Preface Bacteria, the tiny creature inhabiting the earth long before than us, generated oxygen molecule first in the atmosphere by photosynthesis. The oxygen made an environment conducive for the creation of life. The bacteria responsible for inception of our life later became life-threatening and took the leading role in economic losses associated with morbidity and mortality of livestock, poultry and fishes. Antibiotics, the weapon to combat the pathogenic bacteria are also produced by group of beneficial bacteria. Inappropriate use of the weapon is making it blunt although. Throughout my career circling around the pathogenic and beneficial bacterial groups, I felt the importance of these microscopic creatures in our life and society. I wished to disseminate the feelings through the first edition of the book ‘Veterinary Bacteriology’. The second revised edition consists of the general and systematic Veterinary Bacteriology. The book is intended to help undergraduate and post-graduate scholars of Veterinary Microbiology as well as the aspirants of different competitive examinations. The revised edition will also support the person engaged as Government Veterinarian, independent animal health practitioner, or associated with the laboratory for the diagnosis of animal diseases. The book comprises the diagnostic techniques for each bacterial genus ranging from staining parameters to molecular tools with useful photographs. I also tried to keep the language simple as much as possible like the previous edition. I obtained sufficient ‘time’, the most valuable requirement to write a text book for which I am grateful to my family. I am also thankful to all the senior and junior colleagues throughout the country who provided me their best photographs of the microbes.

Microbiology is the branch of science which deals with the diverse minute forms of life such as bacteria, archaea, viruses, fungi, prions, protozoa and algae. The study includes structure, classification, growth and nutrition, natural habitat, genome, antigenic characteristics, virulence determinants, types of toxins produced, pathogenesis, diagnosis and ways to combat the infection caused by the microbes.

Taxonomy (biological systematics) is the branch of science which deals with classification of units or individuals on the basis of similarities and differences. The classification, nomenclature, and identification are three interrelated components of bacterial taxonomy (Cowan, 1965). Classification: Classification is the arrangement of bacteria into groups (taxa) based on the similarities of certain characteristics. Presently 11,000 bacterial species is classified. At the current rate of 600 bacterial species / year it is estimated to take 1000 years to classify all the bacteria! Nomenclature: It is the assignment of specific names to the taxonomic groups following the regulations mentioned in ‘International Code of Nomenclature of Bacteria’ (Euzeby, 1997). International committee on systematic bacteriology (International committee on systematics of prokaryotes, ICSP) standardizes the code. The committee is helped by a number of taxonomic subcommittees on different groups of bacteria. The Code can be amended by the Judicial Commission. The Code contains general considerations, principles, rules and recommendations on the naming of prokaryotes (bacteria) up to the rank of ‘Class’.

Microscope is the primary instrument of a microbiology laboratory and it produces enlarged images of small objects which are invisible by naked eye. With a microscope the operator can get a close view of minute structures which helps in examination and analysis. Examination of minute objects with a microscope is called ‘microscopy’. In microbiology, measurement of the microbial dimension observed under microscope is known as ‘micrometry’. Types of microscopes There are two types of microscopes i.e. light / optical and electron microscope depending on the sources of energy to create the image. The optical microscopes use the lenses and light (artificial or sunlight) to make an image. Following types of optical microscopes are available.

Bacteria can be defined as a group of diverse and ubiquitous prokaryotic single cell microorganisms. The size of bacteria varies with genera/species. In cocci the diameter varies between 0.5-1 µm. The measurement of bacillus / rod shaped bacteria is 4-8 µm ? 1-1.25 µm. The surface area and volume ratio of bacteria is very high. The nutrients are absorbed through a large surface area and it is rapidly distributed into a small volume. So the growth rate and metabolism of bacteria is very high. The bacterial cell mass is packed near the surface and no circulatory system is required to distribute the nutrients. The growth and metabolism rate of bacilli are more than cocci because surface area and volume ratio of a sphere (cocci) is lowest among all the geometrical forms. Shape of bacteria The shape of bacteria is mostly regulated by the rigid cell wall covering the bacteria. Different shapes of bacteria are observed.

