Opportunistic infection: a review

Nano- and micro-polystyrene plastics disturb gut microbiota and intestinal immune system in honeybee

Micro- (MPs) and nano-plastics (NPs) have become emerging pollutants in the environment. Their wide distribution and capacity as a vector of hazardous materials threaten various organisms. Honeybees have been used as bioindicators for pollutants as their gut microbiota offers advantages for addressing how it alters the host health and exploring the processes of environmental pollutants affecting gut community dynamics. In this study, the effects of plastic particles of different sizes on honeybees' health were investigated. Oral exposure to polystyrene (PS) particles with a diameter of 100 nm significantly decreased the whole-body weight and survival rate of honeybees and induced intestinal dysplasia. As the increase of the feeding time from Day 0 to Day 15, the MPs moved to and accumulated in the rectum, where most bee gut symbionts colonized. Scanning electron microscope observation showed that 100-nm PS particles adhered to the germination pore of pollen, while 1- and 10-μm PS particles were attached by gut bacteria. We found that 100-nm PS treatment decreased the relative abundance of Lactobacillus and Bifidobacterium in the guts. Correspondingly, PS treatment stimulated immune inhibitory genes and depressed genes related to detoxification and energy balance. Furthermore, 100-nm PS treated honeybees became more susceptible to the pathogenic Hafnia alvei, leading to a five-times higher mortality rate. These results indicated the adverse impacts of NPs on honeybees, which extends our knowledge regarding the emerging health risks of plastic debris, especially at the nanoscale.

Female immunity in response to sexually transmitted opportunistic bacteria in the common bedbug Cimex lectularius

Besides typical sexually transmitted microbes, even environmental, opportunistic microbes have been found in copulatory organs of insects and even humans. To date, only one study has experimentally investigated the sexual transmission of opportunistic microbes from male to female insects, whereas nothing is known about the transmission from females to males. Even if opportunistic microbes do not cause infection upon transmission, they might eventually become harmful if they multiply inside the female. While the immune system of females is often assumed to target sexually transmitted microbes, most studies ignore the role of mating-associated opportunistic microbes. Variation in immunity between populations has been linked to parasite or bacteria prevalence but no study has ever addressed between-population differences in immune responses to sexually transmitted opportunistic microbes. We here show that bacteria applied to the copulatory organs of common bedbugs, Cimex lectularius, are sexually transmitted to the opposite sex at a high rate, including the transmission from female to male. Bacterial growth in the female sperm-receiving organ was inhibited over the first hours after introduction, but after this initial inhibition bacterial numbers increased, suggesting a shift of investment from immune defence towards reproduction. However, 24 h after the injection of bacteria, male components, or saline as a control, the sperm-receiving organ showed lysozyme-like activity and inhibited the growth of Gram-negative and Gram-positive bacteria in vitro, potentially to mop up the remaining bacteria. Contrasting our prediction, neither bacterial growth nor immune responses differed between populations. Future studies should link transmission dynamics, immune responses and fitness effects in both sexes. Experimental manipulation of environmental bacteria could be used to investigate how transmission frequency and toxicity of sexually transmitted opportunistic microbes shapes bacteria clearance and immune responses across populations.

Mating changes the genital microbiome in both sexes of the common bedbug Cimex lectularius across populations

Many bacteria live on host surfaces, in cells and in specific organ systems. In comparison with gut microbiomes, the bacterial communities of reproductive organs (genital microbiomes) have received little attention. During mating, male and female genitalia interact and copulatory wounds occur, providing an entrance for sexually transmitted microbes. Besides being potentially harmful to the host, invading microbes might interact with resident genital microbes and affect immunity. Apart from the investigation of sexually transmitted symbionts, few studies have addressed how mating changes genital microbiomes. We dissected reproductive organs from virgin and mated common bedbugs, Cimex lectularius L., and sequenced their microbiomes to investigate composition and mating-induced changes. We show that mating changes the genital microbiomes, suggesting bacteria are sexually transmitted. Also, genital microbiomes varied between populations and the sexes. This provides evidence for local and sex-specific adaptation of bacteria and hosts, suggesting bacteria might play an important role in shaping the evolution of reproductive traits. Coadaptation of genital microbiomes and reproductive traits might further lead to reproductive isolation between populations, giving reproductive ecology an important role in speciation. Future studies should investigate the transmission dynamics between the sexes and populations to uncover potential reproductive barriers.

