MRCOG Part 1: Microbiology - Essential Study Guide

This is your essential guide to the Microbiology section of the MRCOG Part 1 exam. We built it from our own experience of sitting the exam, the RCOG syllabus and the official reading list. It lists the microbiology concepts most often tested, section by section.

Why Microbiology matters in MRCOG Part 1

Microbiology is crucial for understanding the infectious diseases that can affect women's health, pregnancy, and the developing foetus. For the MRCOG Part 1, a strong grasp of microbiological principles, including bacterial, viral, fungal, and parasitic pathogens, is essential for diagnosing and managing infections in the context of obstetrics and gynaecology.

Microbiology syllabus, section by section

IBacteriology

Gram-Positive Bacteria

Streptococcus
  • Streptococcus pyogenes (Group A): necrotising fasciitis, toxic shock syndrome, cellulitis
  • Streptococcus agalactiae (Group B): neonatal sepsis, maternal infections, screening and prophylaxis
Staphylococcus
  • Staphylococcus aureus: skin infections, toxic shock syndrome, MRSA (methicillin-resistant S. aureus), surgical site infections
  • Coagulase-negative staphylococci: device-related infections
Other Gram-Positive Bacteria
  • Listeria monocytogenes: listeriosis in pregnancy, neonatal infection

Gram-Negative Bacteria

Enterobacteriaceae
  • Escherichia coli: urinary tract infections, neonatal sepsis, wound infections
  • Klebsiella spp., Proteus spp.: urinary tract infections
  • Campylobacter: Gram-negative, facultative anaerobic rods that can cause bloody diarrhoea in pregnant women at 18 weeks gestation.
Neisseria
  • Neisseria gonorrhoeae: gonorrhoea, pelvic inflammatory disease
  • Neisseria meningitidis: meningitis
Other Gram-Negative Bacteria
  • Pseudomonas aeruginosa: wound infections, ventilator-associated pneumonia, Gram-negative aerobic rod
  • Haemophilus influenzae: Gram-negative aerobic rod

Anaerobic Bacteria

Bacteroides, Prevotella, Fusobacterium
  • Bacterial vaginosis, pelvic inflammatory disease
Clostridium
  • Clostridium difficile: antibiotic-associated diarrhoea, pseudomembranous colitis

Other Bacteria

Spirochetes
  • Treponema pallidum: causes syphilis, gummas are found in tertiary syphilis, condyloma lata are found in secondary syphilis
Organisms with no rigid cell wall
  • Mycoplasma: cannot be grown on inanimate culture but contain ribosomes

IIVirology

Herpesviruses

Herpes Simplex Virus (HSV)
  • HSV-1 and HSV-2: genital herpes, neonatal herpes
  • Primary, initial, and recurrent infections
  • Management in pregnancy
  • Small white umbilicated white papules on the labia majora may indicate genital herpes
Varicella Zoster Virus (VZV)
  • Chickenpox: clinical features, complications, management in pregnancy, incubation period
  • Congenital varicella syndrome: risk, diagnosis, prevention
  • Neonatal varicella
  • VZV-IgG positive and VZV-IgM negative indicates immunity
Cytomegalovirus (CMV)
  • Congenital CMV infection: epidemiology, clinical features, diagnosis, prevention
  • Primary and recurrent infections in pregnancy
  • Long-term sequelae: sensorineural hearing loss
  • CMV lies dormant in monocytes
  • CMV can cause deafness and delayed development of the child
  • Elevated lymphocytes in acute CMV infection
  • Amniotic fluid PCR is the most sensitive test for congenital CMV infection
Human Papillomavirus (HPV)
  • Genital warts, cervical dysplasia, cervical cancer
  • High-risk (16, 18, 31, 33, 45, 52, 58) and low-risk types (6, 11)
  • Vaccination
  • Quadrivalent vaccine contains HPV types 6, 11, 16, 18
Parvovirus B19
  • Fifth disease (erythema infectiosum): clinical features
  • Infection in pregnancy: fetal hydrops, fetal loss
  • Diagnosis and management
  • Can cause an aplastic crisis in people with sickle cell disease
  • Most likely causative organism for a hydropic baby at 20 weeks gestation
Rubella Virus
  • Clinical features of rubella
  • Congenital rubella syndrome: clinical features, prevention
  • Vaccination
  • Incubation period

IIIMycology and Parasitology

Fungi

Candida
  • Candida albicans: vulvovaginal candidiasis (thrush): clinical features, risk factors, diagnosis, treatment, a yeast-like fungus
  • Recurrent candidiasis

Protozoa

Trichomonas vaginalis
  • Trichomoniasis: clinical features, diagnosis, treatment
  • Complications in pregnancy
  • Thin vaginal discharge and vaginal pH of 6.0
Toxoplasma gondii
  • Toxoplasmosis in pregnancy: diagnosis, management, prevention
  • Congenital toxoplasmosis
  • Flu-like symptoms, myalgia, enlarged posterior cervical lymph nodes in pregnant women
  • Spiramycin is the drug of choice for reducing risk of fetal infection

IVOther Important Concepts

Infection Control

Surgical Site Infections
  • Prevention, diagnosis, and management
  • Antimicrobial prophylaxis
  • Re-dosing of prophylactic antibiotics is recommended in major intraoperative haemorrhage

Antimicrobial Stewardship

Principles of Antimicrobial Stewardship
  • Appropriate use of antibiotics
  • Preventing antimicrobial resistance

Laboratory Diagnosis

Gram Staining
  • Procedure and interpretation
Microscopy
  • Darkfield microscopy is useful for visualizing thin organisms such as Treponema pallidum
Specific Tests
  • Clue cells are associated with Gardnerella vaginalis and bacterial vaginosis
  • Amniotic fluid PCR is most sensitive for diagnosis of congenital CMV infection

Other Infections

Actinomycosis
  • Associated with intrauterine contraceptive devices
Group B Streptococcus
  • Most likely infecting organism for baby being treated for meningitis on neonatal intensive care unit after emergency caesarean delivery
Other Viruses
  • HIV: Vertical transmission, risk factors, prevention
  • Molluscum contagiosum can cause small white umbilicated white papules on the labia majora

How to master Microbiology

  • Review: work through each section systematically and understand the core concepts before moving on.
  • Active learning: draw diagrams, build mind maps and explain concepts to someone else.
  • Test yourself: try our free practice questions, then work through the microbiology questions in the Uterio question bank.

Additional resources