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ANAEROBIC BACTERIAANAEROBIC BACTERIAGram Negative Anaerobic RodsGram Negative Anaerobic Rods

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Anaerobic cocciAnaerobic cocci

Doç.Dr.Hrisi BAHARDoç.Dr.Hrisi BAHARIstanbul UniversityIstanbul University

Cerrahpasa Medical FacultyCerrahpasa Medical Faculty

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Lıfe without air….Lıfe without air….●●Anaerobic means "life without airlife without air."

●● Anaerobic bacteria grow in places which completely, or almost completely, lack oxygen.

●● They are normally found in the mouth, gastrointestinal tract, and vagina, and on the skin.

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Anaerobic bacteriaAnaerobic bacteria

●● Obligate anaerobes replicate at sites with low oxidation-reduction potential (eg, necrotic, devascularized tissue).

●●Obligate anaerobes have been categorized Obligate anaerobes have been categorized based on their O2 tolerance: based on their O2 tolerance:

●● Strict anaerobes grow in ≤ 0.4% O2;≤ 0.4% O2;

●● Moderate anaerobes grow in 0.8 to 2.5% O2;0.8 to 2.5% O2;

●● Aerotolerant anaerobes grow in ≥ 2.5% O2.in ≥ 2.5% O2.

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Anaerobic InfectionAnaerobic Infection●● An “anaerobic infection”“anaerobic infection” is an infection

caused by bacteria called anaerobes anaerobes which can not grow in the presence of oxygen.

● ● Anaerobic bacteria can infect deep deep wounds, deep tissues, and internal wounds, deep tissues, and internal organsorgans where there is little oxygen.

●● These infections are characterized by abscess formationabscess formation, foul-smelling pusfoul-smelling pus, and tissue destructiontissue destruction

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Anaerobic InfectionAnaerobic Infection

●● Anaerobic bacteria can cause an infection when a normal barrier is damaged due to to surgery, injury, trauma or disease. surgery, injury, trauma or disease.

●● The low oxygen condition can result from blood vessel disease, shock, injury, blood vessel disease, shock, injury, and surgery.and surgery.

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Anaerobic bacteria can cause Anaerobic bacteria can cause infection anywhere in the bodyinfection anywhere in the body -1-

●● Mouth, head, and neckMouth, head, and neck..

●● Lung.

●● Intraabdominal.Intraabdominal.

●● Female genital tractFemale genital tract

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Anaerobic bacteria can cause Anaerobic bacteria can cause infection anywhere in the body infection anywhere in the body -3-

●● Skin and soft tissueSkin and soft tissue. ●● Central nervous systemCentral nervous system

●● BloodstreamBloodstream

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Specimen collection from the Specimen collection from the site of infectionsite of infection -1-

The keys to effective anaerobic The keys to effective anaerobic bacteria cultures includebacteria cultures include

●● Collecting a contamination-free specimen

●● Protecting it from oxygen exposure

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Specimen collection from the Specimen collection from the site of infection site of infection -2-

●● SwabsSwabs should be avoided when collecting specimens for anaerobic culture because cotton fibers may be detrimental to anaerobes.

●● Abscesses or fluidsAbscesses or fluids can be aspirated using a sterile syringe that is then tightly capped to prevent entry of air.

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Specimen collection from the Specimen collection from the site of infection site of infection -3-

●● Tissue samplesTissue samples should be placed into a degassed bag and sealed, or into a gassed out screw top vial that may contain oxygen-free prereduced culture medium and tightly capped.

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Specimen collection from the Specimen collection from the site of infection site of infection -4-

●● All procedures must be performed aseptically.

●● The physician who collects the specimen should be prepared to take two samples,

One for anaerobic culture and One for aerobic culture, since it is unknown whether the pathogen can grow with or without oxygen.

●● In addition, health care professionals should document any antibiotics that the patient is currently taking and any medical conditions that could influence growth of bacteria.

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Condition predisposing to Condition predisposing to anaerobic infectionsanaerobic infections 1-1-Exposure of a sterile body location to a

high inoculum of indigenous bacteria of mucous membrane flora .

2-2- Inadequate blood supply and tissue necrosis which lower the oxidation and lower the oxidation and reduction potentialreduction potential which support the growth of anaerobes.

