Acinetobacter, Pseudomonas, Yersinia, Campylobacter PDF

Acinetobacter Prof. Abdulaziz Zorgani Dip-Bact, MSc, PhD, FIBS, Dip (HAI) Characteristics Nonfermentative Oxidase negative Nitrate negative Catalase positive Indole negative Nonmotile Strictly aerobic Gram negative coccobacillus Sometimes difficult to decolo...

Acinetobacter Prof. Abdulaziz Zorgani Dip-Bact, MSc, PhD, FIBS, Dip (HAI) Characteristics Nonfermentative Oxidase negative Nitrate negative Catalase positive Indole negative Nonmotile Strictly aerobic Gram negative coccobacillus Sometimes difficult to decolorize Frequently arranged in pairs Microbiology Ubiquitous: Widely distributed in nature (soil, water, food, sewage) and the hospital environment Survive on moist and dry surfaces More than 33 species (A. baumannii; A. lwoffii and A. haemolyticus) >2/3 of Acinetobacter infections are due to A. baumannii Strains commonly isolated in clinical laboratories are called the Acinetobacter calcoaceticus-baumannii complex Acinetobacter a major cause of HAI Ability to survive and spread in the hospital + Rapidly acquire resistance determinants + Unmatched speed to cause infection Outbreaks caused by this organism are rapidly becoming unmanageable Factors Promoting Transmission Long survival time on inanimate surfaces (biofilm) Extensive environmental contamination Highly resistant to antibiotics including carbapenems High proportion of colonized patients, particularly in ICUs (accounts for 10% of ICU infections) Frequent contamination of the hands of health care workers Resistant to drying and disinfectants (chlorhexidine gluconate and phenol-based disinfectants) Difficult to eradicate Hospital sources Hands of staff Floor Ventilators Air supply Humidifiers Jugs Oxygen analysers Bowls Respirometers Soap Bronchoscopes Hand cream Lotion dispensers Plastic screens Bed frames Bed linen Rubbish bins Service ducts /dust Sinks – sink taps Bedside charts Patients Colonization Acinetobacter causes colonization more often than infection (e.g health care workers) Acinetobacter commonly colonizes patients in the intensive care setting Acinetobacter colonization is particularly common in patients who are intubated and in those who have multiple intravenous lines or monitoring devices, surgical drains, or indwelling urinary catheters Major infections due to Acinetobacter Ventilator-associated pneumonia Urinary tract Blood Stream Infection Meningitis Skin/wound infections Nosocomial Infection Risk factors Prematurity – advanced age Colonization of Acinetobacter Mechanical ventilation Chronic lung disease Immumosuppresion Malignancy ICU admission Surgery Indwelling catheter Length of hospital stay Wound, burn Broad spectrum antimicrobial therapy  Acientobacter species Sensitive to many antimicrobials Susceptibility controlling factors Resistant promoting factors Antimicrobial stewardship Long antimicrobial exposure Standard precautions Long ICU stay, Long hospitalization Hand hygiene Indwelling lines and catheters Clean environment and prompt disinfection Artificial ventilation and dialysis Continuing education and training Surgical procedures Active and passive surveillance High antibiotic resistance in hospital Care of invasive equipment Sever immunocompromise due to disease therapy Careful liquid handling-saline, water, injection MDR XDR PDR Resistant to at least three MDR Acinetobacter XDR Acinetobacter classes of antibiotics: + + Definitions 1- All Cephalosporines & Resistance to Resistance to inhibitor combination Carbapenems Polymyxines 2- Fluroquolonies 3- aminoglycosides Therapotic Carbapenems Polymyxines ??? polymyxins Tigecyclines Combinations Cefiderocol Resistance mechanisms Acinetobacter has the ability to develop resistance through several diverse mechanisms, which has led to emergence of strains that are resistant to all commercially available antibiotics Antimicrobial inactivating enzymes Efflux pumps: overexpression The primary driver of clinical outcomes is antibiotic OM permeability changes resistance Naturally carries intrinsic blaOXA-51-like Can acquire resistance genes from other organisms WHO Priority List: Final ranking of antibiotic- resistant bacteria Carbapenem-resistant A. baumanii is one of the critical-priority pathogens on the World Health Organization priority list of antibiotic-resistant