Impact of cefoperazone therapy on fecal flora

The Underrated Gut Microbiota Helminths, Bacteriophages, Fungi, and Archaea

The microbiota inhabits the gastrointestinal tract, providing essential capacities to the host. The microbiota is a crucial factor in intestinal health and regulates intestinal physiology. However, microbiota disturbances, named dysbiosis, can disrupt intestinal homeostasis, leading to the development of diseases. Classically, the microbiota has been referred to as bacteria, though other organisms form this complex group, including viruses, archaea, and eukaryotes such as fungi and protozoa. This review aims to clarify the role of helminths, bacteriophages, fungi, and archaea in intestinal homeostasis and diseases, their interaction with bacteria, and their use as therapeutic targets in intestinal maladies.

Gut fungal mycobiome: A significant factor of tumor occurrence and development

A variety of bacteria, viruses, fungi, protists, archaea and protozoa coexists within the mammalian gastrointestinal (GI) tract such as that fungi are detectable in all intestinal and colon segments in almost all healthy adults. Although fungi can cause infectious diseases, they are also related to gut and systemic homeostasis. Importantly, through transformation of different forms such as from yeast to hyphae, interaction among gut microbiota such as fungal and bacterial interaction, host factors such as immune and host derived factors, and fungus genetic and epigenetic factors, fungi can be transformed from commensal into pathogenic lifestyles. Recent studies have shown that fungi play a significant role in the occurrence and development of tumors such as colorectal cancer. Indeed, evidences have shown that multiple species of different fungi exist in different tumors. Studies have also demonstrated that fungi are related to the occurrence and development of tumors, and also survival of patients. Here we summarize recent advances in the transformation of fungi from commensal into pathogenic lifestyles, and the effects of gut pathogenic fungi on the occurrence and development of tumors such as colorectal and pancreatic cancers.

Antibiotic treatment using amoxicillin-clavulanic acid impairs gut mycobiota development through modification of the bacterial ecosystem

BACKGROUND

Effects of antibiotics on gut bacteria have been widely studied, but very little is known about the consequences of such treatments on the fungal microbiota (mycobiota). It is commonly believed that fungal load increases in the gastrointestinal tract following antibiotic treatment, but better characterization is clearly needed of how antibiotics directly or indirectly affect the mycobiota and thus the entire microbiota.

DESIGN

We used samples from humans (infant cohort) and mice (conventional and human microbiota-associated mice) to study the consequences of antibiotic treatment (amoxicillin-clavulanic acid) on the intestinal microbiota. Bacterial and fungal communities were subjected to qPCR or 16S and ITS2 amplicon-based sequencing for microbiota analysis. In vitro assays further characterized bacterial-fungal interactions, with mixed cultures between specific bacteria and fungi.

RESULTS

Amoxicillin-clavulanic acid treatment triggered a decrease in the total fungal population in mouse feces, while other antibiotics had opposite effects on the fungal load. This decrease is accompanied by a total remodelling of the fungal population with the enrichment in Aspergillus, Cladosporium, and Valsa genera. In the presence of amoxicillin-clavulanic acid, microbiota analysis showed a remodeling of bacterial microbiota with an increase in specific bacteria belonging to the Enterobacteriaceae. Using in vitro assays, we isolated different Enterobacteriaceae species and explored their effect on different fungal strains. We showed that Enterobacter hormaechei was able to reduce the fungal population in vitro and in vivo through yet unknown mechanisms.

CONCLUSIONS

Bacteria and fungi have strong interactions within the microbiota; hence, the perturbation initiated by an antibiotic treatment targeting the bacterial community can have complex consequences and can induce opposite alterations of the mycobiota. Interestingly, amoxicillin-clavulanic acid treatment has a deleterious effect on the fungal community, which may have been partially due to the overgrowth of specific bacterial strains with inhibiting or competing effects on fungi. This study provides new insights into the interactions between fungi and bacteria of the intestinal microbiota and might offer new strategies to modulate gut microbiota equilibrium. Video Abstract.

The effect of antibiotics on the composition of the intestinal microbiota - a systematic review

OBJECTIVE

Antibiotics change the composition of the intestinal microbiota. The magnitude of the effect of antibiotics on the microbiota and whether the effects are short-term or persist long-term remain uncertain. In this review, we summarise studies that have investigated the effect of antibiotics on the composition of the human intestinal microbiota.

METHODS

A systematic search was done to identify original studies that have investigated the effect of systemic antibiotics on the intestinal microbiota in humans.

RESULTS

We identified 129 studies investigating 2076 participants and 301 controls. Many studies reported a decrease in bacterial diversity with antibiotic treatment. Penicillin only had minor effects on the intestinal microbiota. Amoxicillin, amoxcillin/clavulanate, cephalosporins, lipopolyglycopeptides, macrolides, ketolides, clindamycin, tigecycline, quinolones and fosfomycin all increased abundance of Enterobacteriaea other than E. coli (mainly Citrobacter spp., Enterobacter spp. and Klebsiella spp.). Amoxcillin, cephalosporins, macrolides, clindamycin, quinolones and sulphonamides decreased abundance of E. coli, while amoxcillin/clavulante, in contrast to other penicillins, increased abundance of E. coli. Amoxicllin, piperacillin and ticarcillin, cephalosporins (except fifth generation cephalosporins), carbapenems and lipoglycopeptides were associated with increased abundance of Enterococcus spp., while macrolides and doxycycline decreased its abundance. Piperacillin and ticarcillin, carbapenems, macrolides, clindamycin and quinolones strongly decreased the abundance of anaerobic bacteria. In the studies that investigated persistence, the longest duration of changes was reported after treatment with ciprofloxacin (one year), clindamycin (two years) and clarithromycin plus metronidazole (four years). Many antibiotics were associated with a decrease in butyrate or butryrate-producing bacteria.

