|Acute fever, unidentified source||Ertapenem, 1 g q24h IV, or imipenem, 0.5 g q6h IV, or meropenem, 1.0 g q8h IV plus vancomycin 15 mg/kg q12h IV||Broad spectrum, limited toxicity|
|Urinary tract infection||Gram-negative organisms: Third-generation cephalosporin (e.g., ceftazidime, 2.0 g q8–12h), or broad-spectrum penicillin with β-lactamase inhibitor (e.g., piperacillin–tazobactam, 3.375 g IV q6h), or imipenem, or meropenem, or quinolone (e.g., ciprofloxacin, 400 mg IV q12h)|
Gram-positive organisms: Vancomycin, 10–15 mg/kg q12h IV
|Consider imipenem or meropenem if in LTCF or a recurrent infection; use in combination with low-dose aminoglycoside (e.g., gentamicin, 40–60 mg/d) if resistant organisms are probable|
Oral quinolone (e.g., ciprofloxacin, 250 mg BID) appropriate if not seriously ill
Active against enterococci, staphylococci, and streptococci
|Pneumonia||Third-generation cephalosporin (ceftriaxone, 1 g IV q12h) or ertapenem, 1 g IV q24h plus a macrolide (e.g., azithromycin, 0.5 g/24h IV)||Consider using ceftazidime or imipenem for nosocomial pneumonia|
Macrolide (preferably azithromycin, 500 mg on day 1, then 250 mg on days 2–4), or quinolone with antipneumococcal activity (e.g., levofloxacin, 500 mg/d) for oral therapy in less seriously ill patients
|Pressure sores||Broad-spectrum β-lactam agent with β-lactamase inhibitor (e.g., piperacillin–tazobactam), ertapenem or imipenem (doses as above)||Other treatment regimens active against Bacteroides, and enteric gram-negative organisms, may be used. Add vancomycin if gram-positives present in wound|
|Infective endocarditis||Vancomycin, 15 mg/kg IV q12h with gentamicin 1 mg/kg IV or IM q8h||Modify as appropriate after results of cultures and antibiotic susceptibility testing are available|
|Infectious (bacterial) diarrhea||Ciprofloxacin (500 mg PO BID) or other quinolone for 1–3 days.|
|Meningitis||Third-generation cephalosporin (e.g., ceftriaxone, 2 g IV q12h) plus ampicillin, 2 g IV q4h plus vancomycin 10–15 mg/kg IV q6h||Listeria monocytogenes is not susceptible to cephalosporins|
|Septic arthritis||Vancomycin 10–15 mg/kg IV q6h plus ceftazidime 1–2 g IV q8–12h|
Abbreviation: LTCF = long-term care facility.
Note: Therapy should be modified as appropriate after results of Gram stain, culture, and antibiotic susceptibility testing are available. Renal function in patients receiving vancomycin and gentamicin therapy must be carefully monitored.
Urinary tract infection
Urinary tract infection (UTI) is increasingly common with increasing age. This reflects obstruction from prostatic enlargement in men and a variety of changes in the defense mechanisms of the female urinary system. The risk of instrumentation and catheterization, procedures often associated with development of infection, also increases in the elderly population.
Asymptomatic bacteriuria is more common in both elderly men and women than in younger subjects. Multiple studies have demonstrated that treatment of bacteriuria is without value, primarily because it usually recurs after therapy.
Escherichia coli accounts for the bulk of UTIs in young women. In older individuals, the bacteriology is more complex. Infecting organisms are usually from other genera (e.g., Serratia and Pseudomonas) and are often resistant to multiple antibiotics. For this reason, urine culture and sensitivity should always be done before initiating therapy in an elderly individual.
Recent studies indicate treatment of lower UTI in elderly women may be safely done with 3-day therapy. In men, a 2013 study examining 40 000 episodes of UTI showed that shorter course therapy (<7 days) was as effective as longer periods of treatment. While trimethoprim–sulfamethoxazole (TMP–SMX) or a quinolone is a good initial choice for treatment of a lower UTI, resistance to these drugs is increasing in frequency and nitrofurantoin or fosfomycin may be required.
For patients with upper tract infection and for those who are seriously ill, therapy should be initially parenterally. Selection should be guided by Gram stain of the urine. If gram-negative organisms are present, a broad-spectrum β-lactam agent with activity against Pseudomonas aeruginosa (e.g., piperacillin–tazobactam) or a quinolone would be an appropriate initial choice. If a gram-positive organism is present in the Gram stain (nearly always representing staphylococci or enterococci),