Brucellosis Clinical features *The incubation period of brucellosis is 1-3 weeks.The onset is insidious , with malaise , headache, weakness, generalized myalgia and night sweats. *The fever pattern is classically undulant , although continuous and intermittent patterns are also seen.Lymphadenopathy, hepatosplenomegaly and spinal tenderness sacro-iliitis(20-30%) may be present ;arthritis , osteomyelitis ,epididimo-orchitis (up to 40% ) , meningoencephalitis and endocarditis have all been described.
*Untreated brucellosis can give rise to chronic infection, lasting a year or more.This is characterized by easy fatiguability , myalgia , and occasional bouts of fever and depression. *Splenomegaly is usually present.Occasionally infection can lead to localized brucellosis.Bones and joints , spleen ,endocardium , lungs , urinary tract and nervous system may be involved.Systemic symptoms occur in less than one third.
DIAGNOSIS *Blood ( or bone marrow ) cultures are positive during the acute phase of illness in 50%of patients ( higher in B.meitensis ) , but prolonged culture is required . *If using automated blood culture systems (BACTEC) incubate longer than the usual5-7 days.This is less helpful in chronic disease where serological tests of greater value.
*The brucella agglutination test , which demonstrates a fourfold or greater rise in titre (>1 in 160 ) over a 4-weeks period , is highly suggestiveof brucellosis . N.B…..non – agglutinating IgG and IgA molecules can block the agglutinating reaction ( prozone phenomenon ) and the test should be carried out to a high dilution to avoid this. *An elevated serum IgG level is evidence of current or recent ; a negative test excludes chronic brucellosis. *In localized brucellosis antibody titres are low , and diagnosis is usually established by culturing organisms from the involved site.
*PCR for the detection of Brucella in blood gives a rapid diagnosis ,and along with the measurement of IgG and IgM antibodies by ELISA , are highly sensitive and specific
Management *Brucellosis is treated with a combination of doxycycline 200mg daily and rifampicin 600_900 mg daily for 6 weeks, but relapses occur. *Alternatively tetracycline can be combined with streptomycin , which is usually given for only the first 2 weeks of treatment.
Prevention *Prevention and control involve careful attention to hygiene when handling infected animals. , vaccination with the eradication of infection in animals , and pasteurization of milk. *No vaccine is available for use in humans.
Scarlet fever Occurs when the infectious organism ( usually a group A streptoccocus ) produces erythrogenic toxin in an individual who does not posses neutralizing antitoxin antibody
CLINICL FEATURES *The incubation period of this relatively mild disease, which mainly affects children , is 2-4 days following streptoccocal infection , usually in the pharynx. *Regional lymphadenopathy , fever,, rigors , headache and vomiting are present. *The rash, which blanches on pressure, usually appears on the second day of illness ; it initially occurs on the neck but rapidly becomes punctate, erythematous and generalized.
*The rash is typically absent from the face , palms and soles, and is prominent in the flexures .It usually lasts about 5 days and is followed by extensive desquamation of the skin. *The face is flushed, with characteristic circumoral pallor.Early in the disease the tongue has a with coating through which prominent bright red papillae can be seen (‘strawberry tongue ‘) .Later the white coatingdisappears, leaving a raw-looking , bright red colour (‘raspaberry tongue ‘)
*The patient is ineffective for 10-21 days after the onset of rash , unless treated with penicillin. *Scarlet fever may be complicated by peritonsillar or retropharyngeal abscesses and otitis media.
Diagnosis The diagnosis is established by typical clinical features and culture of a throat swab.Elevated antistreptolysin O and anti-DNase B levels in convalescent serum are indicative of streptoccocal infection
Treatment *Penicillin is the drug of choice and is given orally as phenoxymethylpenicillin 500 mg four times daily for 10 days .Individuals allergic to penicillin can be treated effectively with erythromycin 250 mg four times daily for 10 days. *Treatment is usually effective in preventing rheumatic fever and acute glomerulonephritis, which are non-suppurative complications of streptococcal pharyngitis.Unlike acute rheumatic fever,streptococcal nephritis may also complicate streptococcal skin infection.
Staphylococcal toxic shock syndrome (TSS) Serious and life-threatening disease associated with infection by Staph. aureus which is producing toxic shock syndrome toxin I (TSST I). *It is most commonly seen in young women during , or immediately after , menustration and is associated with the use of highly absorbent intravaginal tampons.
*Staph. aureus has been shown to grow in and around the tampon with the liberation of TSSTI.TSS has also been described in both sexes in any age group associated with toxin-producing staphylococcal infections. *The toxin acts as a’ super-antigen’ , triggering significant T- helper cell activation and very high peripheral polymorphonuclear leucocyte numbers.
*TSS has an abrupt onset with high fever , generalized systemic upset ( myalgia , headache , sore throat and vomiting), a generalized erythematous blanching rash resembling scarlet fever ,and hypotension. *It rapidly progresses over a matter of hours to multisystem involvement with cardiac , renal and hepatic compromise , leading to death in 10-20%.Recovery is accompanied at 7-10 days by desquamation.
Diagnosis *Is clinical ( fever ,rash,hypotension plus systemic upset in any person with distant staphylococcal infection). *It may be confirmed in menstrual cases by vaginal examination , the finding of a retained tampon and microbiological examination by Gram stain demonstrating typical staphylococci.Subsequent culture and demonstration of toxin production are confirmatory.
Management *Immediate and aggressive fluid resuscitation with an intravenous antistaphylococcal antibiotics ( flucloxacillin or vancomycin) is required. *The rapid progression of symptoms and signs may require intensive care .Women who recover should be advised not to use tampons for at least 1 year and should also be warned that due to an inadequate antibody response to TSSTI ,the condition can recur.
Streptococcal toxic shock syndrome This is associated with severe group A streptococcal skin infections producing pyogenic exotoxin A.Initially , an influenza- like illness occurs with , in 50% of cases, signs of necrotizing fasciitis.A faint erythematous rash , mainly on the chest , rapidly progresses to a toxic multisystem shock-like state. *N.B…..without aggressive management , multi-organ failure will develop.
*Management includes fluid resuscitation ,linked to parenteral antistreptococcal antibiotic therapy , usually with benzylpenicillin with or without clindamycin.