Smoking and microbiome in oral, airway, gut and some systemic diseases

The human microbiome harbors a diverse array of microbes which establishes a mutually beneficial relation with the host in healthy conditions, however, the dynamic homeostasis is influenced by both host and environmental factors. Smoking contributes to modifications of the oral, lung and gut microbiome, leading to various diseases, such as periodontitis, asthma, chronic obstructive pulmonary disease, Crohn’s disease, ulcerative colitis and cancers. However, the exact causal relationship between smoking and microbiome alteration remains to be further explored.

Smoking is associated with quantifiable differences in the human lung DNA virome and metabolome

BACKGROUND

The role of commensal viruses in humans is poorly understood, and the impact of the virome on lung health and smoking-related disease is particularly understudied.

METHODS

Genetic material from acellular bronchoalveolar lavage fluid was sequenced to identify and quantify viral members of the lower respiratory tract which were compared against concurrent bronchoalveolar lavage bacterial, metabolite, cytokine and cellular profiles, and clinical data. Twenty smoker and 10 nonsmoker participants with no significant comorbidities were studied.

RESULTS

Viruses that infect bacteria (phages) represented the vast majority of viruses in the lung. Though bacterial communities were statistically indistinguishable across smokers and nonsmokers as observed in previous studies, lung viromes and metabolic profiles were significantly different between groups. Statistical analyses revealed that changes in viral communities correlate most with changes in levels of arachidonic acid and IL-8, both potentially relevant for chronic obstructive pulmonary disease (COPD) pathogenesis based on prior studies.

CONCLUSIONS

Our assessment of human lung DNA viral communities reveals that commensal viruses are present in the lower respiratory tract and differ between smokers and nonsmokers. The associations between viral populations and local immune and metabolic tone suggest a significant role for virome-host interaction in smoking related lung disease.

Olfactory cues play a significant role in removing fungus from the body surface of Drosophila melanogaster

Many insects and Dipterans in particular are known to spend considerable time grooming, but whether these behaviors actually are able to remove pathogenic fungal conidia is less clear. In this study, we examined whether grooming serves to protect flies by reducing the risk of fungal infection in Drosophila melanogaster. First, we confirmed that fungi were removed by grooming. Entomopathogenic, opportunistic, and plant pathogenic fungi were applied on the body surface of the flies. To estimate grooming efficiency, the number of removal conidia through grooming was quantified and we successfully demonstrated that flies remove fungal conidia from their body surfaces via grooming behavior. Second, the roles of gustatory and olfactory signals in fungus removal were examined. The wildtype fly Canton-S, the taste deficiency mutant poxn 70, and the olfactory deficiency mutant orco1 were used in the tests. Comparisons between Canton-S and poxn 70 flies indicated that gustatory signals do not have a significant role in fungal removal via grooming behavior in D. melanogaster. In contrast, the efficiency of conidia removal in orco1 flies was drastically decreased. Consequently, this study indicated that flies rely on mechanical stimulus for the induction of grooming and olfaction for more detailed removal.

Faropenem enhances superoxide anion production by human neutrophils in vitro

Neutrophils are important cellular components in the defence against infections and many studies in vitro have shown that some antibiotics affect neutrophil function. We examined the effect of faropenem, a new oral penem antibiotic on neutrophil killing function by determining the generation of superoxide anion in vitro. The production of superoxide anion was measured by chemiluminescence amplified by a Cypridina luciferin analogue in the presence of N-formyl-Met-Leu-Phe (fMLP). Faropenem significantly enhanced chemiluminescence in a dose-dependent manner. The effect of faropenem was maximal at 5 min of incubation time and continued for at least 30 min. The effect of faropenem was also observed when neutrophils were stimulated by a calcium ionophore (ionomycin), while the effect of faropenem did not change in the presence of 12-O-tetra-decanoylphorbolmyristate acetate. Cytosol Ca2+ concentration ([Ca2+]i) monitored with Fura-2 increased in response to fMLP, however, faropenem did not influence the response of [Ca2+]i to fMLP. Our results suggest that faropenem enhanced the generation of superoxide anion by neutrophils, probably at the site where cytosol Ca2+ regulates NADPH oxidase. Faropenem might be potentially advantageous in the treatment of infections because a synergic interaction of antibodies and cytocidal neutrophils is necessary for the early eradication of the pathogenic bacteria.

