Microbiology I: Enterobacteriaceae II and Salmonella

Lactose fermenters that are motile and part of the intestinal flora: … (3)

E. cloacae, E. aerogenes, P. agglomerans

Enterobacter and Pantoea aglomerans infections rise from … (2)

endogenous flora, hospital spread from patient to patient

Enterobacter spp from hospital infections causes (notorious for antimicrobial resistance): … (5)

UTI, BSI, pneumonia, burn infections, catheter-related BSI

…: plant pathogen, linked to contaminated intravenous solutions or catheters

P. agglomerans

…: widespread in the environment, not commonly part of the fecal flora, infections are acquired exogenously, causes nosocomial infections particularly among IVDU

Serratia marcescens

Serratia marcescens causes: … (4)

UTIs (mainly), pneumonia, wound infections, bacteremia

Serrata species survives in harsh environmental conditions, include disinfectants + nosocomial outbreaks from …

contaminated disinfectant containers

… (3): use citrate as their carbon source, commonly associated with UTIs associated with urinary catheters

c. freundii, C. koseri, C. amalonaticus

…: has caused nosocomial outbreaks of neonatal meningitis

c. koseri

…: motile, do not ferment glucose, part of the GI tract flora, infect patients with sever underlying illness

Hafnia alvei

… (2): cause complicated UTIs (catheter related, urinary tract anomalies, kidney stones), urease + (hydrolyze urea, nitrated present in urinalysis)

proteus mirabilis, P. vulgaris

… (2): mostly cause nosocomial UTIs

Providencia stuartii, P. rettgeri

Salmonella are gram (…), motile rods, do not ferment lactose → fresh stools preferred for isolation

-

… (2): are the most common causes of salmonella foodborne illness, transmitted through eggs, poultry, undercooked ground meat, dairy, fresh food contaminated with animal products, contaminated water, contact with animals

S. typhimurium, S. enteritidis

NTS live in intestinal of most … → contamination of fruits and vegetables with animal feces

food animals

… is the first barrier against salmonella

gastric acidity

salmonella adhere to … (2) one ingested

intestinal epithelial apical surface, M-cells of peyer’s patches

…: Salmonella promote cytoskeletal rearrangements bacteria engulfed inside cell → transcytoses to basolateral membrane

bacterial mediated endocytosis

After intestinal invasion and intestinal inflammation salmonella cross epithelial barrier, enter … in the submucosal space and payer’s patches

macrophages

Once salmonella is in the macrophages it has access to the bloodstream and lymphatics → may lead to …

dissemination

Most NTS cause … indistinguishable from other enteric bacteria

self-limited gastroenteritis

Symptoms of NTS gastroenteritis: … (4) that last 3-7 days

watery diarrhea, nausea, vomiting, fever, abdominal cramps

If symptoms of gastroenteritis last longer than 10day the diagnosis … NTS

cannot be

Groups where infections with NTS are severe and may be fatal: … (4)

elderly, HIV+, patients with malignancy, anti-TNF therapy

After resolution the mean duration of NTS carriage is … prolonged by antibiotics

4 weeks

Complicated disease caused by NTS: … (2)

bacteraemia, licalized infections

Bacteriaemia → Salmonella have propensity for … including grafts

infection of vascular sites

risk of endovascular infection complicating NTS bacteremia is 9-25% in people older than 50 with …

atherosclerotic plaques or aneurysms

NTS is the leading cause of … among HIV + patients, recurrent case is an AIDs defining illness

community acquired bacteremia 

NTS causing endocarditis (localized infection) is a risk with …

preexisting valve diseases

NTS CNS (localized infection) effects occur mostly in infants causing … (2)

meningitis, brain abscesses

NTS pulmonary (localized infection) is a risk in patients with: … (3)

lung malignancy, structural lung disease, sickle cell disease

NTS bone (localized infection) is a risk in patients with: … (3)

chronic osteomyelitis, sickle cell disease, immunosuppressed

NTS reactive arthritis (localized infection) risk higher if …

HLAB27 (+)

…: persistent excretion of Salmonella in feces or urine for >12m without disease

Chronic carriage

Salmonella enterica typhi and s. paratyphi cause …

enteric fever

Typhoidal salmonella is a … pathogen

human restricted

…: a syndrome of prolonged high-fever without localized symptoms that may or may not be due to salmonella infection

typhoidal fever

Typhoidal salmonella is transmitted via … of fecally contamianted water or food, it persists for weeks in water, contaminated food, dehydrated formula, iced beverages

ingestion

Typhoidal salmonella cause prolonged bacteraemia even in healthy host without … (2)

overwhelming sepsis, pyogenic foci

Pathogenesis of TS: adhere to intestinal epithelial apical surface and M-cells of peyers patched → bacteria engulfed inside cell “bacterial-mediated endocytosis” → transcytoses to basolateral membrane, invade intestinal mucosa → enter macrophages in submucosal space and Payer’s patches → hijack macrophages, multiply inside them using them as stealth vehicle … to the liver, intestinal lymphoid tissue, gallbladder, bone marrow

disseminate via blood

Intestinal lymphoid tissue, prominent site of inflammation and … for TS

bacterial multiplication

the … is the site for chronic carriage of TS

gallbladder

TS is suspected in …

prolonged fever without sepsis or localized signs

Uncomplicated enteric fever from TS presents with: … (6)

constipation, abdominal cramps, myalgia, headache, malaise, anorexia

a typical sign of enteric fever from TS: …

relative bradycardia with pulse-temperature dissociation

…: rash of blanching pink papules on chest back and abdomen (seen in enteric ferver cause by TS)

rose spots

… that cause … are common finding in enteric fever caused by TS

elevated liver enzymes, hepatosplenomegaly

Complicated enteric fever: … (7)

intestinal hemorrhage, intestinal perforation, encephalopathy, meningitis, Guillain-bare syndrome, transverse myelitis, metastatic abscesses (infrequent)

Chronic carriage of s. typhi is asymptomatic shedding of S. typhi for …, in stools or urine

>1yr

…: approved for >6yr oral administration of live attenuated , not administered in immunosuppressed patients s. typhi

vivotif

…: approved for >2yr, intravascular polysaccharide vaccine VI, safe in immunosuppressed patients, booster needed every 2 years S.typhi

Typhim Vi

Enterobacteriaceae are resistant to: … (3)

penicillin’s, ampicillin, monobactams

Enterobacteriaceae are sensitive to: … (3)

cephamycins, carbapenems, B-lactamase inhibitors

CRE are resistant to: … (6)

penicillin’s, ampicillin, cephamycin, monobactams, carbapenaems, B-lactamases inhibtors

CRE are sesnitive to: … (6)

colistin, aminoglycosides, tigecycline, eravacycline, fosfomycin, ceftazidime