I am a rod-shaped bacterium and I move around with aid of numerous flagella. I appear pink on Gram staining. I live in people's gut but usually don't harm them. I am not very particular about my diet and can grow on any medium. On MacConkey's agar I produce pink coloured colonies. I don't lyse red blood cells. Some members of my kind are virulent and can cause diarrhea and dysentery in children and adults, some cause urinary tract infection and some others cause meningitis of the new born. I can cause various types of illness. I am becoming well known for my ability to share plasmids coding for antibiotic resistance. Who am I?

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I am a rod-like bacterium but my appearance is not constant; I may be short or long. I am pink when stained by Gram stain. I am sometimes covered by a protective coat. I love blood but can't grow on plain blood agar. I grow better when kept in a candle jar. I can turn oxidase paper purple. I satellite around Staphylococcus aureus colonies. I cause serious illness in children and young adults like meningitis, otitis media, croup etc. Who am I?

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I am a rod-shaped bacterium. I appear pink upon Gram staining. I am part of a big family and my species consists of thousands of members antigenically different from each other. I am sometimes protected by a coat, my cell wall and flagella are antigenically variable. I can move around using my multiple flagella. I can't ferment lactose in the MacConkey's agar but I can produce a little H₂S. When I ferment glucose, I don't produce any gas. I infect people when they ingest me, I go through their intestine to blood and multiply in liver, spleen and get back to blood. I love bile and reside in the gall bladder, from here I go back to the intestine and cause ulcers. Sometimes I stay in the host for long time without the host's awareness. Who am I?

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I am spherical in shape but you will find me in grape-like clusters. I appear violet on Gram staining. My colonies have distinct golden-yellow colour. I can grow on ordinary medium but grow best on medium with blood. I can completely lyse red cells. I can gel human or rabbit plasma in a test tube. I am a nasty bug, I can survive in hospital environment and I readily colonize people in the hospitals. I have a huge arsenal of toxins and enzymes can cause variety of illness ranging from boils to toxic shock syndrome. I can destroy penicllin using my enzymes and some of my kind are resistant to multiple antibiotics making it difficult to kill us. Who am I?

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I am a solitary rod-shaped bacterium. I appear pink on Gram staining. I have no flagella and can't move around. I am a part of the large family but none of my species can ferment lactose. When I ferment glucose, I don't produce any gas. I don't ferment mannitol whereas other members of my species can. I infect people when they ingest me. Only a few of us are enough to produce dysentery in the host. I produce a potent toxin that has neurotoxic, cytotoxic and enterocytoxic property. Who am I?

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I am always found in pairs, sometimes the pair appear as short chains. I am protected by a coat that can swell in the presence of specific antiserum. I am not exactly spherical but more lanceolate with sides facing each other being more rounded. I can't survive on simple nutrition and presence of blood boosts my growth. I can lyse blood but only partially. I grow better in a candle jar. As I grow old, I become suicidal. My colonies may have central depression and may appear like carom coin. I don't froth in H₂O₂. Sometimes people carry me in their throat and I often infect their lower respiratory tract. I can infect lungs, middle ear, and even brain. Who am I?

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I am a spherical shaped bacterium almost always found in chains and the chains are well formed when I grow in liquid medium. My diet is special and I can't grow on simple media. When I grow on blood containing medium, I completely lyse the red blood cells. I don't froth in H₂O₂. I can colonize people's throat and infect them readily. My infection is usually restricted to upper respiratory tract but can spread deeper too. When I repeatedly cause infection in children, they develop serious sequelae. Penicillin kills me. Who am I?

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I am a rod-shaped bacterium and remain purple in Gram stain. I have flagella as well as a protective coat around me. I produce spores and their location is variable, wherever they are present they swell my body. I grow only in the absence of oxygen. My spores are hardy and are present everywhere. People get infected when they come into contact with my spores through trauma or ingestion. I can produce large numbers of toxins and enzymes and I can readily invade tissue. Who am I?

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I am a rod-shaped bacterium. Sometimes I may appear a little curved and irregularly stained. I may exist alone or in clumps. My wall is composed of a waxy substance which makes it difficult for you to stain me. I can resist decolourization by weak mineral acids. I am virulent and my presence in an individual indicates only disease. People get infected when they inhale me, I multiply slowly and spread slowly. My multiplication slows down when the host immunity is strong but I strike back when the immunity weakens. I mainly infect the lungs but can spread to any part of the body. I don't grow readily on ordinary culture media and my growth rate is very slow. I can develop resistance to drugs rapidly and can develop resistance to multiple drugs. Who am I?

