Ability to replicate at refrigerator temperatures
- Internalins (InlA and InlB)
- cadherin
o Damages the phagosome membrane, effectively
preventing killing of the organism by macrophages
o Helps bacteria escape from host cell vacuole
Hemolysin (Listeriolysin O (LLO))
Helps the bacteria escape host cell vacuole and
cause membrane disruption
- Phosphatidylinositol-specific phospholipase C (PI-PLC)
Induces phagocytosis through increased adhesion
and penetration into mammalian cells.
- Surface protein (p60).
Nonhemolytic isolates are found to be avirulent and
demonstrate no intracellular spread of the organism
L monocytogenes
forms “rocket tails” via actin
polymerization that allows the bacteria to move rapidly between cells, avoid antibody detection,
and spread hematogenously
L. monocytogenes
- Intracellular mobility via actin polymerization (ActA)
Low temperatures induce enzymes such as RNA
helicase which improves ???
activity and replication at low temperatures
Low temperatures induce enzymes such as RNA
helicase which improves L. monocytogenes’
activity and replication at low temperatures
enables the ability to propel itself
and latch onto enterocytes early in infection, but
eventually losing the flagella the longer the
bacteria is exposed to higher temperatures
Bacterial surface proteins for host cell attachment
- Internalins (InlA and InlB)
An epithelial attachment protein that is found in
abundance in the blood-brain barrier as well as the
placental-fetus barrier which may explain why the
bacteria can infect neonates and cause meningitis.
Cadherin
disease caused by l monocytogenes
Known to cause illness in many species of wild and domestic animals, including sheep, cattle, swine, horses, dogs, cats, rodents, birds, and fishes
- meningitis
- Sepsis, meningitis, encephalitis, spontaneous abortion, or fever and self-limiting gastroenteritis in a healthy adult
- a tropism for the central nervous system (CNS)
- Infections of newborns and immunocompromised adults are the most common
- Early and late-onset listeriosis in newborn
- Most common manifestations: CNS infection and endocarditis.
- Outbreaks have occurred as a result of eating contaminated cheese, coleslaw, and chicken.
- Contaminated ice cream, hot dogs, and luncheon meats have served as vehicles for this foodborne disease.
- intestinal tract infection
Responsible for spontaneous abortion and stillborn
neonates
Signs and symptoms: flulike illness with fever, headache,
and myalgia
result in premature labor or septic
abortion within 3 to 7 days.
source of infection eliminated at birth so self limiting siya
l monocytogenes disease in preggy
disease in newborn l monocytogenes
- Extremely serious
- 50% fatality for babies born alive
- Similar to Streptococcus agalactiae neonatal disease, there
are two forms of neonatal listeriosis: early onset and late
onset.
o Early-onset listeriosis:
From an intrauterine infection that can
cause illness at or shortly after birth.
▪ The result is most often sepsis.
▪ Associated with aspiration of infected
amniotic fluid.
o Late-onset disease
listeriosis
▪ Occurs several days to weeks after birth.
▪ Affected infants generally are full-term
infants and healthy at birth.
▪ Most likely to manifest itself as meningitis.
▪ Fatality rate is lower than in early-onset
infection
- Outbreaks have occurred as a result of eating contaminated
cheese, coleslaw, and chicken. - Contaminated ice cream, hot dogs, and luncheon meats
have served as vehicles for this foodborne disease.
l monocytoegenes
Most common manifestations: CNS infection and
endocarditis.
l monocytogenes
appearance of l monocytogenes
- Gram-positive coccobacillus.
- Subculturing, cells become coccoidal
- Older cultures often appear gram variable.
- Singly, in short chains, or in palisades.
- L. monocytogenes can resemble Streptococcus when
found in the coccoid form - L. monocytogenes can resemble Corynebacterium when
the bacillus forms prevail. - Not usually seen on the CSF smear
- Colonies and hemolysis resemble those seen with S.
agalactiae
how to grow l monocytogenes
- Grows on a special type of agar called Mueller-Hinton agar.
- Grows well on SBA and chocolate agar
- Grows well on nutrient agars and in broths, such as brain heart infusion medium and thioglycolate broth.
- Prefers a slightly increased carbon dioxide (CO2) tension for isolation.
temp for l monocytogenes
Optimal growth temperature: 30° to 35° C, but growth
occurs over a wide range (0.5° to 45° C).
