The most frequent cause of red eye is conjunctivitis. It is caused by inflammation of the conjunctiva which can be infective or allergic and accounts for about 35% of all eye problems presenting to general practice.

Viral conjunctivitis is commonly caused by adenoviruses and it is the most common infectious conjunctivitis.

The common bacterial causes of conjunctivitis are Haemophilus influenzae, Streptococcus pneumoniae, and Staphylococcus aureus.

The clinical features of infective conjunctivitis include:
Acute onset of conjunctival erythema
Feeling ‘grittiness’, ‘foreign body’ or ‘burning’ sensation in the eye.
Watering and discharge which may cause transient blurring of vision

The discharge for viral conjunctivitis is less than that of bacterial conjunctivitis and usually watery.

Although a variety of clinical specimens may be submitted to the
laboratory to recover MTB and NTM, respiratory secretions such
as sputum and bronchial aspirates are the most common. An
early-morning specimen should be collected on three consecutive
days, although recent studies have suggested that the addition of
a third specimen does not significantly increase the sensitivity
of detecting Mycobacteria.

Mycobacterium tuberculosis appear red on acid-fast staining because they take up the primary stain, which is carbolfuchsin, and is not decolorized by the acid alcohol anymore.

Culture on Lowenstein-Jensen medium should be read within 5 to 7 days after inoculation and once a week thereafter for up to 8 weeks.

Nucleic acid amplification assays designed to detect M. tuberculosis complex
bacilli directly from patient specimens can be performed in as little as 6 to 8 hours on processed specimens.

Clostridium difficile, a Gram-positive, anaerobic, spore forming bacteria is present in the gut of approximately 3% of healthy adults (2012 UK HPA estimates). Following use of broad spectrum antibiotics, which alter normal gut flora, Clostridium difficile associated diarrhoea (CDAD) occurs.

About 80% of Clostridium difficile infections are seen in people over the age of 65 and its main clinical features are:
Abdominal cramps, severe bloody and/or watery diarrhoea, offensive smelling diarrhoea, and fever.

Urgent referral to ophthalmology is indicated if the patient with conjunctivitis has any of the following:

Suspected gonococcal or chlamydial conjunctivitis
Corneal involvement associated with soft contact lens use
Severe disease indicated by presence of a pseudomembrane
Conjunctivitis associated with rheumatoid arthritis or in immunocompromised patient. Ophthalmia neonatorum.
Possible herpes infection.
Had recent intraocular surgery. A red flag indicating a serious cause of red eye.
Suspected periorbital or orbital cellulitis.

Bilateral conjunctivitis is not an indication for urgent referral to ophthalmology.

Endocarditis is infective or non infective inflammation (marantic endocarditis) of the inner layer of the heart and it often involves the heart valves.

Risk factors include:
Prosthetic heart valves
Congenital heart defects
Prior history of endocarditis
Rheumatic fever
Illicit intravenous drug use

In the presentation of endocarditis, the following triad is often quoted:
Persistent fever
Embolic phenomena
New or changing murmur

A combination of vancomycin, rifampicin and gentamicin is advised if the patient has a cardiac prostheses, is penicillin allergic, or if methicillin-resistant Staphylococcus aureus (MRSA) is suspected. In this case the patient has a prosthetic valve making this the most appropriate initial treatment regimen.

Flucloxacillin and gentamicin are current recommended by NICE and the BNF for the initial ‘blind’ therapy in endocarditis. This patient has prostheses and this is not the most appropriate initial treatment regimen.

Other features that may be present include heart failure, splenomegaly, finger clubbing, renal features (haematuria, proteinuria, nephritis), and vasculitic features (splinter haemorrhages, Osler’s nodes, Janeway lesions, Roth’s spots).

Conjunctivitis is the most common neonatal manifestation of Chlamydia trachomatis infection. The second commonest neonatal manifestation is pneumonia

Ophthalmia neonatorum refers to any conjunctivitis in the newborn period, irrespective of causative organism. Presently, chlamydia is the single most common cause, accounting for up to 40% of cases. Ophthalmia neonatorum caused by chlamydia typically presents 5 to 14 days after birth with unilateral or bilateral watery discharge that progressively becomes more copious and purulent. There is no associated risk of ulceration and perforation, and the eyes are less inflamed.

