Robert H. K. Eng

Hyperglycemia Associated with Protease Inhibitors in an Urban HIV-Infected Minority Patient Population

BACKGROUND: Hyperglycemia and new-onset diabetes mellitus have been reported to occur in HIV-infected patients treated with protease inhibitors. OBJECTIVE: To determine the effect of protease inhibitor therapy on serum glucose in a predominantly minority patient population. DESIGN: Retrospective record review. SETTING: Clinical HIV program of an urban Veterans Affairs medical center. PATIENTS: All HIV-infected patients receiving a protease inhibitor over a one-year period from September 1996 through August 1997. RESULTS: One hundred seventeen patients not previously known to be diabetic received protease inhibitors; seven (6%) developed symptomatic diabetes mellitus. Eight other patients had one or more serum glucose values >150 mg/dL. Mean random glucose values for patients who did not develop diabetes were higher during therapy than prior to initiation of protease inhibitors. CONCLUSIONS: Urban minority HIV-infected patients receiving combination antiretroviral therapy including a protease inhibitor may be at increased risk for the development of hyperglycemia and diabetes mellitus. Risk factors for diabetes mellitus should be identified and blood glucose monitored in all patients receiving protease inhibitors.

Vancomycin-resistant Enterococcus faecium in a Veterans Affairs Medical Center: Association with antibiotic usage☆☆☆★

BACKGROUNDnColonization and infection with vancomycin-resistant Enterococcus faecium (VREF) has been associated with the use of vancomycin and other antibiotics in individual patients. The objective of this study was to determine the association of VREF with the aggregate usage of antibiotics on nursing units in a hospital.nnnMETHODSnThis was a retrospective correlation study. A usage ratio was calculated for each parenteral antibiotic on each nursing unit as the per-bed usage by weight of that antibiotic divided by its average usage throughout the hospital. An average usage ratio (AUR) for each nursing unit was calculated as the mean of usage ratios of individual antibiotics. The AUR was used to compare the usage of antibiotics among nursing units in the hospital. The incidence of VREF infections on individual nursing units in a Veterans Affairs Medical Center was correlated with the usage of parenteral antibiotics separately and in aggregate in univariate and multivariate regression analyses.nnnRESULTSnThe AUR was strongly and positively correlated with the recovery of VREF on individual nursing units. By univariate analyses, increasing use of each antibiotic tested was associated with isolation of VREF but only clindamycin remained significant in the multivariate model. However, usage of various antibiotics was highly interrelated, and only clindamycin usage was significantly correlated with usage of all other antibiotics studied. Intensive care and acute care units and units with fewer patient beds were more likely to have patients with VREF infection than were subacute care units (p < 0.003) or larger units (p < 0.01).nnnCONCLUSIONSnVREF infections were associated with greater aggregate antibiotic use on nursing units. Determination of antibiotic usage ratios may provide a convenient and useful tool for examining the association of antibiotic usage with other nosocomial infections.

The course of cryptococcal capsular polysaccharide antigenemia/human cryptococcal polysaccharide elimination kinetics

SummaryThe detection of cryptococcal polysaccharides in the serum is diagnostic of cryptococcosis in the absence of rheumatoid factor. The significance of the continued detection of this antigen in the serum during antifungal therapy is not known. Prolonged anti-genemia might indicate ongoing active infection, delayed clearance of the polysaccharides from the blood, or continued release of the polysaccharide antigens from a reservoir of nonviable organisms. In seven cases of cryptococcosis with prolonged and high levels of cryptococcal polysaccharide antigenemia, the courses of antigenemia were determined. During the convalescent phase, the T1/2s were approximately 48 hours for the antigen clearance in all the cases studied. The polysaccharide antigens recovered from the serum of one patient had molecular weights of greater than 200,000 daltons. In rabbits, a single intravenous injection of cryptococcal capsular polysaccharides showed a similarly slow clearance of the antigen with a T1/2 of approximately 24 to 48 hours. These data suggest that adequately treated cases of cryptococcosis may have a predictable rate of antigen clearance from the serum during convalescence.ZusammenfassungDer Nachweis von Cryptococcus-Polysacchariden im Serum sichert — sofern kein Rheumafaktor vorliegt — die Diagnose der Kryptokokkose. Es ist nicht bekannt, welche Bedeutung der Persistenz dieses Antigens im Serum unter der Therapie mit einem Antimykotikum zukommt. Eine prolongierte Antigenämie könnte das Zeichen für eine fortschreitende aktive Infektion, für die verzögerte Elimination der Polysaccharide aus dem Blut oder für eine anhaltende Freisetzung von Polysaccharidantigen aus einem Reservoir nicht lebensfähiger Organismen sein. Der Verlauf der Antigenämie wurde bei sieben Fällen von lange anhaltenden hohen Spiegeln von Cryptococcus-Polysaccharidantigen im Blut bestimmt. Während der Rekonvaleszenz betrug T1/2 für die Antigenclearance in allen untersuchten Fällen etwa 48 Stunden. Die im Serum eines Patienten nachgewiesenen Polysacharidantigene hatten Molekulargewichte von über 200 000 Dalton. Bei Kaninchen war nach der intravenösen Injektion einer Einzeldosis von Cryptococcus-Kapselpolysaccharid eine ähnlich langsame Antigenclearance mit einer T1/2 von 24–48 Stunden nachzuweisen. Daraus läßt sich schließen, daß adäquat behandelte Fälle von Kryptokokkose während der Erholungsphase eine vorausbestimmbare Serum-Antigenclearance haben.