* Cold Enrichment: Can grow at 4° C and used to isolate the
organism from polymicrobial clinical specimens
wet mount prep in l mono cytogenes
▪ Exhibits tumbling motility (end-over-end
motility) when viewed microscopically
▪ Umbrella pattern is seen when the
organism is incubated at room temperature (22° to 25° C) but not at 35°
l monocytogenes camp reaction
▪ More pronounced CAMP reaction is seen
when Rhodococcus equi is used in place
of Staphylococcus aureus. L.
▪ Produces a “block”-type hemolysis
▪ distinguishes L. monocytogenes (+) from
other Listeria spp (-)
- Presumptive identification and confrimatory findings of l monocytogewnes
- Presumptive identification:
o Gram staining
o Tumbling motility
o Positive catalase
o Esculin hydrolysis. - Confirmatory findings:
o Acid production from glucose and positive
o Voges-Proskauer
o Methyl red reactions.
HOW TO TREAT L MONOCYTOGENES
- Preferred Drug: Ampicillin
- Penicillin, aminoglycosides, and macrolides is effective to
treat Listeriosis
- There are three species in the genus Erysipelothrix:
o Erysipelothrix rhusiopathiae
o Erysipelothrix tonsillarum
o Erysipelothrix inopinata
- Only species known to cause disease in humans.
genus Erysipelothrix
ERYSIPELOTHRIX RHUSIOPATHIAE
Commensal and present in vertebrates and invertebrates,
including domestic swine, birds, and fishes.
ERYSIPELOTHRIX RHUSIOPATHIAE
ROute of infection: ERYSIPELOTHRIX RHUSIOPATHIAE
Cuts or scratches on skin
* Human cases typically result from occupational exposure.
Work involves handling fish and animal
products are most at risk.
LOC OF ERYSIPELOTHRIX RHUSIOPATHIO
Survives well in environmental sources: Water, soil, and
plant.
DISEASE CAUSED BY ERYSIPELOTHRIX RUSOPATHIAE
Linked to bacteremia, endocarditis, pneumonia, and other infections.
Produces three types of disease in humans:
ERYSPELOID
SEPTICIMEIA
DIFFUSE CUTANEOUS INFECTION AND SYSTEMIC DISEASE
pneumonia, abscesses, meningitis, endophthalmitis, osteomyelitis, and septic arthritis
A localized skin infection that resembles
streptococcal erysipelas.
Erysipeloid
- Lesions usually are seen on the hands or fingers
because they are inoculated through work
activities. - Signs and symptoms: Low-grade fever,
arthralgia, lymphangitis, and lymphadenopathy
may occur.
ERYSIPELOTHRIX RHISIOPATHIAE IS RESISTANT AND SUSCEPTIBLE TO
o Resistant: Aminoglycosides and Vancomycin
o Susceptible:
Cephalosporins
Fluoroquinolones
APPEARANCE OF ARYSIPELOTHRIX RHUSOPATHIAE
- Thin, rod-shaped, grampositive organism that can form long
filaments - Arranged singly, in short chains, or in a “V” shape.
- V shape arrangement is similar to corynebacterial
- E. rhusiopathiae decolorizes easily, so it may appear gram
variable.
Inoculated in a nutrient broth with 1% glucose and
incubated in 5% CO2 at 35° C.
ERSYPELOTHRIX RHUSOPATHIAE
Gelatin stab culture yields a highly characteristic “test tube
brush–like” pattern at 22° C.
ERYSIPELOTHRIX RHUSOPATHIAE
- Stain gram variable or gram negative.
- Gram-positive type of cell wall
o Peptidoglycan layer is thinner
GARDNERELLA VAGINALIS
Characterized by a malodorous discharge and
vaginal pH greater than 4.5.
bacterial vaginosis (BV)
BV
o Results from a reduction in the Lactobacillus
population in the vagina
o Increase in vaginal pH
GARDNERELLA VAGINALIS
- BV
- Also play a role in UTIs in men and women
- BV is associated with preterm birth and increased risk for acquisition of human immunodeficiency virus (HIV) and other sexually transmitted infections (STIs)
GARDNERELLA VAGINALIS
VF
VAGINOLYSIN
PROTEASE AND SIALIDASE ENZYME
cholesterol-dependent cytolysin that
initiates complex signaling cascades that induce target cell lysis and allow for Gardnerella’s virulence
Vaginolysin
Diagnosis of BV:
o Presence of “clue cells,” large squamous epithelial
cells
o Gram-positive ,gram-variable bacilli and coccobacilli clustered on the edges
o Lactobacillus rods are absent in the wet mount.