bacteria for effective drug development 20 bacteria CDC Priority lists - 2019 ESCAPE pathogens A. baumannii is one of the ESCAPE organisms, a group of clinically important, predominantly health care-associated organisms that have the potential for substantial antimicrobial resistance – E: E. faecium (VRE) – S: S. aureus (MRSA) – C: Clostridium difficile (K: KPC: K. pneumonia Carpabenem) – A: A. baumanii – P: P. aeruginosa – E: ESBL + (Enterobacteriaceae) Treatment Empiric Therapy When determining empiric treatment for a given patient, clinicians should consider: (1) Previous organisms identified from the patient and associated antibiotic susceptibility data in the last six months (2) Antibiotic exposures within the past 30 days, and (3) Local susceptibility patterns for the most likely pathogens Empiric decisions FOR CRAB should be refined based on A careful risk-benefit analysis after reviewing previous culture results Clinical presentation Individual host risk factors Antibiotic-specific adverse event profiles Treatment First line agents for susceptible organisms When infections are caused by antibiotic-susceptible Acinetobacter isolates, there may be several therapeutic options, including a broad-spectrum cephalosporin (ceftazidime or cefepime), a combination beta-lactam/beta-lactamase inhibitor (ie, one that includes sulbactam), or a carbapenem (e.g, imipenem or meropenem) The clinical cure rates with imipenem for ventilator-associated pneumonia is high The beta-lactamase inhibitor sulbactam also has excellent bactericidal activity Emergence of resistance during therapy has been observed with ampicillin-sulbactam, cephalosporins, and carbapenems when used as single agents. For this reason, these agents are sometimes used in combination with an antipseudomonal fluoroquinolone or an aminoglycoside Alternative agents for resistant organisms - Polymyxins (colistin) - Tigecycline - Minocycline - Cefiderocol - Eravacycline https://www.idsociety.org/practice-guideline/amr-guidance-2.0/#Carbapenem-ResistantAcinetobacterbaumannii Key prevention strategies Antimicrobial-Resistant Susceptible Acinetobacter Acinetobacter Acinetobacter Prevent Prevent Transmission Infection Infection Antimicrobial Resistance Effective Optimize Diagnosis Use & Treatment Antimicrobial Use Preventing and Control General Precautions Hand hygiene Use alcohol based hand rub Contact precautions Gown/Gloves Regularly disinfect devices and other patient’s related materials Environmental decontamination Monitoring environmental cleaning (Terminal cleaning) Outbreak recognition and control Pseudomonadaceae Pseudomonas aeruginosa Prof. Abdulaziz Zorgani Dip-Bact, MSc, PhD, FIBS, Dip-HAI  NF-GNB Classification The genus Pseudomonas contains more than 200 species, most of which are saprophytic More than 25 species are associated with humans (most are opportunistic infections), include P. aeruginosa, P. fluorescens, P. putida, P. stutzeri and P. maltophilia P. aeruginosa and P. maltophilia account for ~80% of pseudomonads recovered from clinical specimens Account of 10-15% of clinical isolates caused by GNB Characteristics Slender Gram negative Nonfermentive Has a distinctive fruity odor Oxidase positive Motile (polar) Produce slime Found in soil and water (distilled) Optimum growth 37˚C highly Tolerant it can grow in 6-42 ˚C adaptable Minimal nutritional requirements bacterium Metabolically very versatile Quorum sensing allowing cell-cell communication and adaptation to environmental changes Planktonic Biofilm (community) Biofilms (protective shield) have increased antibiotic tolerance and resistance to host defense responses P. aeruginosa (colony types) Identification of P. aeruginosa is usually based on oxidase test and its colonial morphology: - hemolysis, the presence of characteristic pigments and sweet odor, and can growth at 42 ˚C Pyocyanin Pyoverdin Pyorubin pyomelanin Large smooth Small rough Mucoid  P. aeruginosa (Virulence Factors) P. aeruginosa displays a vast repertoire of both cell-associated and extracellular virulence factors that contribute to its pathogenesis Proteases (produced by 90%) (destructive proteins) Alkaline protease: interferes with fibrin formation and will lyse fibrin Elastase: it cleaves collagen, lyses fibronectin to expose receptors for bacterial attachment on the