Urinary tract infection In spite of a plethora of information, the management of bacterial infections of the urinary tract continues to be a confusing and contradictory area of therapeutics. Perhaps the frequency of this disorder and the usual response of acute symptoms to almost any therapy have dulled the critical objectivity of the medical profession to the problem. However, the patient with urinary in¬ fection, particularly if recurrent, re¬ quires the skill of a knowledgeable phy¬ sician. A few recent studies have pointed the way to more rational man¬

agement.

The specific diagnosis of bacteriuria requires growth of more than 100 000

bacteria per ml of urine collected free of contamination and cultured. In co¬ operative patients a midstream urine is optimal if the specimen can be either cultured immediately or refrigerated. For office practice and for physicians some distance from the laboratory, the dip stick or slide culture provides an inexpensive alternate means to obtain a quantitative culture. These can be in¬ cubated at room temperature in the physician's office and negative cultures discarded after 48 hours. Only positive cultures need be sent to the laboratory for bacterial identification and antimi¬ crobial sensitivity testing. For patients unable to cooperate, a suprapubic as¬ piration should be considered. This safe, simple procedure can be readily learned and will guarantee a urine free from contamination.1 Physicians have tended to rely on symptoms and the presence of pyuria to diagnose infec¬ tion. These findings cannot be equated with bacteriuria and will lead to inappropriate therapy for a variety of in¬ flammatory conditions of the urethra or vagina. The presence of an illness necessitating antimicrobial therapy is sufficient indication for making an exact

etiologie diagnosis.

Escherichia coli accounts for about

80% of urinary tract infections. Sta¬ phylococcus epidermidis is the second most frequent pathogen. Because S. epidermidis, a "noninvasive" organism, can cause classic acute pyelonephritis, microbiologists and physicians must be aware of its significance.2 The majority of urinary tract infections are autogenous; that is, they originate from the patient's own gut or cutaneous flora. Women with recurrent infection often have an abnormal perineal resident

flora, with increased numbers of en¬ terobacteriaceae.3 Host factors involv¬ ing the immune system may be important in the pathogenesis of re¬ current infection but no definitive data are available.4 The "urethral syn¬ drome" is a common, poorly understood entity in women, which is char¬ acterized by the symptom complex of frequency and burning on voiding in association with a negative or lowcount urine culture. There often ap¬

pears to be a temporal relationship to sexual intercourse.5 Urethral cultures frequently grow potential urinary pa¬ thogens and the syndrome appears to respond to antimicrobial therapy. The significance of infection discov¬ ered incidentally during surveys or dur¬ ing investigation of another illness remains controversial. Should these patients be searched out, investigated and treated? Considerable data suggest that this is sound preventive practice in prenatal patients because the risk of acute pyelonephritis is at least 20-fold for patients infected on their first pre¬ natal visit, compared with abacteriuric controls.6 Also, mass screening pro¬ grams in schoolgirls have disclosed pre¬ viously unsuspected infection in 1 to 2% of children.7 As far as is known, only a minority of these children are at risk of progressive renal damage. Radiographic abnormalities are found in 15 to 20% of females with urinary tract infection. These studies should be

initially and, if results are repeated unless there is evidence of progressive disease. In chil¬ dren, primary vesicoureteric reflux, a familial congenital defect of the sub¬ mucosal segment of the ureter, must be excluded by micturition cystourethrography.8 Reflux or obstruction, usually in association with infection, leads to the pyelographic abnormalities of chronic pyelonephritis. Whenever antimicrobials are pre¬ scribed, the expected goals should be precisely defined. These may be eradi¬ cation of infection from the kidneys, the prostate or the bladder; prophylaxis of anticipated infection; or suppression of infection in patients with genitourindone well

normal,

not

ary abnormalities that make eradication difficult. The site of infection is an important determinant of the outcome of therapy. Localization of infection to either the kidneys or bladder is now feasible with an in vitro fluorescent antibody test.9 In females, infection limited to the bladder responds readily to a week's treatment with any drug that gives an adequate urinary antibacterial concen¬ tration. Sulfonamides and nitrofuran¬ toin are inexpensive and effective. These patients must have follow-up urine cultures. Recurrence with the same organism within 2 weeks of ther¬ apy usually indicates relapse due to persistence of bacteria in renal tissue. Renal infections require 2 to 6 weeks of therapy and continuing careful fol¬ low-up. Assuming sensitivity of the or¬ ganism to the drug selected, no convincing comparative studies in proved renal infection have satisfactorily dem¬ onstrated superior efficacy of any one regimen. Even in renal infections, uri¬ nary antibacterial concentrations may be more important than serum concen¬ trations.10 Acute pyelonephritis is often accom¬ panied by bacteremia. If gram-negative