Hepatitis B surface antigen (HBsAg) is a protein on the surface of the hepatitis B virus, that is the first serologic marker to appear in a new acute infection.It can be detected as early as 1 week and as late as 9 weeks. It can be detected in high levels in serum during acute or chronic hepatitis B virus infection. The presence of HBsAg indicates that the person is infectious. The body normally produces antibodies to HBsAg as part of the normal immune response to infection. HBsAg is the antigen used to make hepatitis B vaccine.
Hepatitis B surface antibody (anti-HBs) indicates recovery and immunity from the hepatitis B virus infection. Anti-HBs also develops in a person who has been successfully vaccinated against hepatitis B.
Total hepatitis B core antibody (anti-HBc): Appears at the onset of symptoms in acute hepatitis B and persists for life. The presence of anti-HBc indicates previous or ongoing infection with hepatitis B virus in an undefined time frame. It is not present following hepatitis B vaccination.
IgM antibody to hepatitis B core antigen (IgM anti-HBc) indicates recent infection with hepatitis B virus (<6 months). Its presence indicates acute infection.
The following table summarises the presence of hepatitis B markers according to each situation:
Susceptible to infection:
HBsAg = Negative
Anti-HBc = Negative
Anti-HBs = Negative

Immune due to natural infection:
HBsAg = Negative
Anti-HBc = Positive
Anti-HBs = Positive

Immune due to vaccination:
HBsAg = Negative
Anti-HBc = Negative
Anti-HBs = Positive

Acute infection:
HBsAg = Positive
Anti-HBc = Positive
Anti-HBs = Negative
IgM anti-HBc = Positive

Chronic infection:
HBsAg = Positive
Anti-HBc = Positive
Anti-HBs = Negative
IgM anti-HBc = Negative

H. pylori is recognized as a major cause of type B gastritis, a chronic condition formerly associated primarily with stress and chemical irritants. In addition, the strong association between long-term H. pylori infection and gastric cancer has raised more questions regarding the clinical significance of this organism. There is speculation that long-term H. pylori infection resulting in chronic gastritis is an important risk factor for gastric carcinoma resulting in H. pylori being classified as a carcinogen.

Neisseria gonorrhoeae is a Gram-negative diplococcus that causes gonorrhoea. Gonorrhoea is an acute pyogenic infection of nonciliated columnar and transitional epithelium; infection can be established at any site where these cells are found. Gonococcal infections are primarily acquired by sexual contact and occur primarily in the urethra, endocervix, anal canal, pharynx, and conjunctiva.

In men, acute urethritis, usually resulting in purulent discharge and dysuria (painful urination), is the most common manifestation. The endocervix is the most common site of infection in women. Symptoms of infection, when present, include dysuria, cervical discharge, and lower abdominal pain. Some cases in women may be asymptomatic leading to complications such as pelvic inflammatory disease. Blood-borne dissemination occurs in less than 1% of all infections, resulting in purulent arthritis and rarely septicaemia. Fever and a rash on the extremities can also be present. Other conditions associated with N. gonorrhoeae include anorectal and oropharyngeal infections. Infections in these sites are more common in men who have sex with men but can also occur in women.

Pharyngitis is the chief complaint in symptomatic oropharyngeal infections, whereas discharge, rectal pain, or bloody stools may be seen in rectal gonorrhoea. Approximately 30% to 60% of women with genital gonorrhoea have concurrent rectal infection. Newborns can acquire ophthalmia neonatorum, a gonococcal eye infection, during vaginal delivery through an infected birth canal.

Specimens collected for the recovery of N. gonorrhoeae may come from genital sources or from other sites, such as the rectum, pharynx, and joint
fluid. According to the 2010 STD Treatment guidelines, cephalosporins (e.g., ceftriaxone, cefixime) are currently recommended treatments.

