Alcaligenes Faecalis - Research Paper Example

Alcaligenes faecalis Module and Number Alcaligenes faecalis Introduction According to Feridun Kavuncuoglu, Aydin Unal, Nilufer Oguzhan, Bulent Tokgoz, Oktay Oymak and Cengiz Utas Alcaligenes faecalis was isolated in 1896 by Petruschky from stale beer. Subsequently, numerous strains of the organism have been discovered. Alcaligenes faecalis is a “motile, flagellated, slender, slightly curved, non spore-forming, slowly growing, nonfermenting, nonencapsulated gram-negative aerobe of the family Achromobacter” state Kavuncuoglu et al (118). It is found in the alimentary tract as a harmless saprophyte in 5% to 19% of the normal population. This organism does not usually cause systemic infection. Alcaligenes faecalis has been reported to cause “sepsis, meningitis, peritonitis, enteric fever, appendicitis, cystitis, chronic suppurative otitis media, abscesses, arthritis, pneumonitis, and endocarditis” (Kavuncuoglu et al 118). Because Alcaligenes faecalis is resistant to commonly used antibiotics, the organism is associated with fatal outcomes. Thesis Statement: The purpose of this paper is to investigate Alcaligenes faecalis, and examine various aspects of the organism, its morphology and effects. Taxonomy, Morphology and Functions of Alcaligenes faecalis Hans Riemann and Dean O. Cliver argue that food borne diseases are increasing because of accelerated globalization of food supply, and emphasize the importance of finding new ways of detecting and identifying foodborne pathogens, and the elimination of food-related infections and intoxications. “Alcaligenes faecalis is a Gram-negative, oxidase-positive, and catalase-positive microorganism shaped in the form of a rod, coccal-rod or coccal” (Riemann and Cliver 343). The obligate aerobic bacterium moves with the help of peritrichous flagella, usually eight in number, but may occasionally be up to twelve. Some strains of the microorganism are capable of anaerobic respiration in the presence of nitrate or nitrite (Riemann and Cliver 343). Alcaligenes faecalis generally exists singly, and has a size of 0.5 – 1.0 x 0.5 – 2.6 um. The organism grows optimally at a temperature range of 20-370C. Although not considered as a major food-borne pathogen, it has caused occasional food-borne outbreaks with the typical symptoms of abdominal pain, headache, vomiting and diarrhoea. Further, “A. faecalis is an important food spoilage bacterium” ((Riemann and Cliver 344). Besides soil and water, the organism has been isolated from various sources such as medical specimens including body fluids and body waste matter, and from nematodes and insects. Some species of A. faecalis are commonly found in the intestinal tracts of vertebrates (Riemann and Cliver 344). The scientific classification of Alcaligenes faecalis (Vasanthakumari 335) is as follows: Kingdom: Bacteria Phylum: Proteobacteria Class: Beta Proteobacteria Order: Burkholderiales Family: Alcaligenaceae Genus: Alcaligenes Species: Alcaligenes faecalis (Vasanthakumari 335) Fig.1. White, Glistening Colonies of Alcaligenes faecalis on Blood Agar (Herrera, 2012) Paul G. Engelkirk and Janet L. Duben-Engelkirk observe that identification of Gram staining Alcaligenes faecalis and CDC Alcaligenes – like group 1 reveals that they cannot be differentiated from other non-fermenters. They have similar cellular morphology, and are motile by peritrichous flagella. The colonial morphology reveals that A. faecalis produces white colonies with a thin, spreading, irregular edge (Fig.1). Older colonies, as shown in the illustration above “tend to spread at the periphery and turn the agar a green-apple color” ((Engelkirk and Duben-Engelkirk 332). James T. Staley, Don J. Brenner, Noel R. Krieg and co-authors observe that the type subspecies faecalis of the Species Alcaligenes faecalis contains the type strain of the species. Its morphological characteristics are the same as those of the Genus Alcaligenes. Colonies of the organism on nutrient agar range in color and appearance “from non-pigmented to greyish-white, translucent to opaque, flat to low convex, margin usually entire, usually smooth, sometimes dull or rough” (Staley, Brenner, Krieg et al 654). Particular strains of A. faecalis that were earlier termed A. odorans release a distinctive green apple odor, and produce a greenish discoloration of blood agar. “A. faecalis and CDC Alcaligenes – like group 1 are classified as oxidase positive, indole negative, asaccharolytic nonfermenters” (Engelkirk and Duben-Engelkirk 331). While CDC Alcaligenes-like group 1 can reduce both nitrate and nitrite, A. faecalis can reduce nitrite but not nitrate. Staley et al (654) supports this view, and adds that for most strains, it is possible to undertake anaerobic respiration with nitrite, but not with nitrate, as a sole electron acceptor. Some strains oxidise arsenite. “Alcaligenes faecalis are among the bacterial taxa that are able to combine aerobic denitrification and heterotrophic nitrification” (Staley et al 654); these may contribute to emissions of nitric and nitrous oxide into the atmosphere, even with logarithmic growth of the organism. Sandra Otte, Nicole G. Grobben, Lesley A. Robertson et al agree that nitrous oxide can be a harmful byproduct produced during nitrogen removal from wastewater. Wastewater systems operate under different aeration procedures, hence the researchers investigated the impacts of different oxygen concentrations and oxygen fluctuations on denitrification. “Continuous cultures of Alcaligenes faecalis TUD produced N20 under anaerobic as well as aerobic conditions” (Otte et al 2421). The comparatively highest production of nitrous oxide was observed below a dissolved oxygen concentration of 5%. Under these conditions, it was possible to measure significant activities of nitrite reductase. It was found that after changing from aerobic to anaerobic conditions, there was inadequate nitrite reductase present to sustain growth; hence the culture began to wash out (Otte et al 2421). After a period of 20 hours, the investigators detected nitrite reductase, and perceived that the culture started to recover. They could measure nitrous oxide reductase only after 27 hours, “suggesting sequential induction of the dentrification reductases, causing the transient accumulation of N20” (Otte et al 2421). After the conversion from anaerobic to aerobic conditions, nitrite reduction continued at a lower rate for several hours. Nitrous oxide reduction appeared to end immediately after the transition, indicating inhibition of nitrous oxide reductase, resulting in high N20 emissions, of a maximum of 1,4 mmol liter21h21 (Otte et al 2421). The nitrite reductase was not activated by oxygen, but its synthesis was culminated. Under these conditions, a half-life of 16 to 22 hours for nitrite reductase was calculated. In a “dynamic aerobic-anaerobic culture of Alcaligenes faecalis, a semisteady state in which most of the N20 production took place after the transition from anaerobic to aerobic conditions was obtained” (Otte et al 2421). The nitrite consumption rate in this culture was equal to that in an anaerobic culture, 0.95 and 0.92 mmol liter21h21, respectively, but the production of N20 was greater in the dynamic culture, 28 and 26% of nitrite consumption, respectively, state Otte et al (2421). The physiological and nutritional characteristics of Alcaligenes faecalis reveal that carbohydrates are not its sole source of carbon. The organism is able to achieve good growth on several acid and amino acid bases. It initiates catabolism of aromatic amines not by using a monoamine oxidase, but “by an aromatic amine dehydrogenase that is structurally similar to methylamine dehydrogenase and possesses the same tryptophan tryptophyl-quinone prosthetic group as the latter” (Staley et al 654). Alcaligenes species is clinically significant. It includes A. faecalis and CDC Alkaligenes-like group 1. Among the two species, the one isolated more frequently from clinical specimens is A. faecalis. “Both species can be found in water, soil, and moist areas within the hospital environment” (Engelkirk and Duben-Engelkirk 331). A. faecalis sometimes causes nosocomial infections such as urinary tract infections, pneumonia and septicemia. Alcaligenes faecalis has been found to be resistant to ampicillin, aztreonam, and gentamicin; and has different suceptibility to other antimicrobial agents. Treatment for Alcaligenes faecalis Kavuncuoglu et al (118) investigated the first reported case of Alcaligenes faecalis. An 83-year-old female patient presented with nausea, vomiting, abdominal pain, fever, and cloudy dialysate for 2 days. Since the last 4 years she was undergoing continuous ambulatory peritoneal dialysis (CAPD), because of end-stage renal disease of diabetes mellitus. Two