Microbiology taxonomy 5th edition textbook pdf download

About three quarters of leech species feed on blood extracted from a host while the remainder are predators. Leeches either have a protusible pharynx, commonly called a proboscis, or a non-protusible pharynx which may or may not be armed with jaws. In the proboscisless leeches, the jaws of Arhynchobdellids are at the front of the mouth, and have three blades set at an angle to each other. In feeding these slice their way through the skin of the host, leaving a Y-shaped incision. Behind the blades is the mouth, located ventrally at the anterior end of the body.

It leads successively into the pharynx, a short oesophagus, a crop in some species , a stomach and a hindgut, which ends at an anus located just above the posterior sucker. The stomach may be a simple tube, but the crop, when present, is an enlarged part of the midgut with a number of pairs of ceca that stores ingested blood. The leech secretes an anticoagulant, hirudin, in its saliva which prevents the blood from clotting before ingestion.

The bodies of predatory leeches are similar, though instead of jaws many have a protrusible proboscis, which for most of the time they keep retracted into the mouth. Such leeches are often ambush predators that lie in wait till they can strike prey with the proboscises in a spear-like fashion. The prey is usually sucked in and swallowed whole. Some Rhynchobdellida, however, suck the soft tissues from their prey, making them intermediate between predators and blood-suckers.

When they are hungry, leeches use their anterior suckers to connect to hosts for feeding. Once attached, leeches use a combination of mucus and suction to stay in place while they inject hirudin into the hosts' blood streams. In general, sanguivorous leeches are non host-specific, and do little harm to their host, dropping off after consuming a blood meal.

Some marine species, however, remain attached until it is time to reproduce. If present in great numbers on a host, these can be debilitating, and in extreme cases, cause death. Leeches are unusual in that they do not produce amylases, lipases or endopeptidases. Deficiency of digestive enzymes and of B complex vitamins is compensated for by enzymes and vitamins produced by endosymbiotic microflora.

In Hirudo medicinalis , these supplementary factors are produced by an obligatory symbiotic relationship with two bacterial species, Aeromonas veronii and a still-uncharacterised Rikenella species. Nonbloodsucking leeches, such as Erpobdella punctata , are host to three bacterial symbionts, Pseudomonas , Aeromonas , and Klebsiella spp.

The bacteria are passed from parent to offspring in the cocoon as it is formed. The nervous system of leeches is formed of a small number of large nerve cells; this has resulted in leeches being used as model organisms for the study of invertebrate nervous systems.

The main nerve centre consists of the cerebral ganglion above the gut and another ganglion beneath it, with connecting nerves forming a ring around the pharynx a little way behind the mouth. A nerve cord runs backwards from this in the ventral coelomic channel, with 21 pairs of ganglia in segments 6 to In segments 27 to 33, other paired ganglia fuse to form the caudal ganglion.

Leeches have between two and ten pigment spot ocelli, arranged in pairs towards the front of the body. There are also sensory papillae arranged in a lateral row in one annulation of each segment. Each papilla contains many sensory cells.

Some rhynchobdellids have the ability to change colour dramatically by moving pigment in chromatophore cells; this process is under the control of the nervous system but its function is unclear as the change in hue seems unrelated to the colour of the surroundings.

Leeches can detect touch, vibration, movement of nearby objects, and chemicals secreted by their hosts; freshwater leeches crawl or swim towards a potential host standing in their pond within a few seconds.

Species that feed on warm-blooded hosts move towards warmer objects. Many leeches avoid light, though some blood feeders move towards light when they are ready to feed, presumably increasing the chances of finding a host.

Leeches live in damp surroundings and in general respire through their body wall. The exception to this is in the Piscicolidae, where branching or leaf-like lateral outgrowths from the body wall form gills. Some rhynchobdellid leeches have an extracellular haemoglobin pigment, but this only provides for about half of the leech's oxygen transportation needs. Leeches move using their longitudinal and circular muscles, which other annelids such as earthworms use for peristalsis, with the addition of the use of their posterior and anterior suckers one on each end of the body to enable them to progress by looping or inching along, in the manner of geometer moth caterpillars.

The posterior end is attached to the substrate, and the anterior end is projected forward peristaltically by the circular muscles until it touches down, as far as it can reach, and the anterior end is attached.

Microbiology with Diseases by Taxonomy, 5th Edition For courses in introductory microbiology. The text provides a mobile-friendly Microbiology with Diseases by Taxonomy 4th Edition Study Microbiology with Diseases by Taxonomy 4th Edition discussion and chapter questions and find Microbiology with Diseases by Taxonomy 4th Edition study guide questions and answers.

Test Bank for Microbiology with Diseases by Taxonomy 4th In England, it was known as Boulogne sore throat, as it spread from France. In , Edwin Klebs identified the bacterium causing diphtheria [33] and named it Klebs-Loeffler bacterium. The club shape of this bacterium helped Edwin to differentiate it from other bacteria.

Over the period of time, it was called Microsporon diphtheriticum , Bacillus diphtheriae , and Mycobacterium diphtheriae. Current nomenclature is Corynebacterium diphtheriae.

Friedrich Loeffler was the first person to cultivate C. He also showed that the bacillus produces an exotoxin. Joseph P. It soon replaced tracheostomy as the emergency diphtheric intubation method. In , Shibasaburo Kitasato and Emil von Behring immunized guinea pigs with heat-treated diphtheria toxin. Behring used this antitoxin now known to consist of antibodies that neutralize the toxin produced by C. Successful treatment of human patients with horse-derived antitoxin began in , after production and quantification of antitoxin had been optimized.

In , H. Mulford Company of Philadelphia started production and testing of diphtheria antitoxin in the United States. In , Paul Ehrlich developed a standardized unit of measure for diphtheria antitoxin. This was the first ever standardization of a biological product, and played an important role in future developmental work on sera and vaccines.

In , 10 of 11 inoculated St. Louis children died from contaminated diphtheria antitoxin. The horse from which the antitoxin was derived died of tetanus. This incident, coupled with a tetanus outbreak in Camden, New Jersey, [42] played an important part in initiating federal regulation of biologic products. Ruth was the eldest daughter of former PresidentGrover Cleveland and the former first ladyFrances Folsom.

In , Franklin Royer, from Philadelphia's Municipal Hospital, published a paper urging timely treatment for diphtheria and adequate doses of antitoxin.

Only those who were not exposed to diphtheria were preferably vaccinated. A massive, five-year campaign was coordinated by Dr. As a part of the campaign, 85 million pieces of literature were distributed by the Metropolitan Life Insurance Company with an appeal to parents to 'Save your child from diphtheria.

In , in Dallas, Texas, 10 children were killed and 60 others made seriously ill by toxic antitoxin which had passed the tests of the New York State Health Department. Mulford Company of Philadelphia manufacturers paid damages in every case.

In the s, an estimated , to , cases of diphtheria occurred per year in the United States, causing 13, to 15, deaths per year. In , Alexander Thomas Glenny increased the effectiveness of diphtheria toxoid a modified version of the toxin used for vaccination by treating it with aluminum salts. In , diphtheria outbreaks accompanied war and disruption in Europe. The 1 million cases in Europe resulted in 50, deaths.