CMA JOURNAL/APRIL 19, 1975/VOL. 112 927

rods are responsible, a parenteral aminoglycoside should be the initial drug. As soon as the patient is afebrile, this should be altered to an appropriate, less expensive oral agent. The prostate is an important reservoir for bacteria and therefore may play a role in subsequent relapse. The unique physicochemical environment in this organ makes drug transport into its tissue unpredictable.11 Of the antimicrobials effective against gramnegative rods, only the tetracyclines, trimethoprim and some sulfonamides achieve useful antibacterial concentrations. Eradication of infection may require 3 to 12 months of continuous therapy. Recurrent infections in females are usually due to reintroduction of an organism from the patient's urethral and vaginal flora. When reinfections are frequent and symptomatic, continuous prophylaxis may be indicated. Daily nitrofurantoin, methenamine mandelate with an acidifying agent, or a sulfonamide can reduce the number of recurrences. The combination of trimethoprim with sulfamethoxazole, when taken in a small daily dose, prevents periurethral colonization with en-

terobacteriaceae and greatly reduces the number of expected reinfections.12 Neither toxicity nor the development of resistance has been a problem with long-term, low-dose administration. Patients with long-term indwelling catheters or infections complicated by renal calculi cannot be successfully treated for bacteriuria. Attempts to eradicate infection only lead to infection by progressively more resistant organisms. It is preferable to treat only when acute symptoms supervene, and to use a short course of an effective agent and avoid, if possible, selecting out multiple resistant strains. Minor urologic procedures including dilatation and urethral surgery are often used in females under the supposition that bladder outlet obstruction is responsible for recurrent infection. These procedures have not been subjected to critical controlled evaluation and there is currently no evidence that they alter the pattern of recurrence.13.14

OFFICE DERMATOLOGY. Vancouver. M ayl-2, 1975. Sponsors: division of dermatology, Shaughnessy Hospital; department of medicine, faculty of medicine. University of British Columbia. Information: Continuing education in the health sciences. UBC, Vancouver. BC V6T IWS SCIENTIFIC ASSEMBLY, COLLEGE OF FAMILY PHYSICIANS OF CANADA (SASKATCHEWAN CHAPTER). In conjunction with annual meeting. Plains Health Centre, Regina. May 1-3, 1975. Topics: rehabilitation medicine, office psychiatry, geriatrics. information: Mrs. M.P. Sarich, Administrative assistant, Continuing medical education. Room 408. Ellis Hail, University of Saskatchewan, Saskatoon, Sask. S7N 0W8 OPHTHALMOLOGY SPRING CLINICAL DAY. University Hospital, London, Ont. May 2, 1975. Information: Assistant Dean, Continuing Education, Faculty of Medicine, The University of Western Ontario, London, Ont. N6A 3K7 INTRODUCTORY SEMINAR ON ACUPUNCTURE. Holiday Inn, Yorkdaie, Toronto. May 2-4. 1975. Information: Dr. Elie Cass, President, Acupuncture Foundation of Canada, Ste. 228, 730 Yonge St., Toronto, Ont. M4Y 2B7 ASSESSMENT AND MANAGEMENT OF THYROID FUNCTION. Bristol Place Hotel, Toronto. May 2, 1975. Sponsored by the faculty of medicine of the University of Toronto, The Canadian Society of Endocrinology and Metabolism and The Canadian Society of Clinical Chemists. Information: Ames Educational Institute, 77 Belfield Rd., Rexdale, Ont. M9W 1G6 19TH ANNUAL CANCER SYMPOSIUM. Featuring breast cancer. Western Development Museum, Regina. May 8-9, 1975. Sponsored by Allan Blair Memorial Clinic, Pasqua Hospital, Regina and Saskatchewan Section of Surgery. information: Dr. Arthur Bryant, Allan Blair Memorial Clinic, Pasqua Hospital, Regina, Sask. CARDIOLOGIE EN PRATIQUE G.N.RALE. Institut de Cardiologie de Montr6al. Lea 8-10 mal 1975. Renseignements: Directeur du Service d'6ducation mddicaie continue, Universlt6 de Montr6ai, C.P. 6207, Succursale A, Montr6al, 0u6. H3C 3T7 RECENT ADVANCES IN PSYCHIATRY. Banif Springs Hotel, Banif, Alta. May 12-14, 1975. Information: Director, Division of continuing medical education, University of Alberta, Edmonton. Alta. T6G 2G3