Urinary tract infection caused by Hansenula anomala

A case of urinary tract infection due to Hansenula anomala is reported. The infection occurred in a cadaver kidney transplant patient who was receiving immuno-suppression therapy. Survey of the literature revealed that human infections due to this organism are rare and its causal relationship in urinary tract infection has not been previously reported.

Invasive trichophyton rubrum infection in an immunocompromised host. Case report and review of the literature

Typically confined within the keratinized, epithelial layer of the skin and hence categorized among the dermatophytoses, Trichophyton rubrum infections usually present as superficial, scaling eruptions. In certain clinical settings, however, such as in immunosuppressed hosts, deep local invasion, multivisceral dissemination, and even death due to T. rubrum granulomas have been described. A case of multiple, subcutaneous, neutrophilic abscesses due to T. rubrum in an immunosuppressed renal allograft recipient is described. The pathogenesis, diagnosis, and immunology of invasive T. rubrum infections in immunocompromised hosts are reviewed.

Systemic antibiotic treatment in burned patients

Systemic antibiotics are a valuable therapeutic modality in the burned patient when properly used. Injudicious use, however, may not only fail to be beneficial to the patient but also may produce harmful effects--either through direct toxicity or by contributing to the emergence of resistant strains of micro-organisms. General guidelines and principles for systemic antibiotic use include the following: The burned patient, despite all efforts, will be exposed to microorganisms. No single agent or combination of agents can destroy all the organisms to which the burned patient is exposed. Treatment involves first identifying the organism responsible for clinical sepsis, then choosing appropriate agents. Combinations of antibiotics are not always synergistic or even additive in effect. Multiagent therapy may have the untoward effect of predisposing to superinfection by yeast, fungi, or resistant organisms. Antibiotics should be used for a long enough period to produce an effect, but not long enough to allow for emergence of opportunistic or resistant organisms. Dosages must be adjusted based on serum concentrations when serum assays are available. In general prophylactic systemic antibiotics are indicated in only a few clinical situations including the immediate preoperative and postoperative periods associated with excision and autografting, and possibly in the early phases of burns in children. The penetration of systemic antibiotics into burn eschar remains an area not fully studied; hence, they cannot be the only therapeutic modality used to treat burn wound infection. Systemic dosages of antibiotics in burns will require alteration depending on the clinical status of the patient. The choice of agent requires a thorough knowledge of side effects, toxicity, and potential benefit. Above all, active surveillance and monitoring of the burned patient and the environment in which he or she is being treated is mandatory for effective treatment. The increasing number of new antimicrobial agents has presented a new dilemma to the practicing clinician because many of these agents have not been evaluated thoroughly in the burned population. With further studies, the armamentarium of the burn treatment team will inevitably increase. It is in this manner only that so many of the unanswered questions will be solved, and that infection will start to decline as the major cause of death in the burned population.

Susceptibility of clinical isolates of yeasts to anti-fungal agents

The antimicrobial activity of amphotericin B, 5-fluorocytosine, nystatin, clotrimazole and miconazole were compared in vitro against 244 strains of yeasts that had been isolated from clinical specimens. The yeasts used in this study included 20 species of Candida, Cryptococcus, Saccharomyces Geotrichum, Rhodotorula, Torulopsis and Trichosporon. The majority of the strains (78%) had an MIC of less than or equal to 0.5 microgram/ml for amphotericin B, 81% an MIC of less than or equal to 1 microgram/ml for 5-fluorocytosine, 99% less than or equal to 8 micrograms/ml for nystatin, 91%, less than or equal to 8.0 micrograms/ml for clotrimazole and 98% had an MIC of less than or equal to 4.0 for miconazole. Of the anti-fungal agents tested, 5-fluorocytosine and nystatin were found to have the greatest antifungal activity.

