Lecture 8 - Gram Negative bacteria 1 Flashcards by Deepu pras

What are the classes of gram negative bacteriaceae?

Enterobacteriaceae

Nonfermentative gram negative rods

Oxidase positive fermenters

Miscellaneous, fastidious gram negative rods

Campylobacter and helicobacter

Legionella

Haemophilus

Gram negative coccobacilli

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What are the morphologies that can be found in gram negative bacteria?

Bacilli (enterobacteriaceae)

Cocci, diplococci

Coccobacilli

Fusiform (typically anaerobes)

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How are enterobaceae arranged?

In tribes

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Are enterobacteriaceae pathogenic?

Many are commensals but some are not.

Some are very common pathogens others are pathogenic in certain clinical settings

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What are the 3 biochemical characteristics shared by all enterobacteriaceae?

They utilize glucose fermentatively

They are negative in oxidase test

They reduce nitrate to nitrite

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Where is escherichia normally found?

In the human bowel as a commensal

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What diseases can E.coli do?

They are uropathogenic and are the most common cause of UTIs

Some strains are enteropathogenic causing diarrhoea

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What are the strains of diarrhoea causing E.coli strains called?

Enterohaemorrhagic (EHEC)

Enteropathogenic (EPEC)

Enteroinvasive (EIEC)

Enteroaggregative (EaggEC)

Enterotoxigenic E.coli (ETEC)

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What does shigella do?

Causes bacterial dysentery a severe form of diarrhoea in which stool contains blood and pus

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What are the species of shigella?

Shigella dysenteriae

Shigella flexneri

Shigella boydii

Shigella sonnei

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What are the species of salmonella?

Salmonella enterica

Salmonella bongori

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How are salmonella differentiated?

> 2500 serotypes within species.

They are differentiated based on antigenic differences in cell envelope structures “O” and “H”

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Where are the H antigenic differences located?

On the flagella

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Where are the O antigenic differences located?

on the LPS

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Why is salmonella that causes typhoid fever called salmonella typhi?

It is the serotype name that often is used instead of species name.

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What is the actual name of salmonella typhi?

Salmonella enterica subsp. enterica, serovar typhi

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What do the non-typhoidal serotypes do in humans?

Commensals of various animal species

Self-limiting diarrhoea

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How long does salmonella fever take?

its a long term illness often taking close to a month.

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What are the diseases caused by salmonella called?

typhoid and paratyphoid fever

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What does salmonella do?

abdominal symptoms

diarrhoea

bacteria in blood

Can cause rupture in the bowel

May or may not be found in species

Found in blood

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What are the important citrobacter species?

Citrobacter freundii

Citrobacter diversus

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What are the diseases caused y citrobacter species?

UTIs

Infections such as pneumonia and neonatal meningitis

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What are the klebsiella species?

Klebsiella pneumoniae

Klebsiella oxytoca

Klebsiella ozaenae

Klebsiella rhinoscleromatis

Klebsiella granulomatis

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What does klebsiella pneumoniae do to people?

Necrotising pneumonia that is severe

Rapid in onset

creates sputum known as currant jelly

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Who does klebsiella pneumoniae typically affect?

Causes disease in people who are debilitated, homeless, and alcoholic

What kind of pneumonia does klebsiella cause?

Lobar pneumonia

What are the types of infections caused by klebsiella oxytoca, ozaenae and pneumoniae?

Nosocomial infections such as UTIs Respiratory tract infections and surgical wound infections

What is a huge issue with klebsiella strains?

They are resistant to multiple antibiotics.

What disease does klebsiella granulomatis cause?

Sexually transmitted infection of the tropics

What is the sexually transmitted disease of the tropics called?

Donovanosis or granuloma inguinale

What are the types of donovanosis?

Starts as an ulcer on the genitals then becomes chronically disfiguring

A patient comes to you with an ulcer on his genitals and tells you he was in a tropical region. What is the reason for his symptoms and what is the condition called?

Klebsiella granulomatis and the disease is called donovanosis

What are the enterobacter species?

Enterobacter aerogenes Enterobacter cloacae

What are members of the genus serratia?

Serratia marcescens Serratia liquefaciens

What are the members of the genus morganella?

Morganella morganii

What are the members of the genus providencia?

Providencia stuartii Providencia rettgeri

What are members of the genus Proteus ?

Proteus mirabilis Proteus vulgaris

What disease are proteus mirabilis linked to?

Most common cause of UTIs after E.coli

What are enterobacteriaceae associated with?

Hospital infections Debilitated patients UTIs Respiratory tract infections Surgical wound infections (caused by serratia, klebsiella, proteus, Morganella, providencia, and enterobacter)

Why are hospitals carriers of so many bacteria?

Due to multiple antibiotic resistance

What enterobacteriaceae does not cause hospital infections?

Yersinia

What kind of disease is caused by yersinia pestis?

The plague

What are the types of plague?

Bubonic plague Pneumonic plague Septicaemic plague

What is the untreated mortality rate of the plague?

50 - 90%

How many people were killed in Europe by the plague in the middle ages?

1/4 of Europe's population in the middle ages

How often do people die from the plague today?

Its rare but does happen often in return travellers from areas like madagascar

What does yersinia enterocolitica do?

Mesenteric adenitis (affects lymph nodes in mysentery and mimics appendicitis) Pseudoappendecitis Enterocolitis (infection of colon)

What are the important non-fermentative gram negative rods?

Pseudomonas Stenotrophomonas Burkhoideria Acinetobacter

What is interesting about pseudomonas aeruginosa?

It is a major pathogen It is very resistant to antibiotics

How do pseudomonas look on a clear agar?