years ago, she had experienced on peritonitis episode. The CAPD catheter’s tunnel and exit sites were found to be normal. The white blood cell count of the peritoneal effluent was 8200/mm3, with neutrophils predominant. Gram strain of peritoneal fluid did not reveal any micro-organisms. After microbiological examination, the patient was experimentally given an antibiotic regimen of intravenous cephazolin and amikacin. Peritoneal effluent cultures grew Alcaligenes faecalis which could be effectively treated with the help of amikacin, ciprofloxacin, piperacillin/ tazobactam, meropenem, and ceftazidime. The empirical treatment was changed to 100 mg of ciprofloxacin administered intravenously twice daily (Kavuncuoglu et al 118). The patient’s condition improved rapidly, and her dialysate WBC count decreased to 0/mm3. Intravenous ciprofoxacin therapy was continued for 5 days, after which it was changed to oral ciprofloxacin 250 mg twice daily (Kavuncuoglu et al 118). The total duration of antibiotic therapy was 3 weeks. The tenchkoff catheter was not removed. Significantly, Alcaligenes faecalis is the most frequently isolated member of Alcaligenaceae in the clinical laboratory. It is found in soil and water, and in various clinical specimens such as urine, faeces, and blood. “Infections due to Alcaligenes faecalis are opportunistic and are acquired from moist items such as nebulizers, respirators, and lavage fluid”, state Kavuncuoglu et al (118). The source of peritonitis in the present patient was considered to be the gastrointestinal tract, because of the occurrence of diarrhea before the CAPD-related peritonitis. Crucial findings indicating infection were not available at the peritoneal catheter exit site or the tunnel; and blood cultures did not reveal microorganisms. The investigators concluded that continuous ambulatory peritoneal dialysis (CAPD) “effluent may be contaminated by Alcaligenes faecalis which causes CAPD-related peritonitis but can be successfully treated with antimicrobial treatment without removal of the Tenckhoff catheter (Kavuncuoglu et al 318). Conclusion This paper has highlighted Alcaligenes faecalis, and investigated its taxonomy, morphology, characteristics, functions and treatments for infection. Alcaligenes faecalis is commonly found in soil, water and wastewater treatment plants; hence the bacteria enriched by the denitrification process of activated sludge, are found to produce significant amounts of trace gas emissions of suboptimally functioning wastewater treatment systems (Staley et al 654). Thus, nitrous oxide is a harmful side effect of nitrogen removal from wastewater. Operating under different aeration systems, different oxygen concentrations and fluctuations are found to be effective in denitrification. Further, antimicrobial treatments without removal of Tenckhoff catheter was found to be successful against infection by Alcaligenes faecalis which occurs in body fluids and wastes, causing peritonitis related to continuous ambulatory peritoneal dialysis (CAPD). It is concluded that further research is required on effective methods to counter the harmful effects of the organism which occurs in various sources. Works Cited Engelkirk, Paul G. and Janet L. Duben-Engelkirk. Laboratory Diagnosis of Infectious Diseases: Essentials of Diagnostic Microbiology. The United States of America: Lippincott Williams & Wilkins, 2008. Herrera, Jose. Alcaligenes faecalis. Truman State University, Missouri. http://jherrera.sites.truman.edu/alcaligenes-faecalis/ Kavuncuoglu, Feridun, Aydin Unal, Nilufer Oguzhan, Bulent Tokgoz, Oktay Oymak and Cengiz Utas. First Reported Case of Alcaligenes faecalis Peritonitis. Peritoneal Dialysis International, Vo.30, No.1, p.118-119, January-February 2010. Otte, Sandra, Nicole G. Grobben, Lesley A. Robertson, Mike S.M. Jetten and J. Gijs Kuenen. Nitrous Oxide Production by Alcaligenes faecalis Under Treatment and Dynamic Aerobic and Anaerobic Conditions. Applied and Environmental Microbiology, Vo.2426, No.7, 2421-2426. Riemann, Hans and Dean O. Cliver. Foodborne infections and intoxications. Edition 3. The Netherlands: Academic Press. Staley, James T., David R. Boone, Don J. Brenner, et al. Bergey’s Manual of Systematic Bacteriology: Volume Two: The Probacteria. Edition 2. New York: Springer, 2005. Vasanthakumari, R. Textbook of Microbiology. New Delhi: BI Publications Pvt. Ltd., 2007. Read More