Rapid identification of yeasts by semi-automated and conventional methods

Five different methods for the identification of significant yeast from clinical specimens were compared for their reliability, rapidity and cost-effectiveness. Three commercial methods consisted of semi-automated Abbott's yeasts identification system using MS-2 (Abbott Laboratories, Diagnostic Division, Irving, Texas), API 20C (Analytab Products, Inc., Plainview, NY) and Uni-Yeast-Tek (Flow Labs, Inc., MacLean, VA). Two conventional methods included the modified dye-plur plate auxanographic and rapid tube assimilation method. The 242 coded clinical isolates used in this study included 20 species of Candida, Cryptococcus, Saccharomyces Geotrichum, Rhodotorula, Torulopsis and Trichosporon. The identification accuracies with all the systems ranges between 92.3% to 97.5%. Results were available with Abbott's MS-2 within 24 h, with rapid tube assimilation method in 6-48 h and in 72 h with other systems. Rapid tube assimilation and dye-pour-plate auxanographic methods were least expensive, with labour and material costing around $1.00 per identification, whereas the commercial system cost a little over $5.00.

Mechanism of action of AC-1370 on phagocyte functions

The mechanism of action of a new semisynthetic cephalosporin AC-1370 on phagocyte functions was investigated. AC-1370 enhanced phagocytic functions of macrophages and neutrophils. AC-1370 bound to 27.4% of mouse peritoneal resident cells. Most of the AC-1370-binding cells were macrophages, and few neutrophils bound AC-1370. Culture supernatant of mouse macrophages cultured with AC-1370 significantly augmented phagocytic functions of mouse neutrophils. This activity of the culture supernatant of AC-1370-stimulated macrophages was abolished by digestion with trypsin but not by heat treatment at 56 degrees C for 30 min. The mechanism of the activation of phagocyte functions by AC-1370 is proposed as follows. First, AC-1370 binds to macrophages and causes their activation. Second, trypsin-sensitive and heat-stable soluble factor(s) is released from these macrophages. And finally, neutrophil functions are activated by the factor(s).

Effects of AC-1370, a new semisynthetic cephalosporin, on phagocyte functions

The effects of a new semisynthetic cephalosporin, AC-1370, on phagocyte functions were compared with those of cefoperazone. AC-1370 augmented phagocytosis by mouse macrophages in vitro and in vivo, by mouse neutrophils in vivo, and by human neutrophils in vitro. Cefoperazone suppressed phagocytosis by mouse macrophages and neutrophils. Random migration and chemotaxis of mouse and human neutrophils were increased by the addition of AC-1370. Nitroblue tetrazolium reduction by human neutrophils was enhanced by the addition of AC-1370. Intracellular killing of bacteria by macrophages was also enhanced by AC-1370. Further, bactericidal effects of AC-1370 against Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumoniae were augmented when they were each cultured with mouse or human leukocytes. These results suggest that AC-1370 is an unique beta-lactam antibiotic which has a potentiating effect on phagocyte functions as well as a bactericidal effect.

Effect of Streptococcus faecalis BIO-4R on intestinal flora of weanling piglets and calves

The effect of oral administration of Streptococcus faecalis BIO-4R, an antibiotic-resistant lactic acid bacterium, on the intestinal flora of weanling piglets and cows reared on antibiotic-containing diet was investigated. Fourteen days after administration of the bacteria, the intestinal flora of the piglets was examined. Animals of the administered group had stabilized lactic flora such as bifidobacteria, streptococci, and lactobacilli, whereas most animals of control group had reduced lactic flora. On the other hand, abundant yeasts were detected from the cecum, colon, and feces of the control animals, but the levels were significantly lower in the animals given strain BIO-4R. The density of Salmonella in the intestine appeared to be reduced after the administration of strain BIO-4R. The number of BIO-4R cells was shown to be 10 times lower in the duodenum and jejunum than in the ileum, suggesting that strain BIO-4R might have grown transiently in the ileum. The similar trend toward stabilization of the lactic flora was also observed in cows after administration of BIO-4R. In addition, an antagonistic effect of the strain against yeasts and Salmonella was suggested. These findings indicate that the oral administration of strain BIO-4R is one of the useful methods whereby the potentially deleterious effect of antibiotics on the intestinal flora of farm animals may be minimized.

Direct microscopical versus cultural method in screening for candidiasis among non gravid nigerian women

The incidence of candidiasis in 125 symptomless, non-gravid women in Ile-Ife State Hospital, Ile-Ife, Oyo-State of Nigeria was determined by either microscopic observation or cultural methods. Among the three techniques investigated, the cultural method had the highest recovery rate with 60% of the cultures from 125 patients positive. Statistical analysis of the data (X2) demonstrated a significant difference between the recovery rates at the P less than 0.01 level. The implications of these findings were discussed in the text.

