Microbiology Chapter 28 – Diagnostic microbiology
Healthcare-associated infection (nosocomial infection); infection acquired during a
stay at a healthcare facility.
Growth dependent diagnostic methods;
The growth and observation of pathogens are important strategies for identification of
the causative agent of an infectious disease.
Identification lead to antimicrobial drug testing
Growth independent diagnostic methods;
Serology (immunological detection and nucleic
acid detection of microorganism)
Clinical diagnosis of infectious disease;
samples are used for analysis.
Steps; clinical sample of the patient → isolation
of the pathogen → identification of the isolated
pathogen
The patient specimens must be obtained and handled properly;
▪ Specimen should be obtained from site of infection
▪ Sample must be taken aseptically (het bevat geen stoffen die je ziek kunnen
maken)
▪ Sample size must be large enough
▪ Metabolic requirement for the organism must be maintained during sampling,
storage and transport.
The reliability of diagnostic test depends on;
▪ Specificity; ability of the test to recognize a single pathogen
▪ Sensitivity; the smallest quantity of a pathogen that can be detected
The pathogens can be grown, isolated and identified from patient specimen using
growth media;
▪ General purpose media; support growth of most aerobic and facultative
aerobic organism (blood agar plate)
▪ Enrichment media; contain specific growth factors that enhance growth of
kieskeurige pathogens
▪ Selective media; allow some organisms to grow while inhibiting others (EMB
agar plate)
▪ Differential media; allow identification of organism based on their growth and
appearance on the medium (EMB agar plate)
Urine cultures;
Urinary tract infections are common in women.
Normally no bacteria are present tin the urine in the bladder, but bacteria colonize
urethra.
Detection; use of dipsticks
Identification; cultured using; (gram + no growth, gram – growth)
Healthcare-associated infection (nosocomial infection); infection acquired during a
stay at a healthcare facility.
Growth dependent diagnostic methods;
The growth and observation of pathogens are important strategies for identification of
the causative agent of an infectious disease.
Identification lead to antimicrobial drug testing
Growth independent diagnostic methods;
Serology (immunological detection and nucleic
acid detection of microorganism)
Clinical diagnosis of infectious disease;
samples are used for analysis.
Steps; clinical sample of the patient → isolation
of the pathogen → identification of the isolated
pathogen
The patient specimens must be obtained and handled properly;
▪ Specimen should be obtained from site of infection
▪ Sample must be taken aseptically (het bevat geen stoffen die je ziek kunnen
maken)
▪ Sample size must be large enough
▪ Metabolic requirement for the organism must be maintained during sampling,
storage and transport.
The reliability of diagnostic test depends on;
▪ Specificity; ability of the test to recognize a single pathogen
▪ Sensitivity; the smallest quantity of a pathogen that can be detected
The pathogens can be grown, isolated and identified from patient specimen using
growth media;
▪ General purpose media; support growth of most aerobic and facultative
aerobic organism (blood agar plate)
▪ Enrichment media; contain specific growth factors that enhance growth of
kieskeurige pathogens
▪ Selective media; allow some organisms to grow while inhibiting others (EMB
agar plate)
▪ Differential media; allow identification of organism based on their growth and
appearance on the medium (EMB agar plate)
Urine cultures;
Urinary tract infections are common in women.
Normally no bacteria are present tin the urine in the bladder, but bacteria colonize
urethra.
Detection; use of dipsticks
Identification; cultured using; (gram + no growth, gram – growth)