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Condition which can lowers the blood supply Condition which can lowers the blood supply and can predispose to anaerobic infection are:and can predispose to anaerobic infection are:

●● Trauma, Trauma,

● ● Foreign body Foreign body

●● MalignancyMalignancy

● ● Surgery Surgery

● ● Edema Edema

●● Shock Shock

● ● ColitisColitis

● ● Vascular disease Vascular disease

●● Splenectomy, Splenectomy,

● ● Neutropenia, Neutropenia,

● ● Immunosuppression, Immunosuppression,

● ● Hypogammaglobinemia, Hypogammaglobinemia,

● ● Leukemia, Leukemia,

● ● Collagen vascular Collagen vascular disease disease

●● Cytotoxic drugs Cytotoxic drugs

● ● Diabetes mellitus Diabetes mellitus

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PathophysiologyPathophysiology-1--1-

●● A preexisting infection caused by aerobic or A preexisting infection caused by aerobic or

facultative organisms can alter the local tissue facultative organisms can alter the local tissue conditions and make them more favorable for the conditions and make them more favorable for the growth of anaerobes. growth of anaerobes.

●● Impairment in defense mechanisms due to Impairment in defense mechanisms due to

anaerobic conditions can favor anaerobic anaerobic conditions can favor anaerobic infection.infection.

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PathophysiologyPathophysiology-2--2-

These includeThese include >> Production of leukotoxinsProduction of leukotoxins

>> Phagocytosis intracellular killing Phagocytosis intracellular killing impairmentsimpairments

>> Chemotaxis inhibitionChemotaxis inhibition

>> Proteases degradation of serum proteinsProteases degradation of serum proteins

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Clues to anaerobic infectionClues to anaerobic infection

●● Polymicrobial results on Gram stain or culture.Polymicrobial results on Gram stain or culture.

●● Gas in pus or infected tissues.Gas in pus or infected tissues.

●● Foul odor of pus or infected tissues.Foul odor of pus or infected tissues.

● ● Sulfur granules in pus ofSulfur granules in pus of infected tissues.infected tissues.

●● Necrotic infected tissues.Necrotic infected tissues.

●● Site of infection near mucosa where Site of infection near mucosa where anaerobic microflora normally reside.anaerobic microflora normally reside.

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Infections more likely caused by Infections more likely caused by anaerobic bacteria and suspected as anaerobic bacteria and suspected as

anaerobic infectionsanaerobic infections -1-

●● Brain abscess rain abscess ●● Human or animal bites, Human or animal bites, ●● Aspiration pneumonia and lung Aspiration pneumonia and lung

abscesses,abscesses, ●● Amnionitis, endometritis, septic Amnionitis, endometritis, septic

abortions, tubo-ovarian abscess, abortions, tubo-ovarian abscess, peritonitis and abdominal abscessesperitonitis and abdominal abscesses

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Infections more likely caused by Infections more likely caused by anaerobic bacteria and suspected as anaerobic bacteria and suspected as anaerobic infections anaerobic infections -2-

●● Pus-forming us-forming necrotizing infectionsnecrotizing infections of of soft tissue or musclesoft tissue or muscle

●● Some solid malignant tumorstumors,

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Management of anaerobic Management of anaerobic infection infection -1--1-

The main principles of managing The main principles of managing anaerobic infections areanaerobic infections are

●● Neutralizing the toxins produced by anaerobic bacteria,

●● Preventing the local proliferation of these organisms by altering the environment and preventing their dissemination and spread to healthy tissues.

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Management of anaerobic Management of anaerobic infection infection -2--2-

● ● Toxin can be neutralized by specific antitoxins, mainly in infections caused by Clostridia Clostridia (tetanus and botulism).

●● Controlling the environment can be attained by:

>> Draining the pus, >> Surgical debriding of necrotic tissue, >> Improving blood circulation, >> Improving tissue oxygenation. >> Therapy with hyperbaric oxygen may also be useful.

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Management of anaerobic Management of anaerobic infection infection -3--3-

The main goal of antimicrobials is in restricting the local The main goal of antimicrobials is in restricting the local

and systemic spread of the microorganisms.and systemic spread of the microorganisms.