Growth of bacteria can be defined as change of total population mass, not individual increase in size or mass. Macroscopically visible growth of bacteria on the solid medium is known as ‘colony’. It is estimated that if Escherichia coli are allowed to grow, a single bacterial cell can produce a daughter population with the mass of the whole earth within 2 days! In the environment the bacteria are not actively growing all the time. The mechanisms behind the growth-arrested states of environmental bacteria are not well understood. Bacterial reproduction Bacterial reproduction is an asexual process which occurs by binary fission, budding, fragmentation and condiospore or sporangiospore formation. There is no possibility of genetic exchange (reassortment) as it is originated from a single parent cell. Bacterial gene transfer occurs by transformation, transduction and conjugation methods (discussed later in details). These are one-directional DNA transfer methods and are not associated with reproduction. The donor bacteria can give the genetic material to the recipient and the vice-versa does not occur. Binary fission: In binary fission, bacterial DNA is replicated first and then the parent cell separates. Each daughter cell receives a complete genome, identical to the parent cell. Bacterial DNA replication begins when the cells reach a specific mass. If the cell diameter is constant, longer cells will begin DNA replication earlier than the shorter cells. The shorter cells need time to reach a critical mass required for the initiation of DNA replication. The ugtP proteins were identified to be associated with shorter cells and delayed DNA replication in Gram-positive bacteria (Bacillus subtilis). It was confirmed later that the ugtP act as inhibitor for Z-ring formation.

Normal bacterial flora is the bacteria which live on another living being (human or animals) or inanimate object without causing infection Opportunistic bacteria are part of normal bacterial flora which can produce infection during lowered immunity (immunosuppression) of host or when transferred into other parts of the body Saprophytic bacteria live on dead or decaying organic matter Infection Infection can be defined as a pathological condition occurred due to multiplication of microbes. Intoxication can be defined as pathological condition due to ingestion of microbial toxin (e.g. aflatoxin produced by Aspergillus fungus). Mycetism is the pathological condition due to ingestion of fungus (e.g. toxic mushroom) which produces toxicity within the body of the host

The genetics is the study of inheritance and variability of organisms. Bacterial genetics is a sub-field which specifically studies transmission of genetic information from one bacterium to its progeny or between the interbreeding bacteria and the expression of genetic information. Mutation Hugo de Vries (1848-1935, Dutch botanist) coined the term ‘mutation’. It is originated from a Latin word which means ‘to change’. The heritable change in bacterial DNA sequences is known as bacterial mutation. The mutation will generate a new type of bacteria with altered genotypical and phenotypical characteristics, known as ‘mutant’. The parent bacterial cell from which the mutants are generated is known as ‘wild type’. In nature bacterial mutation is a rare incidence. The spontaneous mutation occurs at a rate of 1 in 105 to 108. The phenotypical expression of mutation occurs quickly as the bacteria are haploid with shorter generation time.

Sir Alexander Ogston, a physician from Scotland, first elucidated the role of Micrococcus in formation of pus. He proposed the name ‘Staphylococcus’ (In Greek ‘staphyle’ means bunch of grapes and ‘kokkos’ means berry). Anton J. Rosenbach isolated two different species of Staphylococcus and named them according to the pigmented appearance of colonies i.e. Staphylococcus aureus (in Latin ‘aurum’ means gold) and Staphylococcus albus (in Latin ‘albus’ means white). The studies of Bumm (1885) established the relationship of Staphylococcus with human infections. Nocard (1887) and Guillebeau (1890) isolated Staphylococcus from mastitis in sheep and cattle, respectively and established its pathogenic role in animals.

Rivolta (1873) first described the chain forming cocci in pus collected from the equine infection. Rosenbach (1884) established the genus Streptococcus’ Nocard and Mollereau (1887) first observed the relationship between the bovine mastitis and Streptococcus agalactiae. Lancefield (1933) classified beta-haemolytic streptococci on the basis of group specific-carbohydrate antigens. Properties of genus 1. Morphology: Streptococci are gram positive cocci, capsulated, non-sporing and non-motile. Each coccus cell is 1µm in diameter. They are arranged in a pair or chain of cells as the cell division occurs in one plane(Figure 1 & 22). The chain formation and the chain length are variable. Streptococcus equi ssp. equi is a constant chain producer. Young cultures are gram positive whereas bacteria present in the pus and older cultures in the laboratory are often stained as gram negative.