CONCLUSION

Antibiotics have profound and sometimes persisting effects on the intestinal microbiota, characterised by diminished abundance of beneficial commensals and increased abundance of potentially detrimental microorganisms. Understanding these effects will help tailor antibiotic treatment and the use of probiotics to minimise this 'collateral damage'.

Regulation of Vaginal Microbiome by Nitric Oxide

In this review, the composition and regulation of vaginal microbiome that displays an apparent microbial diversity and interacts with other microbiota in the body are presented. The role of nitric oxide (NO) in the regulation of vaginal microflora in which lactobacillus species typically dominate has been delineated from the perspective of maintaining gynecologic ecosystem and prevention of onset of bacteriostatic vaginosis (BV) and/or sexually transmitted diseases (STD) including HIV-1 transmission. The interactions between NO and vaginal microbiome and its influence on the levels of Lactobacillus, hormones and other components are described. The recent progress, such as NO drugs, probiotic Lactobacilli and Lactobacillus microbots, that can be explored to alleviate abnormality of vagina microbiome, is also discussed. An identification of Oral-GI-Vagina axis, as well as the relationship between NO and Lactobacillus regulation in the healthy or pathological status of vagina microbiome, surely offers the advanced drug delivery option against BV or STD including AIDS.

Potential mediators linking gut bacteria to metabolic health: a critical view

Growing evidence suggests that the bacteria present in our gut may play a role in mediating the effect of genetics and lifestyle on obesity and metabolic diseases. Most of the current literature on gut bacteria consists of cross‐sectional and correlative studies, rendering it difficult to make any causal inferences as to the influence of gut bacteria on obesity and related metabolic disorders. Interventions with germ‐free animals, treatment with antibiotic agents, and microbial transfer experiments have provided some evidence that disturbances in gut bacteria may causally contribute to obesity‐related insulin resistance and adipose tissue inflammation. Several potential mediators have been hypothesized to link the activity and composition of gut bacteria to insulin resistance and adipose tissue function, including lipopolysaccharide, angiopoietin‐like protein 4, bile acids and short‐chain fatty acids. In this review we critically evaluate the current evidence related to the direct role of gut bacteria in obesity‐related metabolic perturbations, with a focus on insulin resistance and adipose tissue inflammation. It is concluded that the knowledge base in support of a role for the gut microbiota in metabolic regulation and in particular insulin resistance and adipose tissue inflammation needs to be strengthened.

The effect of antibacterial and non-antibacterial compounds alone or associated with antifugals upon fungi

During the last 30 years the incidence of fungal infections has increased dramatically. While the antifungal therapeutic options available are somewhat reduced, most pathogenic microorganisms have an incredible capacity to mutate and acquire resistance. In addition, multiple drugs are often required concomitantly to manage clinically complex disorders. The combination of antibiotics or other compounds with antifungal drugs, simultaneously or sequentially, is commonly adopted in clinical practice, although without a full knowledge of the consequences. Thus, the role of combined therapy and the effect of antibiotics upon fungal growth promotion need to be critically evaluated and understood in order to avoid undesirable drug interactions. With this review we intend discuss the studies that report about antibiotics inhibiting fungal growth, as well as studies describing the synergistic effect of the combined therapy, i.e., associations between antibiotics or other compounds with antifungal drugs. Alternative therapeutic protocols for fungal disease could be designed, taking advantage of such drug combinations. Critical revision of previously published data is crucial in order to define future research strategies.

The mycobiota: interactions between commensal fungi and the host immune system

The body is host to a wide variety of microbial communities from which the immune system protects us and that are important for the normal development of the immune system and for the maintenance of healthy tissues and physiological processes. Investigators have mostly focused on the bacterial members of these communities, but fungi are increasingly being recognized to have a role in defining these communities and to interact with immune cells. In this Review, we discuss what is currently known about the makeup of fungal communities in the body and the features of the immune system that are particularly important for interacting with fungi at these sites.

Characterization and quantification of the fungal microbiome in serial samples from individuals with cystic fibrosis

BACKGROUND

Human-associated microbial communities include fungi, but we understand little about which fungal species are present, their relative and absolute abundances, and how antimicrobial therapy impacts fungal communities. The disease cystic fibrosis (CF) often involves chronic airway colonization by bacteria and fungi, and these infections cause irreversible lung damage. Fungi are detected more frequently in CF sputum samples upon initiation of antimicrobial therapy, and several studies have implicated the detection of fungi in sputum with worse outcomes. Thus, a more complete understanding of fungi in CF is required.

