Laboratory Diagnosis, Prevention and Treatment of Bacte rial Infection
Laboratory Diagnosis, Prevention and Treatment
of Bacterial Infection
Xiao-Kui Guo
Manifestations of Infection: Signs and symptoms vary
according to the site and severity of infection. Diagnosis
requires a composite of information, including history,
physical examination, radiographic findings, and
laboratory data.
Microbial Causes of Infection: Infections may be
caused by bacteria, viruses, fungi, and parasites. The
pathogen may be exogenous (acquired from
environmental or animal sources or from other persons)
or endogenous (from the normal flora).
Specimen Selection, Collection, and
Processing
The quantity material must be adequate
Specimens are selected on the basis of signs and sy
mptoms, should be representative of the disease pro
cess
Contamination of the specimen must be avoided by
using only sterile equipment and aseptic precaution
s
The specimen must be taken to the laboratory and
examined promptly. Special transport media may b
e helpful.
Meaningful specimens to diagnose bacterial infectio
ns must be secured before antimicrobial drugs are
administered.
Microbiologic Examination
Culture:Isolation of infectious agents frequently requires specialized media. Nonsel
ective (noninhibitory) media permit the growth of many microorganisms. Selective
media contain inhibitory substances that permit the isolation of specific types of mic
roorganisms.
Microbial Identification: Colony and cellular morphology may permit preliminary
identification. Growth characteristics under various conditions, utilization of carboh
ydrates and other substrates, enzymatic activity, immunoassays, and genetic probes
are also used.
Antimicrobial Susceptibility: Microorganisms, particularly bacteria, are tested in v
itro to determine whether they are susceptible to antimicrobial agents.
Serodiagnosis:A high or rising titer of specific IgG antibodies or the presence of sp
ecific IgM antibodies may suggest or confirm a diagnosis.
Direct Examination and Techniques: Direct examination of specimens reveals gro
ss pathology. Microscopy may identify microorganisms. Immunofluorescence, imm
uno-peroxidase staining, and other immunoassays may detect specific microbial anti
gens. Genetic probes identify genus- or species-specific DNA or RNA sequences.
Artificial active immunity
Vaccines are antigens prepared from pathogens that can raise a
protective immune response, yet do not cause illness. These
prepared antigens will stimulate both B cells and T cells and help
to create memory cells that can later mount a vigorous immune
response to an encounter with the real pathogen.
Toxoids: a modified form of the toxin that preserves its antigenicity but has lost its
toxicity. This has been spectacularly successful with tetanus and diphtheria.
Inactivated vaccines: The production of protective antibodies is stimulated by usin
g the killed (inactivated) organisms This is done as a routine with vaccines against
pertussis (whooping cough) , typhoid and influenza. There is also an inactivated pol
io vaccine.
Attenuated live vaccines : The approach is to use suspensions of living organisms
that are reduced in their virulence (attenuated) but still immunogenic. This strategy
has yielded: BCG, mumps, measles , and rubella vaccines (now combined); the live
virus polio vaccine.
Special vaccines: polysaccharide vaccine, subunit vaccine, ( conjugate vaccine, bi
o-engineered vaccine, chemical vaccine, synthetic vaccine ), nucleic acid vaccine, i
diotype vaccine, autovaccine, etc.
Artificial passive immunity
Antitoxin: e.g. Tetanus antitoxin and diphtheria antitox
in. It is raised in the horse .It is most important to give
an intented recipient of equine serum a prior test dose t
o exclude hypersensitivity subjects who may have been
sensitized by a previous dose of equine serum.
Pooled immunoglobulin: It contains the normal repert
oire of antibodies for an adult, and can protect against h
epatitis A, and measles.
Specific immunoglobulin: Preparations of specific im
munoglobulin are available for passive immunization a
gainst tetanus, hepatitis B, rabies, varicella-zoster.
Cytokine
Active-passive immunity
involves giving both a vaccine to provide
long-term protection (preventive infection)
and immune globulin to provide immediate
protection (therapeutic and preventive
infectious disease).
stop
人人人人人人人人人人人人人人人人
区区区区
区区区区区区
区区区区区区
区区区区
区区
区区区区区区区区
区区区区区区
区区 2~4 区
区区区区
区区区区区区
区区区区 ~ 区区
区区 2~3 区
区区区区
区区
区区区区区区区
DI = duration of illness, DH = duration of hospitalization, B/BF = blood/body fluid
precautions, D/S = drainage/secretion precautions, E = enteric precautions, C =
contact isolation, S = strict isolation, R = respiratory isolation, TB = tuberculosis
isolation, U = universal precautions.
