Pneumococcal Meningitis

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Pneumococcal meningitis is caused by Streptococcus pneumoniae and is characterized by fever, neck stiffness, bulging fontanelle, irritability, and lethargy. 

-S pneumoniae is the most common cause of meningitis in adults and children 

-Individuals with splenectomy, sickle cell disease, cochlear implants are at higher risk for pneumococcal meningitis 

Symptoms & Signs: nuchal rigidity, irritability, confusion or altered mental status, headache, photophobia, nausea, vomiting, Brudzinski (neck flexion) and Kernig (straight leg raise) signs

Diagnosis: CSF culture 

Treatment: Start antibiotics within 60 minutes if bacterial meningitis is suspected; A 2-week course of intravenous antimicrobial therapy with vancomycin, ceftriaxone, cefotaxime, Penicillin G, Ampicillin 

-Survivors should be followed for neurologic sequelae like hearing loss, motor and cognitive impairment  


Erysipelas

 

Erysipelas is a sharply demarcated superficial dermal bacterial infection, most often caused by invasion of the superficial lymphatics by β-hemolytic group A streptococci (Streptococcus pyogenes) and rarely by S.aureus 

-The most common areas of infection: Legs, followed by the face 

-The most common ages affected: Infants and elderly adults 

-The lesions are red, raised, rapidly advancing with sharply demarcated margins between involved and normal tissues 

-Lesions are painful with bright red edematous indurated appearance giving rise to  “peau d’orange” appearance. 

-Facial lesions can have ‘butterfly’ pattern 

-Milian ear sign: Complete involvement of the ear by erysipelas 

-Nearly always unilateral 

Erysipelas vs.Cellulitis: Erysipelas is painful, raised, indurated plaque with sharply demarcated margins. It is superficial. 

Cellulitis may present with or without purulence


Tick-borne encephalitis (TBE)

Introduction

-Tick-borne encephalitis (TBE) is a flaviviral infection caused by TBE virus with three subtypes: European, Siberian, and Far Eastern. 

-Flaviviruses are positive-sense, single-stranded RNA, icosahedral capsid, enveloped viruses

-The principal reservoirs and vectors for TBE virus are ticks

-The virus is transmitted to humans by ticks.

-Outbreaks happened after ingestion of unpasteurized milk from infected sheep and goat  

Symptoms & Signs 

-The incubation period is 7–14 days for tick-borne exposures and only 3–4 days for milk ingestion.

-Most cases are subclinical

-The disease is characterized by a biphasic illness.

Fever-myalgia phase: Fever, arthralgia, headaches, nausea

CNS phase: headaches, meningitis, encephalitis, paralysis  

-Post-encephalitic syndrome: headaches, balance disorders, fatigue, hearing defects, attention deficits, depression, learning impairment 

Diagnosis 

Labs: leukocytosis, neutrophilia, hyponatremia 

CSF: pleocytosis 

PCR: Virus detection by RT-PCR in ticks from TBE patients 

ELISA: TBE virus IgM and IgG are detected by ELISA

Treatment 

Treatment is supportive.

Prognosis 

Complete recovery in most cases 

Prevention 

-There is no available TBE vaccine in the United States

-Effective vaccines are available in Europe, Canada and China 


Scarlet Fever

Scarlet fever is a syndrome characterized by exudative pharyngitis, fever, and scarlatiniform rash. 

-It is caused by toxin-producing group A β-hemolytic streptococci

-Symptoms and signs include sore throat, fever, rash, strawberry tongue, flushed face, and circumoral pallor 

-Rash: Diffusely erythematous rash resembling a sunburn; superimposed fine red papules give the skin a sandpaper consistency; it blanches on pressure, moves from torso to extremities, prominent on the face, chest, palms, fingers and toes; fades in 2-5 days 

-Forchheimer spots: Petechiae and punctuate red macules on the soft palate and uvula 

-Pastia lines are pink or red lines seen over the elbows and axilla during scarlet fever

-Treatment of scarlet fever is by antibiotics 




Chlamydia

Chlamydial infections

Introduction 

-Chlamydiae are obligate intracellular bacteria, possess both DNA and RNA, and have a cell wall similar to that of gram-negative bacteria.

-Chlamydiae that infect humans are divided into three species, Chlamydia trachomatis, Chlamydia pneumoniae, and Chlamydia psittaci

Chlamydia trachomatis: Chlamydia trachomatis infects only humans; incubation period: 1-3 weeks 

Eye infections: Conjunctivitis, trachoma (leading cause of preventable infectious blindness)

Lung infections: Pneumonia 

Genital infections: Urethritis, Lymphogranuloma venereum 

Joint infections: Reiter’s syndrome 

 Chlamydia pneumoniae: Chlamydia pneumoniae infects only humans; it can cause upper and lower respiratory infections 

Chlamydia psittaci: Chlamydia psittaci infects birds, humans and other animals; it causes psittacosis 

Symptoms & Signs 

Genital infection: Dysuria, urethritis, discharge, which is clearer and less purulent than seen with gonorrhea; Chlamydial infection is asymptomatic in 75% of females

Diagnosis 

Nucleic acid amplification test (NAAT): is the recommended test for screening asymptomatic at-risk and symptomatic individuals 

Culture: In culture, C. trachomatis forms intracytoplasmic inclusions containing glycogen, whereas C. psittaci and C. pneumoniae form inclusions that do not contain glycogen.

Serologic tests:  mainly to diagnose infections by C. psittaci and C. pneumoniae 

Treatment 

-All chlamydiae are susceptible to tetracyclines, such as doxycycline, and macrolides, such as erythromycin and azithromycin.

-Treatment should be offered to sex partners 

-Because of the high rate of coinfection with C.trachomatis and gonococci, any patient with a diagnosis of chlamydia should also be treated for gonorrhea and vice versa 

-Chlamydia urethritis: Azithromycin 1 g orally in a single dose or Doxycycline 100 mg orally twice a day for 7 days 

-The drug of choice for neonatal inclusion conjunctivitis and pneumonia caused by C. trachomatis is oral erythromycin. 

-The drug of choice for C. psittaci and C. pneumoniae infections and for lymphogranuloma venereum is a tetracycline such as doxycycline.

Prognosis 

Untreated chlamydia can cause serious complications 

Men: Epididymitis, sterility

Women: PID, ectopic pregnancy, infertility 

Prevention 

-There is no vaccine against any chlamydial disease

-Educate patients on safer sex practices.

Q.What are the tests of choice for the diagnosis of genital C.trachomatis infections? Nucleic acid amplification tests (NAATs) Q.What is the drug of choice for Chlamydia trachomatis sexually transmitted disease? Azithromycin