Corynebacterium diptheriae was first observed by Klebs in 1883 and was described in details by Loeffler in 1884. So it is also known as ‘Klebs- Loeffler bacillus’. In 1888, Nocard isolated a similar type of bacteria from cases of bovine farcy. In 1894, Preisz described it completely and revealed its similarities with the diphtheria bacilli. Later it was named as Corynebacterium pseudotuberculosis (Preisz-Nocard bacillus). Bollinger (1890) first reported C. renale from the cases of pyelonephritis in cows. The genus Trueperella was proposed by Yassin and others (2011) to describe T. pyogenes previously known as Arcanobacterium pyogenes or Actinomyces pyogenes or Corynebacterium pyogenes. The genus Arcanobacterium was first described (Collins and others, 1982) to include the bacteria originally isolated as Corynebacterium haemolyticum from the wounds of American soldiers. On the basis of 16S rRNA comparisons and menaquinone and phospholipid compositions it is proposed that the species Arcanobacterium pyogenes should be reclassified as members of the new genus Trueperella. The genus Rhodococcus was first introduced by Zopf (1891) as a soil bacterium used in horticulture. Magnusson (1923) described C. equi (Rhodococcus equi) from suppurative pneumonia of a foal.

Murray (1926) and Pirie (1927) first described Listeria independently. In India, animal listeriosis in sheep was first reported by Mahajan (1936) in Andhra Pradesh. Robert Koch first isolated Erysipelothrix in 1876 from a mouse he inoculated with putrefying blood. Koch initially named the bacterium “Bacillus of mouse septicemia”. Pasteur and Dumas (1882) first isolated Erysipelothrix from the infected pigs. Friedrich Loffler (1886) first experimentally produced the infection in pigs. Rosenbach (1909) first described human erysipeloid. The nomenclature of the bacterium is changed several times and Erysipelothrix rhusiopathiae was finally accepted by the scientific community in 1966. The name is originated from Greek words such as ‘erysipelas’ (red skin), ‘trix’ (hair), ‘rhusius’ (reddening) and ‘pathus’ (disease).

In 1850, Bacillus anthracis was first reported by three individuals in two different countries i.e. Delafond and Davaine in France, and Pollender in Germany. They could not establish the relationship of the bacterium with the infection. Absolute proof of the anthrax etiology as B. anthracis was established by Robert Koch during 1876-77. The name Bacillus anthracis was first coined by Cohn (1875) and the disease ‘anthrax’ was first named by Hippocrates (5th century B.C.). In Greek language meaning of ‘anthrax’ is ‘coal’ referring to the black coloured skin or blood in affected animals.

In 1882, Robert Koch first isolated the bacterium, stained with alkaline methylene blue and vesuvin as counter stain and showed its etiologic relationship with tuberculosis. Ehrlich first developed acid-fast stain in 1882 and used for better staining of the bacteria which was adopted by Robert Koch. The acid-fast staining technique was modified later by Franz Ziehl and Friedrich Neelsen, accordingly, it is known as Ziehl-Neelsen (Z-N) staining. In 1890, Koch prepared a glycerine broth extract of the tubercle bacillus, known as ‘tuberculin’. He tried to prepare it as a curative agent; but it was used later in diagnosis. In 1895, Johne and Frothingham described the first case of paratuberculosis in cattle which became known as ‘Johne’s disease’. The causative bacterium was later isolated by Twort and Ingram in 1910. In India, bovine tuberculosis is reported from several states since 1959 (Dhanda and Lall, 1959). The bovine paratuberculosis in India was first reported by Nanda and Singh (1940) from Haryana.

The genus Clostridium belongs to the family Clostridiaceae. The genus name was originated from the Greek word ‘klo ster’, which means ‘spindle’ referring to their individual rod shape. Clostridia are gram positive, large, sporulating anaerobic rods (except C. piliforme which is gram negative). At present, there are more than 200 numbers of species under the genus Clostridium. Among them, 15 species can produce potent toxins and are considered as pathogenic for animals and human. The animal pathogenic clostridia can be classified as neurotoxic, histotoxic and enteric.