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I am slightly curved rod-shaped bacterium. Resemblance of some of my properties to the enteric bacteria are purely coincidental and I am not related to them. I have a single polar flagellum and hence I move very very fast. I don't have any protective coat around me. I can't grow in medium with high salinity but can grow in high alkalinity. I don't readily ferment lactose but if you give me some time, I may do it slowly. I readily ferment sucrose and can turn oxidase paper purple. I infect people when they ingest me large numbers. I colonize their gut but don't penetrate their intestines. I produce a potent enterotoxin that make them lose water and electrolytes. I can cause epidemics but I am not well known for resistance to antibiotics. Who am I?

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I am a rod-shaped bacterium who remains purple in Gram stain. When I divide, my daughter cells don't separate completely and remain attached to me at ends. This is why I appear in Chinese letter pattern. I am non-motile and don't posses any protective coat. I can grow on simple medium but grow better in the presence of serum or blood. My growth is luxurious in serum containing medium and I produce polymetaphosphate granules in abundance. I am not inhibited by potassium tellurite in the medium; I break it down and incorporate tellurium into my colonies. I can produce a powerful exotoxin that can block protein synthesis in humans but the gene for this toxin is not mine, a temperate phage gave that to me. I can infect many parts of the body but I commonly infect the throat. I am not invasive but I can kill the host by my toxin. Who am I?

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I am short and stout rod-shaped bacilli, sometimes upon staining I appear as a 'safety-pin'. I have thin protective coat around me but I have no flagella. I can grow on simple medium but can't ferment lactose. I am a dreaded bacterium. I can multiply in rats, rat fleas, other rodents and even humans. People get infected when they are bitten by an infected rat flea. Infected people can spread me when I infect their lungs. I multiply and spread very fast. I have killed thousands of people in the past and I am always a threat. I am readily killed by ordinary antibiotics. Who am I?

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I am delicate but actively motile, spirally coiled bacterium with hooked ends. I am too thin to be seen under compound microscope by ordinary methods. I may be seen using dark ground microscope or by silver impregnation staining methods. While I live as parasites on rodents and other animals, some members of my genera exist as saprophytes. I can be grown on liquid or semi-solid agar but grow best at lower temperatures. I am highly susceptible to heat and acid environment. I cause disease in human when I am transmitted from my normal animal host in their urine. Who am I?

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I am rod-shaped bacterium who can live on simplest of nutrition and live almost everywhere. I have many flagella but have no protective layer around me. Some of my kind produce a slimy layer around themselves which is useful in colonizing the host. I am inert to several biochemical tests and I don't ferment any sugar. I am oxidative by nature. On MacConkey's agar, I produce pale colonies but can get variably coloured due to a diffusible pigment that I produce. I can produce many types of pigments. I can lyse the red cells completely on blood agar. I colonize hospital environment readily and I am resistant to many of the disinfectants and antibiotics. I can cause a wide range of opportunistic infections and treating my infections are difficult. Who am I?

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Long ago, people thought that I was a virus but I am small bacterium. Although I can't be stained by Gram stain, I am considered as Gram negative. I always live inside host cell and all attempts to grow me on artificial culture media have been failures. I can be grown on egg yolk and cell culture. When I grow inside the host cell, I am seen as inclusion body. I can spread through direct contact including sexual route. I cause occular and genital infections in humans. I am susceptible to tetracycline and macrolides. Who am I?

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I am a long and slender spirally-twisted bacterium with pointed ends. Even though I can't be stained by Gram stain, I am considered as Gram negative. I wriggle and twist when I move using my internal flagella. I am naturally a human pathogen and all attempts to grow me on artificial culture media have been failed. I usually infect people when they indulge in sexual intercourse with infected partner, I am susceptible to penicillin. Who am I?

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I am a rod-shaped bacterium who remains purple in Gram stain. I am special because my protective coat is peptide and not polysaccharide. I don't have any flagella but I can produce spores, which are centrally located. I need oxygen to grow. I don't produce spores in a living host. My spores are infect people when they come in contact with it. I infect people when they inhale me, ingest me or I even enter through abraded skin. I am highly virulent and with help of toxins, I spread rapidly and can kill the person whom I infect. My colonies are rough, edges are wavy and non-hemolytic on blood agar. Who am I?

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I am a spherical-shaped bacterium and I am always found in pairs. The side that faces each other is almost flat. Some of us have a protective coat around ourselves. In infect only humans and in their body I may be seen either inside or outside a neutrophil. I am very particular about my diet and can't grow on simple medium. I prefer to grow on medium with lysed blood than whole blood. I grow better in a candle jar. I can turn oxidase paper purple. I can colonize people's throat and then spread to brain. I can spread in blood and people may have blotches on their skin. Who am I?

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