●● The available parenteral antimicrobials for most The available parenteral antimicrobials for most infections are infections are metronidazolemetronidazole,, clindamycin, clindamycin, chloramphenicol, cefoxitin, a penicillin (i.e. chloramphenicol, cefoxitin, a penicillin (i.e. ticarcillin, ampicillin, piperacillin) and a beta-ticarcillin, ampicillin, piperacillin) and a beta-lactamase inhibitor (i.e. clavulanic acid, lactamase inhibitor (i.e. clavulanic acid, sulbactam, tazobactamsulbactam, tazobactam), and a carbapenem ), and a carbapenem (imipenem, meropenem, doripenem, ertapenem). (imipenem, meropenem, doripenem, ertapenem).

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Management of anaerobic Management of anaerobic infection infection -4--4-

●● An antimicrobial effective against Gram-An antimicrobial effective against Gram-negative enteric bacilli (i.e. aminoglycoside) negative enteric bacilli (i.e. aminoglycoside) or an anti-pseudomonal cephalosporin (i.e. or an anti-pseudomonal cephalosporin (i.e. cefepime ) are generally added to cefepime ) are generally added to metronidazolemetronidazole, and occasionally , and occasionally cefoxitincefoxitin when treating intra-abdominal infectionswhen treating intra-abdominal infections to to provide coverage for these organisms. provide coverage for these organisms.

●● Clindamycin should not be used as a single Clindamycin should not be used as a single agent as empiric therapy for agent as empiric therapy for abdominal abdominal infectionsinfections..

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Management of anaerobic Management of anaerobic infection infection -5--5-

●● Penicillin can be added to Penicillin can be added to metronidazolemetronidazole

in treating of in treating of intracranial, pulmonary and dental intracranial, pulmonary and dental infectionsinfections to provide coverage against to provide coverage against microaerophilic streptococci, and Actinomyces.microaerophilic streptococci, and Actinomyces.

●● Oral agents adequate for polymicrobial oral Oral agents adequate for polymicrobial oral infections include the combinations of , infections include the combinations of , clindamycin and metronidazole plus a macrolideclindamycin and metronidazole plus a macrolide

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Management of anaerobic Management of anaerobic infection infection -6--6-

●● A A macrolidemacrolide can be added to can be added to metronidazolemetronidazole in in

treating upper respiratory infections to cover treating upper respiratory infections to cover

S. aureus and aerobic streptococci. S. aureus and aerobic streptococci.

●● Penicillin can be added to Penicillin can be added to clindamycinclindamycin to supplement to supplement

its coverage against Peptostreptococcus spp. and its coverage against Peptostreptococcus spp. and other Gram-positive anaerobic organismsother Gram-positive anaerobic organisms

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Antimicrobials that areAntimicrobials that are ineffectiveineffective Anaerobic bacteria are very commonly

recovered in chronic infections, and are often found following the failure of therapy with themthem,, such as trimethoprim-trimethoprim-sulfamethoxazole (co-trimoxazole), sulfamethoxazole (co-trimoxazole), aminoglycosidesaminoglycosides and the earlier earlier quinolonesquinolones

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Gram Negative Anaerobic RodsGram Negative Anaerobic Rods

● The anaerobic Gram negative bacilli constitute the predominant bacterial flora of the gastrointestinal tract.

● These organisms outnumber the facultative bacteria approximately 1000:1.

● They are also significant flora on the urogenital and oropharyngeal mucosa.

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Gram Negative Anaerobic RodsGram Negative Anaerobic Rods

● The anaerobic Gram negative bacilli are isolated in over one half of infections involving anaerobes. They can be placed into 5 groups

●● 1)Bacteroides fragilis1)Bacteroides fragilis groupgroup

(bile resistant, VanR, KanR, ColR)

●● 2)Pigmented, saccharolytic2)Pigmented, saccharolytic PrevotellaPrevotella

(bile sensitive, VanR, KanR, ColV)

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●● 3)Pigmented, asaccharolytic3)Pigmented, asaccharolytic PorphyromonasPorphyromonas (bile sensitive, VanS, KanR, ColR)