Effectiveness of antibiotic removal by the antibiotic-binding blood culture systems

The effectiveness of antibiotic removal by the BACTEC aerobic resin-containing blood culture medium (16B) and the Antimicrobial Removal Device (ARD) was compared for 12 antibiotics: ampicillin, cephalothin, cefoperazone, cefotaxime, moxalactam, nafcillin, gentamicin, tobramycin, azlocillin, mezlocillin, piperacillin, and ticarcillin. The ability to recover eight commonly encountered species of bacteria from antibiotic-containing serum by these two systems showed that recovery of antibiotic-exposed bacteria was dependent not only upon the amount and rate of the antibiotic removal but also upon the kinetics of bacterial killing by the antibiotic(s). The 16B medium had difficulty recovering organisms exposed to ticarcillin and moxalactam, whereas the ARD had difficulties with moxalactam and sometimes with cefotaxime and cefoperazone. Although neither system was able to recover all species of microorganisms tested, these in vitro results suggest that to use optimally these new culture systems, knowledge of the suspected pathogen(s), the amount and kind of antibiotic(s) administered, and the rate of bacterial killing by the antibiotic(s) is required.

Recovery of blood-borne bacteria from human urine.

Recovery from the urine of organisms causing bacteraemia may depend on the bacterial species involved. The survival of the more common species of bacteria which cause bacteraemia was examined in human urine, serum and normal saline. All species survived well or grew in serum. Haemophilus influenzae, Streptococcus pneumoniae, Streptococcus sanguis and group A streptococci were killed in all urine samples. The number of colony-forming units of Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus saprophyticus and group B streptococci either remained the same or increased in the urine, while the numbers of Escherichia coli and Klebsiella pneumoniae increased rapidly. These data suggest that the observed differences in recovery from urine of these bacterial species that cause bacteraemia are related to the viability of the species in human urine.

Drug-resistance encountered in the retreatment of Mycobacterium tuberculosis infections.

Patients who had prior anti-tuberculosis medications for pulmonary tuberculosis and who return to the hospital with culture-positive tuberculosis have been considered to be at risk of harboring resistant bacilli (secondary resistance or acquired resistance). The present recommendation for therapy of these patients is to resume earlier anti-tuberculosis medications and to add two new agents until the drug susceptibilities of the bacilli are known. This study reviewed 112 cases of readmissions for active tuberculosis and evaluated the risk of acquired drug resistance in this group. Patients with 6 months or less of prior therapy rarely harbored resistant organisms. Patients with 6-12 months of prior therapy had an 88% possibility of harboring resistant bacilli, but only a 30% risk of harboring multiple-drug resistant bacilli. Patients with 12 months or more of prior therapy had a 66% risk of harboring multiple-drug resistant, difficult-to-treat bacilli. This data would indicate that only those patients who have had prior therapy for 7 months or more require aggressive initial readmission therapy with 4 or more anti-tuberculosis agents. Hopefully this finding will not only help clinicians to identify readmission tuberculosis patients who are at increased risk of harboring resistant organisms but will also help them to be more selective in prescribing aggressive, potentially toxic, multiple-drug regimens.