Adenovirus infection in the immunocompromised patient

Illness associated adenovirus infection is described in 15 immunocompromised patients. Patients were immunocompromised by severe underlying disease, immunosuppressive or corticosteroid therapy or by age (prematurity). Evidence of adenovirus infection was obtained by either viral isolation or, in two cases, characteristic adenovirus inclusion bodies at postmortem study. All clinical illness was associated with high fever (temperature greater than 39 degrees C). Eighty per cent of the patients had severe systemic complaints including malaise, lethargy, fatigue and night sweats; a similar number of gastrointestinal symptoms. Pulmonary complaints were described in 11 of 15 cases and included cough (67 per cent) and tachypnea (53 per cent). Roentgenologic evidence of pneumonia was demonstrated in 12 of 15 patients (80 per cent). Elevation of serum hepatic enzyme levels (serum glutamic pyruvic transaminase (SGPT)) occurred in eight of 11 patients (73 per cent) and was moderate to severe (serum glutamic pyruvic transaminase greater than 450 IU/liter) in five of 11 (45 per cent). Nine patients died; seven after a rapid downhill course and two after a prolonged illness. Evidence of adenovirus infection microscopically by autopsy in the lung, liver or both is demonstrated in four patients with fulminant systemic illness. Adenovirus infection should be considered in the etiology of severe overwhelming illness in the immunocompromised host.

Antagonistic effects of Bacillus natto and Streptococcus faecalis on growth of Candida albicans

The growth-inhibitory effects of Bacillus natto and Streptococcus faecalis on Canida albicans were investigated. When inoculated into the filtrate of a long-term culture of B. natto strain BN (BN), a stock culture of C. albicans RIMD 0301020 lost its viability completely, whereas C. albicans RIMD 0301011, a fresh isolate from a clinical source, did not. In continuous flow (CF) culture the growth of both strains of C. albicans was suppressed by mixed cultivation with BN. On the other hand, in classical batch culture BN did not suppress the growth of C. albicans. S. faecalis BIO-4R, a multi-drug resistant strain, was also antagonistic to C. albicans RIMD 0301011 but symbiotic with BN in CF culture. These findings suggest that BN in concert with S. faecalis BIO-4R may inhibit the growth of C. albicans in the intestinal tract.

Evaluation of a modified dye pour-plate auxanographic method for the rapid identification of clinically significant yeasts. Comparison with two commercial systems

A modified dye pour-plate auxanographic (DPPA) method for the presumptive identification of medically important yeasts was evaluated, in a comparative study with a conventional procedure, the API 20C clinical yeast system (Analytab Products Inc.), and the Uni-Yeast-Tek (UYT) system. The 174 coded clinical isolates were members of the genera Candida, Cryptococcus, Rhodotorula, Saccharomyces, Torulopsis, and Trichosporon. The identification accuracies with DPPA, API, and UYT were 95%, 93%, and 99% respectively. DPPA and API required more time to inoculate but gave rapid identification profiles. UYT was simple to inoculate and both UYT and DPPA were easy to read. Cost analysis of the three rapid methods demonstrated DPPA to be the most economical making it a feasible alternative for small clinical laboratories as well as large laboratories possessing the facilities to make their own media.

Use of systemic antibiotics in the burned patient

A diagnosis of clinical sepsis is the primary indication for administration of systemic antibiotics. Choices of antibiotics for sepsis, where cultures are unavailable, requires a knowledge of current strains in the unit where the patient resides and coverage for both Staphylococcus aureus and Pseudomonas. Dosage requirements are increased in burned patients and serum antibiotic levels must be monitored for maximal effectiveness and minimal toxicity. Localized foci of infection must be identified and eradicated with regional antibiotic therapy or surgery when possible. Gram-negative pneumonia in the patient with an inhalation injury poses special difficulties in therapy. Resistance to antibiotics must be constantly guarded against and isolation procedures followed to avoid its propagation in the burn unit. Combination drug regimens and plasmid-directed therapy may in the future slow down the acquisition of further antibiotic resistance and lead to improved salvage of severely burned patients.

Further modifications of the auxanographic method for identification of yeasts

A modified auxanographic carbohydrate assimilation procedure for the identification of medically important yeasts is described. This method employs a heavy inoculum of unstarved yeasts, autoclaved yeast assimilation medium, pour plates of shallow depth, and commercially available carbohydrate-impregnated disks. The accuracy of this procedure was established in a comparison with the Wickerham broth method.

