A Gram stain result comes back from the lab: Gram-positive cocci in clusters. Before you order the antibiotic, you need to know whether that is Staphylococcus aureus or a coagulase-negative contaminant. That single question determines treatment, prognosis, and whether the patient goes home or to the ICU.
Bacteriology is the study of bacteria: their structure, growth, identification, and the diseases they cause. It is the backbone of clinical microbiology, and the category with the most direct impact on patient care.
This section covers:
Whether you are preparing for MBBS exams, a laboratory science board, or clinical posting, every article is written to answer three questions: What is this organism? Why does it matter clinically? How will you remember it when it appears on an exam or a culture report?
What the laboratory does the moment a blood culture flags positive: the immediate Gram stain, subculture, identification by MALDI-TOF or molecular panels, susceptibility testing, and how to tell a true pathogen from a skin contaminant.
Bacterial virulence factors grouped by the job they do: adhering, invading, resisting phagocytosis, damaging tissue, and persisting. How adhesins, enzymes, capsules, toxins, and bi...
Which genital specimen to collect for which infection, the male and female differences, why gonococcus needs bedside inoculation and never refrigeration, when a swab beats urine, a...
Why tissue is the reference-standard specimen for deep infection, why the microbiology portion must be split off before formalin or decalcification, when to mince instead of grind,...
Why you swab both eyes even when one looks normal, how the specimen changes from conjunctivitis to a corneal ulcer, why eye samples are inoculated at the bedside, and when to think...
Why an open-wound swab is only as good as the technique, how the Levine method samples deep fluid instead of surface flora, how to tell colonization from infection, and when tissue...
How to collect and split pleural, ascitic, pericardial, and synovial fluid across the right containers, why some goes into a blood culture bottle, which anticoagulant not to use fo...
Why an ear-canal swab answers otitis externa but not otitis media, how to sample a discharging ear without collecting canal flora, when tympanocentesis is needed, and why acute oti...
How to take a throat swab that actually samples the tonsils and posterior pharynx, why the tongue and cheeks must be avoided, which test needs which swab, why children need a backu...
The organisms that cause UTI, how to collect and culture urine correctly, and how to read colony counts to separate real infection from contamination.
The rickettsiae explained: obligate intracellular bacteria spread by arthropods that infect blood vessels and cause typhus, spotted fever, scrub typhus, and Q fever, with how the d...
What makes Mycobacterium unique: a waxy, mycolic-acid cell wall that makes these bacteria acid-fast, slow-growing, and hard to treat. An overview of tuberculosis, leprosy, and the...
How Mycobacterium tuberculosis causes tuberculosis: why it survives inside macrophages, how the granuloma leads to latent and active TB, the clinical picture, drug-resistant TB, an...
Antimicrobial stewardship is usually taught as a hospital program. This article teaches the part students actually need: how the microbiology laboratory drives stewardship through...
How the lab detects an AmpC beta-lactamase: the cefoxitin screen, the cloxacillin and boronic acid confirmatory tests, chromosomal versus plasmid-mediated AmpC, and the inhibitor l...
