Microbiology
Principles
Question 12 of 180
Which of the following microbes is transmitted via a vector:
Answer:
Plasmodium falciparum is spread via a vector - the female Anopheles mosquito. Treponema pallidum is spread via direct skin contact or sexual transmission. Clostridium perfringens is spread via the oral-faecal route or direct skin contact. Vibrio cholerae is spread via the oral-faecal route. Mycoplasma tuberculosis is spread via the airborne route.Sources and Spread of Infection
Microbiology / Principles / Controlling Infection
Last Updated: 21st April 2019
Sources of Infection
Infection is caused either by organisms from the host's normal flora (endogenous infection) or by organisms transmitted from another source (exogenous infection).
Endogenous infection will only occur if circumstances permit. For example:
- Inhalation of stomach contents may cause aspiration pneumonia.
- Staphylococcus aureus normally found in the nose may cause infection if inoculated into a surgical wound or cannulation site.
- N.B. Neutropenic patients are especially prone to infection from conditional pathogens.
Examples of exogenous infections include:
- Salmonella enterica spread via ingested poultry.
- Legionella pneumophila spread via poorly maintained air-conditioning cooling towers.
Spread of Infection
Examples of routes of transmission of infection include:
| Route of Transmission | Examples |
|---|---|
| Airborne | Mycoplasma tuberculosis, Measles virus |
| Respiratory droplet | Neisseria meningitidis, Influenza virus |
| Faecal-oral | Salmonella enterica, Campylobacter jejuni |
| Sexual | Neisseria gonorrhoea, HIV |
| Vector-borne | Plasmodium falciparum |
| Transcutaneous (through intact skin) | Leptospira spp., Treponema pallidum |
| Percutaneous (through breached skin) | Staphylococcus epidermidis |
Report A Problem
Is there something wrong with this question? Let us know and we’ll fix it as soon as possible.
Loading Form...
- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