Reservoirs of pseudomonas in an intensive care unit for newborn infants: mechanisms of control

Potential reservoirs of pseudomonas within a neonatal ICU were evaluated. Colonization of infants by the same pseudomonas pyocin types could be classified as a cluster colonization (occurring over three to ten days), or serial colonization (occurring over longer times). Hands of personnel, sink surfaces, and solutions used to rinse nasopharyngeal catheters were identified as the principle reservoirs. Utilization of a liquid iodophor agent for hand washing and of acetic acid for rinsing suction catheters was associated with a significant reduction in the histologic evidence of sepsis and of pneumonia observed among autopsied infants.

Viridans streptococci associated with periapical dental abscesses

Viridans streptococci isolated in apparently pure culture from periapical dental abscess have been examined. It has been found that each abscesses is associated with only one type of a given species of Streptococcus. The distribution of types of Strep. mitis found in abscesses differed from the distribution in healthy mouths, but no particular type occurred significantly more often in abscesses than in mouths.

A double-blind comparison of a new combination (halcinonide-neomycin-amphotericin) and active controls in cutaneous candidiasis and steroid-responsive dermatoses

One hundred patients participated in the studies of cutaneous candidiasis and steroid-responsive dermatoses. Seventy patients with the former diagnosis were treated with either halcinonide-neomycin-amphotericin or hydrocortisone-iodochlorhydroxyquin ointment combinations on a double-blind parallel comparison basis. Similar results were obtained after both therapies. Thirty patients with symmetrical bilateral lesions of steroid-responsive dermatoses were treated with halcinonide-neomycin-amphotericin cream on the lesions on one side of the body and hydrocortisone-iodochlorhydroxyquin cream on the opposite side. A double-blind design was used in directly comparing the response to each of the two drugs. Considering the results of all dermatoses together the test combination was statistically superior to the control cream (p less than 0-05). However, while numerical superiority of good responses to the halcinonide combination was recorded in psoriasis, no statistical significance could be derived due to the limited number of cases. No side-effects occurred with any drug combination use. In the opinion of the authors halcinonide-neomycin-amphotericin cream and ointment are safe and effective in the treatment of cutaneous candiasis and steroid-responsive dermatoses.

Candida arthritis. A manifestation of disseminated candidiasis

Fungal infections infrequently involve the joints. Review of the literature reveals that Candida arthritis is rare, that it is usually a complication of disseminated candidiasis and that it occurs as a primary joint infection without spread from adjacent osteomyelitis. In the patient we describe Candida arthritis and bursitis of separate joints developed as a late manifestation of disseminated infection following "transient" C. tropicalis fungemia. Treatment consisting of aspiration and parenteral amphotericin B eradicated the joint infection without the need for surgery. Bursectomy, however, was required to eradicate the bursal infection. Awareness of this as well as other late complications of candidemia which signify disseminated infection is important. Optimal therapy will be determined only by further clinical experience with this unusual manifestation of Candida infection.

Gas gangrene-like infection with Bacillus cereus in a lymphoma patient

A patient with a diffuse histiocytic lymphoma developed an infection caused by Bacillus cereus during a period of induced granulocytopenia. A fulminant process resembling gas gangrene developed shortly after the accidental penetration by a small piece of metal into his right hand. Incision and drainage as well as antimicrobial therapy did not prevent the loss of the third, fourth and fifth fingers; however, localization and subsequent control of the infection was achieved concomitant with bone marrow recovery.

Studies on the establishment of multi-drug-resistant strain BIO-4R of Streptococcus faecalis in the intestinal tract of germ-free mice. Bacterial interaction and effect of antibiotics

Germ-free ICR mice were mono- or dicontaminated with a multi-drug-resistant strain BIO-4R of Streptococcus faecalis (BIO-4R) and Escherichia coli 026 : K60 (E. coli) and administered aminobenzyl penicillin (ABPC). BIO-4R was established in the intestinal tract at a level of 10(8) viable cells per gram of stool on the fourth day following oral inoculation and the BIO-4R population was stably maintained thereafter. The drug resistance of BIO-4R remained unchanged in the intestinal tract of gnotobiotes throughout the experiment. Highly resistant cells of E. coli were isolated from the feces of some dicontaminated mice after ABPC administration. However, it seems that the high resistance of these E. coli is not due to the transfer of resistance of BIO-4R to E. coli. All animals given a large amount of BIO-4R (10(8) cells) per os survived throughout the study period of two weeks without symptoms.

