Infections

1. Infections Edward Via College of Osteopathic Medicine Department of Geriatrics edited by Edward Warren, MD, Chair Geriatrics, Carolinas Campus, February 2012

2. Goals re Infections • Apply principle of infection in the elderly to detect who needs evaluation. • List the most common infections of the elderly. • Use exams and laboratory evaluations prudently and logically in infections. • Provide proper immunizations to elderly patients.

3. Common Nursing Home Infections • Urinary tract infections • Respiratory infections • Skin or soft tissue infections • Gastroenteritis

4. Disorders That Predispose to Selected Infections • diabetes mellitus (skin, UTI), • chronic obstructive pulmonary disease (pneumonia), • poor swallowing or gag reflex (aspiration pneumonia), • long-term indwelling urinary catheters (UTI), • prosthetic devices (artificial joints leading to septic arthritis), • altered mental status (aspiration pneumonia), or chronic immobility (pressure ulcers)

5. Clinical Manifestations of Infection • Clinical findings may be absent or too subtle to be recognized by the staff. • Clinical findings can be helpful. • Fever • Rubor, Kalor, Dolor, Tumor • Cough and yellow sputum [respiratory infection] • Mental or cognitive function or a decline in physical functional status may be clue to underlying infection.

6. Clinical Manifestations of Infection • Fever may be absent in the elderly with infections. • Single temperature reading of 100ºF (37.8ºC) is both a sensitive and specific predictor of infection in the elderly. • Other suggested temperature criteria indicative of possible infection: • increase in temperature of at least 2ºF (1.1ºC) over baseline • oral temperature of 99ºF (37.2ºC) • rectal temperature of 99.5ºF (37.5ºC) on repeated measurements

7. Roman and Greek Infections • Rubor, kalor, dolor, and tumor:Redness, heat, pain, and swelling. The four classical signs of inflammation, originally recorded by a Roman, Celsus, in the 1st century AD. • Functiolaesa is a term that refers to a loss of function or a disturbance of function. It was identified as the fifth sign of acute inflammation by a Greek, Galen, in the 2nd century AD. • Note that odor is not a sign of infection, even though it, too, is a 3rd declension, feminine, “-or” noun.

8. Clinical Manifestations of Infection Berman et al. determined that infection is present in 77 percent of episodes of "decline in function" defined as new or increasing confusion, incontinence, falling, deteriorating mobility, or failure to cooperate with rehabilitation.

9. Clinical Evaluation of Suspected Infection Examine: • mental status • oropharynx • conjunctiva • skin (all of it) • chest • heart • abdomen • perineum • perirectal area • axillae • central nervous system.

10. Evaluation Some diagnostic tests with poor positive and negative predictive values are used anyway in the evaluation of infection in elderly people. • urine specimens are frequently examined, but • the prevalence of asymptomatic bacteriuria is 15% to 50% in non-catheterized elderly, and • essentially 100 percent in elderly with long-term urinary catheters .

11. Evaluation Tests should be performed only if they have a reasonable diagnostic yield, low risk, reasonable in cost, and potential to improve patient management. (If a test will not cause the clinician to reassess his or her treatment strategy, then there is little justification for ordering the laboratory examination )

12. Indicated Laboratory Tests • CBC ( complete blood count)? • UA (urinalysis)? • BMP (basic metabolic profile)? • Blood Culture? • Chest X-Ray? • Sputum Culture? • Pulse Oximetry? • Stool test for C. difficile toxin? • Stool Culture?

13. Evaluation Provided there are no directives (advanced or current) limiting diagnostic or therapeutic medical interventions, all elderly people with suspected symptomatic infection should have appropriate diagnostic laboratory studies performed promptly.

14. Complete Blood Cell Count with Differential (CBC) High probability of an underlying bacterial infection if • WBC count is elevated (> 14,000 cells/mcl) with or without fever • High percent of neutrophils or left shift (bands >6%) even in the presence of a normal total WBC count (< 10,000 cells/mcl) • CBC shows an elevated total band count (> 1500 cells/mcl). Otherwise likelihood of bacterial infection is low

15. Urinalysis and Culture Symptomatic UTI may present as • Fever and clinical pyelonephritis: flank pain, chills, delirium • Irritative symptoms: dysuria, frequency, urgency, nocturia, hematuria, and worse incontinence These patients deserve a UA, C&S.