RESULTS

We characterized the fungi and bacteria in expectorated sputa from six CF subjects. Samples were collected upon admission for systemic antibacterial therapy and upon the completion of treatment and analyzed using a pyrosequencing-based analysis of fungal internal transcribed spacer 1 (ITS1) and bacterial 16S rDNA sequences. A mixture of Candida species and Malassezia dominated the mycobiome in all samples (74%-99% of fungal reads). There was not a striking trend correlating fungal and bacterial richness, and richness showed a decline after antibiotic therapy particularly for the bacteria. The fungal communities within a sputum sample resembled other samples from that subject despite the aggressive antibacterial therapy. Quantitative PCR analysis of fungal 18S rDNA sequences to assess fungal burden showed variation in fungal density in sputum before and after antibacterial therapy but no consistent directional trend. Analysis of Candida ITS1 sequences amplified from sputum or pure culture-derived genomic DNA from individual Candida species found little (<0.5%) or no variation in ITS1 sequences within or between strains, thereby validating this locus for the purpose of Candida species identification. We also report the enhancement of the publically available Visualization and Analysis of Microbial Population Structures (VAMPS) tool for the analysis of fungal communities in clinical samples.

CONCLUSIONS

Fungi are present in CF respiratory sputum. In CF, the use of intravenous antibiotic therapy often does not profoundly impact bacterial community structure, and we observed a similar stability in fungal species composition. Further studies are required to predict the effects of antibacterials on fungal burden in CF and fungal community stability in non-CF populations.

Fungi of the murine gut: episodic variation and proliferation during antibiotic treatment

Antibiotic use in humans has been associated with outgrowth of fungi. Here we used a murine model to investigate the gut microbiome over 76 days of treatment with vancomycin, ampicillin, neomycin, and metronidazole and subsequent recovery. Mouse stool was studied as a surrogate for the microbiota of the lower gastrointestinal tract. The abundance of fungi and bacteria was measured using quantitative PCR, and the proportional composition of the communities quantified using 454/Roche pyrosequencing of rRNA gene tags. Prior to treatment, bacteria outnumbered fungi by >3 orders of magnitude. Upon antibiotic treatment, bacteria dropped in abundance >3 orders of magnitude, so that the predominant 16S sequences detected became transients derived from food. Upon cessation of treatment, bacterial communities mostly returned to their previous numbers and types after 8 weeks, though communities remained detectably different from untreated controls. Fungal communities varied substantially over time, even in the untreated controls. Separate cages within the same treatment group showed radical differences, but mice within a cage generally behaved similarly. Fungi increased ∼40-fold in abundance upon antibiotic treatment but declined back to their original abundance after cessation of treatment. At the last time point, Candida remained more abundant than prior to treatment. These data show that 1) gut fungal populations change radically during normal mouse husbandry, 2) fungi grow out in the gut upon suppression of bacterial communities with antibiotics, and 3) perturbations due to antibiotics persist long term in both the fungal and bacterial microbiota.

Effects of antibiotics on bacterial species composition and metabolic activities in chemostats containing defined populations of human gut microorganisms

The composition and metabolic activities of the human colonic microbiota are modulated by a number of external factors, including diet and antibiotic therapy. Changes in the structure and metabolism of the gut microbiota may have long-term consequences for host health. The large intestine harbors a complex microbial ecosystem comprising several hundreds of different bacterial species, which complicates investigations on intestinal physiology and ecology. To facilitate such studies, a highly simplified microbiota consisting of 14 anaerobic and facultatively anaerobic organisms (Bacteroides thetaiotaomicron, Bacteroides vulgatus, Bifidobacterium longum, Bifidobacterium infantis, Bifidobacterium pseudolongum, Bifidobacterium adolescentis, Clostridium butyricum, C. perfringens, C. bifermentans, C. innocuum, Escherichia coli, Enterococcus faecalis, Enterococcus faecium, Lactobacillus acidophilus) was used in this investigation. Ampicillin [9.2 μg (ml culture)(-1)] was added to two chemostats operated at different dilution rates (D; 0.10 h(-1) and 0.21 h(-1)), and metronidazole [76.9 μg (ml culture)(-1)] was added to a third vessel (D = 0.21 h(-1)). Perturbations in bacterial physiology and metabolism were sampled over a 48-h period. Lactobacillus acidophilus and C. bifermentans populations did not establish in the fermentors under the imposed growth conditions. Ampicillin resulted in substantial reductions in bacteroides and C. perfringens populations at both dilution rates. Metronidazole strongly affected bacteroides communities but had no effect on bifidobacterial communities. The bacteriostatic effect of ampicillin on bifidobacterial species was growth rate dependent. Several metabolic activities were affected by antibiotic addition, including fermentation product formation and enzyme synthesis. The growth of antibiotic-resistant bifidobacteria in the large bowel may enable them to occupy ecological niches left vacant after antibiotic administration, preventing colonization by pathogenic species.