mucosa of the lung and disrupts the respiratory epithelium and interferes with ciliary function. it cleaves IgG, IgA, and complement Protease IV: virulence factor in the eye (cornea) and lung, degrades complement and IgG, it degrades the iron-binding proteins lactoferrin and transferrin Exotoxin A Similar to structure of diphteria toxin, Cause dermatonecrosis in burns, corneal damage, tissue damage in chronic pulmonary infections and immunosuppressive  P. aeruginosa (Virulence Factors) Three other soluble proteins involved in invasion: Cytotoxin Pore-forming protein affect on neutrophils fibrin formation dermatonecrosis Two hemolysins (synergistically break down lipids and lecithin) invasion Phospholipase produced by 70% Lecithinase Pyocyanin (blue pigment) (cystic fibrosis limit diffusion of oxygen) Impairs the normal function of human nasal cilia Disrupts the respiratory epithelium causes epithelial destruction Inhibits phagocytosis Prevents antibiotics from reaching bacteria Exo Y - alteration of endothelial barrier integrity, following lung injury  Type III secreted toxins and end-organ dysfunction  Exo U , Exo S, Exo Y, Exo T Exo T - work synergistically to impede phagocytosis and disrupt epithelial barriers  d) Pyoverdine (PVD) e) Type 4 pili (T4P) siderophore as an facilitate adhesion iron uptake system and twitching motility c) Flagellins FliC and FliD incorporated within the flagellar f) LPS and OMPs structure (sensor, biofilm formation and mucin adhesion) b) The three main g) The type III secretion quorum sensing system (T3SS) and its (QS) systems (it four main effectors, it control many of its enhance disease severity virulence factors h) The type VI secretion a) Biofilm formation ability system (T6SS) (biofim and composition of the formation, acute and chronic extracellular matrix infection, interbacterial (exopolysaccharides, proteins interactions) and extracellular DNA) i) The type II secretion system (T2SS) and the compounds it releases at least 10 proteins to the extracellular milieu: lytic enzymes (lipases, proteases and elastases), exotoxin A, and pyocyanin  P. aeruginosa Infections P. aeruginosa is capable of causing both acute Opportunistic pathogen that can infect almost any body site and chronic infections given the right predisposing conditions Its pathogenic profile stems from the large and variable arsenal of virulence factors and antibiotic resistance determinants harbored in P. aeruginosa’s genome which confer remarkable metabolic flexibility and the ability to adapt to multiple conditions, including the host immune response  Acute and chronic infections serious infections that requires prompt attention and pertinent clinical decisions to achieve a satisfactory outcome  Respiratory tract infections Primary non-bacteremic (mechanical ventilation) - focal lesions Primary bacteremic (neutropenic cancer, chemotherapy) – rapidly progressing, lungs bilateral brochopneumonia (mortality 70%) Chronic (CF, 1/2500) – lungs become scarred, clogged with alginate (mucoid) Infective endocarditis IV drug abuse (contaminated), prosthetic heart valves Bone and joint infections (osteochondritis) Inflammation of bone and cartilage, Difficult to treat Bacteremia (3rd leading cause of GN BSI) Hematologic malignancy, neutropenia, AIDS, Sever burn, DMs  P. aeruginosa infections serious infections that requires prompt attention and pertinent clinical decisions to achieve a satisfactory outcome CNS infections Brain abscesses meningitis Ear infections Swimmer’s ear Malignant otitis externa (DM, elderly) invade underlying tissue, damage crainial nerve, life threatening Chronic otitis media Eye infections (trauma cornea) Contact lens associated (39%) Cornea melts away Keratitis (corneal ulceration) Neonatal ophthalmia  P. aeruginosa infections serious infections that requires prompt attention and pertinent clinical decisions to achieve a satisfactory outcome Skin and soft tissues Burn wounds Trauma wounds High moisture conditions Ear of swimmers Toe webs of athletes and combat troops, in the perineal region Under diapers of infants On the skin of whirlpool and hot tub users  P. aeruginosa infections serious infections that requires prompt attention and pertinent clinical decisions to achieve a satisfactory outcome Skin and soft tissues Green nails Hospital Acquired