Cohn (1875) first observed and described a branching filamentous microorganism in the ‘concretions’ (coagulated mass) taken from a lacrimal canal, later identified as Actinomyces israelii. Bollinger first reported the yellow granules in jaw tissues of the cattle in 1877 and established the significance of the bacteria as the etiological agent. In 1878, Israel described the first human case. In 1879, Hartz observed the microscopic appearance of granules of Actinomyces and suggested the name Actinomyces bovis. Mosselman & Lihnaux (1890) and Wolf & Israel (1891) first isolated the bacteria in artificial laboratory media from lumpy jaw cases of cattle and human actinomycosis, respectively.

Edmond Nocard (French veterinarian) first isolated filamentous aerobic bacteria from clinical cases of ‘bovine farcy’ in 1888. In 1889, the genus Nocardia was formed by Trevisan and the bacterium originally described by Nocard was named as Nocardia farcinica. In 1891, another similar bacterium (Nocardia asteroides) was isolated by Eppinger from a human brain abscess. Initially it was thought that they are the same bacteria. On the basis of the genetic differences the separate entity was established later. The re-examination of Nocard’s original isolate revealed the existence of two different filamentous bacteria i.e. Mycobacterium and Nocardia. The cause of ‘bovine farcy’ has been subsequently attributed to Mycobacterium. Later, it is proved that Mycobacterium farcinogenes is the actual causative agent of ‘bovine farcy’.

Streptomyces are soil-borne bacteria known for production of several antibiotics, antifungals, antivirals, antitumoral, anti-hypertensives and immunosuppressives. Krainsky (1914) first described S. griseus and named the species Actinomyces griseus. Waksman and Henrici (1948) changed the name to Streptomyces griseus. Dermatophilus congolensis was first described from clinical case of exudative dermatitis in cattle in Congo by Van Saceghem (1915). It is primarily known as an animal pathogen causing acute, sub acute or chronic skin disease. The first cases of human infection with D. congolensis were reported in 1961 in four people who developed skin infection after handling an infected deer in USA.

The family Enterobacteriaceae belongs to the order Enterobacterial. The family comprises 25 genera such as Escherichia, Salmonella, Klebsiella, Yersinia, Proteus, Providencia, Shigella, Enterobacter, Morganella, Edwardsiella, Budvicia, Cedecea, Citrobacter, Ewingella, Hafnia, Kluyvera, Leclercia, Leminorella, Moellerella, Pantoea, Rahnella, Tatumella, Trabulsiella, Serratia and Yokenella, out of which the first 10 genera are consistent pathogenic in humans, animals and birds. Escherichia coli Escherichia coli were first isolated by Theodor Escherich in 1885 from the faeces of infants. It was named in honour of the German pediatrician and its major natural habitat (colon). Previously it was also known as Bacillus coli or Bacterium coli (B. coli).

Lucke (1862) first described that the bluish green discolouration of surgical dressing is associated with the presence of small vibrio like organisms. Gessard (1882) first isolated the bacteria as Pseudomonas. Identification of the etiologic agent of glanders was performed in 1882 by isolating a bacterium from the infected liver and spleen of horse. Since its discovery, the pathogen has been classified as Loefflerella mallei, Pfeifferella mallei, Malleomyces mallei, Actinobacillus mallei, Corynebacterium mallei, Mycobacterium mallei, Pseudomonas mallei, and currently as Burkholdria mallei. The genus Burkholderia was created to accommodate former rRNA group II (Pseudomallei group) Pseudomonas bacteria. It was based on the 16S rRNA sequences, DNA-DNA homology values, cellular lipid and fatty acid composition.