The "Microflora Hypothesis" of allergic disease

Predisposition to allergic disease is a complex function of an individual's genetic background and, as is the case with multi-gene traits, environmental factors have important phenotypic consequences. Over a span of decades, a dramatic increase in the prevalence of allergic disease in westernized populations suggests the occurrence of critical changes in environmental pressures. Recently, it has been shown that the microbiota (i.e. microflora) of allergic individuals differs from that of non-allergic ones and that differences are detectable prior to the onset of atopy, consistent with a possible causative role. Features of the westernized lifestyle that are known to alter the microbiota, such as antibiotics and diet, are also associated with allergy in humans. In this chapter, we discuss the "Microflora Hypothesis" for allergy which predicts that an "unhealthy" microbiota composition, now commonly found within westernized communities, contributes to the development of allergy and conversely, that restoring a "healthy" microbiota, perhaps through probiotic supplementation, may prevent the development of allergy or even treat existing disease. In testing this hypothesis, our laboratory has recently reported that mice can develop allergic airway responses if their microbiota is altered at the time of first allergen exposure.

The 'microflora hypothesis' of allergic diseases

Increasingly, epidemiologic and clinical data support the hypothesis that perturbations in the gastrointestinal (GI) microbiota because of antibiotic use and dietary differences in 'industrialized' countries have disrupted the normal microbiota-mediated mechanisms of immunological tolerance in the mucosa, leading to an increase in the incidence of allergic airway disease. The data supporting this 'microflora hypothesis' includes correlations between allergic airway disease and (1) antibiotic use early in life, (2) altered fecal microbiota and (3) dietary changes over the past two decades. Our laboratory has recently demonstrated that mice can develop allergic airway responses to allergens if their endogenous microbiota is altered at the time of first allergen exposure. These experimental and clinical observations are consistent with other studies demonstrating that the endogenous microbiota plays a significant role in shaping the development of the immune system. Data are beginning to accumulate that a 'balanced' microbiota plays a positive role in maintaining mucosal immunologic tolerance long after post-natal development. Other studies have demonstrated that even small volumes delivered to the nasopharynx largely end up in the GI tract, suggesting that airway tolerance and oral tolerance may operate simultaneously. The mechanism of microbiota modulation of host immunity is not known; however, host and microbial oxylipins are one potential set of immunomodulatory molecules that may control mucosal tolerance. The cumulative data are beginning to support the notion that probiotic and prebiotic strategies be considered for patients coming off of antibiotic therapy.

Limited value of routine stool cultures in patients receiving antibiotic therapy

In the laboratory investigation of suspected community acquired diarrhea, stool cultures may be ordered on patients receiving antibiotic therapy. Because many antibiotics cause profound changes in intestinal microbial flora, the value of these cultures is not known. To determine the effect of concurrent antibiotic therapy on results of routine stool cultures in the isolation of enteropathogens, a retrospective analysis of fecal cultures submitted during a 14-month period was performed. Of 930 specimens from 856 patients, there were 236 samples (25.4%)from 223 patients (26.1%) receiving antibiotics. Of these, 198 cultures (83.9%)from 186 patients (83.4%) receiving antibiotic therapy showed no growth on all media or growth of only gram-positive organisms. None of these specimens revealed enteropathogens. The results of this study demonstrate that there is little value in culturing of stools of patients receiving antibiotics. Significant cost savings can be realized by elimination of these cultures.

The effects of amoxicillin therapy on skin flora in infants

In order to determine the effect of amoxicillin therapy on the perineal skin microbial flora in infants, we took quantitative bacterial and fungal cultures of perineal and sternal areas from 25 infants treated with amoxicillin (40 mg/kg/day) for 10 days. Specimens were obtained prior to therapy, within 3 days of conclusion of therapy, and 14-16 days later. Immediately following therapy, a decline in the number of bacterial isolates occurred on both the perineum (89 to 47) and sternum (84 to 39). The greatest decline occurred in the number of anaerobic bacteria (mostly Peptostreptococcus spp. and Propionibacterium acnes). Other organisms that were less often isolated were aerobic streptococci and Staphylococcus epidermidis. The number of Candida albicans isolates increased from 3 to 11 (p < 0.05) on the perineum, and 1 to 7 (p < 0.025) on the sternum. Four of the infants developed diaper dermatitis. The density of C. albicans increased more than 14-fold following amoxicillin therapy. Cultures done 14-16 days after cessation of therapy revealed an increase in the number of bacterial isolates on the perineum (47 to 72) and on the sternum (39 to 61) and a decline in recovery of C. albicans. This study demonstrates the effects of amoxicillin on the ecology of skin microbial flora in infants-a decrease in the number of bacterial isolates and an increase in recovery of C. albicans.

Changes in intestinal flora after administration of panipenem/betamipron or sulbactam/cefoperazone for treatment of postoperative infections in gastrectomy patients

To determine the effect of antibiotics used for the treatment of postoperative infections on the normal intestinal flora in patients who have undergone gastroenterological surgery, we performed a prospective randomized study in patients who had undergone distal gastrectomy. Cefazoline was administered up to postoperative day 3 for prophylaxis. For the treatment of postoperative infections, either panipenem/betamipron (PAPM/BP; n = 5) or sulbactam/cefoperazone (SBT/CPZ; n = 5) was adminstered to ten patients with signs of postoperative infections. Feces were examined for bacteria before and 4 and 7 days after the commencement of administration of these therapeutic antibiotics. The anaerobic bacterial count decreased significantly in four of five patients treated with SBT/CPZ, from 1010.2+/-0.36/g before treatment to 105.22+/-3.51/g. In the PAPM/BP-treated group, the anaerobic bacterial count did not change after antibiotic therapy. We also investigated the major genera of colonic anaerobes, and found that the numbers of bifidobacteria were maintained during PAPM/BP administration. However, in the SBT/CPZ group, the number of bifidobacteria decreased to below the detection limit in four of five patients. Little change was observed in the aerobic bacterial count in either group. However, Enterobacteriaceae were replaced by enterococcus or candida in all patients from the SBT/CPZ group and in one of five patients from the PAPM/BP group. Physicians should be alert for the possible clinical consequences of changes in intestinal microflora after antibiotic treatment of postoperative infections.

