Hospital-acquired pneumonia or nosocomial pneumonia refers to any
pneumonia contracted by a patient in a hospital at least 48–72 hours after
being admitted. It is thus distinguished from community-acquired pneumonia. It is
usually caused by a bacterial infection, rather than a virus.
HAP is the second most common nosocomial infection and accounts for 15–20% of the
total. It is the most common cause of death among nosocomial infections and is
the primary cause of death in intensive care units.
HAP typically lengthens a hospital stay by 1–2 weeks.
Signs and symptoms New or progressive infiltrate on the
chest X-Ray with one of the following: Fever > 37.8 °C
Purulent sputum Leukocytosis > 10.000 cells/μl
Types Bacterial pneumonia: The majority of
cases related to various gram-negative bacilli and Staphylococcus aureus,
usually of the MRSA type. Others are Haemophilus spp.. In the ICU results
were S. aureus(17.4%), Pseudomonas aeruginosa, Klebsiella pneumoniae and
Enterobacter spp., and Haemophilus influenzae.
Viral pneumonia: influenza and respiratory syncytial virus and, in the
immunocompromised host, cytomegalovirus- cause 10-20% of infections.
= Ventilator-associated pneumonia= Ventilator-associated pneumonia is a
sub-type of hospital-acquired pneumonia which occurs in people who are receiving
mechanical ventilation. VAP is not characterized by the causative agents;
rather, as its name implies, definition of VAP is restricted to patients
undergoing mechanical ventilation while in a hospital. A positive culture after
intubation is indicative of ventilator-associated pneumonia and is
diagnosed as such. In order to appropriately categorize the causative
agent or mechanism it is usually recommended to obtain a culture prior to
initiating mechanical ventilation as a reference.
= Healthcare-associated pneumonia= HCAP is a condition in patients who can
come from the community, but have frequent contact with the healthcare
environment. Historically, the etiology and prognosis of nursing home pneumonia
appeared to differ from other types of community acquired pneumonia, with
studies reporting a worse prognosis and higher incidence of multi drug resistant
organisms as etiology agents. The definition criteria which has been used
is the same as the one which has been previously used to identify bloodstream
healthcare associated infections. Definition
Healthcare-associated pneumonia can be defined as pneumonia in a patient with
at least one of the following risk factors:
hospitalization in an acute care hospital for two or more days in the
last 90 days; residence in a nursing home or long-term
care facility in the last 30 days receiving outpatient intravenous therapy
within the past 30 days receiving home wound care within the
past 30 days attending a hospital clinic or dialysis
center in the last 30 days having a family member with known
multi-drug resistant pathogens Causes
In some studies, the bacteria found in patients with HCAP were more similar to
HAP than to CAP; compared to CAP, they could have higher rates of
Staphylococcus aureus and Pseudomonas aeruginosa, and less Streptococcus
pneumoniae and Haemophilus influenzae. In European and Asian studies, the
etiology of HCAP was similar to that of CAP, and rates of multi drug resistant
pathogens such as Staphylococcus aureus and Pseudomonas aeruginosa were not as
high as seen in North American studies. It is well known that nursing home
residents have high rates of colonization with MRSA. However, not all
studies have found high rates of S. aureus and gram-negative bacteria. One
factor responsible for these differences is the reliance on sputum samples and
the strictness of the criteria to discriminate between colonising or
disease-causing bacteria. Moreover, sputum samples might be less frequently
obtained in the elderly.Aspiration is thought to be the most important cause
of HCAP. Dental plaque might also be a reservoir for bacteria in HCAP.
Treatment Patients with HCAP are more likely than
those with community-acquired pneumonia to receive inappropriate antibiotics
that do not target the bacteria causing their disease.
In 2002, an expert panel made recommendations about the evaluation and
treatment of probable nursing home-acquired pneumonia. They defined
probably pneumonia, emphasized expedite antibiotic treatment and drafted
criteria for the hospitalization of willing patients.
For initial treatment in the nursing home, a fluoroquinolone antibiotic
suitable for respiratory infections, or amoxicillin with clavulanic acid plus a
macrolide has been suggested. In a hospital setting, injected
fluoroquinolones or a second- or third-generation cephalosporin plus a
macrolide could be used. Other factors that need to be taken into account are
recent antibiotic therapy, known carrier state or risk factors for resistant
organisms, or suspicion of possible Legionella pneumophila infection.
