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Respiratory Alterations and Management 361

TABLE 14.6 Preferred antimicrobial agents in pneumonia 6

Type of infection Preferred agent(s)
Community-acquired pneumonia
Streptococcus pneumoniae PCN-susceptible: Penicillin G, amoxicillin, clindamycin, doxycycline, telithromycin
PCN-resistant: cefotaxime, ceftriaxone, vancomycin, and fluoroquinolone
Mycoplasma Doxycycline, macrolide
Chlamydophila pneumoniae Doxycycline, macrolide
Legionella Azithromycin, fluoroquinolone (including ciprofloxacin), erythromycin (rifampicin)
Haemophilus influenzae Second- or third-generation cephalosporin, clarithromycin, doxycycline, β-lactam/β-
lactamase inhibitor, trimethoprim/sulfamethoxazole, azithromycin, telithromycin
Moraxella catarrhalis Second- or third-generation cephalosporin, trimethoprim-sulfamethoxazole,
macrolide doxycycline, β-lactam–β-lactamase inhibitor
Neisseria meningitidis Penicillin
Streptococci (other than S. pneumoniae) Penicillin, first-generation cephalosporin
Anaerobes Clindamycin, β-lactam–β-lactamase inhibitor, β-lactam plus metronidazole
Staphylococcus aureus Methicillin-susceptible Oxacillin, nafcillin, cefazolin; all rifampin or gentamicin
Methicillin-resistant Vancomycin, rifampicin or gentamicin
Klebsiella pneumoniae and other Enterobacteriaceae Third-generation cephalosporin or cefepime (all aminoglycoside) carbapenem
(excluding Enterobacter spp.)
Hospital-acquired infections
Enterobacter spp. Carbapenem, β-lactam–β-lactamase inhibitor, cefepime, fluoroquinolone; all +
aminoglycoside in seriously ill patients
Pseudomonas aeruginosa Anti-pseudomonal β-lactam + aminoglycoside, carbapenem + aminoglycoside
Acinetobacter Aminoglycoside + piperacillin or a carbapenem

alveolar infiltrates, resulting in about 20% of patients Pandemics of influenza were observed a number of times
requiring respiratory support. The SARS outbreak pro- in the twentieth century, and were believed to have
voked a rapid and intense public health response coordi- involved viruses circulating in humans that originated
nated by the World Health Organization (WHO), from influenza A viruses in birds. The ‘Spanish influenza’
resulting in a cessation of disease transmission within ten pandemic of 1918–19 resulted in the death of over 50
months. 35 million people worldwide and remains unprecedented in
its severity. 35
INFLUENZA PANDEMICS The first reported infection of humans with avian influ-
Epidemics of influenza occur regularly and are associated enza viruses occurred in Hong Kong in 1997, with six
with high morbidity and mortality. Incidence is usually recorded fatalities. The increased virulence of this disease
highest in the young, while mortality is highest in the was observed in the acuity of those affected by the out-
elderly population. Those with preexisting respiratory break of the highly pathogenic avian influenza virus
conditions such as asthma or COPD experience particu- (H5N1) in 2004–2005. Most patients presented with
35
larly high morbidity and mortality. In contrast, when non-specific symptoms of fever, cough and shortness of
influenza occurs on a pandemic scale it has been shown breath. In many patients this progressed rapidly to ARF
to affect greater numbers of younger and otherwise requiring ventilation and other supportive measures. The
healthy people. majority of people affected (90%) were less than 40 years
of age with case fatality rates highest in the 10–19-year-
A feature of the influenza virus that explains why it con- old age group. 36
tinues to be associated with epidemic and pandemic
disease is its high frequency of antigenic variation. This The most recent influenza pandemic declared by WHO
occurs in two of the external glycoproteins and is referred occurred in 2009 when a novel H1N1 influenza A virus
to as antigenic drift or antigenic shift, depending on the emerged in Mexico and the USA. This virus contained
extent of the variation. The result of this is that new genes from avian, human and swine influenza virus and
37
viruses are introduced into the population, and due to affected millions of people worldwide. Patients typically
the absence of immunity to the virus, a pandemic of presented with nonspecific flu-like symptoms, however in
influenza results. 6 a quarter of patients this was accompanied by diarrhoea