General procedure for collecting and processing
specimens for aerobic and/or anaerobic bacterial culture
Agglutination test in which inert particles (latex beads or heat-killed S aureu
s Cowan 1 strain with protein A) are coated with antibody to any of a variety
of antigens and then used to detect the antigen in specimens or in isolated ba
cteria.
of Bacterial Infection
Xiao-Kui Guo
Manifestations of Infection: Signs and symptoms vary
according to the site and severity of infection. Diagnosis
requires a composite of information, including history,
physical examination, radiographic findings, and
laboratory data.
Microbial Causes of Infection: Infections may be
caused by bacteria, viruses, fungi, and parasites. The
pathogen may be exogenous (acquired from
environmental or animal sources or from other persons)
or endogenous (from the normal flora).
Specimen Selection, Collection, and
Processing
The quantity material must be adequate
Specimens are selected on the basis of signs and sy
mptoms, should be representative of the disease pro
cess
Contamination of the specimen must be avoided by
using only sterile equipment and aseptic precaution
s
The specimen must be taken to the laboratory and
examined promptly. Special transport media may b
e helpful.
Meaningful specimens to diagnose bacterial infectio
ns must be secured before antimicrobial drugs are
administered.
Microbiologic Examination
Culture:Isolation of infectious agents frequently requires specialized media. Nonsel
ective (noninhibitory) media permit the growth of many microorganisms. Selective
media contain inhibitory substances that permit the isolation of specific types of mic
roorganisms.
Microbial Identification: Colony and cellular morphology may permit preliminary
identification. Growth characteristics under various conditions, utilization of carboh
ydrates and other substrates, enzymatic activity, immunoassays, and genetic probes
are also used.
Antimicrobial Susceptibility: Microorganisms, particularly bacteria, are tested in v
itro to determine whether they are susceptible to antimicrobial agents.
Serodiagnosis:A high or rising titer of specific IgG antibodies or the presence of sp
ecific IgM antibodies may suggest or confirm a diagnosis.
Direct Examination and Techniques: Direct examination of specimens reveals gro
ss pathology. Microscopy may identify microorganisms. Immunofluorescence, imm
uno-peroxidase staining, and other immunoassays may detect specific microbial anti
gens. Genetic probes identify genus- or species-specific DNA or RNA sequences.
Artificial active immunity
Vaccines are antigens prepared from pathogens that can raise a
protective immune response, yet do not cause illness. These
prepared antigens will stimulate both B cells and T cells and help
to create memory cells that can later mount a vigorous immune
response to an encounter with the real pathogen.
Toxoids: a modified form of the toxin that preserves its antigenicity but has lost its
toxicity. This has been spectacularly successful with tetanus and diphtheria.
Inactivated vaccines: The production of protective antibodies is stimulated by usin
g the killed (inactivated) organisms This is done as a routine with vaccines against
pertussis (whooping cough) , typhoid and influenza. There is also an inactivated pol
io vaccine.
Attenuated live vaccines : The approach is to use suspensions of living organisms
that are reduced in their virulence (attenuated) but still immunogenic. This strategy
has yielded: BCG, mumps, measles , and rubella vaccines (now combined); the live
virus polio vaccine.
Special vaccines: polysaccharide vaccine, subunit vaccine, ( conjugate vaccine, bi
o-engineered vaccine, chemical vaccine, synthetic vaccine ), nucleic acid vaccine, i
diotype vaccine, autovaccine, etc.
Artificial passive immunity
Antitoxin: e.g. Tetanus antitoxin and diphtheria antitox
in. It is raised in the horse .It is most important to give
an intented recipient of equine serum a prior test dose t
o exclude hypersensitivity subjects who may have been
sensitized by a previous dose of equine serum.
Pooled immunoglobulin: It contains the normal repert
oire of antibodies for an adult, and can protect against h
epatitis A, and measles.
Specific immunoglobulin: Preparations of specific im
munoglobulin are available for passive immunization a
gainst tetanus, hepatitis B, rabies, varicella-zoster.
Cytokine
Active-passive immunity
involves giving both a vaccine to provide
long-term protection (preventive infection)
and immune globulin to provide immediate
protection (therapeutic and preventive
infectious disease).
stop
人人人人人人人人人人人人人人人人
区区区区
区区区区区区
区区区区区区
区区区区
区区
区区区区区区区区
区区区区区区
区区 2~4 区
区区区区
区区区区区区
区区区区 ~ 区区
区区 2~3 区
区区区区
区区
区区区区区区区
DI = duration of illness, DH = duration of hospitalization, B/BF = blood/body fluid
precautions, D/S = drainage/secretion precautions, E = enteric precautions, C =
contact isolation, S = strict isolation, R = respiratory isolation, TB = tuberculosis
isolation, U = universal precautions.
General procedure for collecting and processing
specimens for aerobic and/or anaerobic bacterial culture
Agglutination test in which inert particles (latex beads or heat-killed S aureu
s Cowan 1 strain with protein A) are coated with antibody to any of a variety
of antigens and then used to detect the antigen in specimens or in isolated ba
cteria.