Antibiotics affecting gastrointestinal colonization of mice by yeasts

A group of three-month old, male Crl:CD1(ICR) BR mice, was fed chow containing Candida albicans, while another group of the same type of mice was fed regular chow. Both groups were treated subsequently with either antibiotics or normal saline for 10 days. Stool cultures were performed before treatment, at the end of treatment, and one week after the end of treatment, to determine the level of colonization of the gastrointestinal tract by the yeast. The stools of mice fed Candida and treated with antibiotics had substantially higher Candida counts than control mice fed C. albicans and treated with saline. The highest concentrations of the yeast were observed in the stools of mice treated with cefotaxime as compared to those of mice treated with pefloxacin, amikacin and amoxicillin. No Candida was found in the stools of mice fed regular chow and treated with antibiotics or saline. Dissemination of Candida was not observed in the visceral organs of any mouse.

Natural history of bloodstream infections in a burn patient population: the importance of candidemia

Because of a perceived increase in Candida bloodstream infections in our burn unit, we retrospectively reviewed all the microbiologic data and the medical records of 209 patients with burns admitted during a 42-month period. Twice weekly burn wound cultures demonstrated that Candida species were the tenth most frequently isolated organisms (69/191 patients, 36%). Despite the low frequency of isolation from burn wounds, Candida species were the most common organisms found in blood cultures and urine cultures. Of 49 patients with positive blood cultures, 16 (33%) had clinically significant culture growth of yeasts: Candida albicans, 12; Candida parapsilosis, 2; Candida tropicalis, 1; and Torulopsis glabrata, 1. Patients with candidemia were more likely than patients with blood culture growth of other organisms to have burn wound cultures that grew Candida (15/16 vs 21/33, p = 0.02), larger burns (61% vs 38%, p < 0.001), and death (63% vs 27%, p = 0.02). Multivariate analysis demonstrated that the total number of blood cultures with microorganism growth and large burn size were the greatest independent risk factors for candidemia. These data demonstrate that yeasts are pathogens of major importance in patients with burns, suggesting that in patients with burns who have suspected sepsis and large burn injury or a previous bacteremia, strong consideration should be given to administration of amphotericin B initiation of empiric antibacterial therapy.

Modulation of the intestinal flora of mice by parenteral treatment with broad-spectrum cephalosporins

A study was performed to determine the effect of parenteral treatment with four broad-spectrum cephalosporins (cefoperazone, ceftriaxone, ceftazidime, and cefepime) on the number of aerobic gram-negative rods and on the outgrowth of Candida albicans and a multiresistant strain of Citrobacter freundii in the feces of mice. The estimated fractions of a parenteral dose that were excreted into the gastrointestinal tract were 0.37 for cefoperazone, 0.11 for ceftriaxone, 0.03 for ceftazidime, and 0.002 for cefepime. All four cephalosporins significantly decreased the number of aerobic gram-negative rods in the feces, and virtually all gram-negative rods were eliminated at high doses of cefoperazone, ceftazidime, and ceftriaxone. Furthermore, at high doses these three compounds led to a significant increase of the outgrowth of resistant Citrobacter freundii. The outgrowth of Candida albicans was increased at high doses of cefoperazone and ceftriaxone, whereas ceftazidime and cefepime did not have this effect. The most profound changes in the gastrointestinal ecology were observed during treatment with high doses of cefoperazone. The results suggest that the colonization resistance of the gastrointestinal tract can be substantially decreased by parenteral treatment with cefoperazone and, to a lesser extent, with ceftriaxone and ceftazidime.

Effects of broad-spectrum antimicrobial agents on yeast colonization of the gastrointestinal tracts of mice

Male Crl:CD1 (ICR) BR mice, 3 months old, were fed regular chow or chow containing Candida albicans. Subsequently, both groups were treated with either antibiotics or normal saline for 10 days. Stool cultures were obtained to determine the extent of C. albicans colonization immediately before treatment, at the end of treatment, and 1 week after the discontinuation of treatment. Animals in the antibiotic-treated groups had substantially higher Candida counts than control animals fed C. albicans, especially if they received ceftriaxone, cefoperazone, or ticarcillin-clavulanic acid. There was no evidence of Candida dissemination to internal organs.

Effects of aztreonam on fecal flora and on vitamin K metabolism

The effects of aztreonam on fecal flora and on descarboxy prothrombin (PIVKA-II) in plasma and gamma-carboxyglutamic acid (Gla) in urine as an index of vitamin K metabolism were studied in seven children (age range, 2 months to 2 years) with urinary tract infections. Daily doses of aztreonam were 60 to 80 mg/kg. Stool specimens were obtained before the treatment, on days 3 to 5 of aztreonam use, and from 3 to 5 days after the cessation of treatment. The counts of enterobacteria decreased (P less than 0.01) and those of streptococci increased (P less than 0.05) during aztreonam treatment. The anaerobic organisms, especially bifidobacteria and bacteroides, showed no marked change. PIVKA-II and Gla were investigated before and during the treatment with aztreonam. PIVKA-II was not detected in seven patients before or during aztreonam use. There were no significant differences in the levels of Gla in urine before or during the treatment.

