Enterobacteria

• Enterobacteriaceae is the most important family among G– rods.
• The worst pathogens among Enterobacteriaceae are Yersinia pestis, which causes the plague, and anthropopatogenous serovars of Salmonella Typhi/Paratyphi, which cause typhoid fever, septicemia with high fever and headache.
• Obligatory pathogens among Enterobacteriaceae are Salmonella, Shigella and Yersinia for intestinal infections, sometimes a systemic infection may occur.
• Yersinia pestis is the causative agent of the black plague and is vectored by fleas (Xenopsylla cheopsis), not necessary if the person is infected by inhalation or ingestion of bacteria.
• The source (reservoir) of Yersinia pestis is mainly rats (black rats more than brown rats), and the forms of the disease include bubonic plague (buboes= enormously enlarged lymph nodes), pneumonic plague, and septicemic plague.
• Yersinia enterocolitica and Y. pseudotuberculosis are causative agents of diarrhea and are similar to that caused by zoopathogenic salmonellas, but less frequent and more commonly connected with enlarged lymph nodes.
• Salmonella needs a high infectious dose, being food- borne disease and grows on Endo, MAL and XDL agar.
• Salmonella Enterica serovar Enteritidis causes intestinal problems and is transmitted through fecal-oral transmission, contaminated food (especially eggs, raw poultry and pork meat), and causes Salmonellosis (diarrhea without blood, fever, vomiting, sepsis possible in patients with weakened immune system, newborns...).
• Salmonella Enteritidis has O antigens: 1, 9, 12 and H antigens: g, m.
• Salmonella Typhi, a serovar of Salmonella, causes septic typhoid/paratyphoid diseases and its portal of entry is the gastrointestinal tract (contaminated water), with an incubation period of 10–14 days and symptoms including high fever, severe headache, and diarrhea is absent.
• Salmonella Typhi has antigens: 9, 12 and H antigens: d capsular antigen: Vi.
• Salmonella endocarditis causes endocarial problems.
• Shigella is transmitted through fecal-oral transmission and causes Shigellosis, also known as Dirty hand disease, with a small infectious dose, easily transmitted by dirty hands, WC handle or contaminated water, symptoms including diarrhea with blood and mucus, fever, abdominal cramps, vomiting.
• Shigella has antigens: b, d, and H antigens: g, m.
• Escherichia coli is a member of the Enterobacteriaceae family and is part of the intestinal microflora.
• ETEC (enterotoxic E coli) is mostly found in travellers.
• STEC (shiga toxigenous E coli; this group also contains EHEC – enterohaemorhagic E coli) can cause hemolytic uremic syndrome, which is characterized by diarrhea, vomiting, fever, anemia, petechiae, renal failure, and neurological symptoms.
• DAEC (Diffusely-Adherent EC) and EaggEC (Enteroaggregative EC) are types of E coli that causes watery traveler’s diarrhea and vomiting.
• Escherichia coli is a beneficial component of intestinal microflora that produces bacteriocins that do not enable other bacteria to colonize the mucous membrane.
• Escherichia coli is a facultative anaerobe.
• EAggEC (enteropathogenic E coli) is a type of E coli that causes traveler’s diarrhea.
• EAEC (Enteroaggregative EC) is a type of E coli that causes traveler’s diarrhea.
• Escherichia coli can have hemolysis on BA.
• EPEC (enteropatogenous E coli) is mostly found in newborns and babies.
• STEC (shiga toxigenous E coli; this group also contains EHEC – enterohaemorhagic E coli) can cause hemolytic uremic syndrome, which is characterized by diarrhea, vomiting, fever, anemia, petechiae, renal failure, and
• EIEC (enteroinvasive E coli) is a type of E coli.
• Some other intestinal bacteria are strict anaerobes.
• Salmonella is not a dirty- hands disease due to the high infescious dose.
• Systemic enterobacteria are Yersinia pestis and Salmonella typhi and paratyphi.
• Intestinal enterobacteria are Salmonella enteritis, Shigella and others Yersinias.
• Opportune enterobacteria are E. coli, Klebsiella, Enterobacter, Serratia, Proteus, Providencia, Morganella, Citrobacter and Hafnia.
• Shigellosis has also the name of bacillar dysentery, completely different from amoeba dysentery.
• Functions of E. coli are protective (avoid colonization), supply vitamins (E and K) and are facultative anaerobes.
• Extraintestinal strains of enterobacteria causes 3 forms: UTI (from UPEC), sepsis and wound infections and respiratory problems.
• Enterobacter, Kleibsella and Pantoea are often capsulated.
• Kleibsella pneuomonia causes nosocomial, pneumonia and sepsis. They are often multiresistant to ESBL, Amp C beta lactamase.
• Proteus, Providencia, Morganella are proteolytic bacteria (in diagnostic typical bad smell of their colonies) which occasionally cause UTI and different other infections.
• CItrobacter is similar to Salmonella but differs due to + ONPG.
• Proteus mirabilis and vulgaris have typical swarming growth and smell. They manifest as Rauss phenom on BA.