18th ANNUAL POSTGRADUATE COURSE IN ME. DICAL TECHNOLOGY. Royal Inland Hospital, Kamloops. May 12-16, 1975. Information: Dr. Glenn M. Martin, Director, Postgraduate course In medical technology, Royal Inland Hospital, 311 ColumbIa St., Kamloops, BC V6A 2R7 REFRESHER COURSE IN FAMILY PRACTICE. Sun. nybrook Medical Centre, Toronto. May 12-30, 1975. Lectures and in-office experience. Information: Dr. .1K. Ross, Chairman, Refresher course. Sunnybrook Medical Centre, 2075 Bayview Ave., Suite 1001, Toronto, Ont. M4N 3M5 CHEST DISEASES. Clinical day. University Hospital, London, Ont. May 14. 1975. Information: Assistant Dean. Continuing Education, Faculty of Medicine, The University of Western Ontario, London, Ont. N6A 3K7 ANESTHETIC EMERGENCIES. Civic Hospital Auditorium, North Bay, Ont. May 14, 1975. Information: Ontario Medical Foundation, 242 St. George St., Toronto, Ont. M5R 2P4 SYMPOSIUM ON ARTERIAL HYPERTENSION. Constellation Hotel. Toronto. May 14. 1975. InformatIon: Dr. A. Rapoport, Toronto Western Hospital, 399 Bathurst St., Toronto, Ont. M5T 2S8 COMPLICATIONS IN THE RECOVERY ROOM. Northern College of Arts and Technology, Kirkland Lake, Ont. May 15, 1975. Information: Ontario Medical Foundation, 242 St. George St., Toronto Ont. M5R 2P4 ENDOCRINOLOGIE P.DIATRIOUE. Holiday Inn, Montr4al (centre yule). Lea 15-16 mal 1975, Ran. seignements: Directeur du Service d'6ducatlon m4dicale continue, Unlverslt6 de Montr6al. C.P. 6207, Succursale A, Montr6al. 0u6. H3C 3T7 RESPIRATORY PATHOPHYSIOLOGY. Royal Victoria Hospital, Montr6al. May 15-17, 1975. Cosponsor: American College of Physicians. Information: Secretary, Postgraduate Board, RVH, 687 Pine Ave. W, Montr6al, Qu6. H3A lAl HIGH ANESTHETIC RISKS. St. Mary's Hospital Auditorium, Timmins, Ont. May 16, 1975. Information: Ontario Medical Foundation, 242 St. George St., Toronto, Ont. M5R 2P4 RADIOACTIVE ISOTOPES. University of Toronto. May 20-30, 1975. Information: Director, Division of postgraduate medical education, University of Toronto, Toronto, Ont. M5S 1A8

ALLAN R. RONALD, MD Infectious diseases Health Sciences Centre Winnipeg, Man.

92& CMA JOURNAL/APRIL 19, 1975/VOL. 112

References 1. DovE GA, BAILEY AJ, Gowaa PE, Ct al: Diagnosis of urinary-tract infection in general practice. Lancet 2: 1281, 1972 2. BAILEY RR: Significance of coagniase-negative staphylococcus in urine. J Infect Dis 127: 179, 1973 3. BRUCE AW, ChADWICK P, HAssas. A, et al: Recurrent urethritis in women. Can Med Assoc 1 108: 973, 1973 4. HANSON LA: Host-parasite relationships in urinary-tract infections. J Infect Dis 127: 726, 1973 5. BROOKS D, MAUDAR A: Pathogenesis of the urethral syndrome in women and its diagnosis in general practice. Lancet 2: 893, 1972 6. SAVAGE WE, HAJJ SN, KASS EH: Demographic and prognostic characteristics of bacteriuria in pregnancy. Medicine 46: 385, 1967 7. SILVERBERO DS, ALLARD MJ, ULAN RA, et al: City-wide screening for urinary abnormalities in schoolgirls. Can Med Assoc 1 109: 981, 1973 8. ROLLESTON OL, SHANNON FE, UTLEY WLF: Relationship of infantile vesicoureteric reflux to renal damage. Br Med 1 1: 460, 1970 9. THOMAS V, SHIILOKOR A, FARLAND M: Anti-