Suppression of colonic microflora by cefoperazone and evaluation of the drug as potential prophylaxis in bowel surgery

We evaluated the activity of cefoperazone (CPZ) on the intestinal flora in terms of its use as a single prophylactic drug in colon surgery. Twenty-four healthy male volunteers between the ages of 20 and 40 were assigned to receive either CPZ, oral neomycin-erythromycin, or no antibiotics. A mechanical bowel preparation, Golytely, was also given to each of the subjects. With intravenous CPZ, antibiotic levels in the stool ranged from less than 2 to 649 micrograms/ml and the total fecal bacterial counts dropped 3 to 4 log10 CFU/g. Higher levels of CPZ were detected in the stools when an oral dose was added, 1,446 to 5,445 micrograms/ml, and the bacterial counts were reduced maximally 4 to 6 log10 CFU/g. The combination of the oral and intravenous doses produced suppression of the microflora and high levels in blood, all with a single antibiotic.

Amoxicillin and diaper dermatitis

Multiple skin sites and the gastrointestinal tract of 57 infants with otitis media were cultured quantitatively for Candida albicans before and after antibiotic therapy. Ten days of systemic therapy with amoxicillin was associated with a twofold increase in the recovery of C. albicans from the rectum and skin. Infants who developed diaper dermatitis had a significant increase in the number of C. albicans organisms recovered from these sites. We conclude that the use of amoxicillin increases the risk for developing diaper dermatitis.

Colonization resistance of the human intestinal microflora: testing the hypothesis in normal volunteers

Colonization resistance is the mechanism whereby the intestinal microflora protects itself against incursion by new and often harmful microorganisms. Some authors have claimed that colonization resistance is related to the integrity of the anaerobic flora, but this point has not been established in humans. In previous studies in our laboratory cefoxitin, piperacillin, cefoperazone or aztreonam were administered intravenously to healthy volunteers in order to study changes in the intestinal flora and acquisition of new strains. Seven of 16 antibiotic-treated subjects were colonized with gram-negative bacilli, but no correlation was observed between this colonization and the suppression of either anaerobes or any other component of the fecal flora. Marked strains of Escherichia coli and Pseudomonas aeruginosa were also administered by mouth in order to test acquisition of new bacteria. The fed bacteria were found in the stools of both antibiotic-treated and control subjects; the antibiotics had no apparent influence on the ability of these strains to colonize the intestinal tract. Our work, along with findings of others, supports the concept that colonization resistance occurs in humans and is diminished by antibiotic administration. However, it does not support the hypothesis that colonization resistance is related to the anaerobic microflora.

Effect of a single dose of cefotaxime or ceftriaxone on human faecal flora. A double-blind study

The effect of cefotaxime and ceftriaxone on faecal flora was investigated in women undergoing routine vaginal or abdominal hysterectomy. Three groups of 9 patients received, in a double-blind fashion and just before surgery, cefotaxime 2g intravenously, ceftriaxone 2g intravenously or no antibiotic (controls). Stools were collected before prophylaxis (sample 1) and after surgery (samples 2 and 3). The only alteration after cefotaxime was a decrease of non-fastidious aerobic Gram-negative flora in sample 2. The same effect was more pronounced after ceftriaxone (p less than 0.01) which, in addition, increased yeast colonies (p less than 0.05) in sample 2. In sample 3, more resistant (MIC greater than 32 mg/L) aerobic and anaerobic bacteria were found after ceftriaxone (log10 median 7.5 and 9.0, respectively) than after cefotaxime (4.2 and 6.0) or in controls (4.4 and 6.6) [p less than 0.01 in each case]. Group D streptococci and Gram-positive cocci remained unchanged in the 3 groups. Clostridium difficile cytotoxin assays were negative. The effects on faecal flora were more pronounced after ceftriaxone.

Factors affecting colonization and dissemination of Candida albicans from the gastrointestinal tract of mice

Male ICR Swiss mice (2 to 3 months old) were fed Candida albicans in their drinking water for 3 days, followed by no treatment, antibiotics in their drinking water (daily), or immunosuppressants given by intraperitoneal injection (two to three times weekly) over a 3- to 4-week period. The organs of animals were processed to determine the numbers of C. albicans and total aerobic bacteria per g of tissue. Untreated animals had mean Candida counts during the 1-month period of 10(2.3) CFU/g of cecum. Animals in six of eight antibiotic-treated groups had mean cecal Candida counts higher than those of control animals (P less than 0.05), with clindamycin-gentamicin producing the highest counts (10(4.7) CFU/g). Cyclophosphamide produced counts (10(4.3) CFU/g) which were higher (P less than 0.05) than those resulting from methotrexate (10(3.0) CFU/g) or steroid (10(2.7) CFU/g) treatment. Cyclophosphamide-clindamycin-gentamicin treatment was associated with the highest (P less than 0.05) levels of Candida colonization (10(6.5) CFU/g). Mice receiving immunosuppressants plus clindamycin-gentamicin were more likely to disseminate C. albicans than were mice receiving antibiotics alone (P less than 0.001). Our findings suggest that colonization of the guts of mice by C. albicans can be facilitated by manipulating the aerobic, anaerobic, or both types of gut flora. The combined effect of immunosuppressants on both Candida gut colonization and dissemination appears multifactorial and deserves further investigation.

