A nurse is teaching a prenatal client about listeriosis and dietary modifications during pregnancy. Which of the following statements by the client indicates an understanding of the teaching?

The correct answer is Choice C.

Choice A rationale: Thiazide diuretics cause potassium and chloride loss, leading to metabolic alkalosis, not respiratory alkalosis. Hypokalemia decreases hydrogen ion excretion, increasing bicarbonate levels. Metabolic alkalosis is characterized by pH >7.45 and HCO₃⁻ >26 mEq/L rather than decreased PaCO₂.

Choice B rationale: Vomiting leads to metabolic alkalosis due to gastric acid loss. Hydrogen ion depletion increases bicarbonate concentration, shifting pH above normal. Arterial blood gases typically show increased HCO₃⁻ (>26 mEq/L) with a compensatory increase in PaCO₂ (>45 mmHg), not respiratory alkalosis.

Choice C rationale: Salicylate intoxication initially induces hyperventilation, reducing PaCO₂ levels below 35 mmHg and increasing pH above 7.45, leading to respiratory alkalosis. As toxicity progresses, metabolic acidosis may develop due to lactic acid accumulation, but early stages primarily present with respiratory alkalosis.

Choice D rationale: Hypoventilation leads to CO₂ retention, increasing PaCO₂ above 45 mmHg, forming carbonic acid (H₂CO₃) and causing respiratory acidosis. Blood gases show pH <7.35 with elevated PaCO₂, not respiratory alkalosis, which is caused by excessive CO₂ elimination through hyperventilation.

The correct answer is c. Ampicillin.

Rationale:

• Group B Streptococcus (GBS) B-hemolyticis a bacterium that can colonize the vagina and rectum of pregnant women.While usually harmless to the mother,it can be passed to the newborn during birth and cause serious infections,including pneumonia,meningitis,and sepsis.
• Ampicillinis thefirst-line antibioticrecommended by the Centers for Disease Control and Prevention (CDC) for theprevention of GBS disease in newborns.It belongs to thepenicillin classof antibiotics,which are highly effective against GBS and generally well-tolerated by pregnant women and newborns.
• Doxycyclineis not recommended for GBS prophylaxis due to its poor penetration into amniotic fluid and potential for causing tooth discoloration and bone development problems in newborns.
• Cefotetanis an alternative option for women with penicillin allergy,but ampicillin is still preferred due to its lower cost and broader spectrum of activity against GBS strains.
• Fluconazoleis an antifungal medication and has no activity against GBS bacteria.

Detailed Rationale for Each Choice:

a. Doxycycline:

• Rationale against:
  • Poor penetration into amniotic fluid:Doxycycline does not effectively reach the amniotic sac,where the baby is surrounded,and therefore may not adequately protect the newborn from GBS infection.
  • Adverse effects in newborns:Doxycycline can cause tooth discoloration and bone development problems in infants exposed in utero.

b. Cefotetan:

• Rationale for:
  • Alternative for penicillin allergy:Cefotetan is a cephalosporin antibiotic effective against GBS and can be used in women with penicillin allergy.
• Rationale against:
  • Second-line option:Ampicillin is the preferred choice due to its lower cost and broader spectrum of activity against GBS strains.

c. Ampicillin:

• Rationale for:
  • First-line antibiotic:Ampicillin is the CDC-recommended first-line antibiotic for GBS prophylaxis due to its:
    • High effectiveness against GBS:Ampicillin has a broad spectrum of activity against GBS strains.
    • Good safety profile:Ampicillin is generally well-tolerated by pregnant women and newborns.
    • Cost-effectiveness:Ampicillin is a relatively inexpensive antibiotic compared to other options.

d. Fluconazole:

• Rationale against:
  • Antifungal medication:Fluconazole is an antifungal medication and has no activity against GBS,which is a bacterium.