ABSTRACT

The spectrum of nontuberculous mycobacterial infections has changed. Improved understaning  of immunopathogenesis of slow growing mycobacterial disease has been accompanied by a higher number of cases in patients with, or without cancer. In recent years, difficult-to-treat infections due to rapidly growing mycobacteria are on the rise, this may in part reflect newer molecular identification methods; however, rise in susceptible immunosuppressed patient population and frequently used indwelling prosthetic devices are also important contributors in this trend. Despite resistance to a number of available antimicrobilas, newer agents may provide the much-needed treatment options for high-risk cancer patients with nontuberculous mycobacterial infection-disease.

ABSTRACT

Cancer as such does not impact distribution of antimicrobials; however, various pathophysiological changes in cancer patients may do so. Neutropenia, cachexia, hypoproteinemia, and effusions are common situations in cancer patients that may change the concentrations of antibiotics in blood and tissues. Such changes should be taken into account and dosage regimens adapted accordingly. As the therapeutic management of cancer patients becomes more complex, drug-drug interactions in oncology are of particular importance. Commonly used antibiotics that are most likely involved in drug-drug interactions are rifampin and its derivates, the macrolides erythromycin and clarithromycin, the fluoroquinolone ciprofloxacin and trimethoprim/sulfonamide combinations. Knowing the interaction profiles of individual agents and potential outcomes of the interaction allows healthcare providers to minimize the risk.

ABSTRACT

Many cancer treatment centers have documented a decline in the proportion of bacterial infections caused by aerobic gram-negative bacilli in the past two decades. Nevertheless, these organisms still cause a wide spectrum of infection (from benign colonization to disseminated disease), and are associated with substantial morbidity and mortality in patients with cancer, particularly during episodes of neutropenia. The most significant problem to develop in recent years has been the emergence of resistance among most gram-negative pathogens, with some organisms acquiring multiple resistance mechanisms which render them multi-drug-resistant. Exacerbating this problem is the fact that the pipeline for new drug development is relatively dry. This has led to the increased use of combination regimens and the revival of older agents such as colistin. Greater emphasis needs to be placed on antimicrobial stewardship and on strict adherence to infection control policies, in order to reduce the frequency of and limit the spread of these organisms. Bacteroides and other anaerobic Gram-negative bacteria may lead to life threatening infections, presence of refractory hypotension, high grade fever, acute intravascular hemolysis and disseminated coagulation, and early onset of tissue necrosis are the hallmark of this devastating disease. A high level of suspicion and prompt systemic therapy coupled with surgical excision of devitalized tissue when possible may improve outcomes.

ABSTRACT

Development of prophylactic, pre-emptive, and therapeutic strategies has reduced the morbidity and mortality of viral infections after HSCT. However, the future success of such strategies is threatened by the increasing emergence of antiviral-resistant virus strains.  In some cases, resistance is common enough to warrant changes in recommendations for prophylaxis (e.g  influenza in the 2008-9 season)².   In other cases (HSV, VZV, CMV, HBV), resistance has not yet altered the primary class of agent(s) utilized for prophylaxis or pre-emptive therapy at the majority of centers, but clinicians should have a heightened awareness of the possibility of antiviral resistance, and a low threshold to alter therapy in the setting of high viral loads, unusual clinical presentations, or refractoriness to standard therapy.  A detailed  overview of the scoop of this problem and strategies for managing patients with these difficult to treat infections is presented in this chapter.

ABSTRACT

The respiratory viruses as a group are the most common cause of an acute infectious illness in developed societies.  The immunocompromised state of many cancer patients constitutes the basis for the frequent failure of the host to promote a normal and rapid recovery from an acute respiratory viral infection and results in a more severe and prolonged infection that causes significant morbidity and mortality in these patients.  Those respiratory viruses that are most prevalent and most prone to produce lower respiratory illnesses and pneumonia in healthy hosts, RSV, influenza viruses and parainfluenza viruses, are those most likely to cause severe illness and pneumonia leading to hospitalization in immunocompromised persons.  However, viruses less prone to produce a lower respiratory illness but that are highly prevalent, such as rhinoviruses, may frequently be associated with severe illness.  The limited availability of antivirals and vaccines for the acute respiratory viruses means that these infections will continue to be important for many years and dictate a need for utilizing infection control procedures as much as possible, particularly in hospitals and institutions, so as to minimize spread.  Efforts to develop specific vaccines are important as their use could prevent as well as reduce exposure of cancer patients to these viruses.  Development of specific antivirals is important for use in immunocompromised patients as normal recovery mechanisms may be seriously impaired.