Malaria is an infectious disease transmitted by female of theAnophelesgenus of mosquito. It is a parasitic infection caused by the genusPlasmodium. Five species are recognized as causing disease in humans;Plasmodium falciparum,Plasmodium ovale,Plasmodium vivax,Plasmodium malariaeandPlasmodium knowlesi.
The classic symptom of malaria is the malarial paroxysm, a cyclical occurrence of a cold phase, where the patient experiences intense chills, a hot stage, where the patient feels extremely hot and finally a sweating stage, where the fever declines and the patient sweats profusely. On examination the patient may show signs of anaemia, jaundice and have hepatosplenomegaly without evidence of lymphadenopathy.

Plasmodium falciparum is the most serious form and is responsible for most deaths. Severe or complicated malaria is suggested by the presence of impaired consciousness, seizures, hypoglycaemia, anaemia, renal impairment, respiratory distress and spontaneous bleeding.
Plasmodium falciparum is the most likely type in this case in view of the presentation.
Haemoglobinuria and renal failure following treatment is suggestive of blackwater fever, which is caused byPlasmodium falciparum. An autoimmune reaction between the parasite and quinine causes haemolysis, haemoglobinuria, jaundice and renal failure. This can be fatal.
The benign malarias: P.vivax, P. malariae and P.ovale are usually treated with chloroquine. A course of primaquine is also required in P.vivax and P.ovale infection. Artesunate is the drug treatment of choice for Plasmodium falciparum malaria. Quinine can still be used where artesunate is not available. Often combination therapy with drugs such as doxycycline or fansidar is also required.

Escherichia coli O157 is a serotype of Escherichia coli.
The Escherichia coliO157 strain is ‘enterohaemorrhagic’ and causes severe forms of acute haemorrhagic diarrhoea. It can also cause non-haemorrhagic diarrhoea.

Incubation period of Escherichia coli O157 is usually 3-4 days and bloody diarrhoea usually begins on the 3rd or 4th day of the infection.

Infections with Escherichia coliO157 are more common during the warmer months than in winter.

Haemolytic uraemic syndrome develops in approximately 6% of patients. It is commonly seen in children and in the elderly.

Escherichia coli O157 can also cause:
Haemorrhagic colitis
Haemolytic uraemic syndrome
Thrombotic thrombocytopenic purpura but not immune thrombocytopenic purpura.

The NICE guidelines do NOT recommend isolating a patient with viral conjunctivitis from others or skipping school or work. The disease is contagious, but the spread of the disease can be controlled by maintaining good hygiene practices such as:
1. frequent hand washing
2. use of separate flannels and towels
3. Avoid close contact with others

Antibiotic prescriptions are not part of the NICE guidelines for viral conjunctivitis as they will not affect the course of the disease. Most cases of viral conjunctivitis are self-limiting and resolve within one to two weeks.

The NICE guidelines recommend that symptoms may be eased with self-care measures such as:
1. Bathing/cleaning the eyelids with cotton wool soaked in sterile saline or boiled and cooled water to remove any discharge
2. Cool compresses applied gently around the eye area
3. Use of lubricating drops or artificial tears

The following are the NICE guidelines on the management of bacterial conjunctivitis:
– Infective conjunctivitis is a self-limiting illness that usually settles without treatment within 1-2 weeks. If symptoms persist for longer than two weeks they should return for review.
– Seek medical attention urgently if marked eye pain or photophobia, loss of visual acuity, or marked redness of the eye develop.
– Remove contact lenses, if worn, until all symptoms and signs of infection have completely resolved and any treatment has been completed for 24 hours.
– Lubricant eye drops may reduce eye discomfort; these are available over the counter, as well as on prescription.
– Clean away infected secretions from eyelids and lashes with cotton wool soaked in water.
– Wash hands regularly, particularly after touching the eyes.
– Avoid sharing pillows and towels.
– It is not necessary to exclude a child from school or childcare if they have infective conjunctivitis, as mild infectious illnesses should not interrupt school attendance. An exception would be if there is an outbreak of infective conjunctivitis, when advice should be sought from the Health Protection Agency by the school.
– Adults who work in close contact with others, or with vulnerable patients, should avoid such contact until the discharge has settled.

Infective causes of bloody diarrhoea include:
Salmonella spp
Campylobacter spp
Schistosomiasis
Entamoeba histolytica (Amoebiasis )
Shigella spp
Clostridium difficile
Yersinia spp
Enteroinvasive Escherichia coli

Enterotoxigenic Escherichia coli is non-invasive and does not cause inflammation of the gut and bloody diarrhoea. It presents with copious watery diarrhoea and usually are not associated with abdominal cramping.

E. coli may cause several different gastrointestinal syndromes. Based on virulence factors, clinical manifestation, epidemiology, and different O and H serotypes, there are five major categories of diarrheagenic E. coli, enterotoxigenic E. coli (ETEC), enteroinvasive E. coli (EIEC), enteropathogenic E. coli (EPEC), enterohemorrhagic E. coli (EHEC), and enteroadherent, which includes diffusely adherent E. coli (DAEC) and enteroaggregative E. coli (EAEC). These five categories are sometimes
collectively referred to as enterovirulent E. coli or diarrheagenic E. coli.

Norwalk virus is part of the Caliciviridae family of viruses which are single-stranded RNA viruses and are the most common cause of infectious gastroenteritis in the US.

Rotaviruses are the most common cause of viral gastroenteritis
in infants and children. With the introduction in 2006 of a human-bovine rotavirus vaccine (RV5; RotaTeq, Merck), a delay in the onset of rotavirus
season was seen. RotaTeq is a series of three oral vaccines beginning at 6 to 12 weeks of age. A second vaccine, Rotarix (RV1; GlaxoSmithKline, Middlesex, England), was approved in June 2008.

Cryptosporidium causes an illness characterized by abdominal cramping, watery diarrhoea, vomiting, fever, and anorexia. This organism is resistant to chlorine, so public swimming pools can be the source of an outbreak.

G. lamblia has a worldwide distribution and has frequently been identified as the causative agent of outbreaks of gastroenteritis and traveller’s diarrhoea.

The endocervix is the most common site of Neisseria gonorrhoeae infection in women. Symptoms of infection, when present, include dysuria, cervical discharge, and lower abdominal pain. However, 50% of cases in women may be asymptomatic leading to complications such as pelvic inflammatory disease (PID), which may cause sterility, ectopic pregnancy, or perihepatitis.

PID is also known as Fitz-Hugh-Curtis syndrome is defined as an inflammation of the upper genital tract due to an infection in women. The disease affects the uterus, fallopian tubes, and ovaries. It is typically an ascending infection, spreading from the lower genital tract.

The recommended intramuscular or oral regimens for PID are as follows:

Ceftriaxone at 500 mg IM in a single dose (for persons weighing ≥150 kg, administer 1 g of ceftriaxone); plus doxycycline at 100 mg PO BID for 14 days with metronidazole at 500 mg PO BID for 14 days.

Erysipelas is a rare infection of the skin and subcutaneous tissues observed frequently in elderly patients. It is characterized by an acute spreading skin lesion that is intensely erythematous with a plainly demarcated but irregular edge. It is most commonly caused by Streptococcus pyogenes or Group A Streptococcus (GAS).

GAS are susceptible to penicillin, which remains the drug of choice for treatment. For patients allergic to penicillin, erythromycin can be used.

S. pyogenes colonizes the throat and skin on humans, making these sites the primary sources of transmission. Infections resulting from S. pyogenes include pharyngitis, scarlet fever, skin or pyodermal infections, and other septic infections. In addition, the sequelae rheumatic fever and acute glomerulonephritis can occur as a result of infection with S. pyogenes.

Agammaglobulinemia is mostly associated with S. pneumoniae.

The M protein is attached to the peptidoglycan of the cell wall and extends to
the cell surface. The M protein is essential for virulence. The polysaccharide capsule is characteristic of S. pneumoniae.