Infection (HAI) UTI, BSI, VAP Urinary tract infections Usually HAI and related long term catheterization, instrumentation or surgery Summary P. aeruginosa is capable of causing both acute and chronic infections. Its pathogenic profile stems from the large and variable arsenal of virulence factors and antibiotic resistance determinants harbored in genome, which confer remarkable metabolic flexibility and the ability to adapt to multiple conditions, including the host immune response  Mechanisms of antimicrobial resistance Mechanisms of antimicrobial resistance can be divided into intrinsic antibiotic resistance (① outer membrane permeability, ② efflux systems, and ④antibiotic-modifying enzymes or ⑤ antibiotic-inactivating enzymes), acquired antibiotic resistance (⑥ resistance by mutations and acquisition of resistance genes), and adaptive antibiotic resistance (③ biofilm-mediated resistance) ① Alteration of OMP porins decreases the penetration of drugs into cells by reducing membrane permeability ② The efflux system directly pumps out drugs Drug-hydrolyzing and modification enzymes render them ④⑤ inactive. Similarly, some enzymes cause target alterations so that the drug cannot bind its target, resulting in drug P. aeruginosa is one of the MDR ESKAPE inactivity pathogens Antibiotic resistance genes carried on plasmids can be Carbapenem-resistance P. aeruginosa is ⑥ acquired via horizontal gene transfer from the same or listed among the “critical” group of different bacterial species pathogens by WHO QS signaling molecules activate the formation of biofilms, Carbapenem-resistance P. aeruginosa is ③ which act as physical barriers and prevent antibiotics penetrating the cell listed as “serious threat” by CDC Treatment Aggressive antibiotic therapy Extended spectrum β-lactam (carbenicillin but not ceftriaxone, ceforaxime and cefotaxime) + aminoglycoside (tobramycin but not kanamycin) Fluoroquinolone (ciprofloxacin but not moxifloxacin) Polymixin can be used as a last resort, but this is risky Carbapenems but not ertapenem Abscess drainage, debridement Difficult-to-treat (DTR) is defined as P. aeruginosa exhibiting non- susceptibility to all of the following: piperacillin-tazobactam, ceftazidime, cefepime, aztreonam, meropenem, imipenem-cilastatin, ciprofloxacin, and levofloxacin (resistant to 5 main anti-pseudomonals)  PATIENT RISK FACTORS Associated comorbidities Risk factors for P. aeruginosa ◊ Diabetes ◊ Trauma ◊ Receipt of broad-spectrum antimicrobial therapy in ◊ COPD ◊ Elderly the last 90 days (mainly cephalosporines, ◊ Moderate/sever renal/liver disease CRITICALLY ILL ◊ Immunosuppression/neutropenia fluroquinolones or carbapenems) OR AND/OR AND/OR ◊ History of prolonged hospitalization and/or LTCFs ◊ Solid tumor ◊ Invasive devices SEPTIC SHOCK ◊ Structure lung disease ◊ Immunosuppression ◊ Organ transplantation ◊ Current or prior ICU admission ◊ Hemodialysis AT LEAST ONE RISK FACTOR NO RISK FACTORS EMPIRICAL THERAPY Local epidemiology for P. aeruginosa strains BSI and VAP Ceftolozane/tazobactam>ceftazidime/avibactam YES resistant to cephalosporines, OR piperacillin/tazobactam or carbapenem >25% Carbapenem>piperacillin/tazobactam >cefepime>ceftazidime De-escalate to NO PLUS single agent when Aminoglycosides/colistin/fosfomycin EMPIRICAL THERAPY the antimicrobial Complicated UTI or IAI BSI and VAP, skin and soft tissue infections Ceftolozane/tazobactam>ceftazidime/avibactam susceptibility Carbapenem>piperacillin/tazobactam> ±metronidazole testing becoming cefepime>ceftazidime OR available Carbapenem> piperacillin/tazobactam or Complicated UTI cefepime>ceftazidime ± metronidazole Carbapenem>piperacillin/tazobactam> cefepime> PLUS ceftazidime Aminoglycosides/colistin/fosfomycin Aminoglycosides/colistin P. aeruginosa Diagnosis It grows well on most laboratory media It is identified on the basis of its Gram morphology, positive oxidase reaction Pyocin typing  Yersinia ~1000 – 2000 cases each year are reported to the WHO Prof. Abdulaziz Zorgani Dip-Bact, MSc, PhD, FIBS, Dip-HAI Yersinia species Consists of 11 named species, All Yersinia infections are zoonotic, with humans the accidental hosts The best known human pathogens within the genus Yersinia are Y. pestis, Y. enterocolitica, and Y. pseudotuberculosis Yersinia spp. are responsible for disease syndromes ranging