The prevalence survey as an infection surveillance method in an acute and long-term care institution.

A point prevalence survey of infections was done in 22 patients areas at the Albany VA Medical Center between September 17 and 28, 1979. The study was designed by a consultant epidemiologist, two infectious disease physicians, a biostatistician, two infection control nurses, a microbiologist, and a clinical pharmacist. A 16-page worksheet was designed for rapid and complete data collection, with computer codes and programming cross references incorporated. A total of 572 patients were seen and evaluated for signs and symptoms of infection; cultures were taken if indicated, and charts were reviewed. Urine cultures were obtained in 95% of patients. Data available for analysis will allow for a description of the characteristics of the patient population, identification of the most prevalent sites of infection and causative organisms, an analysis of antimicrobial agent use, and a description of the risk factors and their interactions that may influence the acquisition of infection.

The effect of diabetes mellitus on chemotactic and bactericidal activity of human polymorphonuclear leukocytes.

We studied the bactericidal activity (against P. aeruginosa) and chemotactic ability of polymorphonuclear leukocytes from 26 diabetic patients in three treatment groups (oral hypoglycemic, daily insulin, and continuous insulin infusion). Patients were studied before entry into intensified management protocols, and after intensified management in 11 of the 26 patients. Diabetic serum had a persistent inhibitory effect on both diabetic and normal white cells, but normal serum was unable to fully correct diabetic white cell killing to control values. After intensified management of diabetes, there was an improvement in bactericidal function of diabetic patient white cells, but not in the effect of diabetic serum. Diabetic serum, and to a lesser extent diabetic white blood cells, are defective mediators of killing of P. aeruginosa. Chemotaxis was normal in all patient groups. These findings confirm the earlier work of others showing that some patients with diabetes mellitus have a defect in host defense against infection with bacteria.

Pulmonary O2 toxicity: role of endogenous tumor necrosis factor.

The role of endogenous tumor necrosis factor (TNF) in the pathogenesis of pulmonary O2 toxicity was investigated. Intratracheal insufflation of anti-TNF antibodies prolonged the survival of rats exposed to 100% O2. No TNF bioactivity or immunoreactive protein was detectable in the alveolar lavage fluid or lung homogenate of rats exposed to normoxia or hyperoxia. However, levels of pulmonary TNF mRNA were markedly enhanced in rats exposed to hyperoxia. These results suggest that hyperoxia may cause the production of low level TNF, which in turn enhances O2 toxicity.

Antibacterial effects of levofloxacin, erythromycin, and rifampin in a human monocyte system against Legionella pneumophila.

The antibacterial activities of levofloxacin, erythromycin, and rifampin against intracellular Legionella pneumophila L-1033, serogroup 1, were studied. In an in vitro system utilizing adherent human monocytes, L. pneumophila L-1033, a phagocytosis time period of 1 h, and antibiotic (levofloxacin, erythromycin, and/or rifampin) at 1 to 10 times the MIC, the CFU/ml values for the monocyte lysate were determined during 0- to 4-day time periods. The decrease in CFU/ml with levofloxacin at pH 7.4 was rapid, occurring within 24 h, and was drug concentration dependent (P < 0.01). The decrease in CFU with rifampin was first observed at 48 h (P < 0.01), while only a minimal decrease in CFU/ml was observed with erythromycin. Combination of levofloxacin and rifampin and of levofloxacin and erythromycin at ten times their MICs significantly decreased the CFU/ml value (P < 0.01), to the value attained by levofloxacin alone, while combination of rifampin and erythromycin did not. Removal of levofloxacin after 24 h of incubation resulted in regrowth of L. pneumophila L-1033, while a continued slow decrease in CFU/ml was seen following rifampin removal; CFU/ml values were unaffected by the removal of erythromycin. At 4 days, and even in assays performed following antibiotic removal, the CFU/ml value continued to be lower in the levofloxacin and rifampin assays than in the assays with erythromycin. Levofloxacin had a significantly higher bactericidal activity against L. pneumophila L-1033 than erythromycin or rifampin. In these assays, the addition of erythromycin or rifampin did not affect the antibacterial activity of levofloxacin.

Antibacterial effect of telithromycin (HMR 3647) and comparative antibiotics against intracellular Legionella pneumophila.

