تبلیغات
downloader3116

داستان راستان اول

بافت شناسی:

بیماری توکسوپلاسما گوندی در انسان یکی از شایع ترین بیماری ها در سراسر جهان است.تقریبا نیم بیلیون از انسانها انتی بادی توکسو پلاسما گوندی را در بدن خود دارند.

شیوع این بیماری در انسان و حیوانات ممکن است در قسمت های مختلف هر بار بروز کند.علت این گوناگونی روشن شده است. حالات محیط و عادت فرهنگی و و نوع حیوانات از  علت هایی است.که درجه پراکندگی طبیعی توکسو پلاسما گوندی را تعیین میکند.

تنها مقداری از  مردم دچار عفونت ارثی می شوند.نوعی ایمن یافتن مادر از بچه ی بیمار مادر زادی ست که در حاملگی های بعدی بچه بیمار به دنیا نمی اورد.

بیماری می تواند به طور مکرر در موش ها و موش های صحرایی و خوک افریقایی و همستر بدون عفونت مجدد از مبدا خارجی اتفاق  بیافتد.توکسوپلاسمای وابسته به بعد تولد به وسیله ی گوشت خام و نپخته و به وسیله ی خوردن غذای الوده به وسیله ی کیستهای مدفوع گربه اتفاق می افتد.

گزارش شده که هردو سبک از بیماری علت کلنیکی توکسوپلاسموزیسی دارد.توکسوپلاسما گوندی معمولا در حیواناتی که گوشت خوارند اتفاق می افتد و عفونت در دام ها و تیور مانند گوسفندان و خوک ها کمتر گزارش شده است

 

REFERENCES

Dubey JP, Beattie CP: Toxoplasmosis of Animals and Man. CRC Press, Boca Raton, FL, 1988

Gazzinelli RT, Denkers EY, Sher A.: Host resistance to Toxoplasma gondii: model for studying the selective induction of cell-mediated immunity by intracellular parasites. Infect Agent Dis 2:139, 1993

Georgie VA: Management of toxoplasmosis. Drugs, 48:179, 1994

Guerina NG, Hsu HW, Meissner HC, Meissner HC, et al. Neonatal serologic screening and early treatment for congenital Toxoplasma gondii infection. N Eng J Med, 330:1858, 1994

Remington, JS, McLeond R, Desmonts G.: Toxoplasmosis. In: Remington JS, Klein JO, (eds.): Infectious Diseases of the Fetus and Newborn Infant. Philadelphia: W.B. Saunders Company, 1995

 

organisms (32–43% of patients; reviewed by Ferrieri et al., 2002). In

general, the principles of antibiotic treatment of paediatric endocarditis

are similar to those for the treatment of adults.

Prevention and Control

When patients are known to have predisposing cardiac abnormalities,

great care should be taken to protect them from the risk of endocarditis

when undergoing any dental, surgical or investigational procedures

which might induce a transient bacteraemia. However, even if carried

out perfectly, this approach is not likely to prevent all episodes of

endocarditis since up to 50% of cases occur in individuals without

previously diagnosed cardiac abnormalities (Hoen et al., 2002). For

the identified at-risk group, the appropriate antibiotic prophylaxis is

summarized in Table 2.6.

The main principle governing these prophylactic regimens is that a

high circulating blood level of a suitable bactericidal agent should be

achieved at a time when the bacteraemia would occur. For bacteraemia

arising during dental surgery, additional protection may be

achieved by supplementing the use of systemic antibiotics with locally

applied chlorhexidine gluconate gel (1%) or chlorhexidine gluconate

mouthwash (0.2%) 5 min before the procedure. Dental procedures that

require antibiotic prophylaxis include extractions, scaling and surgery

involving gingival tissues. A most important consideration for

patients who are at risk of endocarditis is that their dental treatment be

planned in such a way that the need for frequent antibiotic prophylaxis

and the consequent selection for resistant bacteria among the resident

flora is avoided. For multistage dental procedures, a maximum of two

single doses of penicillin may be given in a month and alternative

drugs should be used for further treatment, and penicillin should not

be used again for 3–4 months.

Abscesses Caused by Non-b-Haemolytic Streptococci

Streptococci are frequently isolated from purulent infections in

various parts of the body, including dental, central nervous system

(CNS), liver and lung abscesses. Commonly, there is a mixture of

several organisms in the pus, which may contain obligate anaerobes as

well as streptococci and other facultative anaerobes. Consequently, it

may be difficult to determine the contribution that any single strain or

species is making to the infectious process. The source of these

bacteria is usually the patient’s own commensal microflora and may

be derived from the mouth, upper respiratory tract, gastrointestinal

tract or genitourinary tract.

Members of the anginosus group of streptococci (previously known

as S. milleri group, or SMG, streptococci) have a particular propensity

to cause abscesses. The development of reliable identification and

speciation methods for this group of streptococci has allowed

epidemiological analysis to determine whether there is a correlation

between species and anatomical site of infection (reviewed by Belko

et al., 2002). Studies indicate that S. intermedius was more frequently

isolated from infections of the CNS and liver, S. constellatus was

more frequently isolated from lung infections, whereas S. anginosus

was more frequently associated with infections of the gastrointestinal

and genitourinary tracts and with soft-tissue infections. Although

studies have identified several virulence determinants of anginosus

group streptococci (see Pathogenesis), we have little understanding of

the bacterial–host interactions that define the body-site specificity

identified by these epidemiological studies.

Pathogenesis

Members of the anginosus group of streptococci possess multiple

pathogenic properties that may contribute to disease. These include

adhesion to host tissue components such as fibronectin, fibrinogen

and fibrin–platelet clots (Willcox, 1995; Willcox et al., 1995) and the

aggregation of platelets (Willcox et al., 1994; Kitada, Inoue and

Kitano, 1997) (Table 2.7).

Abscesses are frequently polymicrobial in nature, and studies

suggest that coinfection of streptococci with strict anaerobes such as

Fusobacterium nucleatum and Prevotella intermedia, both common