Amsel’s clinical criteria
used to diagnosis BV
if three of four criteria are found:
1. Homogeneous, thin, white discharge that
smoothly coats the vaginal walls
2. Clue cells
3. pH of vaginal fluid greater than 4.5
4. Fishy odor of vaginal discharge before or after
addition of 10% potassium hydroxide, the whiff
test (positive).
detect vaginal fluid sialidase activity
o Affirm VP III (Becton Dickinson, Sparks, MD)
o DNA hybridization probe test
o OSOM BV Blue test (Sekisui Diagnostics,
Framingham, MA
for definitive
identification of G. vaginalis
16S rRNA gene sequencing
Gram staining of the vaginal fluid to
examine the predominant strain of bacteria to make a
microbiological diagnosis of BV
Nugent CriteriaQ
GARDNERELLA VAGINALIS
GROWS BEST IN
- It takes more than 24 hours to develop visible colonies
- Grows best in 5% to 7% CO2 at a temperature of 35° to 37° C.
Medium of choice: Human blood bilayer Tween (HBT)
agar.
Also produces β-hemolytic colonies on media made with
rabbit or human blood, but not sheep blood
(NONHEMOLYTIC ON SBA AND PIN POINT)
Differential Diagnosis
OF BV
PROPER PELVIC EXAM, = exclude other similarly presenting diseases such as herpes simplex virus
SPECULUM EXAM, = can look for cervicitis and a wet mount of the vaginal discharge can determine if there is candidiasis or trichomoniasis
CERVICAL SWAB = can be sent for chlamydia and gonorrhea
GARDNERELLA VAGINALIS
Treatment
- Drug of choice: Clindamycin and Metronidazole
are a primary clue that a
clinical sample contains Nocardia spp.
Finely beaded, branching rods
Colony, microscopic morphology and types of infections
caused, sometimes resemble those of fungi, but these
organisms are true bacteria.
NOCARDIA
isolation of __________ from patients should be carefully evaluated for the presence of disseminated disease,
immunocompromised hosts
Nocardia
was considered the most prominent
Nocardia human pathogen
Nocardia asteroides
more virulent than the other
members of the N. asteroides complex, since infection with this species is more likely to result in disseminated disease
N. farcinica
different susceptibility pattern, showing
consistent susceptibility to erythromycin and ampicillin
NOCARDIOA
N. NOVA
VF OF NOCARDIA
Superoxide dismutase and catalase
nocobactin = ironchelating compound
occurs from the inhalation of the
organism present in dust or soil and is the most common manifestation of disease.
NOCARDIA
PULMONARY INFECTION
DISEASE CAUSED BY NOCARDIA
- Infection occurs by two routes: pulmonary and cutaneous.
- Serious infection
- brain abscess infection
- 40% of the diagnoses are made at autopsy.
Pulmonary infections
- Confluent bronchopneumonia
- thick and purulent sputum
- no sulfur granules
Cutaneous infections
- acetinmycotic mycetomas
- Direct inoculation of Nocardia species by transcutaneous routes results in three forms of infection: cellulitis, lymphocutaneous disease, or actinomycetoma
- Primary cutaneous nocardiosis
- Lymphocutaneous nocardiosis/sporotrichoidtype
- Actinomycetoma
No sulfur granules (masses of filamentous organisms bound
together by calcium phosphate) develop, and no sinus tract
formation occurs.
Confluent bronchopneumonia
Cutaneous Infection IN NOCARDIA
IS OFTEN caused by what species
N. brasiliensis is the most frequent cause of this form of
nocardiosis
most common cause of actinomycotic
mycetoma.
N. brasiliensis
are
characterized by swelling, draining sinuses, and granules
mycetomas
MYCETOMAS
- As the infection progresses, burrowing sinuses open to the
skin surface and drain pus. - The pus may be pigmented and contain “sulfur granules”
- Sulfur granules appear yellow or orange and have a distinct
granular appearanc
Direct inoculation of Nocardia species by transcutaneous
routes results in three forms of infection:
cellulitis,
lymphocutaneous disease, or actinomycetoma
This Nocardia
infection is marked by the presence of a primary
pyodermatous lesion frequently associated with areas of
chronic drainage and crusting. progresses to the
formation of lymphatic abscesses
Lymphocutaneous nocardiosis/Sporotrichoidtype
te-stage infection,
characterized by a chronic, localized, slowly progressive,
and subcutaneous and bone disease, usually involving the
foot and often painless
Actinomycetoma
Chalky, matte, velvety, or powdery appearance
and may be white, yellow, pink, orange, peach, tan,
or gray pigmented.
