John P. Anhalt

Incidence, distribution, and outcome of episodes of infection in 100 orthotopic liver transplantations

Of 83 patients who underwent 100 orthotopic liver transplantations, 53 had a single transplant procedure and at least 6 months of follow-up. In this main study group of 53 patients, major infections developed in 28 (53%) (a mean of 1.8 major episodes per infected patient). Of 51 major infections, 27 were bacterial, 19 were viral, 3 were protozoan, and 2 were fungal. Of the 27 bacterial infections, 22 (81%) occurred in the first 2 months after transplantation. Of the 40 bacterial isolates in the 27 bacterial infections, gram-positive aerobic bacteria were isolated in 26 (65%), anaerobic bacteria in 8 (20%), and aerobic gram-negative bacteria in 6 (15%). Only 1 of 16 bacteremic episodes was due to a gram-negative aerobic bacterium. Cytomegalovirus (CMV) infection occurred in 30 of the 53 patients (57%) and was symptomatic and invasive in 18. CMV infection was diagnosed a mean of 26 days after transplantation. Infections due to Pneumocystis carinii occurred later (2 to 3 months after transplantation). Death from infection occurred in 4 of the 53 patients (8%). In the group of 16 patients with two or more liver transplantations, fungal infection occurred in 2 and CMV infection in 13. In all 16 patients who underwent more than one liver transplantation, a major infection developed. The observations made in the main study group were consistent with findings in 13 patients with one liver transplantation but less than 6 months of follow-up. Infection is a major complication after liver transplantation, generally occurring in the first 2 months. Our observations suggest that the use of selective bowel decontamination may be associated with a relatively lower incidence of gram-negative aerobic bacterial infections.

Xanthomonas maltophilia: an emerging nosocomial pathogen.

Xanthomonas maltophilia is a potentially pathogenic organism with a broad clinical spectrum. Nosocomial colonization and infection are the most common manifestations. The incidence of clinical isolation of X. maltophilia is on the rise, possibly in part because of the selective pressure from the new antimicrobial agents to which it is resistant. The organism is usually resistant to commonly used antimicrobial agents, including most cephalosporins, aztreonam, antipseudomonal penicillins, imipenem, and the quinolones.

Prevention of Infection in Critically Ill Patients by Selective Decontamination of the Digestive Tract

OBJECTIVE To determine whether selective decontamination of the digestive tract using oral and nonabsorbable antimicrobial agents and parenteral cefotaxime prevents infection in critically ill patients. DESIGN Randomized, controlled trial without blinding. SETTING Surgical trauma and medical intensive care units in a tertiary referral hospital. PATIENTS One hundred fifty patients admitted to surgical trauma and medical intensive care units during a 3-year interval, whose condition suggested a prolonged stay (greater than 3 days). INTERVENTION Patients were randomly allocated to an experimental group (n = 75) that received cefotaxime, 1 g intravenously every 8 hours for the first 3 days only, and oral, nonabsorbable antibiotics (gentamicin, polymyxin, and nystatin by oral paste and oral liquid) for the entire stay in the intensive care unit. Control patients (n = 75) received usual care. MEASUREMENTS The number of infections, total hospital days, and deaths, as well as the number of days in intensive care unit, were recorded. RESULTS Control patients experienced more infections (36 compared with 12, P = 0.04), including bacteremias (14 compared with 4, P = 0.05) and pulmonary infections (14 compared with 4, P = 0.03). Although total hospital days, days in intensive care, and the overall death rate all were lower in the treatment group, these differences were not statistically significant. Clinically important complications of selective decontamination of the digestive tract were not encountered. CONCLUSIONS Selective decontamination of the digestive tract decreases subsequent infection rates, especially by gram-negative bacilli, in selected patients during long-term stays in the intensive care unit.

Assay of Gentamicin in Serum by High-Pressure Liquid Chromatography

A procedure is described that uses high-pressure liquid chromatography for assay of gentamicin in serum. The technique involves extraction of gentamicin from serum by using a CM-Sephadex column and analysis by reverse-phase, ion-pair chromatography. Continuous-flow, post-column derivatization with o-phthaladehyde is used to form fluorescent products for detection. The possible scope of this method for analysis of other aminoglycoside antibiotics is illustrated by application to sisomicin and netilmicin.

Urinary Tract Infection Caused by Nontyphoidal Salmonella: Report of 30 Cases

Thirty cases of nontyphoidal Salmonella bacteriuria were identified by review of cultures performed at the Mayo Clinic (Minn.) from 1985 to 1989 and at the Federal Public Health Laboratory Innsbruck (Austria) from 1979 to 1989. All patients had symptoms of an acute urinary tract infection (UTI). In 24 cases nontyphoidal Salmonella was the sole pathogen isolated. Only 1 patient presented with concomitant gastroenteritis and 2 had experienced episodes of diarrhea during the weeks before the UTI, but 15 patients had positive stool cultures in the absence of a gastrointestinal illness. Among all positive urine cultures at the Mayo Microbiology Laboratory, 0.015% were positive for nontyphoidal Salmonella; at the Federal Public Health Laboratory Innsbruck, 0.024% of organisms cultured from urine were nontyphoidal salmonellae. In the majority of our patients, Salmonella UTI did not differ clinically from UTI caused by other members of the Enterobacteriaceae; only in renal transplant recipients was the course of genitourinary salmonellosis more serious. While some urinary isolates of nontyphoidal Salmonella may be fecal contaminants, all 30 isolates recovered from urine during this study were considered to be the cause of symptomatic UTI.