Green coloured

What condition does pseudomonas aeruginosa cause in the ear?

Otitis externa caused by inflammation as a result of inflammation due to narrow ear canal and prolonged pseudomonas

How does pseudomonas aeruginosa affect burn patients?

Colonises their skin and prolongs healing

How does pseudomonas aeruginosa affect urinary tract?

causes UTIs

What are all the conditions caused by pseudomonas aeruginosa?

Otitis externa UTIs Colonises skin of burn victims Lung infection in people with cystic fibrosis lung infection in patients that are mechanically ventilated Septicaemia in those with leukaemia, organ transplants, and IV drugs

How does pseudomonas aeruginosa affect people in hospitals?

Exacerbates their condition

What does stenotrophomonas maltophilia cause?

Nosocomial infection in debilitated patients Lower respiratory tract infections in debilitated patients and those with cystic fibrosis Septicaemia in debilitated patients (especially neutropaenic cancer patients)

What does Burkholderia pseudomallei do?

Tropical infection melioidosis Severe pneumonia soft tissue abscesses septicaemia (high fatality)

What countries typically contain Burkholderia?

in South east Asia and Nothern Australia

Where is Burkholderia typically found?

In soil, infects humans through contamination of abrasions or through inhalation

How does burkholderia pseudomallei deal with antibiotics?

It is very antibiotic resistant

Where is acinetobacter typically found?

In soil and aquatic environments

What part of the body does acinetobacter typically colonize?

Colonises human skin and respiratory tract

Are acinetobacter nosocomial infections

Yes but they are also opportunistic and resistant to multiple antibiotics

Who does acinetobacter baumannii typically affect?

Immunocompromised patients and it causes nosocomial infections, intravenous catheter related bacteraemia and UTI

What is acinetobacter baumannii infection associated with (lifestyle)?

Smoking and alcohol

What is acinetobacter baumannii infection associated with (conditions)?

Chronic obstructive pulmonary disease Diabetes

What is acinetobacter lwoffi a cause of?

nosocomial infection in immunocompromised patients. pneumonia intravenous catheter related bacteraemia UTI

What are the enterobacteriaceae that are common causes of urinary tract infections?

E.coli (most common cause of UTIs) Klebsiella Proteus (second most common cause after E.coli)

What are the enterobacteriaceae that are bacteria which inhabit hospitals?

Citrobacter (freundii and diversus) Klebsiella

What are the enterobacteriaceae that are responsible for diarrhoeal illness?

E.Coli (4 strains cause diarrhoeal illness they are EHEC, ETEC, EIEC, EPEC, EaggEC) Shigella Salmonella Yersinia enterocolitis

What are the enterobacteriaceae that are responsible for typhoid and paratyphoid fever?

Salmonella (Typhoidal serotypes: • Salmonella Typhi (eg. S. enterica subsp. enterica, serovar Typhi • Salmonella Paratyphi types A, B & C)

What are the enterobacteriaceae that are responsible for plague?

Yersinia pestis

What are the non-fermentative Gram negative rods that are responsible for nosocomial illness?

Pseudomonas aeruginosa Stenotrophomonas maltophilia Acinetobacter baumannii Acinetobacter lwoffii

What are the non-fermentative Gram negative rods that are responsible for UTI illness?

Pseudomonas aeruginosa (generally hospital acquired rather than community acquired) Acinetobacter baumannii

What are the non-fermentative Gram negative rods that exhibit antibiotic resistance?

Pseudomonas aeruginosa Stenotrophomonas maltophilia Burkholderia pseudomallei Acinetobacter baumannii

What is the defining feature of gram negative rods?

They don't metabolise glucose by fermentative pathways (or don't utilize it at all)

What are the types of Vibrio?

Vibrio cholera species Non-cholera vibrio species

What kind of disease do Vibrio cholerae produce?

Certain strains produce severe diarrhoeal illness

What is the fatality rate like in cholera?

High particularly in undernourished people and people ill with other illnesses

Which strains of vibrio cholera produce severe illness?

The strains that produce the cholera toxin

How is cholera acquired?

faecal oral contamination and often through water

What does cholera toxin do?

Enters enterocytes which control electrolyte and fluid balance of the body. This results in an impairment of electrolyte and water regulation. Result is very profuse dehydration is the result.

What is used to classify vibrio cholera?

The antigens of the cell wall

What serotype causes most epidemics/pandemics of cholera?

Type-01

What are the other types of Vibrio cholerae?

Non type-01

How many non type-01 serotypes are there?

139

What infections are vibrio alginolyticus typically seen in?

Skin and soft tissue infections following wounds in marine environments Otitis externa in ear

What does vibrio parahaemolyticus cause?

gastroenteritis from contaminated seafood

What is the most virulent disease of the non-cholera vibrios?

Vibriovulnificus

What kind of illness does vibrio vulnificus cause?

Severe septicaemic illness in immunocompromised hosts Severe cellulitis and skin necrosis after contamination of wounds with seawater

What are the important genera of oxidase positive fermenters?

Vibrio spp. Aeromonas spp.

What are the important genera of oxidase positive fermenters?

Vibrio spp. Aeromonas spp.

What are aeromonas?

genus of curved gram negative rods found in aquatic environments

Where do aeromonas live?

Aquatic environments and the gut of leeches

What kind of disease do aeromonas cause?

Aggressive skin and soft tissue infection complicating wounds in marine environments and following leech therapy

What are aeromonas species like?

vibrio alginiticus

Do aeromonas species and alginiticus species react to antibiotics?

Yes but they also spread really quickly