NOCARDIA
beaded appearance may be confused as chains of
gram-positive cocci
NOCARDIA
Can have a dry, crumbly appearance similar to
breadcrumbs
NOCARDIA
Examination of colonies with a dissecting
microscope may reveal the presence of aerial
hyphae (production of spores)
NOCARDIA
Branching isolate that is partially acid fast on
staining with carbolfuchsin and decolorizing with a
weak acid (0.5% to 1% sulfuric acid) compared
with 3% hydrogen chloride in the stain for
mycobacteria.
NOCARDIA
Direct examination specimen: Tissue and pus from draining
sinuses
NOCARDIA
Broad, interwoven, septate hyphae that are wider
(2 to 5 µm) compared to actinomycotic mycetoma
Eumycotic mycetoma
HOW TO GROW NOCARDIA
- Grow well on most common nonselective laboratory media
- Incubated at temperatures between 22° and 37° C,
- 3 to 6 days or more may pass before growth is seen.
- Recovered on simple media containing a single organic
molecule as a source of carbon. - Media containing antimicrobial agents used for isolating
fungi should not be used because they susceptible to many
of the agents used in these media. - SBA: some isolates are β-hemolytic
- Thayer-Martin agar may enhance recovery by inhibiting
the growth of contaminating organisms. - They also grow on nonselective buffered charcoal–yeast
extract agar
Phenotypic tests are used to identify relevant Nocardia spp.
o Substrate hydrolysis (casein, tyrosine, xanthine,
and hypoxanthine)
o Other substrate and carbohydrate use,
arylsulfatase, and gelatin liquefaction
o Antimicrobial susceptibility profile
o Fatty acid analysis by high-performance liquid
chromatography
most reliable identification
method for nocardia
16S rRNA gene sequencing
nocardia is susceptible to
trimethoprim sulfamethoxazole
(mild to tolerate diseases)
combination therapy with TMP SMX plus amikacin (life threatening heart, disseminated disease, infection of immunocomporomised, cns disease)
Cetrafioxone (cns disease)
TMP SMX and/or minocycline and/or amoxicillin-clavulanate
(Improves on iv and no cns disease)
Sulfonamide
nocardia is resistant to
Penicillin
Antifungal agents
actinomyces is found in
Actinomyces species are members of the endogenous flora of mucous membranes and are frequently cultured from the gastrointestinal tract, bronchi, and female genital tract
- The major sites of actinomycoses are cervicofacial, abdominopelvic, and thoracic
most common cause of human disease among the
Actinomyces species is
A. israelii
never been cultured from nature, and
no person-to-person spread has been documente
actinomyces
Infections are associated with the breakdown of normal
physical barriers, such as disruption of mucosal membranes
in the mouth and gastrointestinal tract
Actinomyces
Certain conditions may predispose to infection, including
erupting secondary teeth, dental extractions and caries,
gingivitis, and gingival trauma
Actinomyces
diagnosis of ______ in children should alert the
astute physician to consider an underlying immunodeficiency such as chronic granulomatous disease.
