Morganella morganii

Background

Gram-negative, facultative anaerobic rod
Member of the tribe Proteeae (along with Proteus and Providencia)
Important cause of nosocomial infections, particularly catheter-associated urinary tract infections
Typically affects immunocompromised, elderly, or nursing home residents

Urinary Tract Infection
- Most common presentation
- Often associated with long-term indwelling urinary catheters
- Urease-producing organism (leads to alkaline urine and Struvite stone/Staghorn calculi formation)
- Purple urine bag syndrome (rare, but classic association)
Skin and Soft Tissue Infection
- Surgical site infections
- Snake bites (Common isolate in oral flora of snakes, infections secondary to cobra/viper bites)
Sepsis/Bacteremia
- High mortality rate with inadequate initial antibiotic coverage due to resistance profile
Meningitis
- Rare, typically nosocomial or secondary to brain abscess/otogenic infection
Chorioamnionitis (Rare)

Urinalysis: Alkaline pH (often > 7.5 due to urease)
CBC: Leukocytosis
Lactate: Elevated in sepsis
Blood cultures: Mandatory if febrile or hypothermic
Imaging:
- CT if concern for struvite stones/obstruction
- CT with IV contrast Soft Tissue if concern for necrotizing fasciitis (snake bite/wound)

Source control
- Remove/replace indwelling urinary catheter
- Debridement of infected wounds/bites
Antibiotic considerations relating to beta-lactamase
- Intrinsic resistance to many beta-lactams
- Avoid first/second generation cephalosporins and ampicillin
- Inducible resistance may occur with 3rd generation cephalosporins (Ceftriaxone)
Preferred agents: Carbapenems, Cefepime, Fluoroquinolones, or Aminoglycosides

Category	Antibiotic	Sensitivity
Penicillins	Penicillin G	R
	Penicillin V	R
Anti-Staphylocccal Penicillins	Methicillin	R
	Nafcillin/Oxacillin	R
Amino-Penicillins	AMP/Amox	R
	Amox-Clav	R
	AMP-Sulb	R
Anti-Pseudomonal Penicillins	Ticarcillin	S
	Pip-Tazo	S
	Piperacillin	S
Carbapenems	Doripenem	S
	Ertapenem	S
	Imipenem	S
	Meropenem	S
	Aztreonam	S
Fluoroquinolones	Ciprofloxacin	S
	Levofloxacin	S
	Moxifloxacin	S
1st G Cephalo	Cefazolin	R
	Cephalexin	R
2nd G. Cephalo	Cefotetan	R
	Cefoxitin	R
	Cefuroxime	R
3rd G. Cephalo	Cefotaxime	X1
	CefTRIAXone	X1
	CefTAZidime	S
	Cefdinir	X1
4th G. Cephalo	Cefepime	S
Aminoglycosides	Gentamicin	S
	Tobramycin	S
	Amikacin	S
	Clindamycin	R
Macrolides	Erythromycin	R
	Azithromycin	R
Tetracyclines	Doxycycline	X1
	Tigecycline	R
Glyco/Lipoglycopeptides	Vancomycin	R
	Daptomycin	R
Urinary Agents	Nitrofurantoin	R
	Fosfomycin	R
Other	Trimethoprim	R
	TMP-SMX	S
	Metronidazole	R
	Linezolid	R
	Colistimethate	R
	Polymyxin B	R

S susceptible/sensitive (usually)
I intermediate (variably susceptible/resistant)
R resistant (or not effective clinically)
S+ synergistic with cell wall antibiotics
U sensitive for UTI only (non systemic infection)
X1 no data
X2 active in vitro, but not used clinically
X3 active in vitro, but not clinically effective for Group A strep pharyngitis or infections due to E. faecalis
X4 active in vitro, but not clinically effective for strep pneumonia
Note: Morganella has intrinsic resistance to Oxacillin, Ampicillin, Amoxicillin, most 1st/2nd Gen Cephalosporins, Macrolides, Lincosamides, Glycopeptides, Nitrofurantoin, and Polymyxins (Colistin).

Authors: