1. What microorganism do you believe is to blame for this illness (be specific)? Provide background information on this organism, history, morphology, virulence factors, toxins
Hemophilus Influenza is a cocobacillus that is small, pleomorphic and is gram-negative. It is non-motile and does not form spores. It is also a facultative anaerobe. Some strains of Hemophilus influenza have a capsule composed of polysaccharide (Deverajan, 2012), (CDC, 2013). There are 6 different stereotypes of the virus, labeled a-f. This division is based on the biochemical differences in the capsules (Deverajan, 2012). Some strains of Hemophilus Influenza do not possess capsules and are therefore referred to as nonencapsulated Hemophilus Influenza. They are also sometimes called nontypeable Hemophilus influenza. Identification of the different strains is done by slide agglutination for stereotyping (Deverajan, 2012). A Polymerase chain reaction for capsular typing can also be done (Deverajan, 2012), (CDC, 2013).
Type b (Hib) influenza turns out to be the most virulent strain of Hemophilus influenza with its capsule made up of ribitol phosphate. This strain accounts for a large percentage of all invasive disease in children and up to half of the disease in adults. Some of the diseases caused by Hemophilus influenza type b include bacteremia, cellulitis, epiglottitis, meningitis, septic arthritis, pneumonia and empyema (Deverajan, 2012).
Hemophilus influenza requires two erythrocyte factors for growth. They include X (hemin) and V (Nicotinamide-adenine-dinucleotide). The factors are released after red blood cells have been lysed. Transmission of the virus is by direct contact or inhalation of droplets from the respiratory tract (Deverajan, 2012).
2. What information from the patient’s symptoms contributed to your decision? Did this information allow you to rule out any other possible culprits? What information from the patient’s history and/or lab samples that contributed to your decision? Support your answers with factual evidence and logical reasoning.
The patient presented with a preceding history of a cold which had been running for a week. However, the patient also has a high fever, stiff neck and a severe headache and complains of weakness. The immediate symptoms point to an inflammatory process going on in the meninges covering the brain so Edwin actually has meningitis from an infection. Moreover, the preceding history of a cold points to Hemophilus influenza as the culprit. Although the symptoms point to meningitis, they do not actually point to Hemophilus influenza as the culprit. Moreover, the history of Edwin staying in an overcrowded dormitory also supports an infection with Hemophilus influenza since outbreaks occurs in areas that are overcrowded (CDC, 2013). There are some other organisms that can give a similar presentation. For instance, in HIV encephalitis, the individual also presents with signs of meningitis so it is not impossible that Edwin could be suffering from the same thing. The gram staining result that turned out to be negative makes me question the correctness of my diagnosis. However, the other history and investigation findings are in support of an infection with Hemophilus influenza. Also, the low white blood cell count indicates that Edwin has a low immunity at this period which is consistent with viral infections. This fact will also make me consider my differential which is HIV encephalitis. However, from the history provided, there is not mention of multiple sexual partners, history of sharing of sharp objects or history of chronic diarrhea which are some of the symptoms that HIV illness would bring.
3. What is the epidemiology of this disease? Identify risk factors for this disease and describe the disease course/outcome in humans.
In the United states, before the advent of vaccination against Hemophilus influenza type b in 1988, about 64-129 cases per 100000 children under the ages of 5 years were recorded. However, this figure has reduced by more than 99% by the year 2000 because of availability of vaccination(Deverajan, 2012).
Moreover, in 2006, a surveillance report for Hemophilus influenza infection reported 0.04 cases of Hemophilus influenza type b per 100000 of the general population and 0.36 cases of non Hemophilus influenza type b infection per 100000 (Deverajan, 2012).
Internationally, before the advent of vaccination, invasive Hemophilus influenza type b disease was the number one cause of infectious disease in children worldwide. However, the vaccine is now widely available in the United States, Europe, some countries in Africa and the Middle East (Deverajan, 2012), (Selner, 2012).
Risk factors for Hemophilus influenza type b include exposure factors like household crowding, large household size, childcare attendance, low socioeconomic status, and low parental level of education. Other factors (Host factors) include race; in which African Americans, Hispanics and Native Americans are more likely to contact it (Deverajan, 2012). The presence of another chronic disease also predisposes to the infection. Overall mortality form Hemophilus influenza type be meningitis is said to be approximately 5%. There could also be some neurological sequelae like sensorineural hearing loss, behavioral abnormalities, and impairment of vision among other things (Deverajan, 2012), (Selner, 2012).
4. What steps can be taken to treat the illness? How and why are the treatments?
Antibiotic therapy is the mainstay of treatment for Hemophilus influenza infection. Intravenous third-generation cephalosporin can be initiated as a treatment before drug sensitivity results are available. The empirical treatment is carried out for duration of 7-14 days (Selner, 2012).
The use of an anti-inflammatory agent, like Dexamethasone is also an important component of the treatment. This is in a bid to prevent the neurological deficit that can accompany the infection as morbidity (Deverajan, 2012), (Selner, 2012).
Also, as part of the treatment, other supportive care and management of complications as they arise is also essential. These include management of shock, seizures, subdural empyema and inappropriate secretion of Antidiuretic hormone (Deverajan, 2012).
For the treatment of nonencapsulated Hemophilus influenza infection, antibiotics like amoxicillin can be used. In the face of treatment failure as a result of beta lactamase production, treatment with amoxicillin and clavulanate can be used (Deverajan, 2012). If the individual is allergic to penicillins, erythromycin can be combined with Sulfisoxasole. In case of complications, a neurosurgeon may need to be consulted in order to manage complications of the nervous system (Deverajan, 2012). Also in cases of complicated infections, an infectious disease specialist may need to be consulted for assistance.
CDC (2013). Hemophilus Influenzae type b. CDC. Retrieved on 13th October, 2013 from <http://www.cdc.gov/vaccines/pubs/pinkbook/downloads/hib.pdf>
V Devarajan (2012). Hemophilus Influenzae Infections Treatment & Management. Medscape Reference. Retrieved on 13th October, 2013 from <http://emedicine.medscape.com/article/218271-treatment#showall
M Selner (2012). Aseptic Meningitis. Healthline. Retrieved on 13th October, 2013 from <http://www.healthline.com/health/aseptic-meningitis?toptoctest=expand>