The activity of the ketolide telithromycin (HMR 3647) against intracellular Legionella pneumophila strain L-1033 was compared with the activities of erythromycin and levofloxacin. To assay intracellular antibacterial activity, human monocytes were allowed to adhere to wells in 24-well tissue culture plates and were then exposed to L. pneumophila cells for 1 h to allow phagocytosis to occur. Antibiotics were added to the wells after removal of unphagocytosed bacteria. Quantitative bacterial cell counts were made from lysed monocytes at 0, 24, 48, 72 and 96 h. The antibacterial effects of antibiotics against intracellular L. pneumophila L-1033 were concentration and time dependent; at 10 x MIC the activity of telithromycin was greater than that of erythromycin and was less than that of levofloxacin (P < 0.01); telithromycin-rifampicin combinations showed no synergy or interference; and removal of telithromycin from assays at 24 h did not affect its intracellular antibacterial activity. In conclusion, the ketolide telithromycin has excellent activity against intracellular L. pneumophila strain L-1033 and should be evaluated for therapy of legionnaires' disease.

Effects of cytokines and fluconazole on the activity of human monocytes against Candida albicans.

This study evaluates the effects of cytokines, used singly and in combination, on the microbicidal activity of human monocyte-derived macrophages (MDM) against intracellular Candida albicans in the presence and absence of fluconazole. In the absence of fluconazole, the addition of tumor necrosis factor alpha (TNF-alpha), interleukin-1beta (IL-1beta), gamma interferon (IFN-gamma), or IL-4 had no effect on the growth of C. albicans. In contrast, the addition of granulocyte-macrophage colony-stimulating factor (GM-CSF) resulted in decreased growth (P < 0.05), while the addition of IL-10 resulted in increased growth (P < 0.01). In the presence of fluconazole, only the addition of IFN-gamma resulted in an increase in the growth of C. albicans. In the presence or absence of fluconazole, all cytokine combinations except IFN-gamma plus GM-CSF caused significant decreases in growth (P < 0.01). IL-10 and IL-4 did not influence the activity of TNF-alpha or IL-1beta. In the absence or presence of C. albicans the addition of fluconazole, all of the cytokines studied, and combinations of fluconazole and selected cytokines caused increases in nitric oxide (NO) production (P < 0.01). Similar observations were made for superoxide (O(2)(-)) only in the presence of C. albicans. The greatest concentrations of NO and O(2)(-) were produced when C. albicans alone was present in the assays. Our results demonstrate that in the presence of low concentrations of fluconazole (0.1 times the MIC), selected cytokines and their combinations significantly increase the microbicidal activity of MDM against intracellular C. albicans.

Synergy with cefsulodin or piperacillin and three aminoglycosides or aztreonam against aminoglycoside resistant strains of Pseudomonas aeruginosa.

Fifty-one strains of Pseudomonas aeruginosa, with resistance to one or more amino-glycosides, were tested for synergy with cefsulodin or piperacillin plus amikacin, tobramycin, gentamicin or aztreonam by the agar dilution technique. Cefsulodin plus any one of the three aminoglycosides regardless of the degree of resistance to the aminoglycoside was synergistic against P. aeruginosa for two thirds of the isolates. In contrast, synergy rates with piperacillin were much less uniform. The highest rate of synergy with piperacillin (90.0%) was observed with gentamicin for the gentamicin resistant strains. The lowest rate of synergy was observed with piperacillin plus amikacin (32.2%) for isolates with moderate resistance to amikacin. Synergy for strains with moderate resistance to amikacin was observed more commonly with cefsulodin than with piperacillin. Synergy for strains with a known mechanism of resistance to amikacin was more common with cefsulodin regardless of the mechanism of resistance. Cefsulodin or piperacillin in combination with aztreonam was rarely synergistic (less than 12%).

Antimicrobial effect of clindamycin in combination with aztreonam or aminoglycosides against Klebsiella spp.

The antimicrobial effect of clindamycin combined with aztreonam or an aminoglycoside (gentamicin, tobramycin or amikacin) was studied against 84 strains of Klebsiella pneumoniae and 18 strains of K. oxytoca with an agar dilution technique. Clindamycin concentrations of 1-20 mg/l and an inoculum of 10(4) cuf/spot were used. Anaerobic incubation of agar plates was associated with an increase in the MIC of aminoglycosides and no change or a decrease in the MIC of aztreonam. Lower concentrations of clindamycin (1-2 mg/l) were associated with a decrease in the MIC of aztreonam for 18% and an increase in the MIC of aminoglycosides for between 7% and 44% of the strains, depending upon the precise concentration used. However, higher concentrations of clindamycin (10-20 mg/l) were associated with a decrease in the MIC of aztreonam for between 36 and 87% and an increase in the MIC of aminoglycosides for between 13 and 64% of the isolates. These observations could be important when treatment plans for mixed aerobic/anaerobic infections including mixed Klebsiella spp. are considered.

Levofloxacin penetrates human monocytes and enhances intracellular killing of Staphylococcus aureus and Pseudomonas aeruginosa.

Intracellular bacteria often cause relapsing and refractory infections. However, these infections can be treated effectively with antibiotics such as ofloxacin which penetrate into the cells containing bacteria. As levofloxacin, the levorotatory isomer of ofloxacin, has enhanced antibacterial activity, we tested the levofloxacin concentration in human monocytes and the effects of intracellular levofloxacin on monocyte killing of Staphylococcus aureus strain ATCC 29213 and Pseudomonas aeruginosa strain PA1348A. Human monocytes were incubated with levofloxacin at various pH values and temperatures. Following incubation, the monocytes were separated from incubation media, and intracellular (C) and extracellular (E) levofloxacin concentrations were determined. Mean C/E ratios after 15 min of incubation with 6 and 12 mg/L levofloxacin at pH 7.4 were 6.4 and 7.1, respectively. C/E ratios were similar at pH 7.4 and 8.0, but decreased at lower pH values. To study the effects of levofloxacin on intracellular killing of S. aureus and P. aeruginosa, opsonized bacteria were added to monolayers of monocytes. Following phagocytosis, monocytes were incubated with various concentrations of levofloxacin, ciprofloxacin and rifampicin, alone or in combination. Levofloxacin (2.5 and 4 mg/L) significantly reduced the survival of cell-associated S. aureus and was more effective than ciprofloxacin at similar concentrations (P < 0.01). Enhanced killing of cell-associated P. aeruginosa by levofloxacin (0.5 and 1.0 mg/L) was also observed. Activities of levofloxacin and ciprofloxacin against cell-associated P. aeruginosa were similar. Addition of rifampicin did not augment the bactericidal activity of levofloxacin. Since levofloxacin is concentrated in human monocytes and increases their bactericidal activity against intracellular bacteria, it should be considered for treatment of infections caused by susceptible intracellular bacteria.

Susceptibility of Pseudomonas aeruginosa to serum bactericidal activity. A comparison of three methods with clinical correlations.

Twenty-nine blood culture isolates of Pseudomonas aeruginosa were tested by three established methods to determine the effect of in vitro conditions on the survival of this organism in human serum. Clinical correlations were made to determine the relationship of serum resistance as defined by each method to clinical outcome. Major differences of bacterial survival in the presence of pooled normal human serum and in classification of isolates (sensitive, intermediate, resistant) were observed among the three methods. Isolates grown in broth for preparation of inocula demonstrated significantly greater sensitivity to serum bactericidal activity than those grown on agar. The use of organisms in early logarithmic growth phase or increased concentrations of serum augmented the serum sensitivity of these isolates. No correlation was observed between serum bactericidal activity and antibiotic susceptibility, pyocine type, patient mortality, or underlying disease. All strains of serotype 6 or 11 (immunotype 1 or 2) were serum-sensitive by one of the three methods. This study indicates that by testing isolates of P. aeruginosa under a variety of in vitro conditions, it is possible to identify a few isolates that are highly sensitive or resistant to serum under all conditions. The survival of the majority of strains of P. aeruginosa in human serum is highly dependent on in vitro conditions. Conclusions regarding the role of serum bactericidal activity in host defense must be drawn cautiously when based solely on in vitro tests.

Comparison of the effect of three adrenal corticosteroids on human granulocyte function against Pseudomonas aeruginosa.

The effect of hydrocortisone, methylprednisolone, and dexamethasone on the phagocytic and bactericidal capabilities of normal human granulocytes (PMN) was studied under previously described optimal conditions for Pseudomonas aeruginosa, PA 1348A. At hydrocortisone and methylprednisolone concentrations of 1,000 micrograms/ml, delayed phagocytosis was clearly observed, whereas dexamethasone 400 micrograms/ml had no effect on phagocytosis. The bactericidal effect of PMN on PA 1348A was significantly reduced by all three corticosteroids at highest concentrations (p less than 0.05). However, the effect of methylprednisolone was greatest and that of dexamethasone was least evident, 25% and 10% reduction in PMN bactericidal activity, respectively. Following exposure to the highest concentrations of corticosteroids, TEM observations correlated well with the PMN functional assays. While the observations of PMN and bacteria in controls, hydrocortisone, and dexamethasone preparations were similar, evidence for incomplete phagocytosis, lack of vacuole coalescence, minimal disruption of bacterial cell walls, and dividing bacteria in phagosomes were evident in methylprednisolone preparations. These PMN functional and TEM observations suggest that of the three corticosteroids studied, methylprednisolone appears most deleterious to the PMN phagocytic and bactericidal activity.

Oropharyngeal and fecal carriage of Pseudomonas aeruginosa in hospital patients.

This prospective study was designed to determine the incidence of rectal and/or oropharyngeal colonization rates of patients with Pseudomonas aeruginosa upon admission to a general hospital and the risk of becoming colonized while hospitalized. Consecutive 186 admissions (180 patients) to one medical ward, one surgical ward, and the intensive care unit were studied over a period of 5 months. Rectal and oropharyngeal swabs for P. aeruginosa were obtained on admission, weekly thereafter, and/or upon discharge. Forty-two patients (22.6%) were colonized on admission, 20 patients (10.8%) acquired P. aeruginosa during hospitalization. Colonization on admission was observed twice as frequently on the surgical ward and in the intensive care unit as on the medical ward. Positive rectal cultures were more frequent than oropharyngeal cultures throughout the study (P less than 0.01). For patients admitted culture positive or culture negative, the probabilities of remaining culture positive or culture negative, respectively, remained at 44 and 72% after 35 days of hospitalization. The most common P. aeruginosa serotypes were 1, 6, and 10, and pyocin types 1, 3, and 10 were predominant. There was no statistical difference in the serotypes or pyocin types detected on admission or acquired during hospitalization. Except for two hospital-acquired first isolates which were resistant to moxalactam, all first isolates were susceptible to the four antibiotics tested. During the study, one isolate became resistant to azlocillin, gentamicin, and tobramycin, while two isolates became resistant to moxalactam. A statistical analysis was performed for 13 risk factors for all colonized and noncolonized patients. Colonization detected at the time admission was positively associated with age ( > 65 years), previous surgery of the gastrointestinal tract for neoplasm, and anemia ( P< 0.05). In contrast, for patients who entered the study culture negative, none of the analyzed 13 risk factors was associated with an increased probability for colonization. This observation included the administration of antimicrobial agents singly or in combination or both.

Antibody to human endogenous retrovirus peptide in urine of human immunodeficiency virus type 1-positive patients.

Human endogenous retrovirus (HERV)-like sequences are normal inherited elements that constitute several hundredths of the human genome. The expression of genes located within these elements can occur as a consequence of several different events, including persistent inflammation or genotoxic events. Antibodies to endogenous retroviral gene products have been found in a number of infectious, chronic, and malignant diseases, suggesting a role in disease initiation and progression. We studied human immunodeficiency virus type 1 (HIV-1)-infected patients for evidence of urine antibody to a HERV peptide and investigated correlates with clinical and laboratory parameters. Forty-three HIV-1-infected patients in documented asymptomatic, symptomatic, or AIDS stages of disease and 21 age- and gender-matched, uninfected controls were tested for antibody to HERV-related peptide 4.1. Urine specimens were examined in a blinded fashion with the Calypte Biomedical Corp. experimental enzyme immunoassay for antibody to peptide 4.1. Results were compared with demographic data, medical history, clinical state of disease, and results of other laboratory tests. Thirty-six percent of the asymptomatic (Centers for Disease Control and Prevention [CDC] category A) and 81.3% of both the symptomatic (CDC category B) and AIDS (CDC category C) patients were positive for antibody to HERV-related peptide 4.1. None of the controls were positive. In this study, antibodies to HERV-related peptide 4.1 were found more frequently in patients with advanced stages (categories B and C) of HIV-1 disease than in those patients with an earlier stage (category A) of HIV disease. In HIV patients, severe immunosuppression, defined as having had at least one opportunistic infection, correlated with the expression of antibody to a HERV-related peptide.

A prevalence survey of infections in a combined acute and long-term care hospital.

A prevalence survey of infections among 572 acute and long-term care patients in the Albany Veterans Administration Medical Center was conducted in September 1979. Presence of infection was determined by patient examination and chart review. Urine specimens from 94% of patients were cultured. The total number of clinically significant infections was 178; 117 were nosocomial (20.5 per 100 patients). The prevalence rate of nosocomial infections was highest on the Intermediate Service (long-term medical care) followed by the Surgical and Medical Services. Sites with the highest nosocomial infection rates were urinary tract (10.7), skin and subcutaneous tissues (5.1), and surgical wounds (3.0) per 100 patients. Nosocomial infections increased with age and length of hospital stay which partially explained the higher rate on the Intermediate Service. Patients using condom drainage and Foley catheters showed similarly high rates of bacteriuria. Antimicrobial drug use was 17% for acute care patients and 4% for long-term and psychiatry patients. Excepting Providencia stuartii urinary tract infection confined to the Intermediate Service, the bacterial isolates and their antibiotic susceptibilities were similar for the acute and long-term care services.