16. Urinalysis and Culture • The frail elderly are often unable to provide a midstream voided urine specimen for diagnostic testing. • The gold standard for both genders is in-and-out catheterization, especially if an appropriately collected voided urine cannot be obtained. • Residents with indwelling urethral catheters should have urine obtained by aspiration from the catheter port and not from the drainage bag.

17. Urinalysis and Culture • Significant bacteriuria is > 100,000 cfu/ml urine. • Microscopic pyuria (> 10 WBC’s/high-power field of spun urine) or a positive dipstick for leukocyte esterase are not highly predictive of UTI, but the absence of pyuria can exclude UTI (negative predictive value nearly 100%) • Absence of significant pyuria obviates the need for a culture.

18. Urinalysis and Culture • These tests frequently demonstrate bacteria because of the high prevalence (15% to 50%), of asymptomatic bacteriuria. • Prospective studies show that untreated asymptomatic bacteriuria, without long-term indwelling urinary catheters, persist for as long as two years without increased morbidity or mortality.

19. Basic Metabolic Profile • Elderly people with poor oral intake are likely to be at enhanced risk for dehydration in the setting of fever. • This historic clue may indicate a population in whom baseline electrolyte, BUN, and serum creatinine determinations are of particular importance.

20. Bacteremia and Blood Culture Most frequent sites of acquired bacteremia in the elderly: • Urinary tract (approximately 55%), • Respiratory tract (approximately 10%), • Skin or soft tissue (approximately 10%), • Intra-abdominal foci (approximately 5%), • Infected intravenous catheters (3%), and • Unknown (approximately 15%)

21. Bacteremia and Blood Culture • Nonspecific symptoms, such as lethargy, confusion, falls, abdominal pain, nausea, vomiting, and incontinence, are frequently noted in older persons at the onset of documented bacteremia. • Fever ( 100ºF; 37.8ºC) • Shaking chills, shock • Total band neutrophil count > 1500/mcl

22. Bacteremia and Blood Culture • Sepsis is so severe that there is a 50% mortality rate within 24 hours. • Hospitalization is indicated if aggressive treatment is to be given. • The blood culture will best be done there.

23. Bacteremia and Blood Culture Blood cultures are helpful in establishing a definitive microbiologic diagnosis in the elderly with • Suspected polymicrobial bacteremia, probable urosepsis, and long-term indwelling urethral catheters • Infected pressure ulcers • Suspected urosepsis • Infections (pneumonia, pyelonephritis, cellulitis, etc.) where the resident appears ill enough to warrant hospitalization but will be cared for in lesser settings.

24. Pneumonia • Respiratory tract infection usually presents with classical manifestations: cough [75%], fever [62% ], and adventitious breath sounds [55%]). • A respiratory rate >25 breaths/min (nl 16 – 25) had a sensitivity of 90% and a specificity of 95% for the diagnosis of pneumonia and a positive and negative predictive value of 95%.

25. Chest X-ray • Clinical diagnosis of pneumonia can be difficult. • Pneumonia is an important contributor to mortality for the elderly. • Document pneumonia by chest X-ray. • It may reveal other high-risk conditions that indicate further evaluation (eg, multilobe infiltrate, congestive heart failure, large pleural effusions, mass lesions).

26. Sputum examination • Sputum should be obtained at the onset of suspected pneumonia to assess for purulence and to culture. • It should be submitted for Gram stain, screened for squamous epithelial cells, and cultured if quality is adequate. • Sputum should have <25 epithelial cells per low power field to be sure it is not saliva (recollect if need be).