actinomyces
The major sites of actinomycoses are
cervicofacial,
abdominopelvic, and thoracic
disease caused by actinomyces
Infections are associated with the breakdown of normal physical barriers, such as disruption of mucosal membranes in the mouth and gastrointestinal tract
- Certain conditions may predispose to infection, including erupting secondary teeth, dental extractions and caries, gingivitis, and gingival trauma
- in children should alert the astute physician to consider an underlying immunodeficiency such as chronic granulomatous disease. Virtually all infections are polymicrobial
- Certvicofacial actinomycosis
- thoracic disease
-acute pneumonitis - abdominal and pelvic actinomycosis
-acute inflammatory lesions
-osteomyelitis
-stimulates ptb
-chronic inflammation, fibrosis, and
cavitation that result in the invasion and destruction of
surrounding structures
actinomyces is susceptible to
Thoracic, abdominal, or soft tissue abscesses may require a medico-surgical approach with drainage and extensive resection of affected tissues and excision of sinus tracts combined with prolonged antibiotic therapy
Penicillins and extended spectrum penicillins, cephalosporins, carbapenems, and tetracycline
Amoxicillin
or penicillin-allergic patients, doxycycline, erythromycins, and clindamycins have proven to be suitable alternatives
actinomyces israelii is resistant to
A. israelii have developed resistance to penicillin
most challenging aspect of diagnosis of infection by
members of the Actinomycetes is the
inclusion of these
organisms in the differential diagnosis of patients with
chronic cavitary pulmonary disease, especially the
immunocompromised patient
Both species present as masqueraders in many clinical
presentation
actinomycosis and nocardiosis
presence of beaded, branching, gram-positive bacilli
in any clinical specimen should alert the clinician to
consider both
aerobic Nocardia and anaerobic
Actinomyces
transportation of actinomyces
Actinomyces are microaerophilic or
facultative, specimens should be transported in
anaerobic transport media and cultured under strict
anaerobic conditions
Nocardia species will grow on standard blood culture
media, but the use of selective media such as _________________________________may be useful
Thayer
Martin with antibiotics
Cause mycetomas, which are identical to those caused by
Nocardia.
Actinomadura
Actinomaduraudes
Actinomadura madurae and Actinomadura
pelletieri.
is cellobiose and xylose positive
A. madurae
- Gram Stain Morphology: Moderate, fine, intertwining,
branching with short chains or spores, fragmentation - Colony Appearance on Routine Agar: White-to-pink
pigment, mucoid, molar tooth appearance after 2 weeks’
incubation; sparse aerial hyphae
Actinomadura
- Primarily saprophytes found as soil inhabitants
Streptomyces
specimens has been increasingly isolated from many
clinical specimens, including sputum, wound, blood, and
brain
Streptomyces anulatus
- Gram Stain Morphology: Extensive branching with chains
and spores; does not fragment easily - Colony Appearance on Routine Agar: Glabrous or waxy
heaped colonies; variable morphology; wide range of
pigmentation from cream to brown-black; white aerial
hyphae
Streptomyces
Distinguished by simple biochemical tests.
Gordonia
Absence of arylsulfatase and mycelia
gordonia
Infections are postsurgical sternal wounds, coronary artery
infection, and infection from central venous catheters.
gordonia
gordonia is susceptible to
Susceptible: β-lactams, quinolones, aminoglycosides,
macrolides, and other agents active against gram-positive
organisms.
Colony appearance on Routine Agar: Somewhat
pigmented; G. sputi smooth, mucoid, and adherent; G.
bronchialis dry and raised
gordonia
- Contact with farm animals and feces is an important risk
factor. - Lung infections account for about 80% of human disease
phodococcus
Rhodococcus - Most common human isolate
Rhodococcus equi
SBA: Colonies resemble Klebsiella and can form a salmon
pink pigment on prolonged incubation, especially at room
temperature
rhodococcus
Filaments w/ some branching,
diphtheroid-like with minimal branching or coccobacillary;
colony growth appears as coccobacilli in “zigzag”
configuration
rhodococcus
Colony Appearance on Routine Agar: Nonhemolytic;
round; often mucoid with orange-to-red, salmon-pink
pigment developing within 4–7 days; pigment may vary
widely
rhodococcus
- Causative agent of Whipple disease.
Tropheryma whipplei
Facultative intracellular pathogen first identified in 1991 by
using PCR from a duodenal biopsy specimen
Tropheryma whipplei
Trypheryma whipplei loc
- Found in human feces, saliva, and gastric secretions
- Ubiquitous in the environment
Symptoms: diarrhea, weight loss, malabsorption, arthralgia,
and abdominal pain.
tropheryma whipplei -
T. whipplei can be identified with
PCR or 16S rRNA gene
sequencing
how to treat tropheryma whipplei
Drug of Choice:
Initially w/ Doxycycline and Hydroxychloroquine for 1 year followed by Doxycycline for life
diagnosis for tropheryma whipplei specimen
Diagnosis is best made by microscopic examination of
endoscopic biopsy specimens.