body-coated bacteria in the urine and the site of urinary-tract infection. N Engi I Med

290: 588, 1974 10. STAMEY IA, FAIR WR, TIMOTHY MM, et al: Serum versus urinary antimicrobial concentrations in cure of urinary-tract infection. N Engi I Med 291: 1159, 1974

11. STAMEY TA, MEARES EM, WINNINGHAM DO:

Chronic bacterial prostatitis and the diffusion of drugs into prostatic fluid. I Urol 103: 187, 1969

12. HARDING 0KM, RONALD AR: A controlled study of antimicrobial prophylaxis of recurrent urinary infection in women. N Engi / Med 291: 597, 1974

13. WALKER D, RSCHARD GA: A critical evaluation of urethral obstruction in female children. Pediatrics 51: 272, 1973 14. KAPLAN OW, SAMMONS TA, KINGS LR: A blind comparison of dilatation, urethrotomy, and medication alone in the treatment of urinary tract infection in girls. I Urol 109: 917, 1973

ARTHRITIS IN OFFICE PRACTICE - CLINICAL DAY. Royal Victoria Hospital, Montr6al. May 21, 1975. Information: Secretary, Postgraduate board, RVH, 687 Pine Ave. W, Montr6al, Ou.. H3A IAl ORTHOPEDIC SURGERY. Clinical seminar, University Hospital, London, Ont May 21, 1975. Information: Assistant Dean, Continuing Education, Faculty of Medicine, The University of Western Ontario, London, Ont. N6A 3K7 PEDIATRIC ALLERGY AND IMMUNOLOGY. Toronto. May 21-23, 1975. Sponsors: American Academy of Pediatrics; The Hospital for Sick Children, Toronto. information: Dr. G.E. Hughes, Director of educational affairs, American Academy of Pediatrics, P0 Box 1034, Evanston, IL 60204, USA ENTRETIENS OPHTALMOLOGIOUES DE MAISONNEUVE. Holiday Inn, Montr6al (centre villa). Los 21-23 mel 1975. Renseignements: Directeur du Service d'6ducation m.dicale continue, Universit6 de Montreal, C.P. 6207, Succursale A, Montr6al, 0u6. H3C 3T7 McGILL ANNUAL REVIEW COURSE IN ANESTHESIA. Royal Victoria Hospital, Montr6al. May 26-30, 1975. Information: Secretary, Postgraduate board, RVH, 687 Pine Ave. W, Montr6al, 0u6. H3A lAI CPRI SYMPOSIUM. Children's Psychiatric Research Institute, London, Ont. May 28, 1975. Information: Assistant Dean, Continuing Education, Faculty of Medicine, The University of Western Ontario, London, Ont. N6A 3K7 MANAGEMENT OF THE OLDER PATIENT. Sarnia Golf and Curiing Club, Sarnia, Ont. May 28, 1975. information: Ontario Medical Foundation, 242 St. George St. Toronto, Ont. M5R 2P4 DERMATOLOGY FOR FAMILY PHYSICIANS. St. Micheel's Hospital, Toronto. May 28. 1975. Information: Director, Division of postgraduate medical education, University of Toronto, Toronto, Ont. M55 lAB ANESTHESIA REFRESHER COURSE. For family physicians. McMaster University Medical Centre, Hamilton. May 30-31, 1975. Information: Dr. D.V. Catton, Professor and chairman, Department of anesthesia, McMaster University Medical Centre, 1200 Main St. W, Hamilton, Ont. L85 4J9

continued on page 979

Editorial: urinary tract infection.

Urinary tract infection In spite of a plethora of information, the management of bacterial infections of the urinary tract continues to be a confusing...
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