27. Pulse oximetry • Hypoxia (arterial oxygen partial pressure <60 torr) is an important indicator to assess acute severity and short term mortality for patients with pneumonia. • Impending respiratory failure can be suspected at the bedside if the patient has a respiratory rate >25 breaths/min, and an oxygen saturation of <90%. • These guidelines assume that the resident had a normal O2 sat on room air before the illness.

28. Influenza A • The most serious viral respiratory infection for older persons • Clusters or outbreaks of influenza occur frequently in nursing facilities with attack rates approaching 35% • Diagnosed clinically during an outbreak • Enzyme immunoassays, can detect influenza A viral antigen in clinical specimens within 24 hours on nasal swabs in acutely ill patients (sensitivity 70%)

29. Skin and Soft Tissue Infections Cellulitis is diagnosed clinically. It is an acute infection of the skin, extending to involve the subcutaneous tissue. • Group A streptococci and Staphylococcus aureus are the most frequent pathogens isolated. • The infected area is firm from infiltration by the infection. This is different than an abscess, which may have cellulitis surrounding a pocket of pus. • Aspiration samples are often disappointing for culture.

30. Skin and Soft Tissue Infections • Infected pressure ulcers are often associated with cellulitis and tissue abscesses. • It is difficult to determine whether a pressure ulcer is infected or colonized because these sites of skin breakdown are usually coated with exudative material and always colonized with pathogenic bacteria. • Surface cultures are misleading and worthless. They are mentioned here only to be condemned.

31. Scabies • Major problem in facilities • Scabies skin infestations are caused by the human scabies mite, Sarcoptesscabiei var. hominis. • Transmitted by direct contact with the organism, primarily by person-to-person contact, or rarely indirectly through contact with infected clothing, linen, or other fomites. • An etiologic diagnosis should be attempted by light microscopic demonstration of mites, eggs, or mite feces on mineral oil preparation from several scrapings of typical scabies "burrows“. • A dermatology consult may be needed.

32. Gastroenteritis • Viral – the vast majority of cases • Clostridium difficile • Food borne outbreaks caused by enterotoxigenic pathogens (Clostridium perfringens and S. aureus) • Invasive enteropathogens (Salmonella or Shigella species, Campylobacter jejuni or Escherichia coli O157:H7)

33. Gastroenteritis • C. difficile diarrhea • Suspected in any person exposed to systemic antimicrobial therapy in the previous 30 days who is experiencing at least three watery or unformed stools in 24 hours and/or abdominal pain. • A single specimen of diarrheal stool is submitted for C. difficilecytotoxin assay (not a culture). • If the test is negative and diarrhea persists , then additional specimens should be submitted for toxin assay. Empiric treatment is also appropriate.

34.   Stool culture Severe fever, abdominal cramps, and/or bloody diarrhea or WBCs in the stool indicate the need for a stool culture for enteric pathogens: C. jejuni, Salmonella and Shigella species, and E. coli O157:H7

35. Immunizations An ounce of prevention is worth a pound of cure. • Flu shots • Pneumovax • Tetanus • Zoster

36. Influenza • Use the trivalent inactivated vaccine for the current season. • Follow the current epidemic and get information about when to start and stop immunizing at http://www.cdc.gov/flu/weekly/ • Avoid immunizing those with allergies to eggs, chickens, and PMH of Guillian-Barre.

37. Pneumovax • Immunize those under 65 with COPD every 5 years. • Immunize everybody once only after age 65.

38. Tetanus • The tetanus immunization has always been paired with diphtheria immunization in a Td, until now. • Now there is a recommendation that everybody have a Tdap (tetanus, diphtheria, and acellular pertussis) once. • Give the Tdap any time, not necessarily at the 10 year mark. • In patients who have not had 3 Td’s yet, make the Tdap the next one and complete the series with Td’s. • The primary vaccination series is 2 doses 4 weeks apart and a 3rd in 6 months. • If the primary series is not completed, then simply pick up where it was left off.

39. Zoster • The CDC advises everyone over age 60 to have one dose. • This is advised whether they have had zoster or not. • It is a live vaccine and must be avoided in the immunocompromised. • It costs $250 and has an NNT of 59