In 2005, the American Thoracic Society and Infectious Diseases Society of
America have published guidelines suggesting antibiotics specifically for
HCAP. The guidelines recommend combination therapy with an agent from
each of the following groups to cover for both Pseudomonas aeruginosa and
MRSA. This is based on studies using sputum samples and intensive care
patients, in whom these bacteria were commonly found.
cefepime, ceftazidime, imipenem, meropenem or piperacillin–tazobactam;
plus ciprofloxacin, levofloxacin, amikacin,
gentamicin, or tobramycin; plus linezolid or vancomycin
In one observational study, empirical antibiotic treatment that was not
according to international treatment guidelines was an independent predictor
of worse outcome among HCAP patients. Guidelines from Canada suggest that HCAP
can be treated like community-acquired pneumonia with antibiotics targeting
Streptococcus pneumoniae, based on studies using blood cultures in
different settings which have not found high rates of MRSA or Pseudomonas.
Besides prompt antibiotic treatment, supportive measure for organ failure are
also important. Another consideration goes to hospital referral; although more
severe pneumonia requires admission to an acute care facility, this also
predisposes to hazards of hospitalization such as delirium,
urinary incontinence, depression, falls, restraint use, functional decline,
adverse drug effects and hospital infections. Therefore, mild pneumonia
might be better dealt with inside the long term care facility. In patients
with a limited life expectancy, end-of-life pneumonia also requires
recognition and appropriate, palliative care.
Prognosis Healthcare-associated pneumonia seems to
have fatality rates similar to hospital-acquired pneumonia, worse than
community-acquired pneumonia but less severe than pneumonia in ventilated
patients. Besides clinical markers like tachypnea or a high white cell count,
the prognosis seems to be influenced by the underlying associated diseases and
functional capacities. Many patients have a decreased health condition after
the episode. Epidemiology
Several studies found that healthcare-associated pneumonia is the
second most common type of pneumonia, occurring less commonly than
community-acquired pneumonia but more frequently than hospital-acquired
pneumonia and ventilator-associated pneumonia. In a recent observational
study, the rates for CAP, HCAP and HAP were 60%, 25% and 15% respectively.
Patients with HCAP are older and more commonly have simultaneous health
problems. The number of residents in long term
care facilities is expected to rise dramatically over the next 30 years.
These older adults are known to develop pneumonia 10 times more than their
community-dwelling peers, and hospital admittance rates are 30 times higher.
Nursing home-acquired pneumonia Nursing Home-Acquired pneumonia is an
important subgroup of HCAP. Residents of long term care facilities may become
infected through their contacts with the healthcare system; as such, the microbes
responsible for their pneumonias may be different from those traditionally seen
in community-dwelling patients, requiring therapy with different
antibiotics. Other groups include patients who are admitted as a day case
for regular hemodialysis or intravenous infusion. Especially in the very old and
in demented patients, HCAP is likely to present with atypical symptoms.
Risk factors Among the factors contributing to
contracting HAP are mechanical ventilation, old age, decreased
filtration of inspired air, intrinsic respiratory, neurologic, or other
disease states that result in respiratory tract obstruction, trauma,
surgery, medications, diminished lung volumes, or decreased clearance of
secretions may diminish the defenses of the lung. Also, poor hand-washing and
inadequate disinfection of respiratory devices cause cross-infection and are
important factors. Pathogenesis
Most nosocomial respiratory infections are caused by so-called skorvatch
microaspiration of upper airway secretions, through inapparent
aspiration, into the lower respiratory tract. Also, "macroaspirations" of
esophageal or gastric material is known to result in HAP. Since it results from
aspiration either type is called aspiration pneumonia.
Although gram-negative bacilli are a common cause they are rarely found in
the respiratory tract of people without pneumonia, which has led to speculation
of the mouth and throat as origin of the infection.
Diagnosis In hospitalised patients who develop
respiratory symptoms and fever one should consider the diagnosis. The
likelihood increases when upon investigation symptoms are found of
respiratory insufficiency, purulent secretions, newly developed infiltrate
on the chest X-Ray, and increasing leucocyte count. If pneumonia is
suspected material from sputum or tracheal aspirates are sent to the
microbiology department for cultures. In case of pleural effusion thoracentesis
is performed for examination of pleural fluid. In suspected
ventilator-associated pneumonia it has been suggested that bronchoscopy(BAL) is
necessary because of the known risks surrounding clinical diagnoses.
= Differential diagnosis= Atelectasis
Congestive heart failure Pulmonary embolism
Treatment Usually initial therapy is empirical. If
sufficient reason to suspect influenza, one might consider oseltamivir. In case
of legionellosis, erythromycin or fluoroquinolone.
A third generation cephalosporin + carbapenems + beta lactam & beta
lactamase inhibitors References
External links Hospital-Acquired, Health Care
Associated, and Ventilator-Associated Pneumonia from the Cleveland Clinic
Cecil Textbook of Medicine Further reading
Carratalà J, Garcia-Vidal C. "What is healthcare-associated pneumonia and how
is it managed?". Curr. Opin. Infect. Dis. 21: 168–173.
doi:10.1097/QCO.0b013e3282f4f248. PMID 18317041.).
Morrow L. Critical Decisions for the Treatment of Health-care-Associated
Pneumonia in the ICU.