●● 4)Non‑pigmented Bacteroides and non-4)Non‑pigmented Bacteroides and non-pigmented Prevotella pigmented Prevotella

(bile sensitive, VanR, KanR/S, ColV)

●● 5)Fusobacterium species5)Fusobacterium species

(bile variable, VanR, KanS, ColS)

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BBacteroidesacteroides fragilis fragilis (Bile Resistant) Group(Bile Resistant) Group

● Seventy percent of the isolates from this group are B. fragilis and B. thetaiotaomicron; other members include B. ovatus, B. vulgatus,

B. distasonis.

● Gram Stain-pale irregularly staining pleomorphic cells with rounded ends. Colonies are usually non-hemolytic, grey to white, smooth entire and convex 1-3 mm in diameter; The indole reaction can used to separate the most common isolates of this group; B. fragilis is indole negative while B.thetaiotaomicron is indole positive; both are catalase positive.

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BBacteroidesacteroides fragilis fragilis (Bile Resistant) Group(Bile Resistant) Group

● It is important to identify this group because it is significantly more resistant to antimicrobic therapy than other anaerobes; most resistance is mediated, in part, through the production of production of β-lactamases.β-lactamases.

● The B. fragilis group is found predominantly associated with abdominal or peritoneal abdominal or peritoneal anaerobic infectionsanaerobic infections; they are GI tract commensals, but may be recovered on occasion from the female genital tract.

● They are not considered commensal flora of the oropharynx.

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Pigmented, saccharolytic, bile Pigmented, saccharolytic, bile sensitive Gram negative sensitive Gram negative rodsrods

● Gram Stain-pale staining coccobacilli, may be pleomorphic; young cultures may appear gram variable. Pigment production may take up to two weeks, faster on laked rabbit blood. Pigmentation may vary from light tan to black; intensity of pigment is useful for identification of members within the group.

● Prevotella melaninogenica, ● P. denticola, ● P. corporisIndole negative; ColR/s, KanR, VanR; lightpigment (may require prolonged incubation; >5 days)● Prevotella intermedia, P. nigrescensIndole positive, ColS, KanR, VanR, black pigment,

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Pigmented, asaccharolytic, bile Pigmented, asaccharolytic, bile sensitive Gram negative sensitive Gram negative rodsrods

Gram Stain-pale staining coccobacilli, may be pleomorphic; colonies are often mucoid.

Porphyromonas asaccharolyticusPorphyromonas asaccharolyticus..

P. gingivalisP. gingivalis..

P. endodontalisP. endodontalis..

They are indole positive,

ColR, VanS, KanR, dark pigment, lipase

negative.

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Pigmented, asaccharolytic, bile Pigmented, asaccharolytic, bile sensitive Gram negative sensitive Gram negative rodsrods

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Non‑pigmented, bile‑sensitive Non‑pigmented, bile‑sensitive speciesspecies

● This group includes B. ureolyticusB. ureolyticus and B. gracilisB. gracilis Both species can produce a flat colony that

pits the agar and both are sensitive to kanamycin.

● Both are recovered from a wide range of infections including, pulmonary, abdominal, urogenital and soft tissue.

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Non‑pigmented, bile‑sensitive Non‑pigmented, bile‑sensitive speciesspecies

Several species of non-pigmented PrevotellaPrevotella are placed in this group.

P. buccaeP. buccae and P. oralisP. oralis are found in the oral cavity and are recovered from pulmonary infections.

P. biviaP. bivia and P. disiensP. disiens are recovered from female genital infections.

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FusobacteriumFusobacterium

Fusobacterium species are found as commensal flora of the oropharynx as well as the gastrointestinal tract and female urogenital tract.33 of the most common isolates are

F. nucleatum F. nucleatum ,,F.necrophorumF.necrophorum,,

F.mortiferumF.mortiferum.

Fusobacteria are usually bile sensitiveFusobacteria are usually bile sensitive,

Van R, Col S, Kan S

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• The fusobacteria are generally involved in the same types of infections as the pigmented PrevotellaPrevotella andand PorphyromonasPorphyromonas species.

• F. necrophorum infections are often refractile to standard therapy for anaerobic infections.

• This species has been reported to produce a leukocidinleukocidin that may enhance its potential for virulence.

