Micro Lec 4

Question 1

Normal flora of the genital tract can be found where in males

Answer 1

Externally - skin type commensals
Internally - essentially sterile due to prostate secretions and flushing by urine

Question 2

Normal flora of the genital tract can be found where in females

Answer 2

Variable; influenced by hormones, pregnancy, menstruation etc.
Neonates; lactobacilli, E.coli, diphtheroids,
staphylococci, streptococci
Pre-pubescent girls; coliforms and enterococci
Puberty; lactobacilli
Menopause; similar to pre-pubescent

Question 3

What microscopy should be carried out in GTI

Answer 3

• Wet prep microscopy
  -Trichomonas vaginalis
  -Culture in enrichment media and microscopy
• Gram stain
  -Bacterial vaginosis (BV)
  -Clue cells
  -Neisseria gonorrhoeae

Question 4

What are genital samples cultured for

Answer 4

Candida species
-Sabouraud dextrose agar (Sab)
N. gonorrhoeae
-Fastidious organisms requiring 5-10% CO2
-48 h incubation at 37C
-Eg, Thayer Martin Medium, New York City Formulation

Question 5

How are GTI samples processed

Answer 5

Nucleic acid amplification testing (NAAT)

Question 6

How does NAAT work

Answer 6

NAAT detects C. trachomatis and N. gonorrhoeae in one sample

Question 7

What are the advantaged and disadvantages of NAAT

Answer 7

Advantages
Sensitive, detecting very low bacterial loads
Disadvantages
No antibiotic susceptibility results
Additional swab required for sensitivity testing

Question 8

What pathogens are sexually and what non-sexually transmitted

Answer 8

Non-sexually transmitted
Overgrowth of;
Yeast, Candida albicans
Anaerobes
Gardnerella vaginalis
Coliforms

Sexually transmitted
Typical STIs
Gonorrhoea
Chlamydia
Syphilis
Chancroid
Trichomoniasis
Genital Herpes
HIV

Question 9

What is bacterial vaginosis (BV) due to

Answer 9

Imbalance in naturally occuring bacterial flora

Question 10

What is BV associated with

Answer 10

Decrease in lactobacilli
Increase in others including anaerobic
Mobiluncus species (Gram-positive bacillus)
Gardnerella vaginalis (Gram-variable, facultative anaerobic coccobacillus)

Question 11

List the clinical symptoms of BV

Answer 11

• vaginal secretion increased in pH; > pH 4.5, normally 3.5 -4.2)
  White/grey secretion with fishy odour
  Release of a fishy odour on adding alkali - 10% KOH solution
  Presence of clue cells

Question 12

Where are sexually transmitted infections greatest

Answer 12

Young heterosexuals under the age of 25 years
Men who have sex with men (MSM)
Ethnic minority groups

Question 13

Outline the features of Neisseria gonorrhoeae

Answer 13

Gram-negative diplococcus, with adjacent flattened sides
Strict aerobe
Obligate human pathogen that dies readily outside the body

Question 14

How does gonorrhoea present in males

Answer 14

Causes Urethritis
Inflammation of urethral mucous membranes
Purulent urethral discharge, usually clearly apparent
Dysuria

Question 15

List possible gonorrhoea complications in males

Answer 15

Ascending infection in males leads to epididymitis - inflammation of the epididymis

Prostatis (inflammation of the prostate)

Orchitis (inflammation of the testis, occasional sterility)

Conjunctivitis

Proctitis (rectal infection) can be asymptomatic

Question 16

How does gonorrhoea present in females

Answer 16

Urethritis
Inflammation of urethra and cervix mucous membranes
Purulent endocervical discharge
Itching
Dysuria
Lower abdominal pain
50% of women are asymptomatic

Question 17

What are the possible complications of gonorrhoea in females

Answer 17

Ascending infection from the cervix to fallopian tubes (salpingitis), ovaries (ovaritis) = Pelvic inflammatory disease (PID)
Also,
Conjunctivitis
Proctitis (rectal infection) can be asymptomatic
Up to 40% co-infected with C. trachomatis

Question 18

What are the typical GIT samples

Answer 18

Females;
Endocervical swab or urethral swab preferable
Males;
Urethral exudate if symptomatic
Urethral swab if asymptomatic

Question 19

How does disseminated gonococcal infection (DGI) present

Answer 19

1% of genital tract infections
75% of these are women
In both sexes,
Rash (often pustular)
Fever
Myalgia
Arthralgia, migratory polyarthritis, septic arthritis
Endocarditis
Meningitis

Question 20

How is DGI diagnosed

Answer 20

blood culture and joint fluid culture, CSF

Question 21

Outline the features of neonatal gonococcal infection

Answer 21

Maternally transmitted - vertical transmission
Conjunctivitis of neonated - opthalmia neonatorum
Affects the corneal epithelium, causing microbial keratitis, ulceration and perforation

Question 22

How is neonatal gonococcal infection treated

Answer 22

systemic penicillin G or a cephalosporin

Question 23

How is gonorrhoea diagnosed

Answer 23

Gram stain of exudate - 90-95% sensitive in symptomatic males, 50-70% in females
Culture on selective medium is most sensitive diagnostic method
– Chocolate blood-based media with growth factors and antibiotics (e.g. vancomycin [Gram+ves], colistin [Gram- ves], trimethoprim [Proteus swarming], nystatin [yeasts]
Moist atmosphere, 35-37oC and 5-7% CO2, incubate up to 72 h
Colonial morphology, Gram stain, oxidase positive

Question 24

What test can confirm N. gonorrhoeae

Answer 24

Carbohydrate utilization tests
- glucose, maltose, sucrose and lactose

Question 25

How is N. gonorrhoeae confirmed

Answer 25

Serological tests with specific antibody NAAT available for conformation - the latter may detect chlamydia trachomatis at same time MALDI-TOF

Question 26

How is gonorrhoea treated and controlled

Answer 26

Treat without delay to limit complications and reduce opportunities for transmission High incidence of co-infection with other STIs, especially chlamydia Antibiotic resistance is now widespread Penicillin was drug of choice from 1940s to 1970s, but plasmid-mediated penicillinase-producing N. gonorrhoeae (PPNG) emerged in 1976 Multiple-resistant strains now widespread 2005; 21% resistant to ciprofloxacin, 18% to penicillin Ceftriaxone or cefixime now first line in UK Single dose effective for uncomplicated infection; 7-10 days for complicated infections

Question 27

Outline the features of resistant N. gonorrhoeae

Answer 27

High-level azithromycin resistance Outbreak detected initially in Leeds Initially among men who have sex with men Resistance develops quickly, few antibiotics remain effective; combination therapy recommended One case of failed dual treatment reported July 2016 HPR 10(30) (9 September