Presence of characteristic periodic acid–Schiff staining is
strongly suggestive of
Whipple disease
disease caused by tropheryma whipplei
- Symptoms: diarrhea, weight loss, malabsorption, arthralgia,
and abdominal pain. - Neurologic and sensory changes often occur
- Associated with culture-negative endocarditis
- Rare but is seen more commonly in middle-aged men
- Asymptomatic carriage or a mild self-limiting gastroenteritis
occurs in children after ingestion of the organism.
Aerobic or facultative anaerobic bacilli that form
endospores
bacillus
Do not grow on Columbia colistinnaladixic acid agar.
bacillus
bacillus
- nonpigmented
- confused with aerotolerant strains of the
other primary endospore-forming genus, Clostridium - Survival is aided by the formation of spores, which are
resistant to conditions to which vegetative cells are
intolerant - Grow well on SBA and other commonly used enriched
media - lab contaminant
-insect and plant pathogen
-human infections (anthracis and cereus)
bacillus vs clostridium
form endospores aerobically and
anaerobically, whereas Clostridium spp. form endospores
anaerobically only.
Known to cause an anthrax-like disease in gorillas,
chimpanzees, and other animals in Africa.
B. cereus biovar anthracis
Depends on a glutamic acid capsule and a three
component protein exotoxin.
B. ANTHRACIS
vf of b antharcis
-capsule
-3 proteins:rotective antigen (PA), EF, and LF,
- PA with EF,
Edema
PA and LF combine
death
denylate cyclase that increases the concentration
of cyclic adenosine monophosphate (cAMP) in host cel
ef
protease that kills host cells by disrupting the
transduction of extracellular regulatory signals
lf
Spread by animals feeding on plants contaminated with the
spores or from contaminated soil.
anthrax
Cases mostly occurred among postal workers as a result of
exposure to sporetainted material (powder in or on
envelopes) sent through the mail, although the actual
source remains unknown for some cases.
anthrax
4 anthracis found in humans
cutaneous, inhalation or pulmonary, and gastrointestinal and injectional
hen wounds are
contaminated with anthrax spores acquired through skin
cuts, abrasions, or insect bites
cutaneous anthrax
Cutaneous Anthrax
- A small pimple or papule appears at the site of inoculation
2 to 3 days after exposure. - A ring of vesicles develops, and the vesicles coalesce to
form an erythematous ring - A small dark area appears in the center of the ring and
eventually ulcerates and dries, forming a depressed black
necrotic central area known as an eschar or black eschar - Lesion is sometimes referred to as a malignant pustule,
even though it is not a pustule and is not malignant. It is
painless and does not produce pus, unless it becomes
secondarily infected with a pyogenic organism
- Usually, the infection remains localized, but regional
lymphangitis and lymphadenopathy appear - If septicemia occurs, symptoms of fever, malaise, and
headache are seen
cutaneous anthrax
- Also called woolsorter’s disease
Inhalation Anthrax
It resembles an upper respiratory tract infection, such as
that seen with colds and flu.
Inhalation Anthrax
initial and severe phase of inhalation anthrax
- The initial, mild form of the disease lasts 2 to 3 days. It is
followed by a sudden severe phase in which respiratory
distress is common. - The severe phase of the disease has a high mortality rate.
The respiratory problems (dyspnea, cyanosis, pleural
effusion) are followed by disorientation, coma, and death. - The severe phase (onset of respiratory symptoms to death)
may last only 24 hours
Occurs when the spores are inoculated into a lesion on
the intestinal mucosa after ingestion of the spores
Gastrointestinal Anthrax
- Symptoms: abdominal pain, nausea, anorexia, and
vomiting. - Bloody diarrhea can also occur
- This form of the disease is difficult to diagnose, the fatality
rate is higher than in the cutaneous form
gastrointestinal anthrac
Injectional Anthrax
- Characterized by soft tissue infection associated with
“skin popping” or other forms of injection drug use and
results from the direct injection of the spores into tissue. - Can be associated with necrotizing fasciitis, organ failure,
shock, coma, and meningitis, and it has a much higher rate
of mortality. - Soft tissue infections have not been associated with black
eschar formation. Lack of eschar, severity of disease, and
increased mortality rate make this form clinically distinct
Approximately 5% of patients with anthrax (cutaneous,
inhalation,
gastrointestinal,
or
injectional)
develop
meningitis, with a greater proportion of cases occurring in
the i
nhalation and injectional forms.
when does Unconsciousness and death, happen after initial exposure to b anthrax
Unconsciousness and death, if they occur, follow 1 to 6 days
after initial exposure.
