Clinical Review

UPDATE: INFECTIOUS DISEASE

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The focus here is twofold: dealing with H1N1 influenza in vulnerable populations and taking up strategies to prevent postoperative infection in women undergoing cesarean delivery


 

References

Six recent articles stand out in the field of infectious disease:

  • an assessment of outcomes of seriously ill patients who were hospitalized early in the course of the H1N1 influenza epidemic. The authors highlight major differences in the epidemiology of this infection, compared with regular seasonal flu
  • an examination of outcomes of pregnant women who developed H1N1 influenza
  • an exploration of the use of blunt needles during cesarean delivery to prevent glove perforation
  • an evaluation of the utility of prophylactic antibiotics in ostensibly low-risk women undergoing scheduled cesarean delivery
  • a look at the timing of antibiotic prophylaxis for cesarean delivery
  • a comparison of skin preparation techniques in the prevention of surgical-site infection.

The focus on cesarean delivery in most of these studies seems particularly appropriate, now that this operation has become the most frequently performed major surgical procedure in US hospitals.

H1N1 virus hits hardest during pregnancy and chronic illness

Jain S, Kamimoto L, Bramley AM, et al, for 2009 Pandemic Influenza A (H1N1) Virus Hospitalizations Investigation Team. Hospitalized patients with 2009 H1N1 influenza in the United States, April-June 2009. N Engl J Med. 2009;361(20):1935–1944.

This retrospective survey of patients hospitalized for at least 24 hours for treatment of influenza-like illness included 272 patients who were given a diagnosis of H1N1 influenza, based on real-time, reverse-transcriptase, polymerase chain reaction assay. Sixty-seven (25%) of these patients were admitted to an ICU, and 19 (7%) died. All of the patients who died had been treated in an ICU, and two thirds had an underlying medical condition. Three of the deaths involved pregnant women. None of the patients who died received antiviral therapy within 48 hours of the onset of symptoms. Those who died were also less likely to have been vaccinated against seasonal influenza in 2008–2009.

Details of the trial

The 272 patients included in this study sample represented 25% of the total number of patients hospitalized in the United States for treatment of influenza between April and mid-June 2009. They exhibited the following characteristics:

  • median age: 21 years
  • race and ethnicity: 30% were Hispanic, and 27% were non-Hispanic white
  • most common symptoms: fever and cough, although diarrhea or vomiting was reported in 39% of patients
  • underlying medical illness: present in 73% (198 patients), including 60% of children and 83% of adults. At least two underlying medical conditions were present in 32% of patients. Asthma was the most common comorbid condition
  • pregnancy: 18 patients were pregnant. Four of the pregnant patients also had asthma, and two had diabetes
  • obesity: 29% of adults were obese. Morbid obesity was present in 26%. More than 75% of obese and morbidly obese patients had at least one underlying medical illness
  • bloodwork at admission: 20% of patients were leukopenic; 37% were anemic; and 14% were thrombocytopenic
  • chest film: 40% of patients who underwent chest radiography had findings consistent with pneumonia. Findings included bilateral infiltrates in 66 patients, a unilobar infiltrate in 26, and multilobar infiltrates in two
  • antiviral therapy: 75% ultimately received antiviral drugs, with a median time from onset of illness to initiation of therapy of 3 days (range, 0–29 days). Only 39% received antiviral therapy within 48 hours of the onset of symptoms
  • antibiotic therapy: 79% of patients received antibiotics for presumed superimposed bacterial infection. The most commonly used antibiotics were ceftriaxone, azithromycin, vancomycin, and levofloxacin.

Study offers 4 useful lessons

The study by Jain and colleagues offers clinically applicable lessons:

  • it reinforces the point that children and young adults, including pregnant women, are at increased risk of serious morbidity and mortality
  • it demonstrates that most seriously affected patients have at least one underlying medical condition, such as asthma
  • it highlights the importance of pregnancy and morbid obesity as major conditions that contribute to serious complications from influenza. The 7% prevalence of pregnant patients is significantly higher than the 1% prevalence that would typically be expected with seasonal influenza. Similarly, the 26% prevalence of morbid obesity greatly exceeds the estimated 5% prevalence in the adult US population
  • it confirms the importance of treating patients early in the course of their illness with antiviral drugs such as oseltamivir. Notably, none of the patients who died received treatment within 48 hours of the onset of illness, when the drugs are most likely to be effective.

How to treat H1N1 influenza

The vast majority of strains of the 2009 H1N1 virus are susceptible to oseltamivir and zanamivir, but essentially all strains are resistant to amantadine and rimantadine.1 Therefore, all individuals who are hospitalized should be treated with one of two regimens:

  • oseltamivir, 75 mg orally, twice daily for at least 5 days
  • zanamivir, 10 mg by inhalation, twice daily for at least 5 days.

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