Appropriateness of empiric gentamicin and vancomycin therapy for bacteremias in chronic dialysis outpatient units in the era of antibiotic resistance.

Bacteremias in inpatient chronic HD units have been described, but there is little information on bacteremias in ambulatory HD units. To determine the frequency of bacteremia and pathogen distribution in ambulatory chronic HD units, we retrospectively reviewed our experience with 107 bacteremias in 5 chronic ambulatory HD units over a 3 year period. The object of the study was twofold. The first objective was to determine if bacteremias in ambulatory HD setting were substantially different in frequency or type than in the inpatient HD setting. Secondly, febrile patients suspected of having bacteremia in chronic HD patients are often empirically treated with vancomycin and gentamicin. Chronic HD patients require repeated and frequent venous access for HD. Bacteremias are common in chronic HD patients and may be primary or secondary and are often related to venous access site infections. The distributions of bacteremia pathogens in chronic HD patients are predominantly reflective of skin flora, i.e., staphylococci and to lesser extent aerobic Gram-negative bacilli. After S. aureus (MSRA/MSSA) and coagulase-negative staphylococcus (CoNS), enterococci are the next most important Gram-positive pathogens in bacteremic HD patients. Most strains of E. faecalis are sensitive to vancomycin and for practical purposes should be considered as vancomycin sensitive enterococci (VSE). In contrast, most strains of E. faecium are resistant to vancomycin and should be considered as vancomycin resistant enterococci (VRE). We retrospectively reviewed 107 patients on chronic ambulatory HD to determine the adequacy of empiric vancomycin and gentamicin prophylaxis. We found amikacin is preferred to gentamicin and that meropenem is an effective alternate substitution for gentamicin and vancomycin combination therapy.

Infections associated with steroid use.

Patients receiving chronic steroids have an increased susceptibility to many different types of infections. The risk of infection is related to the dose of steroid and the duration of therapy. Although pyogenic bacteria are the most common pathogens, chronic steroid use increases the risk of infection with intracellular pathogens such as Listeria, many fungi, the herpes viruses, and certain parasites. Clinicians should consider both common and unusual opportunistic infections in patients receiving chronic steroids.

New uses of older antibiotics.

Despite the development of extended-spectrum penicillins, cephalosporins, and quinolones, the older antimicrobial agents, doxycycline, minocycline, TMP-SMX, clindamycin, and metronidazole, still play an important role in the treatment of infectious diseases. All of these older drugs are well absorbed by the oral route, attaining serum levels equivalent to those achieved by parenteral administration. The availability of generic forms of the older drugs reduces their cost. Besides traditional uses, some older drugs have become the preferred therapy for newly recognized infectious diseases. Doxycycline is the preferred drug for rickettsial tickborne diseases, ehrlichiosis and early Lyme disease. TMP-SMX is the preferred drug for I. belli and Cyclospora. Minocycline has been used to treat MRSA and MRSE infections. Clindamycin or metronidazole combined with a quinolone is an excellent oral regimen for polymicrobial infections. [table: see text]

Treatment of legionnaires' disease.

Erythromycin has been the most commonly used drug for the treatment of legionnaires' disease; however, failures have occurred and adverse effects are common. Doxycycline intravenously is preferred and is less expensive. The newer macrolides/azalides, clarithromycin and azithromycin, have excellent in vitro activity against Legionella and fewer adverse effects than erythromycin. The fluoroquinolones, particularly levofloxacin, are the most active anti-Legionella antibiotics available. Other agents with activity against Legionella pneumophila include minocycline, rifampin, and trimethoprim-sulfamethoxazole. The preferred therapy of legionellosis in immunocompromised patients are quinolone/macrolide combinations, eg, levofloxacin plus azithromycin.

Klebsiella pneumoniae pneumonia.

Klebsiella pneumoniae is an uncommon cause of community-acquired pneumonia except in alcoholics. Klebsiella may mimic pulmonary reactivation tuberculosis because it presents with hemoptysis and cavitating lesions. Klebsiella pneumoniae is a difficult infection to treat because of the organism's thick capsule. Klebsiella is best treated with third- and fourth-generation cephalosporins, quinolones, or carbapenems. Monotherapy is just as effective as a combination treatment in Klebsiella pneumoniae because newer agents are used. In the past, older agents with less anti-Klebsiella activity were needed for effective treatment. The patient we present was initially thought to have pulmonary tuberculosis, and when found to have Klebsiella pneumoniae, the suggested treatment was monotherapy with ceftriaxone. The patient was treated parenterally initially, and then was treated for 3 weeks with oral ofloxacin.