from gastroenteritis (fecal-oral route and rarely is deadly) to plague (highly fatal systemic disease) Three pandemics, first known as the Justinian Plague, the second (black death), the third stared in China ❖ Common characteristic is their ability to resist phagocytic killing using type III secretion system  Yesinia pestis (plague)  Gram-negative, short, plump bacillus, capsulated, Giemsa and Wayson stain "safety pin" appearance (bipolar staining), nonmotile, temperature range 4-40 C, facultative intracellular (macrophage) There are TWO forms of Y. pestis infection: urban plague, for which rats are the natural reservoirs, and sylvatic plague, which causes infections in squirrels, rabbits, field rats, and domestic cats Causes plague, which is a disease primarily of rodents; transmitted by fleas Five forms of plague, bubonic, septicemic, pneumonic, meningeal, pharyngeal May cause skin ulceration at its portal of entry, petechia, bruising and gangrene Y. pestis has two plasmids that encode virulence genes: (1) fraction 1 which codes for an antiphagocytic capsule, and (2) plasminogen activator, which degrades complement components C3b and C5a, preventing opsonization and phagocytic migration Y. pestis degrades fibrin clots, permitting to spread rapidly Other virulence factors are serum resistance and V antigen implicated in immunosuppressive activity and the ability to acquire iron from blood via yesiniabactin gene  Y. pestis ❖ Transmitted subcutaneously (bubonic) through a bite of an infected flea or rat, but can also be transmitted by air (especially during pandemics of the disease) ❖ Upon infection with Y. pestis, the mouse innate immune system responds to some extent, but not so strongly as to completely eliminate the bacteria, leading to the prolonged presence of a moderate amount of bacteria (the mouse is a reservoir) ❖ On the other hand, the human innate immune system cannot respond to the bacteria at all, even though TLR4 signaling is not suppressed LPS ❖ LPS-containing hypo-acylated lipid-A species that act as partial agonists to mouse cells, but act as neither agonists nor antagonists to human cells ❖ TTSS secretes effector outer proteins Yop B & D form pores and Yop O,H,M,T,J,E injected into cytoplasm, Yop J inhibit apoptosis of macrophage. Then bacteria continue to multiply in these protective macrophage Y. pestis LPS Lipid A is conserved among a wide variety of GNB, it is easily recognized by host cells for activation of defensive innate immunity, thereby enhancing pathogenicity The PS moiety of LPS primary plays protective roles for Y. pestis such as prevention from complement attacks or camouflage Lipid A, is recognized by the Toll-like receptor 4 (TLR4)/MD-2 complex, which transduces signals for activation of host innate immunity → inflammation Lipid A with six acyl groups (hexa-acylated form) has been indicated to be a strong stimulator of the TLR4/MD-2 complex Modifications of the lipid A structure to less-acylated forms have been observed in some bacterial species Y. pestis LPS, which contains hexa-acylated lipid A when the bacterium grows at 27°C (vector flea), and shifts to contain less-acylated forms when grown at the human body temperature of 37°C This alteration forms following transmission from fleas to humans contributes predominantly to the virulence of this bacterium over other virulence factors  Transmission Urban plague is maintained in rat populations and is spread among rats or between rats and humans by infected fleas. Fleas become infected during a blood meal from a bacteremic rat. After the bacteria replicate in the midgut to form a mass "blockage phenomenon“ “cohesive biofilm”, the organisms can be transferred (regurgitate) to another rodent or to humans. Urgent treatment with antibiotics and isolation. Urban plague has been eliminated from most communities by the effective control of rats and better hygiene. IN CONTRAST  Sylvatic plague is difficult or impossible to eliminate because the mammalian reservoirs (>200 species) and flea vectors are widespread (enzootic cycle)  Infections can also be acquired through the ingestion of contaminated animals or the handling of contaminated animal tissues  Although the organism is highly infectious P- to -P spread is uncommon except in pulmonary involvement DIAGNOSIS: aspirated fluid from