Effect of broad-spectrum parenteral antibiotics on "colonization resistance" of intestinal microflora of humans

Studies with animals have shown that the normal intestinal microflora protects against colonization by new strains ("colonization resistance") and that this protective effect may be related to the anaerobic component of the microflora. However, colonization resistance has not been shown in humans. We administered cefoxitin, piperacillin, cefoperazone, and aztreonam intravenously to healthy subjects for 9 days and monitored the acquisition of new isolates in the fecal flora. Seven of sixteen antibiotic-treated subjects but none of four untreated controls became colonized by gram-negative bacilli. However, there was no correlation between colonization and the particular drug given or the extent of suppression of anaerobes or of any other component of the fecal microflora. Cefoxitin and piperacillin were associated with the greatest increases in the numbers of drug-resistant bacteria and in fecal beta-lactamase content. The results of this study support the concept that colonization resistance occurs in humans and is diminished by antibiotic administration but fail to support the hypothesis that resistance is related to the anaerobic microflora.

Effect of broad-spectrum parenteral antibiotics on composition of intestinal microflora of humans

We compared the effects of four beta-lactam drugs with widely differing antibacterial and pharmacological properties on the composition of the intestinal flora. Cefoxitin, piperacillin, cefoperazone, and aztreonam were given intravenously for 9 days to healthy volunteers. Cefoperazone reduced the numbers of aerobic and anaerobic bacteria to undetectable levels. At the other extreme, cefoxitin had little effect on the normal flora. Aztreonam markedly reduced the numbers of aerobes, whereas piperacillin had a variable effect on both aerobic and anaerobic bacteria. There was extensive overgrowth of enterococci in subjects given cefoxitin or aztreonam, which have little activity against this species, and of yeasts in subjects given cefoperazone or piperacillin. Cefoperazone reached concentrations of 2,727 to 8,840 micrograms/g in the feces, whereas the other agents were generally undetectable. These results show that the new beta-lactam antibiotics produce widely varying effects on the fecal microflora after parenteral administration and that these effects are consistent with the antibacterial and pharmacological properties of the drugs.

Effect of imipenem-cilastatin therapy on fecal flora

Alteration of fecal flora was prospectively studied in 21 children receiving imipenem-cilastatin therapy under protocol for therapy of infections. Although no profound reduction in facultative or anaerobic flora was observed, qualitative and quantitative increases in organisms which were resistant or less susceptible to imipenem occurred. Of 21 patients, 13 (62%) had increases in counts of Enterococcus spp. of at least 10(3) organisms per g (wet weight) of stool, and 7 (33%) had acquisition of or similar increases in counts of Candida species. No change in susceptibility of isolates to imipenem was demonstrable during therapy. However, the MICs for 50 and 90% of the strains of Enterococcus spp. (2 and 8 micrograms/ml, respectively) were higher than those previously reported.

The effect of antimicrobial agents on fecal flora of children

Influences of antibiotics on the fecal flora in children were studied for oral ampicillin, penicillin V, erythromycin, cefaclor, and gentamicin and for intravenous ampicillin, methicillin, cefpiramide, and ceftazidime. All antibiotics affected the normal flora, although the quality and quantity of the changes were variable. No substantial differences were noted between the oral and intravenous use of ampicillin with regard to its effect on the flora. Three penicillins, ampicillin, penicillin V, and methicillin, caused remarkable changes. The characteristic pattern observed was the considerable suppression of Bifidobacterium, Streptococcus, and Lactobacillus species. Although enterobacteria did not significantly change in number, Klebsiella spp. frequently replaced Escherichia coli. In patients given erythromycin and cefaclor, the reduction in the number of Bifidobacterium spp. was 1 log10 and that of members of the family Enterobacteriaceae was 3 log10. Gentamicin administered orally caused a drastic change, including a remarkable decline of E. coli to less than 2 log10/g of feces. Cefpiramide, a parenteral expanded-spectrum cephalosporin, suppressed normal flora so markedly that almost all species of organisms were eradicated, and the active growth of yeasts was promoted (2.6 log10 increase). Ceftazidime caused similar changes as cefpiramide, but the changes were less extensive. Yeasts increased after treatment with most antibiotic groups. This increase was particularly prominent in patients given oral penicillins and expanded-spectrum cephalosporins.