Louis Pasteur (1881) first isolated the bacterium from fowl cholera outbreak and attenuated the bacteria to develop a vaccine for the chicken. Trevisan (1887) coined the generic name ‘Pasteurella’ in honour of Louis Pasteur. Lignieres (1900) proposed the name of the species according to the animals acted as the major hosts such as Pasteurella aviseptica for fowls, P. suiseptica for pigs, P. boviseptica for bovines, P. oviseptica for ovines and P. leptiseptica for rabbits. Rosenbuch and Merchant (1939) proposed the name of single species Pasteurella multocida which is in use till date. Mannheimia is an exclusive animal pathogen and is associated with ‘shipping fever’ or bovine respiratory disease (BRD) in cattle. Kitt (1885) first described the bacterium as Bacterium bipolare multocidum isolated from shipping fever in cattle. The nomenclature was further changed into Bacillus boviseptica and finally into Pasteurella haemolytica. Based on fermentation capability of arabinose and trehalose, P. haemolytica was subdivided into two biotypes (A and T) and several capsular serotypes. The biotype A (with 12 capsular serotypes) was classified under a new genus Mannheimia due to disparities in 16S rDNA sequence, cultural and pathological characteristics.

Lignieres and Spitz first isolated Actinobacillus from the cattle with actinomycosis like condition in Argentina in 1902. The findings were also confirmed by Nocard in 1902. Later the isolated bacterium from the cattle was named as Actinobacillus lignieresii in memory of Lignieres. Pfeiffer (1892) first isolated Haemophilus influenzae as a cause of human influenza and it is also known as ‘Pfeiffer’s bacillus’. Other workers isolated and described different species of the genus Haemophilus from animals and birds. In 1903, Friedberger, a research assistant of Pfeiffer, isolated similar kind of bacteria from prepuce of dogs which was described later as Haemophilus canis. In 1925, Mitchell isolated Haemophilus ovis from the respiratory tract of sheep. Lewis and Shope (1931) isolated and illustrated Haemophilus suis from the infected pigs. Glasser found the association between fibrinous serositis, polyarthritis in pigs (Glasser’s disease) and a small gram-negative rod as early as 1910, later became known as Haemophilus parasuis. The bacteria was first isolated by Hjarre and Wramby in 1943. De Blieck (1931) isolated a hemophilic bacterium from the birds suffering with ‘infectious coryza’ and named the bacteria as Bacillus haemoglobinophilus coryzae gallinarum. Later it became known as Haemophilus paragallinarum (Avibacterium paragallinarum).

Clinical conditions similar to brucellosis have been described since the time of Hippocrates (450 BC). J. A. Marston (1861) first described brucellosis as gastric remittent fever in Malta, the Southern European island country. Sir David Bruce (1886) first isolated small coccobacilli from an infected soldier’s spleen and purified the culture in 1887, and named Micrococcus melitensis. Later the genus was renamed as Brucella in his honour. Similarly, Bang and Stribolg (1897) first isolated Brucella abortus from abortion material of a cow. Traum in 1914 isolated Bacillus abortus suis, currently known as Brucella suis. In 1953, Brucella ovis was firs isolated in New Zealand by Budlle and Boyes from the aborted material of sheep. Carmichael and Bruner (1968) first isolated B. canis from the aborted placenta of a dog. In India first report of ‘contagious abortion’ associated with Brucella was found in annual report (1918) of imperial veterinary research institute (presently Indian veterinary research institute), Mukteswar, Uttarakhand and later in 1942 by Polding.

Since the periods of Hippocrates and Lord Buddha cholera like symptoms was described in human. The first outbreak of cholera was described in India in 1817. Filippo Pacini (1854), an Italian anatomist, observed a gram-negative bacterium associated with human cholera. Robert Koch (1884) first isolated and confirmed the association of ‘comma-shaped bacteria’, later designated as Vibrio cholerae with the disease in Calcutta (India). In 1959, Sambhu Nath De, Professor of Pathology at Nilratan Sircar Medical College in Calcutta discovered the exotoxin produced by V. cholerae and a simple method (rabbit ligated ileal loop assay) to study the in vitro effect of exotoxins. The Ganges delta of India and Bangladesh is considered as the worst affected place with cholera although the infection is widespread throughout the world. The spread of cholera in different continents occurred through six ‘waves’ (‘pandemics’) since 1817. The current seventh pandemic (7P) was originated in Indonesia (Sulawesi) in 1961 and spread throughout Asia, Africa and Latin America. In 1963, the seventh pandemic reached South Asia and circulated for more than 50 years with intermittent transmission to other continents. The recent major 7th pandemic outbreak was detected in Haiti causing more than 9400 deaths in 2010 which was originated through patients from endemic countries. In 1886, Escherich observed Campylobacter like organisms in stool samples of children with diarrhoea. In 1913, McFaydean and Stockman first confirmed the bacteria as Campylobacter in foetal tissues of aborted sheep. Confirmatory tests were also carried out by Smith in 1918 when similar bacteria were isolated from aborted bovine foetuses. The bacteria were then known as Vibrio foetus. In 1963, due to certain differentiating characteristics, the organisms were separated from Vibrionaceae family and the new genus Campylobacter (means ‘curved rod’) under Campylobacteraceae family was proposed.