Malaria is a protozoal infection of red blood cells and the liver. It is caused by the parasite belonging to the genus Plasmodium. It is transmitted by the female mosquito Anopheles.

Several species with distinct features:
P. vivax/P. ovale
P. malariae
P. falciparum

The common symptoms of malaria are:

Paroxysms of fever – a cyclical occurrence of:
1) a cold phase – the patient experiences intense chills
2) a hot stage – the patient feels extremely hot
3) a sweating stage – the fever declines and the patient sweats profusely
– Fever recurs at regular intervals (48hrs, 72hrs): Variable by species of Plasmodium

Anaemia (RBC infection)
– Severity varies by species of Plasmodium
– Haemolytic: sometimes jaundice

Splenomegaly

Also nonspecific symptoms:
– Sweating
– fatigue
– malaise
– arthralgias
– headache
– Sometimes cough, vomiting, diarrhoea

Patients with sickle cell disease are prone to infection of the bone and bone marrow in areas of infarction and necrosis. Although Staphylococcus aureus is the most common cause of osteomyelitis in the general population, studies have shown that in patients with sickle cell disease, the relative incidence of Salmonella osteomyelitis is twice that of staphylococcal infection.

Bacillus cereusis is the correct answer. It is a Gram-positive, rod-shaped, beta-haemolytic bacterium that causes ‘fried rice syndrome’.

Hardy spores in rice can survive boiling. When left at room temperature for long periods prior to frying these spores germinate. The emetic enterotoxin-producing strains cause nausea and vomiting between 1 and 6 hours after consumption while the diarrheagenic enterotoxin-producing strains (commonly associated with ingestion of meat, vegetables and dairy products) causes abdominal pain and vomiting, which starts 8-12 hours after ingestion.

Infectious mononucleosis can be diagnosed using specific EBV antibodies and a variety if unrelated non-EBV heterophile antibodies. These antibodies can be detected by two main screening tests:

The monospot test uses horse red blood cells. It agglutinates in the presence of heterophile antibodies.

Sheep red blood cells is used in Paul-Bunnell test. The blood agglutinates in the presence of heterophile antibodies.

If a patient presents with one of the following types of wounds, they are at risk of contracting tetanus and should be vaccinated immediately:
1) Contaminated puncture-type wounds from gardening and farming (as they may contain tetanus spores)
2) Wounds containing foreign bodies
3) Open (compound) fractures
4) Wounds or burns with sepsis
5) Animal bites and scratches (animal saliva does not contain tetanus spores unless the animal was routing in soil or lives in an agriculture setting)

Extremely high-risk tetanus-prone wounds are any of the above wounds with one of the following:
1) Any wound contaminated by materials containing tetanus spores, e.g., soil, manure
2) Burns or wounds with extensive devitalised tissue
3) Wounds or burns with surgical intervention delayed for more than six hours even if the initial injury was not heavily contaminated

The CDC recommends that adults who have never been vaccinated for tetanus receive a quick shot of the tetanus vaccine along with a booster dose ten years later. A tetanus-prone wound in an unvaccinated individual should also receive a high dose of tetanus immunoglobulin. The injected antibodies will prevent tetanus infection as the patient does not have any pre-existing antibodies against the disease.

In this case, the patient has a high risk, contaminated wound. He should receive a high dose of tetanus immunoglobulin along with the tetanus vaccine. (The preventative dose of tetanus immunoglobulin is 250 IU in most cases unless over 24 hours have passed since the injury or the wound is heavily contaminated, then 500 IU should be given.) His physician also needs to be contacted to arrange the remainder of the course as indicated in this case.