Pasteurella multocida pneumonia.

Pasteurella multocida, a gram-negative coccobacillus which colonizes the nasopharynx and gastrointestinal tract of many animals, is a well known cause of soft tissue infection after animal bites. Human infection can also occur after non-bite animal exposure, usually via inhalation of contaminated secretions. The respiratory tract is the second most common site of Pasteurella infection after soft tissue infection. Most patients with Pasteurella pulmonary infection are elderly with underlying lung disease, either COPD, bronchiectasis, or malignancy. The spectrum of disease includes pneumonia, tracheobronchitis, lung abscess, and empyema. Clinical features of Pasteurella respiratory tract infections are indistinguishable from other pathogens. A history of cat or dog exposure should alert the clinician to consider Pasteurella as a potential pulmonary pathogen in an elderly patient with chronic lung disease. The preferred drug for the treatment of Pasteurella infections is penicillin. Alternately, doxycycline is highly effective against P multocida.

Treatment of fever.

Fever is an important indicator of disease and should not be routinely suppressed by antipyretics. There is considerable evidence that fever may actually benefit the host defense mechanism. In most patients, fever is short-lived and causes only minor discomfort. Antipyretic agents are effective in lowering temperature, but have significant side effects. Routine antipyretic therapy should be avoided but may be necessary in individual patients with underlying cardiovascular or neurologic disorders.

Third-generation cephalosporins.

Third-generation cephalosporins are broad-spectrum antimicrobial agents useful in a variety of clinical situations. No one cephalosporin is appropriate for all infectious disease problems. Cefotaxime and ceftizoxime have the best gram-positive coverage of the third-generation agents. Ceftazidime and cefoperazone are the only third-generation drugs that provide antipseudomonal coverage. Ceftriaxone's long half-life allows for once-daily dosing, making ceftriaxone an excellent drug for outpatient antibiotic therapy of community-acquired infections. Ceftriaxone is also useful for the treatment of Lyme disease and sexually transmitted diseases. The third-generation cephalosporins except for cefoperazone penetrate cerebrospinal fluid and are indicated for the treatment of bacterial meningitis. Their proven record of clinical efficacy, favorable pharmacokinetics, and low frequency of adverse effects make third-generation cephalosporins the preferred antibiotic in many clinical situations.

Tetracyclines.

Tetracyclines are relatively safe drugs with a broad antimicrobial spectrum. Doxycycline remains the preferred tetracycline agent for most indications. Doxycycline has a long half-life, which makes convenient twice-a-day dosing possible. It is well absorbed orally even in the presence of food, has excellent tissue penetration, and does not require a dose adjustment in renal insufficiency. Doxycycline is a useful agent for the treatment of atypical pneumonias, sexually transmitted diseases, traveler's diarrhea, rickettsial infections, and Lyme disease. Minocycline is the preferred drug for MRSA colonization/infection.

The selection and use of cephalosporins: a review.

Cephalosporins are among the most frequently prescribed antibiotics as a result of their broad spectrum of microbiologic activity, favorable pharmacokinetics, low incidence of adverse reactions, and proven clinical efficacy for a wide variety of infections. Cephalosporins differ in their gram-positive, gram-negative, and anaerobic spectra, serum half-lives, penetration of the cerebrospinal fluid, and resistance to beta-lactamases. The first-generation and some second-generation agents maintain excellent activity against streptococci and staphylococci, while the third-generation agents have expanded gram-negative coverage. Two third-generation cephalosporins, ceftazidime and cefoperazone, are active against Pseudomonas. Ceftizoxime has become the workhorse third-generation cephalosporin. The fourth-generation agent cefepime provides excellent activity against gram-positive and gram-negative pathogens, including antibiotic-resistant Enterobacteriaceae. A major dilemma facing the practitioner is how to select the "right" cephalosporin for a particular patient, as no one drug will satisfy all clinical needs. This review describes a practical approach to selecting an appropriate cephalosporin for common infectious disease problems.

Postoperative Serratia marcescens endophthalmitis.

Endophthalmitis after ophthalmic surgery is a rare but serious complication. Postoperative endophthalmitis presents clinically with conjunctival erythema and lid edema with eye pain and decrease in visual acuity. Diagnosis requires invasive culture techniques because postoperative external eye cultures are not reflective of intraocular organisms. The most common pathogens causing postoperative endophthalmitis are staphylococci and streptococci. Less common organisms associated with exogenous endophthalmitis include gram-negative aerobic bacilli and fungi. We report a case of Serratia marcescens postoperative endophthalmitis in a normal host.