Guillame de Baillou (1673), a physician, described an outbreak of recurrent severe cough that could induce vomition and suffocation in human in Paris. The infection was described as ‘Quintan^tussis which was later confirmed as ‘whooping cough’. The causative agent Bordetella pertussis was discovered by Jules Bordet and Octave Gengou in 1906 in Paris. The Gram-negative bacilli were isolated from sputum of Jules Bordet’s son. Bordetella bronchiseptica was first isolated by Ferry (1911) and M’Gowan (1911) who considered the bacteria as the cause of distemper in dogs. Later B. bronchiseptica was known as primary cause of ‘kennel cough’ infection along with the Canine Adenovirus and Canine Parainfluenza virus. Moreno- Lopez named the bacteria B. bronchiseptica. The genus Moraxella was named after Morax who first isolated the bacteria from human conjunctivitis in 1896.

Properties 1. Bacteroides, Dichelobacter and Fusobacterium are major gram negative anaerobes isolated from human and animals. Other gram negative anaerobes are listed below (Table-1). 2. The bacteria are tolerant to oxygen in comparison to strict anaerobes. The bacteria do not die after oxygen exposure. 3. The bacteria naturally inhabit the intestine and mucosal surfaces of human and animals. Majority of them are opportunistic pathogens. Often they cause mixed bacterial infection along with aerobes. The aerobes remove oxygen and create an anaerobic condition favourable for their growth. The aerobes may also supply other growth requirements. For e.g. Porphyromonas asaccharolytica requires vitamin K for its growth, supplied by another aerobic bacterium, not the host.

Antony Van Leeuwenhoek (1681) first observed the spirochetes under the microscope and described them. In 1833, Ehrenberg used the name Spirochaeta for free living spiral shaped organisms. Obermeir (1873) first described a spirochete of pathogenic significance isolated from human patients with relapsing fever. Inada (1916) first isolated Leptospira icterohaemorrhagiae from human patients of Weil’s disease. In 1980, Nogochi proposed the name as Leptospira. In India, Taylor and Goyale (1931) first reported Leptospira from human patients suffering with jaundice in Andaman Islands. Ayyar (1932) first reported Leptospira from dogs in Chennai city.

The word ‘Mycoplasma’ is originated from the Greek word mykes (fungus) and plasma (formed). It was first used by Albert Bernhard Frank (1889), a German biologist. He thought it was a fungus. An older name for Mycoplasma was pleuropneumonia-like organisms (PPLO), referring to organisms similar to the causative agent of contagious bovine pleuropneumonia (CBPP).It was later found that the fungus-like growth pattern of Mycoplasma mycoides is unique to the species. It was first isolated in 1898 by Edmond Nocard and E. Roux from bovine lungs. Mycoplasma pneumoniae was considered as a virus previously. Eaton and his co-workers cultured the causative agent of human primary atypical pneumonia (PAP) or ‘walking pneumonia’. It was known as ‘Eaton’s agent’. In the early 1960s, Leonard Hayflick, in Philadelphia, was first to isolate and cultivate the causative agent of primary atypical pneumonia and identified the agent as a Mycoplasma pneumoniae. Properties of genus 1 Morphology: Mycoplasma have no cell wall and therefore are resistant to the antibiotics used to inhibit the cell wall synthesis like penicillin, cephalosporin and vancomycin. The bacteria are the smallest prokaryote (0.3-0.8µm). They are pleomorphic due to absence of the rigid cell wall. The different shapes include ring, globules, filaments and elementary bodies. Due to their plasticity in shape and size, they can be passed through the membrane filter with pore size of 0.45µm. The cell membrane is constituted of trilaminar structure enriched with phosphoprotein, lipoprotein, glycolipid, phospholipid and sterol. So Mycoplasma require sterol for their growth.