Young cultures stain gram positive; as the cells age, or if
they are under nutritional stress, they become gram
variable.
b atnhrax
encapsulated gram-positive rods in blood
is strongly presumptive for
B. anthracis identification.
spore stain
Spores can be observed with a spore stain. With this
technique, vegetative cells stain red, and the spores stain
green Spores can be observed with a spore stain. With this
technique, vegetative cells stain red, and the spores stain
green
Medusa head
B. anthracis.
Colonies have a tenacious consistency, holding tightly to the
agar surface, and when the edges are lifted with a loop, they
stand upright without support.
b anthracis
be isolated from normally sterile sites, such as
blood, lung tissue, and CSF, selective media are not usually
needed for recovery.
b anthracis
Grows in high-salt (7% sodium chloride) and low pH (<6)
conditions.
b anthracis
Capsule production by B. anthracis can be detected by
India ink
Presence of both antigens (polysaccharide and capsule) is
confirmation for B. anthracis
treatment of b anthracis
The initial therapy should be a multidrug regimen, including a fluoroquinolone and one or more additional agents with good CNS penetration.
Vaccne
Penicillin, tetracycline, fluoroquinolones, and chloramphenicol
ciprofloxacin or doxycycline be used for initial intravenous therapy until antimicrobial susceptibility results are known
Initial therapy of inhalation anthrax: Ciprofloxacin or doxycycline plus one or two additional antimicrobial agents, depending on disease severity.
clindamycin = inhibit exotoxin production. *
metronidazole= injectional anthrax
ciprofloxacin or doxycycline =postexposure prophylaxis for pulmonary anthrax
B. cereus is similar to B. anthracis in many ways—
morphologically and metabolically
o β-hemolytic frosted glass–appearing colony
o Spore-forming
b cereus
o insect pathogen
o produces parasporal crystals that can be observed
by using phase contrast microscopy or spore
staining.
B. thuringiensis
Common cause of food poisoning and opportunistic
infections in susceptible hosts.
b cereus
diseases caused by b cereus
Common cause of food poisoning and opportunistic infections in susceptible hosts.
food poison: diarrheal or emetic
eye infection,endophthalmitis, panophthalmitis, and keratitis with abscess formation
(occur more frequently in intravenous drug abusers, neonates, and immunosuppressed and postsurgical
patients. )
few reports of B. cereus strains carrying the B.
anthracis toxin genes that caused severe pneumonia
similar to pulmonary anthrax
diarrheal form of b cereus
Associated with ingestion of meat or
poultry, vegetables and pastas
* Incubation period of 8 to 16 hours.
* Signs and symptoms:
o Abdominal pain and diarrhea.
o About 25% of individuals have vomiting
o Fever is uncommon.
* The average duration of the illness is 24 hours.
* Diarrheal form is clinically indistinguishable from diarrhea
caused by Clostridium perfringens.
emetic form
- Signs and symptoms:
o Predominant symptoms of nausea and vomiting 1
to 5 hours after ingestion of contaminated food.
o Diarrhea is present in about one third of affected
individuals.
eported in nonsterile alcohol pads used as an
antiseptic measure before injections.
b cereus
treatment of b cereus
Treatment with vancomycin or clindamycin with or without an aminoglycosid
SELF LIMITNG
b cereus is resistant to
resistant to penicillin
and all of the other β-lactam antibiotics except the
carbapenems
- These organisms have been reported to cause food
poisoning, bacteremia, meningitis, pneumonia, and other
infections. - They are more commonly seen as contaminants
other bacillus species
other bacillus species
These include, but are not limited to:
o Bacillus subtilis
o Bacillus licheniformis
o Bacillus circulans
o Bacillus pumilus
o Bacillus sphaericus q
are two well-known
antibiotics obtained from Bacillus species. Several
species are used as standards in medical and
pharmaceutical assays
Bacitracin and polymyxin
The spores of the___________ are used to test heat sterilization
procedures, and B. subtilis subsp. globigii, which is
resistant to heat, chemicals, and radiation, is widely used
to validate alternative sterilization and fumigation
procedures
obligate thermophile B.
stearothermophilus
Rarely encountered but cause disease:
Listeria,
Erysipelothrix, Corynebacterium diphtheriae, and Bacillus
anthracis