FusobacteriumFusobacterium

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FUSOBACTERIUMFUSOBACTERIUM

F.nucleatum F.necrophorum

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F. nucleatum GroupF. nucleatum Group F. nucleatum colonies often fluoresce chartreuse

under UV light. Gram stain usually demonstrates pale staining rods with pointed ends ((F. nucleatumF. nucleatum ss. nucleatumss. nucleatum is always is always fusiform).fusiform).

F. nucleatumF. nucleatum is indole positive. indole positive.

This group is usually involved with infections of the head and neck as well as lower respiratory tract infections.

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F. necrophorumF. necrophorum• F. necrophorum is considered to be a

particularly virulent anaerobic pathogen. It has been isolated from severe infections in children and young adults. These infections often begin as pharyngotonsillitis and metastasize to produce multiple abscesses.

• F. necrophorum infections are often refractile to standard therapy for anaerobic infections. This species has been reported to produce a leukocidin that may enhance its potential for virulence.

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F. mortiferum-varium GroupF. mortiferum-varium Group

●This group differs from other members of the genus in that they are resistant to 20% bile. Members of this group often demonstrate bizarre forms when Gram stained. Most members are also indole negative and positive for esculin hydrolysis.

● Colonies of F. mortiferum-varium do not fluoresce.

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Lemierre's syndromeLemierre's syndrome • Lemierre's syndromeLemierre's syndrome (or “Lemierre's

disease”, also known as “postanginal sepsis” and “human necrobacillosis”) is a form of thrombophlebitis usually caused by the bacterium Fusobacterium necrophorum and occasionally by other members of the genus Fusobacterium

(F. nucleatum, F. mortiferum and F. varium etc.) and usually affects young, healthy adults

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Lemierre's syndromeLemierre's syndromePathophysiologyPathophysiology ●Lemierre's syndrome is initiated by an infection of

the head and neck usually with pharyngitis but it can also be initiated by an otitis, a mastoiditis, a sinusitis or a parotitis.

● During the primary infection, F. necrophorumF. necrophorum colonizes the infection site and the infection spreads to the parapharyngeal space. The bacteria then invade the peritonsillar blood vessels where they can spread to the internal jugular vein. In this vein, the bacteria cause the formation of a thrombus containing these bacteria .

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Lemierre's syndromeLemierre's syndrome

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Anaerobic cocciAnaerobic cocci

● They live in the normal flora of skin, mouth, intestinal tract, and genitourinary tract

●Anaerobic Gram-positive cocciGram-positive cocci of clinical significance are found in one genera

PeptostreptococcusPeptostreptococcus

● There is one There is one Gram-negative Gram-negative genusgenus

VeillonellaVeillonella

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Anaerobic cocciAnaerobic cocci

Clinical ManifestationClinical Manifestation

●Anaerobic cocci are not involved in any single Anaerobic cocci are not involved in any single specific disease process; rather, they may be specific disease process; rather, they may be present in a great variety of infections involving present in a great variety of infections involving all areas of the human bodyall areas of the human body

●They cause a great variety of infections including abscesses, gangrene, cellulitis, abscesses, gangrene, cellulitis, bacteremia, pneumonia, peritonitis, bite bacteremia, pneumonia, peritonitis, bite wounds, and pelvic inflammatory diseasewounds, and pelvic inflammatory disease

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Anaerobic cocciAnaerobic cocciPathogenesisPathogenesis● Infection usually results from invasion of

damaged tissue by normal microbial flora. ● Most infections are polymicrobic. however,

approximately 10%–15% of all clinical isolates come from pure culture infections.

TreatmentTreatment Antibiotic therapy (e.g., penicillin, clindamycin),

abscess drainage, debridement of necrotic tissue

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Anaerobic gram-positive cocciAnaerobic gram-positive cocci

● The species of anaerobic gram-positive cocci isolated most commonly include

*Finegoldia magna (Peptostreptococcus magnus)

*Peptostreptococcus asaccharolyticus,*Peptostreptococcus anaerobius,*Peptostreptococcus prevotii, and*Peptostreptococcus micros

● The species of anaerobic gram-negative cocci isolated most commonly include

*Veillonelaa parvula

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