History of rickettsial infections went back to 16th century and it has long been associated with famine and war. Epidemic typhus had major impact to decide over the outcome of several wars. The epidemic alone killed or caused great sufferings to over 1,00,000 people during World Wars. However, the causative agent was not determined until the early part of the 20th century. Rocky Mountain spotted fever (RMSF) was the first detected rickettsial infection in 1896 in Idaho Valley, USA. It was originally known as ‘black measles’ due to its clinical appearance in the form of characteristic spotted rash throughout the body. Howard Taylor Ricketts, an American pathologist for the first time described the causative agent of Rocky Mountain spotted fever and was able to isolate it in the laboratory animals during 1902-1909. He was a dedicated scientist and on several occasions injected himself with the pathogen for experiment. The causative pathogen of Rocky Mountain spotted fever, Rickettsia rickettsii was named after him. Later, the family Rickettsiaceae as well as the order Rickettsiales was named after him. Ernest William Goodpasture, an American pathologist and physician, invented the methods of isolation and culturing the rickettsial pathogens in chicken embryos and fertilized chicken eggs.

The word ‘chlamydia’ comes from the Greek word ‘chlamys’ means ‘cloak draped around the shoulder’. It describes how the intracytoplasmic inclusions produced by the bacterium appear under the microscope(‘draped’ around the host cell nucleus). Chlamydia was first discovered by a Czech zoologist and parasitologist, Stanislaus von Prowazek in 1907 in Berlin. Originally because of its structure it was thought to be a virus. In 1963 it was recognized as a bacterium rather than a virus. Properties of genus 1. Morphology: Chlamydia are Gram-negative, non-motile, pleomorphic and obligate intracellular bacteria. The Gram-negative cell wall consists of cytoplasmic and outer membrane. However, they lack peptidoglycan layer. Moreover, they also encode major outer membrane protein (MOMP), the key antigenic determinant used for serological differentiation of chlamydiae. They are poorly stained by Gram’s stain. Chlamydiae are readily stained by Castaneda (blue in appearance), Giemnez and Macchiavello (red in appearance) methods. However, Giemsa staining is preferable to stain the inclusions (chlamydial micro colony) in the cell culture. Inclusion bodies of the Chlamydiae are basophilic in nature. The staining of the inclusion bodies may differ depending on the species. In C. trachomatis, the inclusion bodies contain glycogen matrix and can be easily stained with iodine solution.

Index A Abattoir 461 Abortion 128, 143, 144, 156, 169, 173, 186, 258, 307, 318, 313, 366, 367, 375, 381, 382, 383, 386, 387, 401, 402, 423, 424, 430, 431, 437, 447, 462, 467, 471, 477, 478 Abortus, melitensis, ovis, suis-PCR (AMOS- PCR) 385 Abscesses 111, 127, 143, 144, 146, 317, 333 Acid fast 11, 33, 134, 149, 175, 176, 189, 192, 247, 256, 259, 262, 325, 375 Actinobacillus 38, 89, 147, 325, 340, 343, 345, 353, 354, 355, 356, 357, 358, 359, 362, 363, 366, 367, 368, 369, 370, 371, 372, 374, 410 Actinomyces 33, 44, 133, 247, 248, 249, 250, 251, 255, 261, 374 Afu-A 362 Agglutination 11, 102, 113, 130, 158, 191, 231, 244, 272, 286, 308, 309, 313, 319, 336, 342, 349, 350, 360, 370, 371, 383, 384, 404, 409, 414, 433, 459, 463, 468 Alpha toxin 104, 198, 200, 202, 224, 225, 227, 229, 230, 234, 237, 238, 245