Evaluation of calcofluor white stain for detection of Pneumocystis carinii

A rapid calcofluor white (CFW) stain for detecting Pneumocystis carinii was evaluated prospectively. Eighty-nine bronchoalveolar lavage (BAL) specimens, 21 open-lung biopsy (OLB) tissues, 2 induced sputums, 1 expectorated sputum, 2 tracheal secretions, and 1 bronchial secretion from 102 patients were examined for P. carinii cysts by both the CFW stain and a modified methenamine silver (MS) stain. Twenty episodes of P. carinii pneumonia were detected: 19 of these episodes were detected by CFW stain, and 16 of those episodes were detected by MS stain. Discrepancies between the two staining methods were resolved by review of the clinical histories and, in one case, by testing an OLB specimen. Neither staining procedure gave false-positive results with any specimen. More cysts were detected in CFW-stained specimens than in MS-stained specimens (p = 0.05). CFW stain is a simple, rapid, and inexpensive method for detecting P. carinii in clinical specimens and is at least as sensitive as MS stain.

Results of a 6-Month Survey of Stool Cultures for Escherichia coli O157:H7

Escherichia coli O157:H7 is a recently recognized enteric pathogen that causes acute hemorrhagic colitis. Although the infection is usually self-limited, it may be complicated by hemolytic uremic syndrome and thrombotic thrombocytopenic purpura. At our institution, stool specimens are now routinely cultured for this organism. To determine the prevalence of E. coli O157:H7-associated diarrhea in our patient population, we surveyed all submitted stool cultures for 6 months for this organism. Specimens were screened for non-sorbitol fermenting E. coli and confirmed by slide-agglutination and immobilization testing. Of 2,164 specimens, 10 yielded E. coli O157:H7. It was the fourth most common bacterial stool pathogen found. Bloody diarrhea and abdominal pain were the most common symptoms of the infected patients. E. coli O157:H7 causes sporadic infections in our patient population and should be considered in the differential diagnosis of acute hemorrhagic colitis.

Evaluation of TestPack Strep A for the Detection of Group A Streptococci in Throat Swabs

The performance of TestPack Strep A (Abbott Laboratories), a rapid enzyme immunoassay, was compared with a culture-based method for the detection of group A streptococci in 648 throat swabs. The rapid test correctly detected 99 of the 128 positive and 511 of the 520 negative specimens, a sensitivity of 77% and a specificity of 98%. Although highly specific, TestPack Strep A is less sensitive than culture techniques for the detection of group A streptococci in throat swabs.

Empiric Therapy With Moxalactam Alone in Patients With Bacteremia

Moxalactam was administered (20 mg/kg intravenously every 8 hours) as single-drug empiric antimicrobial therapy to 63 patients with bacteremia who were neither neutropenic nor immunosuppressed. Six patients (10%) had microorganisms that were susceptible to moxalactam and resistant to all other antimicrobial agents tested; two patients (3%) had microorganisms that were resistant to moxalactam and other agents tested. Of these 63 patients, 47 (75%) were cured with moxalactam therapy. Nine patients (14%) had breakthrough bacteremia while receiving other antimicrobial therapy and were cured subsequently with moxalactam therapy alone. The two major risk factors for failure of moxalactam therapy were polymicrobial bacteremia and an extrahepatic intra-abdominal source of infection; these two conditions frequently coexisted. Six of nine patients with polymicrobial bacteremia died. Superinfection (one pseudomonal, five enterococcal) was responsible for 6 of the 16 treatment failures. Enterococcal superinfection occurred exclusively among patients who had received relatively prolonged therapy with moxalactam for extrahepatic intra-abdominal infection, especially intraabdominal abscess. These five patients died, and postmortem examination showed that enterococcal superinfection was the major cause of death in all. Mild, reversible adverse reactions associated with use of moxalactam occurred in 14 of the 63 patients (22%). None had clinically overt bleeding. The use of moxalactam alone seems to be safe and effective and a cost-effective alternative empiric antimicrobial therapy for most patients with bacteremia who are not immunosuppressed or neutropenic and who are not at high risk of having Pseudomonas or polymicrobial bacteremia.

Comparison of direct specimen testing utilizing testpack strep A with testing of specimens following a two-hour broth enrichment

In a previous study, we demonstrated that a 2-h enrichment of throat swabs in broth followed by a direct fluorescent antibody test was significantly more sensitive than the Abbott TestPack Strep A for the detection of group-A streptococci. In this study, in an effort to simplify the technique, we utilized broth enrichment with an enzyme immunoassay detection method. A total of 1017 pharyngeal specimens were tested with TestPack Strep A (DTP), culture on a selective streptococcal agar, and a 2-h broth enrichment in Todd-Hewitt broth (THB) followed by TestPack Strep A (ETP). Subculture of the THB was used to arbitrate discordant test results. The sensitivities and specificities respectively were as follows: DTP (69% and 99%), ETP (90% and 98%), and SSA (97% and 100%). This enrichment method offers significantly greater sensitivity than direct testing for antigen yet still allows the potential for finalized same-day reporting of results.