Page 231 - Review of Medical Microbiology and Immunology ( PDFDrive )

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PART II Clinical Bacteriology
220
patients and in drug abusers who lick needles prior to
linase, penicillins cannot be used.
injection. Eikenella corrodens is also called Bacteroides
ureolyticus.
Hafnia
Erwinia
Hafnia species are gram-negative rods (members of the
Erwinia species are gram-negative rods (members of the
Enterobacteriaceae) found in soil and water and are rare
opportunistic pathogens.
Enterobacteriaceae) found in soil and water and are rarely
involved in human disease.
mebooksfree.com mebooksfree.com mebooksfree.com Kingella mebooksfree.com
Lactobacilli are rare causes of opportunistic infection. mebooksfree.com
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Erysipelothrix
Kingella kingae is a gram-negative rod in the normal flora
Erysipelothrix rhusiopathiae is a gram-positive rod that
of the human oropharynx. It is a rare cause of opportunistic
infection and endocarditis.
causes erysipeloid, a skin infection that resembles erysipe-
las (caused by streptococci). Erysipeloid usually occurs on
the hands of persons who handle meat and fish.
Lactobacillus
Lactobacilli are gram-positive non–spore-forming rods
Eubacterium
found as members of the normal flora in the mouth, colon,
Eubacterium species are gram-positive, anaerobic, non–
and female genital tract. In the mouth, they may play a role
in the production of dental caries. In the vagina, they are
spore-forming rods that are present in large numbers as
the main source of lactic acid, which keeps the pH low.
part of the normal flora of the human colon. They rarely
cause human disease.
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HACEK Group
Micrococci are gram-positive cocci that are part of the
This is a group of small gram-negative rods that have in
common the following: slow growth in culture, the require-
normal flora of the skin. They are rare human pathogens.
ment for high CO levels to grow in culture, and the ability
2
Mobiluncus
to cause endocarditis. They are members of the human
oropharyngeal flora and can enter the bloodstream from
Mobiluncus species are anaerobic gram-positive, curved rods
that site. The name “HACEK” is an acronym of the first
that often stain gram-variable. They are associated with bac-
letters of the genera of the following bacteria: Haemophilus
terial vaginosis in women. Gardnerella (see above), a facul-
aphrophilus and Haemophilus paraphrophilus, Actinobacillus
tative rod, is often found in this disease as well.
(Aggrigatibacter) actinomycetemcomitans, Cardiobacterium
hominis, Eikenella corrodens, and Kingella kingae.
Haemophilus aegyptius Moraxella
Moraxella species are gram-negative coccobacillary rods
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that resemble the diplococcal appearance of the Neisseriae.
Haemophilus aegyptius (Koch-Weeks bacillus) is a small
Moraxella catarrhalis is the major pathogen in this
gram-negative rod that is an important cause of conjuncti-
genus. It causes otitis media and sinusitis, primarily in
vitis in children. Certain strains of H. aegyptius cause
Brazilian purpuric fever, a life-threatening childhood infec-
people with chronic obstructive pulmonary disease. It is
tion characterized by purpura and shock. This organism is
found only in humans and is transmitted by respiratory
also known as Haemophilus influenzae biogroup aegyptius.
aerosol. Trimethoprim-sulfamethoxazole or amoxicillin-
clavulanate can be used to treat these infections. Most clini-
Haemophilus ducreyi
cal isolates produce β-lactamase. Moraxella nonliquefaciens
This small gram-negative rod causes the sexually transmit-
ted disease chancroid (soft chancre), which is common in
of the eyelid); Staphylococcus aureus is the other. The usual
tropical countries but uncommon in the United States. The
treatment is local application of antibiotic ointment, such
disease begins with penile lesions, which are painful; non- is one of the two common causes of blepharitis (infection
as erythromycin.
mebooksfree.com mebooksfree.com mebooksfree.com Peptococci are anaerobic gram-positive cocci, resembling mebooksfree.com
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indurated (soft) ulcers; and local lymphadenitis (bubo).
The diagnosis is made by isolating H. ducreyi from the
Peptococcus
ulcer or from pus aspirated from a lymph node. The organ-
ism requires heated (chocolate) blood agar supplemented
staphylococci, found as members of the normal flora of the
with X factor (heme) but, unlike H. influenzae, does not
require V factor (NAD). Chancroid can be treated with
mouth and colon. They are also isolated from abscesses of
various organs, usually from mixed anaerobic infections.
erythromycin, azithromycin, or ceftriaxone. Because many
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