Medical brain notes 42

  GROUP B STREPTOCOCCUS   Group B streptococcus (GBS)  (or Streptococcus agalac-tiae ) is an important cause of perinatal infections. Asymptomatic lower genital tract colonization occurs in up to 30% of pregnant women, but cultures may be posi-tive only intermittently, even in the same patient. Approximately 50% of infants exposed to the organism in the lower genital tract will become colonized. For most of these infants, such colonization is of no consequence, but without treatment, GBS sepsis occurs in approximately 0.2 infants per 1000 live births annually.   There are two manifestations of clinical infection of the newborn, termed early-onset and late-onset, occur-ring at roughly equal frequency.  Early-onset  infection manifests as septicemia and septic shock, pneumonia, or meningitis and occurs during the first week of life. Early-onset infection is much more common in preterm infants than in term infants.  Late-onset  infection occurs later...

  HERPES Herpes simplex virus (HSV)  is a double-stranded DNAvirus that can be differentiated into HSV type 1 (HSV-1) and HSV type 2 (HSV-2). Herpes simplex virus type 1 is the primary etiologic agent of herpes labialis, gingivostomatitis, and keratoconjunctivitis. Most genital infections with HSV are caused by HSV-2, but genital HSV-1 infections are be-coming increasingly common, particularly among adoles-cent and young women. Up to 80% of new genital infections among women may be due to HSV-1, with the highest rates occurring in adolescents and young adults. Herpes infec-tions are categorized as follows:   ·    Primary  occurs in a woman with no evidence of priorHSV infection (seronegative to both HSV-1 and HSV-2).   ·    Nonprimary first episode  occurs in a woman with ahistory of heterologous infection (first HSV-2 infection with a prior HSV-1 infection).   ·            ...

  RUBELLA   Rubella  (German, or 3-day, measles) is an RNA virus withimportant perinatal impact if infection occurs during pregnancy. Widespread immunization programs in the last 30 years have prevented periodic epidemics of rubella, but some women of reproductive age lack immunity to this virus and are therefore susceptible to infection. Once infec-tion occurs, immunity is life-long. A history of prior infec-tion is an unreliable indicator of immunity.   If a woman develops rubella infection in the first trimester of pregnancy, there is an increased risk of both spontaneous abortion and congenital rubella syndrome. Although most infants with congenital rubella appear nor-mal at birth, many subsequently develop signs of infection. Common defects associated with the syndrome include congenital heart disease (e.g., patent ductus arteriosus), mental retardation, deafness, and cataracts. The risk of congenital rubella is related to the gestational age at the time of infe...

  HEPATITIS   Viral hepatitis is one of the most common and potentially serious infections that can occur in pregnant women. Six forms of viral hepatitis have now been identified, two of which, hepatitis A and hepatitis B, can be prevented effec-tively through vaccination.   Hepatitis A   Hepatitis A virus  (HAV) is transmitted from person toperson primarily through fecal–oral contamination. Good hygiene and proper sanitation are important to prevent in-fection. However, vaccination is the most effective means of preventing transmission. The hepatitis A vaccine is available as both a single-antigen vaccine and as a combination vac-cine (containing both HAV and HBV antigens). Prior to vaccine availability, HAV accounted for one-third of cases of acute hepatitis in the United States. HAV infection does not progress to chronic infection. Diagnosis is confirmed by demonstration of anti-HAV IgM antibodies. HAV infection has no specific effects on pregnancy or the fet...

  HIV/AIDS SYNDROME   Worldwide, women account for nearly 50% of those in-fected with HIV. The CDC estimates that 27% of those living with acquired immune deficiency syndrome (AIDS) in the United States are women. Of these women, 71% were exposed through heterosexual contact and 27% through injection drug use. One percent of those living with AIDS are children under the age of 13, most of whom acquired the infection perinatally.   The usual estimated latency period from untreated HIV to AIDS is about 11 years.  HIV infection becomes AIDS as thehelper (CD4  + ) lymphocyte count decreases and the host becomes more susceptible to other types of infections. With the availability of increasingly effective antiretrovi-ral drugs, life span and quality of life have improved dra-matically.     Pathophysiology   HIV is a single-stranded, RNA, enveloped human retrovirus that has the ability to become incorporated into the cellular DNA of CD4 +  cells su...

  HUMAN PAPILLOMAVIRUS   More than one-third of sexually active women have been exposed to at least one type of the  human papillomavirus(HPV).  Genital wart lesions  (condyloma acuminata)  often increase in size and area during pregnancy due to rel-ative immune suppression. If extensive, cesarean delivery may be necessary to avoid excessive trauma to the lower genital tract. In pregnancy, cryotherapy, laser therapy, and trichloroacetic acid may be used to treat genital HPV le-sions.  Podophyllin, 5-fluorouracil, and interferon are not rec ommended, as they may be toxic to the fetus.  Because there arelimited data regarding imiquimod use in pregnancy, it is generally avoided. Treatment of genital HPV lesions is often delayed until after pregnancy, as spontaneous reso-lution may occur. Transmission of HPV from mother to infant is very rare but manifests as laryngeal papillomato-sis. Cesarean delivery does not prevent perinatal transmis-sion of HPV....

  SYPHILIS   Syphilis  is a systemic disease caused by the motile spirochete Treponema pallidum.  The spirochete is transmitted by directcontact, invading intact mucous membranes or areas of abraded skin. A painless ulcer at the site of inoculation fol-lows, usually within 6 weeks following exposure. The ulcer is firm, with elevated edges; it lasts for several weeks. One to 3 months later, a skin rash occurs, or, in some patients, raised lesions  (condyloma lata)  appear on the genitalia.   T. pallidum  is generally considered to cross the placentato the fetus after 16 weeks of gestation. Transmission can occur at any stage of maternal infection and has been doc-umented at as early as 6 weeks of gestation.   Spontaneous abortion, stillbirth, and neonatal death are more frequent in any untreated patient, whereas neonatal infection is more likely in primary or secondary rather than latent syphilis. Newborns with congenital syphilis may be asymp...

  GONORRHEA   Antepartum screening for  Neisseria gonorrhoeae  should be performed early in pregnancy for women with risk factors or symptoms and repeated in the third trimester for women at high risk  (see Table 16.1). Rates in pregnancy range from1% to 7%, depending on the population. Diagnosis is made by PCR. All cases of gonorrhea must be reported to health care officials. Treatment is with an extended spectrum or 3rd-generation cephalosporin. Tetracyclines and fluoroquinolones are contraindicated in pregnancy. Infection above the cervix (i.e., of the uterus, including the fetus, and the fallopian tubes) is rare after the first weeks of pregnancy. At delivery, however, infected mothers may transmit the organism, causing gonococcal ophthalmia in the neonate. All neonates receive routine prophylactic treat-ment with sterile ophthalmic ointment containing eryth-romycin or tetracycline, which is generally effective in preventing neonatal gonorrhea.