Rapid methods for identification of yeasts

Opportunistic infections by yeasts have been implicated as one of the major causes of complications in the compromised patient. Rapid recognition and identification of these yeasts is essential for patient management, but conventional liquid medium methods for completing identification tests are cumbersome and time consuming. Rapid tests have been devised based on modifications of methods commonly used in bacteriology. These rapid methods included tests for carbohydrate and nitrate assimilation, fermentation, and urease production. These were compared with several current methods for accuracy of results, for time to final identification, and for economy of time and reagents. In addition, the usual tests for pseudogerm tube formation, for production of hyphae or pseudohyphae, and for growth temperatures were included. The rapid tests achieved 96% or better accuracy compared with expected results, and 46 species of yeasts were identified in 1 to 2 days compared with the 10 to 14 days required by conventional liquid culture methods.

Opportunistic endocarditis following open-heart surgery

The incidence of endocarditis following open-heart operations is declining, but the relative incidence of endocarditis by the opportunistic organisms, both bacterial and fungal, has increased. These "opportunists" require careful identification and sensitivity testing so that appropriate therapy can be planned. In cases of candida endocarditis, a positive precipitin test and elevated candida antibody titer may provide an earlier means of diagnosis than blood cultures. These patients should be treated promptly with adequate dosages of specific antimicrobial or antifungal agents. Reoperation should be considered early if there is evidence of valve dehiscence or embolic phenomena or if drug therapy fails to control the infection.

Fungal septicemia in surgical patients

Opportunistic systemic fungal infections are more frequent than generally realized. Increased awareness and a high index of suspicion of fungal super-infection in the presence of sepsis is required to bring about recognition and therapy. The intravenous catheter is an important portal of entry or may act as a foreign body favoring localization of a septic process. In its presence, fungemia must be guarded against. Whenever an intravenous catheter is removed, its tip should be cultured. Removal alone may be a critical item in therapy. In febrile patients, in whom the course of fever is not established, frequent blood cultures with attention directed specifically at fungi should be obtained. Fungi are not easily isolated and identified and only by requesting special attention from the microbiologist can the diagnosis be established in the average institutional laboratory in time to permit appropriate therapy. Since available therapeutic measures are strikingly effective when instituted early, awareness and alertness on the part of the clinician constitute the key to cure.

Properties of silver sulfadiazine-resistant Enterobacter cloacae

Two silver sulfadiazine-resistant isolates of Enterobacter cloacae obtained in a burns unit where the drug was in use were studied. These strains were resistant to elevated levels of the drug, and they were cross-resistant to silver benzoate, but not to silver nitrate. Growth of the strains in nutritionally poor defined media sensitized them to the inhibitory action of the drug. Exposure of the bacteria to penicillins rendered them susceptible to silver sulfadiazine. The resistant bacteria harbored episomes for resistance to carbenicillin and kanamycin; however, resistance to silver sulfadiazine could not be transferred by these episomes. Twenty-three strains of E. cloacae isolated in a general hospital were sensitive to much lower levels of the drug (</=50 mug/ml).

Silver sulfadiazine: in vitro antibacterial activity

Isolates (657) representing 22 bacterial species were tested for susceptibility to silver sulfadiazine. All of the strains tested were inhibited by concentration levels of the drug which are easily achieved topically. It is suggested that silver sulfadiazine may be useful as a broad-spectrum antimicrobial substance for the prevention and treatment of infections of burns and wounds.

Amphotericin B therapy in an anephric patient

Serum levels of amphotericin B were serially determined during and after a course of therapy in an anephric patient who developed systemic candidiasis after an unsuccessful renal transplantation. There was no progressive accumulation of drug in serum, and the pattern of disappearance of drug from serum was similar to that published for patients with normal renal function. The dialyzability of amphotericin B was studied in vivo during a 6-h period of hemodialysis, by an in vitro dialysis of amphotericin B in water by using similar equipment, and a Pellicon membrane filter which retains molecular species of 100,000 molecular weight and higher. These studies revealed that the drug is not dialyzable with conventional hemodialysis membranes, regardless of protein binding in plasma, and is excluded from passing through the Pellicon membrane filter.