lymph nodes, sputum (staining) TREATMENT: streptomycin and/or tetracycline Y. pestis Pathogenicity Bubonic plague (inflammatory swelling of the lymph nodes) is characterized by an IP of no more than 7 days Patients have a high fever and a painful bubo in the groin or axilla Bacteremia develops rapidly if patients are not treated, and as many as 75% die. About 10% of these patients will get pneumonic plague Pneumonic plague The IP 2 to 3 days. Initially, patients experience fever and malaise, and pulmonary signs develop within 1 day. P to P spread occurs by droplets (highly infectious). The mortality rate in untreated patients exceeds 90% within 2-6 days after symptoms The black Septicemic plague symptoms include fever, chills, delirium, hypotension, hypothermia is common, tachycardia, shock and bleeding into the organ or skin, can spread to other organs (spleen, liver, CNS, meninges), may cause intravascular coagulation and endotoxic shock Generalized purpura may be observed and can progress to necrosis and gangrene of the distal extremities Y. enterocolitica Most common form of Yersinia, found worldwide most common in children (yersiniosis) Found in pigs, cats, rodents, rabbit and dogs (natural reservoir) Some infections result from eating contaminated market meat especially pork (major reservoir) and vacuum-packed beef, unpasteurized milk or water. It is able to survive refrigerator temperatures Mainly causes acute gastroenteritis after an IP of 1 to 10 days (average, 4 to 6 days), the patient experiences disease characterized by diarrhea (98%), fever (40%), and abdominal pain (88%) that last as long as 1 to 2 weeks Infection is nearly always self-limited, and no beneficial effect of antibiotics A chronic form of the disease can also develop and persist for months At least 54 different O antigens and 19 H antigens Serotype 3, 8, and 9 account for most human infection  Y. pseudotuberculosis Known for its role as a human enteric and foodborne pathogen, but it also commonly infects wildlife and domestic mammals rodents, particularly guinea pigs, wild animals Clinically closely resembles that of Y. enterocolitica Other manifestations seen in adults are septicemia with mesenteric lymphadenitis, similar to appendicitis, arthritis, intraabdominal abscess, hepatitis, and osteomyelitis SYNDROME SETTING CHARACTERISTICS Enterocolitis Young children Diarrhea Mesenteric adenitis Older children Mimic appendicitis (Occationally) Focal Infection Variable Pharyngitis, abscesses, cellulitis, pneumonia (Extra-intestinal) (Uncommon) Bacteremia (rare) Compromised host High fatality rates Post-infection adults Arthritis (1-2 weeks post diarrhea) Laboratory Diagnosis Yersinia enterocolitis: Most labs use a selective/differential medium such as MacConkey, Hektoen Enteric, XLD, or SS is also used. Isolation from stool is enhanced by "cold enrichment" or selective growth media CIN The presence of leukocytes or red blood cells in stool is variable Diagnosis of plaque can be made from samples of blood (96% positive), urine, sputu, and aspiration of lymph nodes. Y. pestis may be observed on a peripheral blood smear stained with Wright-Giemsa reveals rod-shaped bacteria. A Wayson stain demonstrates the typical "safety pin" appearance (bipolar staining). Gram stain shows small Gram-negative coccobacilli Y. pseudotuberculosis Motile at 18 to 22 C macConkey Peripheral blood smear shows toxic Cefsulodin-Irgasan-Novobiocin granulations and Dohle bodies Campylobacter Prof. Abdulaziz Zorgani Dip-Bact, MSc, PhD, FIBS, Dip-HAI Characteristics Campylobacter enteritis was recognized mid Campylobacter jejuni. Courtesy of Markus Aebi. 1970s when selective isolation media were developed Generally microaerophilic; grow in 3-15% oxygen, campylobacter supplemented with 2-10% Co2; thermophilic (42°C) Gram-negative, small, S-shaped (curved) Catalase, oxidase and hippurate hydrolysis positive, Non-saccharolytic, non-spore forming Remain viable in: Faeces; milk, water, vaginal Prestons agar discharge, poultry litter Differentiation of Campy species related to human disease 32 Campylobacter species and 13 subspecies Each species of Campylobacter has a favoured reservoir  Epidemiology The primary diseases are gastroenteritis (campylobacteriosis) and septicemia, commonly observed in infants and young children (