Klebsiellais a genus of non-motile,Gram-negative, rod-shaped bacteriawith a prominent polysaccharide-based capsule. They are routinely found in the nose, mouth and gastrointestinal tract as normal flora, however, they can also behave as opportunistic pathogens.
Infections with Klebsiella spp. areusually nosocomial. They are an important cause of ventilator-associated pneumonia (VAP), urinary tract infection, wound infection and bacteraemia. Outbreaks of infections with Klebsiellaspp. in high-dependency units have been described and are associated with septicaemia and high mortality rates. Length of hospital stay and performance of invasive procedures are risk factors forKlebsiellainfections.
Primary pneumonia withKlebsiella pneumoniaeis a rare,severe, community-acquired infection associated with a poor outcome.
Klebsiella rhinoscleromatis causes a progressive granulomatous infection of the nasal passages and surrounding mucous membranes. This infection is mainly seen in the tropics.
Klebsiella ozanae is a recognised cause of chronic bronchiectasis.
Klebsiella organisms are resistant to multiple antibiotics including penicillins. This is thought to be a plasmid-mediated property. Agents with high intrinsic activity againstKlebsiellapneumoniaeshould be selected for severely ill patients. Examples of such agents include third-generation cephalosporins (e.g cefotaxime), carbapenems (e.g. imipenem), aminoglycosides (e.g. gentamicin), and quinolones (e.g. ciprofloxacin). These agents may be used as monotherapy or combination therapy. Aztreonam may be used in patients who are allergic to beta-lactam antibiotics.
Species with ESBLs (Extended spectrum beta-lactamase) are resistant to penicillins and also cephalosporins such as cefotaxime and ceftriaxone
.

Since the introduction of the HIB vaccine, most cases of acute epiglottitis are now caused by Streptococcus spp. The condition is now rare in children.

Ciprofloxacin is recommended for use as meningococcal chemoprophylaxis in all age groups and in pregnancy, and is the most appropriate for this patient.

However, rifampicin is the drug of choice for meningococcal chemoprophylaxis because it is licensed for chemoprophylaxis, but multiple doses are necessary and it is not readily available in community pharmacies. It also interacts with oral contraceptives.

Clostridium difficile, a Gram-positive, anaerobic, spore forming bacteria is present in the gut of approximately 3% of healthy adults (2012 UK HPA estimates). Following use of broad spectrum antibiotics, which alter normal gut flora, Clostridium difficile associated diarrhoea (CDAD) occurs.

Alcohol hand gel is not effective against Clostridium Difficile spores. Hand washing with soap and water is very essential for healthcare workers who come in contact with it.

Wearing an apron and gloves, and isolation to a side room are important contact precautions. They are, however, ineffective if hand washing is neglected.

Although oral vancomycin is the first-line treatment for C. difficile associated diarrhoea, it will not limit patient to patient spread.

According to the CDC definition, a patient co-infected with HIV can be diagnosed with AIDS if he or she has:
A CD4 T-cell count of less than 200 cells/mm3 or;
A CD4 T-cell percentage of total lymphocytes of less than 15% or;
An AIDS defining infection

A Streptococcal throat infection is not an AIDS defining infection.

A normal CD4 count ranges from 500-1000 cells/mm3. A CD4 (not CD8) count of less than 200 cells/mm3 is AIDS defining.

The CD4 count can vary from day to day and depending upon the time that the blood test is taken. It can also be affected by the presence of other infections or illnesses. Treatment with anti-retroviral therapy should be considered at CD4 count of less than 350 cells/mm3.

Serum concentrations of the p24 antigen (the viral protein that makes up most of the core of the HIV) are usually high in the first few weeks after human immunodeficiency virus (HIV) infection and testing for p24 antigen is therefore a useful way of diagnosing very early infection.

Currently, ceftriaxone in combination with azithromycin or doxycycline is the combination of antibiotics used in the treatment of gonorrhoea.

Helicobacter pylori is a curved or helix-shaped, non-spore forming, Gram-negative, microaerophilic bacteria. It is motile, having multiple flagella at one pole. It has a lipopolysaccharide component in its outer membrane.

Bronchiolitis is a common respiratory infection that occurs in infancy between the ages of 3-6 months and in the winter months. It is most commonly caused by the respiratory syncytial virus (70% of cases)

Although it can also be caused by parainfluenza virus, adenovirus, coronavirus, rhinovirus, and influenza virus, these are not the most common causes