The influence of third-generation cephalosporins on the aerobic intestinal flora

The influence of three third-generation cephalosporins with varying degrees of biliary excretion on the aerobic flora was investigated. The faecal flora prior to therapy with one of these substances consisted mainly of anaerobic bacilli. Escherichia coli was present in concentrations of 10(9) organisms/g stool. Candida albicans and enterococci were observed in concentrations of 10(5) - 10(6) organisms/g stool. Within 24 hours after the administration of ceftriaxone and cefoperazone, the gram-negative aerobic flora was completely eradicated. C. albicans and enterococci increased to 10(9) organisms/g stool. Between the third and tenth days (mean 6.7 days) of therapy Pseudomonas aeruginosa, Enterobacter and Citrobacter in this order of frequency reappeared in the faecal flora with complete resistance to all betalactam antibiotics. C. albicans and enterococci decreased to 10(7) organisms/g stool. The anaerobic flora was largely unaltered. In contrast, cefotaxime had only a moderate influence on the aerobic faecal flora. Concentrations of gram-negative organisms decreased to 5 X 10(7) organisms/g stool during the first five days of therapy; the concomitant increase in C. albicans and enterococci was approximately 1 log 10. No alterations in the susceptibility pattern were observed. We would like to emphasize that substantial alterations of the faecal flora and the susceptibility pattern of antibiotics may accompany the use of antimicrobial agents, particularly those with a high degree of biliary elimination.

Impact of injectable cephalosporins on the gastrointestinal microflora: observations in healthy volunteers and hospitalized patients

A disturbed microbiological ecosystem of the gut flora is frequently seen as a consequence of antibiotic therapy. Because this impact on the physiological balance is known to be causative for severe nosocomial infections and is mainly seen with antibiotics that are massively excreted via the bile (e.g. broadspectrum penicillins, ceftriaxone and cefoperazone), we investigated cefotaxime (CTX), cefotiam (CTM), cefmenoxime (CMX), ceftazidime (CAZ), ceftizoxime (CZX) and cefazolin + netilmicin (CEZ + NTL) in healthy volunteers. The respective daily i.v. doses, days of medication and numbers of volunteers were: CTX 3 g, 1 d, n = 8; CTM 6 g, 3 d, n = 15; CMX 4 g, 3 d, n = 15; CAZ 4 g, 1 d, n = 8; CZX 4 g, 1 d, n = 8; CEZ + NTL 2 X 3 g + 1 X 3 mg/kg/day, 4 d, n = 15. CTX was also investigated in 11 selected hospitalized patients. One or two stool specimens were taken before, during and several days after medication. The microorganisms were also tested for ampicillin and CEZ resistance on selective media. Ampicillin and CEZ resistance was much higher in hospitalized patients than in volunteers (mainly Proteus and Serratia sp.): 90% vs. 42% and 63.6% vs. 43%, respectively. CTX did not affect the anaerobes (Bacteroides sp. and lactobacilli) that are antagonistic to clostridia and Candida. No selection of strains resistant to ampicillin or CEZ occurred. In hospitalized patients, the level of resistance to these drugs was lower after treatment than before.(ABSTRACT TRUNCATED AT 250 WORDS)

Alterations in human fecal flora, including ingrowth of Clostridium difficile, related to cefoxitin therapy

To evaluate the effects of parenteral cefoxitin therapy on human fecal flora, we cultured fecal specimens obtained from six patients before, during, and after therapy and used standard methods to identify and quantify all microorganisms. The major changes (observed in at least three patients) included the acquisition or proliferation of group D Streptococcus species, coagulase-negative Staphylococcus species, cefoxitin-resistant members of the family Enterobacteriaceae, Pseudomonas species, and various species of the Bacteroides fragilis group. The most striking finding was ingrowth of Clostridium difficile, noted in five of the six patients. There was concomitant eradication or decrease of cefoxitin-susceptible Enterobacteriaceae family members, Bacteroides species other than the B. fragilis group, Clostridium species other than C. difficile, and Lactobacillus species. These marked alterations of fecal flora may have important clinical consequences.

In vitro antibacterial activity of the combination of clindamycin and ceftazidime

A total of 49 anaerobic and 52 aerobic or facultative bacteria were tested for their susceptibilities to clindamycin and ceftazidime alone and in combination. Synergy was noted for 11 strains, whereas antagonism was not detected. The combination of clindamycin and ceftazidime may prove to be useful for the treatment of severe mixed infections caused by anaerobes and aerobes or facultative bacteria.

The effect of piperacillin prophylaxis on the colonic microflora In patients undergoing colorectal surgery

Piperacillin was given parenterally in doses of 4 g every 8 h for two days to 20 patients undergoing colorectal surgery. A series of serum and fecal specimens were taken to analyse piperacillin concentrations. Tissue samples from the gut wall were taken during surgery. The maximum serum concentrations during surgery were reached 15 min after piperacillin administration. On Day 0 the mean half-life was 1.9 h and the mean area under the serum concentration curve was 536.8 mg/l. The piperacillin concentrations in the tissue samples ranged from 4.2 to 103.5 mg/kg. The tissue/serum ratio was 0.45. The piperacillin concentrations in the fecal samples ranged from not detectable to 101.2 mg/kg. Fecal samples were also collected during the investigation period for the cultivation of aerobic and anaerobic bacteria. Of the aerobic bacteria, enterococci, streptococci and enterobacteria decreased in on fourth of the patients during the prophylaxis period. Anaerobic bacteria, e. g. cocci, gram-positive rods, fusobacteria and bacteroides, decreased in two thirds of the patients during the same period. After the piperacillin administration period, the aerobic and anaerobic colon microflora returned to the pre-treatment pattern in most patients. Postoperative infections due to Escherichia coli, Morganella morganii, Bacteroides fragilis, peptococci and peptostreptococci occurred in two patients.