Clinical bacteriology involves the diagnosis and treatment of infectious diseases through microbiological techniques. It determines the causative agents of infections, and tests the effectiveness of antibiotics against isolated bacteria. Bacteria are unicellular prokaryotes that can rapidly grow and inhabit many environments. In clinical bacteriology, physicians want to know if a specimen contains pathogens, what type, and their antibiotic susceptibility. Appropriate specimens are collected and tested through staining, culturing, and antibiotic susceptibility testing to identify pathogens and determine the most effective treatments. The final report is used by physicians to interpret and treat patients.

1. Clinical Bacteriology 1st Lecture Assistant Professor Dr. Sanaria Fawzi
An Introduction to Clinical Bacteriology
 Bacteriology:
is a science that deals with the study of bacteria, including
structure, morphology, genetics, classification and identification
of bacterial species.
 Clinical Bacteriology:
is a branch of clinical microbiology, which is a medical science
that concerned with the diagnosis and treatment of infectious
diseases by adaptation of microbiological techniques .
So, this field of science is concerned about :
 Determining the etiological agent of infectious diseases.
 Testing the ability of various antibiotics to inhibit or
kill the isolated bacteria.

2. Bacteria: are prokaryotic, unicellular, free – living
organisms. Having both DNA & RNA with a
complex cell wall structure and capable of
performing all essential processes of life e.g. growth,
metabolism & reproduction.
The small size, simple design, and broad metabolic
capabilities of bacteria allow them to grow and divide
very rapidly and to inhabit and flourish in almost any
environment.

3. The role of clinical bacteriology
Clinical bacteriology begins when the patient
presents symptoms of infection to the
physician.
An initial diagnosis is made, and the
physician then orders diagnostic medical
and laboratory procedures.
Q: What does the physician wants to know?
 Does the specimen contain pathogens?
 What type of pathogens?
 What are the antimicrobial susceptibility
profiles of the pathogens in the specimen?

4. Hence,
 In the lab., the appropriate specimens are
collected, labeled, and the lab workers perform a
direct stain, a culture, and an antibiotic
susceptibility test (typical tests that may involve
the clinical bacteriology lab).
Biochemical, serological, molecular, and
automated procedures are performed as needed.
 The final report of the identification and
antibiotic susceptibility test is sent to the
physician.
 The physician interprets the report and treat the
patient appropriately.
Note: Diagnosis and effective treatment of infection
depends not just on isolating an organism, but in
establishing link between the laboratory findings,
recognized syndrome, and the patient's clinical
condition.

6.  The common practice in clinical bacteriology is to
identify “significant” organisms from cultures.
Significance is determined in part by the quantitation
of an organism relative to other organisms present,
the “pathogenicity” of isolates, and the site from which
the specimen was obtained. When the organisms
present are known to be part of the expected flora
from a particular body site, the result reported is often
“routine (site) flora”. For example, coagulase-negative
staphylococci are normal inhabitants of the skin,
gastrointestinal tract, vagina, urethra, and the upper
respiratory tract. Therefore, their isolation from
superficial ulcers, wounds, and sputum cannot usually
be interpreted as clinically significant.